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Sample records for suspected west nile

  1. West Nile Virus

    Science.gov (United States)

    West Nile virus (WNV) is an infectious disease that first appeared in the United States in 1999. Infected mosquitoes ... and usually go away on their own. If West Nile virus enters the brain, however, it can be life- ...

  2. What's West Nile Virus?

    Science.gov (United States)

    ... OK for Kids? Your Teeth Heart Murmurs What's West Nile Virus? KidsHealth > For Kids > What's West Nile Virus? Print A A A en español ¿Qué es ... Virus del Nilo Occidental? What exactly is the West Nile virus? And why is everyone talking about mosquitoes ? Even ...

  3. West Nile Virus

    Science.gov (United States)

    ... of Whether Lower Respiratory Tract Infections Improve with Antibacterial Treatment , February 13, 2018 NIH Scientists Adapt New ... ecological patterns in the United States, and insecticide resistance. Read more about West Nile virus biology, genetics ...

  4. West Nile Virus Neuroinvasive Disease

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2009-07-01

    Full Text Available Epidemiological features of West Nile Virus (WNV disease among children (<18 years of age reported to the Centers for Disease Control and Prevention from 1999 through 2007 were analyzed and compared with those of adult WNV neuroinvasive disease (WNND, in a study at CDC&P, Fort Collins, CO.

  5. West Nile Virus: Prevention and Control

    Science.gov (United States)

    ... R S T U V W X Y Z # West Nile virus Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . West Nile Virus Home Prevention Prevención y control Symptoms, Diagnosis, & Treatment ...

  6. West Nile Virus: Symptoms and Treatment

    Science.gov (United States)

    ... R S T U V W X Y Z # West Nile virus Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . West Nile Virus Home Prevention Prevención y control Symptoms, Diagnosis, & Treatment ...

  7. NNDSS - Table II. West Nile to Zika

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. West Nile to Zika - 2018. In this Table, provisional cases of selected notifiable diseases (≥1,000 cases reported during the preceding year), and...

  8. NNDSS - Table II. West Nile virus disease

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. West Nile virus disease - 2017. In this Table, provisional cases of selected notifiable diseases (≥1,000 cases reported during the preceding...

  9. FAQ: West Nile Virus and Dead Birds

    Science.gov (United States)

    ... Related Links Mosquito Surveillance Software West Nile Virus & Dead Birds Recommend on Facebook Tweet Share Compartir On ... What should I do if I find a dead bird? State and local agencies have different policies ...

  10. West Nile Virus Infection in Sheep.

    Science.gov (United States)

    Rimoldi, G; Mete, A; Adaska, J M; Anderson, M L; Symmes, K P; Diab, S

    2017-01-01

    West Nile virus (WNV) infection has been detected in many species of birds and mammals, but scant information is available about the disease in small ruminants. West Nile virus was diagnosed in 6 sheep with neurological signs and encephalitis, in California between 2002 and 2014. All sheep had severe lymphoplasmacytic meningoencephalitis. Lymphoplasmacytic myelitis was also detected in 2 sheep where the spinal cord was examined. Brain tissue was positive for WNV detected by polymerase chain reaction in 6 of 6 sheep and by immunohistochemistry (IHC) in 5 of 6 sheep. Viral antigen was not detected by IHC in extraneural tissues in the 3 sheep examined. West Nile virus RNA was sequenced from 2 of 6 sheep, and each one clusters closely with WNV isolated from mosquito pools from nearby locations at similar times. West Nile virus was the most common cause of viral encephalitis in sheep diagnosed at this laboratory between 2002 and 2014, accounting for 6 of 9 sheep.

  11. NNDSS - Table II. West Nile virus disease

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. West Nile virus disease - 2015.In this Table, provisional cases of selected notifiable diseases (≥1,000 cases reported during the preceding...

  12. West Nile virus: North American experience

    Science.gov (United States)

    Hofmeister, Erik K.

    2011-01-01

    West Nile virus, a mosquito-vectored flavivirus of the Japanese encephalitis serogroup, was first detected in North America following an epizootic in the New York City area in 1999. In the intervening 11 years since the arrival of the virus in North America, it has crossed the contiguous USA, entered the Canadian provinces bordering the USA, and has been reported in the Caribbean islands, Mexico, Central America and, more recently, South America. West Nile virus has been reported in over 300 species of birds in the USA and has caused the deaths of thousands of birds, local population declines of some avian species, the clinical illness and deaths of thousands of domestic horses, and the clinical disease in over 30 000 Americans and the deaths of over 1000. Prior to the emergence of West Nile virus in North America, St. Louis encephalitis virus and Dengue virus were the only other known mosquito-transmitted flaviviruses in North America capable of causing human disease. This review will discuss the North American experience with mosquito-borne flavivirus prior to the arrival of West Nile virus, the entry and spread of West Nile virus in North America, effects on wild bird populations, genetic changes in the virus, and the current state of West Nile virus transmission.

  13. West Nile Virus Drug Discovery

    Directory of Open Access Journals (Sweden)

    Siew Pheng Lim

    2013-12-01

    Full Text Available The outbreak of West Nile virus (WNV in 1999 in the USA, and its continued spread throughout the Americas, parts of Europe, the Middle East and Africa, underscored the need for WNV antiviral development. Here, we review the current status of WNV drug discovery. A number of approaches have been used to search for inhibitors of WNV, including viral infection-based screening, enzyme-based screening, structure-based virtual screening, structure-based rationale design, and antibody-based therapy. These efforts have yielded inhibitors of viral or cellular factors that are critical for viral replication. For small molecule inhibitors, no promising preclinical candidate has been developed; most of the inhibitors could not even be advanced to the stage of hit-to-lead optimization due to their poor drug-like properties. However, several inhibitors developed for related members of the family Flaviviridae, such as dengue virus and hepatitis C virus, exhibited cross-inhibition of WNV, suggesting the possibility to re-purpose these antivirals for WNV treatment. Most promisingly, therapeutic antibodies have shown excellent efficacy in mouse model; one of such antibodies has been advanced into clinical trial. The knowledge accumulated during the past fifteen years has provided better rationale for the ongoing WNV and other flavivirus antiviral development.

  14. 21 CFR 866.3940 - West Nile virus serological reagents.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false West Nile virus serological reagents. 866.3940... virus serological reagents. (a) Identification. West Nile virus serological reagents are devices that consist of antigens and antisera for the detection of anti-West Nile virus IgM antibodies, in human serum...

  15. West Nile Virus: Review of the Literature

    Science.gov (United States)

    Petersen, Lyle R.; Brault, Aaron C.; Nasci, Roger S.

    2015-01-01

    IMPORTANCE Since its introduction in North America in 1999,West Nile virus has produced the 3 largest arboviral neuroinvasive disease outbreaks ever recorded in the United States. OBJECTIVE To review the ecology, virology, epidemiology, clinical characteristics, diagnosis, prevention, and control of West Nile virus, with an emphasis on North America. EVIDENCE REVIEW PubMed electronic database was searched through February 5, 2013. United States national surveillance data were gathered from the Centers for Disease Control and Prevention. FINDINGS West Nile virus is now endemic throughout the contiguous United States, with 16 196 human neuroinvasive disease cases and 1549 deaths reported since 1999. More than 780 000 illnesses have likely occurred. To date, incidence is highest in the Midwest from mid-July to early September. West Nile fever develops in approximately 25% of those infected, varies greatly in clinical severity, and symptoms may be prolonged. Neuroinvasive disease (meningitis, encephalitis, acute flaccid paralysis) develops in less than 1% but carries a fatality rate of approximately 10%. Encephalitis has a highly variable clinical course but often is associated with considerable long-term morbidity. Approximately two-thirds of those with paralysis remain with significant weakness in affected limbs. Diagnosis usually rests on detection of IgM antibody in serum or cerebrospinal fluid. Treatment is supportive; no licensed human vaccine exists. Prevention uses an integrated pest management approach, which focuses on surveillance, elimination of mosquito breeding sites, and larval and adult mosquito management using pesticides to keep mosquito populations low. During outbreaks or impending outbreaks, emphasis shifts to aggressive adult mosquito control to reduce the abundance of infected, biting mosquitoes. Pesticide exposure and adverse human health events following adult mosquito control operations for West Nile virus appear negligible. CONCLUSIONS AND

  16. NNDSS - Table II. West Nile virus disease

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. West Nile virus disease - 2016. In this Table, provisional* cases of selected†notifiable diseases (≥1,000 cases reported during the preceding...

  17. Vaccines in development against West Nile virus.

    Science.gov (United States)

    Brandler, Samantha; Tangy, Frederic

    2013-09-30

    West Nile encephalitis emerged in 1999 in the United States, then rapidly spread through the North American continent causing severe disease in human and horses. Since then, outbreaks appeared in Europe, and in 2012, the United States experienced a new severe outbreak reporting a total of 5,387 cases of West Nile virus (WNV) disease in humans, including 243 deaths. So far, no human vaccine is available to control new WNV outbreaks and to avoid worldwide spreading. In this review, we discuss the state-of-the-art of West Nile vaccine development and the potential of a novel safe and effective approach based on recombinant live attenuated measles virus (MV) vaccine. MV vaccine is a live attenuated negative-stranded RNA virus proven as one of the safest, most stable and effective human vaccines. We previously described a vector derived from the Schwarz MV vaccine strain that stably expresses antigens from emerging arboviruses, such as dengue, West Nile or chikungunya viruses, and is strongly immunogenic in animal models, even in the presence of MV pre-existing immunity. A single administration of a recombinant MV vaccine expressing the secreted form of WNV envelope glycoprotein elicited protective immunity in mice and non-human primates as early as two weeks after immunization, indicating its potential as a human vaccine.

  18. West Nile virus, Texas, USA, 2012.

    Science.gov (United States)

    Murray, Kristy O; Ruktanonchai, Duke; Hesalroad, Dawn; Fonken, Eric; Nolan, Melissa S

    2013-11-01

    During the 2012 West Nile virus outbreak in Texas, USA, 1,868 cases were reported. Male patients, persons >65 years of age, and minorities were at highest risk for neuroinvasive disease. Fifty-three percent of counties reported a case; 48% of case-patients resided in 4 counties around Dallas/Fort Worth. The economic cost was >$47.6 million.

  19. Why We Need West Nile Virus Testing

    Centers for Disease Control (CDC) Podcasts

    2016-09-27

    Dr. Rodrigo Hasbun, a professor of infectious diseases at McGovern Medical School at UT Health, discusses the need for West Nile virus testing in Texas.  Created: 9/27/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 9/27/2016.

  20. Sultam Thiourea Inhibition of West Nile Virus▿

    Science.gov (United States)

    Barklis, Eric; Still, Amelia; Sabri, Mohammad I.; Hirsch, Alec J.; Nikolich-Zugich, Janko; Brien, James; Dhenub, Tenzin Choesang; Scholz, Isabel; Alfadhli, Ayna

    2007-01-01

    We have identified sultam thioureas as novel inhibitors of West Nile virus (WNV) replication. One such compound inhibited WNV, with a 50% effective concentration of 0.7 μM, and reduced reporter expression from cells that harbored a WNV-based replicon. Our results demonstrate that sultam thioureas can block a postentry, preassembly step of WNV replication. PMID:17452483

  1. Vector competence of the stable fly (Diptera: Muscidae)for West Nile virus.

    Science.gov (United States)

    Stable flies, which are notorious pests of cattle and other livestock, were suspected of transmitting West Nile virus (WNV) among American white pelicans at the Medicine Lake Wildlife Refuge in northeastern Montana in 2006-2007. However the ability of stable flies to transmit the virus was unknown. ...

  2. West Nile virus population genetics and evolution

    Science.gov (United States)

    Pesko, Kendra N.; Ebel, Gregory D.

    2015-01-01

    West Nile virus (WNV) (Flaviviridae: Flavivirus) is transmitted from mosquitoes to birds, but can cause fatal encephalitis in infected humans. Since its introduction into North America in New York in 1999, it has spread throughout the western hemisphere. Multiple outbreaks have also occurred in Europe over the last 20 years. This review highlights recent efforts to understand how host pressures impact viral population genetics, genotypic and phenotypic changes which have occurred in the WNV genome as it adapts to this novel environment, and molecular epidemiology of WNV worldwide. Future research directions are also discussed. PMID:22226703

  3. [Birds, mosquitoes and West Nile virus: little risk of West Nile fever in the Netherlands].

    Science.gov (United States)

    Duijster, Janneke W; Stroo, C J Arjan; Braks, Marieta A H

    2016-01-01

    Due to increased incidence of West Nile fever (WNF) in Europe and the rapid spread of West Nile virus (WNV) in the US, it is commonly thought that it will only be a matter of time before WNV reaches the Netherlands. However, assessing whether WNV is really a threat to the Dutch population is challenging, due to the numerous factors affecting transmission of the virus. Some of these factors are known to limit the risk of WNF in the Netherlands. This risk is determined by the interaction between the pathogen (WNV), the vectors (Culex mosquitoes), the reservoirs (birds) and the exposure of humans to infected mosquitoes. In this paper, we discuss the factors influencing introduction, establishment and spread of WNV in the Netherlands. The probability that each of these three phases will occur in the Netherlands is currently relatively small, as is the risk of WNF infection in humans in the Netherlands.

  4. [West Nile virus. II. Immunopathophysiology in humans].

    Science.gov (United States)

    Lanteri, Marion C; Diamond, Michael S; Norris, Philip J; Busch, Michael P

    2011-04-01

    Since its emergence in 1999 in America, West Nile virus (WNV) has become the leading cause of arboviral encephalitis in the United States. The infection is often asymptomatic but, when clinical manifestations occur, a broad range of symptoms is observed from flu-like symptoms to more serious neurological disorders that can sometimes lead to death. No treatment or vaccine is available for humans. Ongoing studies are trying to understand the host-virus dynamics that lead to the development of severe neurological symptoms in a minority of infected subjects. The amount of knowledge that was gained from parallel studies in animals and humans, comparing asymptomatic and symptomatic individuals, and using what was known of other Flaviviruses, will eventually translate to the development of potential therapeutic and prophylactic solutions. This review presents a synthesis of the most relevant findings concerning the immune response to WNV and its impact on disease outcome and gives an overview of the most promising therapeutic and prophylactic solutions.

  5. NNDSS - Table II. Varicella to West Nile virus disease

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. Varicella to West Nile virus disease - 2014. In this Table, all conditions with a 5-year average annual national total of more than or equals 1,000...

  6. West Nile Virus Ecology in a Tropical Ecosystem in Guatemala

    Science.gov (United States)

    Morales-Betoulle, Maria E.; Komar, Nicholas; Panella, Nicholas A.; Alvarez, Danilo; López, María R.; Betoulle, Jean-Luc; Sosa, Silvia M.; Müller, María L.; Kilpatrick, A. Marm; Lanciotti, Robert S.; Johnson, Barbara W.; Powers, Ann M.; Cordón-Rosales, Celia

    2013-01-01

    West Nile virus ecology has yet to be rigorously investigated in the Caribbean Basin. We identified a transmission focus in Puerto Barrios, Guatemala, and established systematic monitoring of avian abundance and infection, seroconversions in domestic poultry, and viral infections in mosquitoes. West Nile virus transmission was detected annually between May and October from 2005 to 2008. High temperature and low rainfall enhanced the probability of chicken seroconversions, which occurred in both urban and rural sites. West Nile virus was isolated from Culex quinquefasciatus and to a lesser extent, from Culex mollis/Culex inflictus, but not from the most abundant Culex mosquito, Culex nigripalpus. A calculation that combined avian abundance, seroprevalence, and vertebrate reservoir competence suggested that great-tailed grackle (Quiscalus mexicanus) is the major amplifying host in this ecosystem. West Nile virus transmission reached moderate levels in sentinel chickens during 2007, but less than that observed during outbreaks of human disease attributed to West Nile virus in the United States. PMID:23149586

  7. [West Nile virus transmission risk in the Czech Republic].

    Science.gov (United States)

    Vlčková, J; Rupeš, V; Horáková, D; Kollárová, H; Holý, O

    2015-06-01

    West Nile Virus (WNV) belongs to the family Flaviviridae. It is transmitted to humans by mosquitoes, capable of sucking blood on birds and mammals, most often by mosquitoes of the genus Culex. In humans, the virus was first identified in 1937 in the West Nile region, Uganda, Africa. Later, the virus spread and caused more or less severe epidemics of West Nile fever in North Africa, Europe, Asia, and North and South America. During the last two decades, WNV has been on the rise and is currently ranked as one of the most prevalent arboviruses in the world. In humans, WNV infection mostly occurs as asymptomatic, but may have a more severe or even fatal course in older and weakened patients. Humans may become infected not only by mosquitoes that acquire the virus from infected birds, but also through a blood transfusion, organ transplant, breast milk and transplacental transmission, or contact with infected animals, their blood, and tissues. The first autochthonous human case of West Nile fever in the Czech Republic was reported from South Moravia in 1997. In 2013, another case of West Nile fever emerged in this country, in the Ostrava area. The issue of WNV has recently been studied from many different perspectives, as evidenced by many original and review papers. This article briefly reviews the essential knowledge about this virus and its spread.

  8. Neuromuscular Manifestations of West Nile Virus Infection

    Directory of Open Access Journals (Sweden)

    A. Arturo eLeis

    2012-03-01

    Full Text Available The most common neuromuscular manifestation of West Nile virus (WNV infection is a poliomyelitis syndrome with asymmetric paralysis variably involving one (monoparesis to four limbs (quadriparesis, with or without brainstem involvement and respiratory failure. This syndrome of acute flaccid paralysis may occur without overt fever or meningoencephalitis. Although involvement of anterior horn cells in the spinal cord and motor neurons in the brainstem are the major sites of pathology responsible for neuromuscular signs, inflammation also may involve skeletal or cardiac muscle (myositis, myocarditis, motor axons (polyradiculitis, peripheral nerve (Guillain-Barré syndrome, brachial plexopathy. In addition, involvement of spinal sympathetic neurons and ganglia provides a plausible explanation for autonomic instability seen in some patients. Many patients also experience prolonged subjective generalized weakness and disabling fatigue. Despite recent evidence that WNV may persist long term in the central nervous system or periphery in animals, the evidence in humans is controversial. WNV persistence would be of great concern in immunosuppressed patients or in those with prolonged or recurrent symptoms. Support for the contention that WNV can lead to autoimmune disease arises from reports of patients presenting with various neuromuscular diseases that presumably involve autoimmune mechanisms (GBS, other demyelinating neu¬ropathies, myasthenia gravis, brachial plexopathies, stiff-person syndrome, and delayed or recurrent symptoms. Although there is no specific treatment or vaccine currently approved in humans, and the standard remains supportive care, drugs that can alter the cascade of immunobiochemical events leading to neuronal death may be potentially useful (high-dose corticosteroids, interferon preparations, and intravenous immune globulin containing WNV-specific antibodies. Human experience with these agents seems promising based on anecdotal

  9. A Review of Vaccine Approaches for West Nile Virus

    Science.gov (United States)

    Iyer, Arun V.; Kousoulas, Konstantin G.

    2013-01-01

    The West Nile virus (WNC) first appeared in North America in 1999. The North American lineages of WNV were characterized by the presence of neuroinvasive and neurovirulent strains causing disease and death in humans, birds and horses. The 2012 WNV season in the United States saw a massive spike in the number of neuroinvasive cases and deaths similar to what was seen in the 2002–2003 season, according to the West Nile virus disease cases and deaths reported to the CDC by year and clinical presentation, 1999–2012, by ArboNET (Arboviral Diseases Branch, Centers for Disease Control and Prevention). In addition, the establishment and recent spread of lineage II WNV virus strains into Western Europe and the presence of neurovirulent and neuroinvasive strains among them is a cause of major concern. This review discusses the advances in the development of vaccines and biologicals to combat human and veterinary West Nile disease. PMID:24025396

  10. West Nile Virus Surveillance and Diagnostic: A Canadian Perspective

    Directory of Open Access Journals (Sweden)

    Michael A Drebot

    2003-01-01

    Full Text Available A surveillance program has been in place since 2000 to detect the presence of West Nile virus (WNV in Canada. Serological assays are most appropriate when monitoring for human disease and undertaking case investigations. Genomic amplification procedures are more commonly used for testing animal and mosquito specimens collected as part of ongoing surveillance efforts. The incursion of WNV into this country was documented for the first time in 2001 when WNV was demonstrated in 12 Ontario health units during the late summer and fall. In 2002 WNV activity was documented by avian surveillance in Ontario by mid-May with subsequent expansion of the virus throughout Ontario and into Quebec, Manitoba, Saskatchewan and Nova Scotia. Human cases were recorded in both Ontario and Quebec in 2002 with approximately 800 to 1000 probable, confirmed and suspect cases detected. The possible recurrence and further spread of WNV to other parts of Canada in 2003 must be anticipated with potential risk to public health. The continued surveillance and monitoring for WNV-associated human illness is necessary and appropriate disease prevention measures need to be in place in 2003.

  11. The Buzz-z-z on West Nile Virus

    Centers for Disease Control (CDC) Podcasts

    2012-01-12

    In this podcast for kids, the Kidtastics talk about West Nile Virus and how to protect yourself from it.  Created: 1/12/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 1/12/2012.

  12. Clinical sentinel surveillance of equine West Nile fever, Spain

    DEFF Research Database (Denmark)

    Saegerman, C.; Alba-Casals, A.; García-Bocanegra, I.

    2016-01-01

    West Nile fever (WNF) is a viral zoonotic infection caused by a mosquito-borne flavivirus of the Flaviviridae family. According to a comparative study, the passive surveillance of horses by equine veterinarians appeared to be the most cost-effective system in the European context of WNF. Clinical...

  13. Delinquent mortgages, neglected swimming pools, and West Nile virus, California.

    Science.gov (United States)

    Reisen, William K; Takahashi, Richard M; Carroll, Brian D; Quiring, Rob

    2008-11-01

    Adjustable rate mortgages and the downturn in the California housing market caused a 300% increase in notices of delinquency in Bakersfield, Kern County. This led to large numbers of neglected swimming pools, which were associated with a 276% increase in the number of human West Nile virus cases during the summer of 2007.

  14. Modelling West Nile virus transmission risk in Europe

    NARCIS (Netherlands)

    Vogels, Chantal B.F.; Hartemink, Nienke; Koenraadt, Constantianus J.M.

    2017-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can

  15. Seasonal abundance and molecular identification of West Nile virus ...

    African Journals Online (AJOL)

    Federal Medical Centre, Microbiology Unit, Pathology Department. 2. University of Ibadan, Virology. Abstract: Background: West Nile virus (WNV) infection, is an .... density and increased construction of civil infrastruc- tures within the city. Abeokuta is inhabited by the Yoruba speaking tribe in South-Western, Nigeria.

  16. West Nile Virus Fitness Costs in Different Mosquito Species.

    Science.gov (United States)

    Coffey, Lark L; Reisen, William K

    2016-06-01

    West Nile virus (WNV) remains an important public health problem causing annual epidemics in the United States. Grubaugh et al. observed that WNV genetic divergence is dependent on the vector mosquito species. This suggests that specific WNV vector-bird species pairings may generate novel genotypes that could promote outbreaks. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Domestic goose model for West Nile virus vaccine efficiency testing

    Science.gov (United States)

    West Nile virus (WNV) is an emergent pathogen in the Americas, first reported in New York during 1999, and has since spread across the United States (USA), Central and South America causing neurological disease in humans, horses and some bird species, including domestic geese. No WNV vaccines are li...

  18. West Nile Virus: Biology, Transmission, and Human Infection

    Science.gov (United States)

    Colpitts, Tonya M.; Conway, Michael J.; Montgomery, Ruth R.

    2012-01-01

    Summary: West Nile Virus was introduced into the Western Hemisphere during the late summer of 1999 and has been causing significant and sometimes severe human diseases since that time. This article briefly touches upon the biology of the virus and provides a comprehensive review regarding recent discoveries about virus transmission, virus acquisition, and human infection and disease. PMID:23034323

  19. Purpura fulminans associated with acute West Nile virus encephalitis.

    Science.gov (United States)

    Shah, Sheevam; Fite, Laura Paul; Lane, Natalie; Parekh, Palak

    2016-02-01

    Purpura fulminans is a progressive thrombotic disorder that presents with widespread purpura due to deficiency or dysfunction of protein C or protein S. Lesions present as well-demarcated erythematous macules that progress to irregular areas of hemorrhagic necrosis.West Nile virus is a member of the Flaviviridae family transmitted to humans through the bite of various mosquito species. It manifests as West Nile fever in 25% of those infected and less commonly as neuroinvasive disease. An African American man in his fortiespresented with altered mental status and was noted to have evidence of disseminated intravascular coagulation according to his lab data. He then developed dusky skin discoloration and systemic flaccid bullae with desquamation. Biopsy was consistent with purpura fulminans and the patient eventually developed symmetric peripheral gangrene, requiring amputations of all four extremities. Infectious work up revealed positive testing for IgM and IgG antibodies in serum and cerebrospinal fluid leading to the diagnosis of acute West Nile Virus encephalitis. We present this case to describe the rarely reported association of purpura fulminans with West Nile Virus infection. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Vectoren van het West Nile-virus in Nederland

    NARCIS (Netherlands)

    Reusken, C.B.E.M.; Takken, W.

    2006-01-01

    Om de risico¿s voor de volksgezondheid bij introductie van het West Nile-virus (WNV) goed te kunnen inschatten, is het nodig om te weten in welke inheemse muggen WNV zich kan handhaven. In dit bericht wordt een overzicht gegeven van WNV-vectoren en potentiële risico¿s voor Nederland

  1. Increase in West Nile Neuroinvasive Disease after Hurricane Katrina

    OpenAIRE

    Caillou?t, Kevin A.; Michaels, Sarah R.; XIONG, XU; Foppa, Ivo; Wesson, Dawn M.

    2008-01-01

    After Hurricane Katrina, the number of reported cases of West Nile neuroinvasive disease (WNND) sharply increased in the hurricane-affected regions of Louisiana and Mississippi. In 2006, a >2-fold increase in WNND incidence was observed in the hurricane-affected areas than in previous years.

  2. Subacute brachial diplegia associated with West Nile virus myelitis.

    Science.gov (United States)

    Zafar, Sahar F; Ubogu, Eroboghene E

    2012-06-01

    Brachial diplegia is a clinical term used to describe weakness restricted to the upper extremities. We report a case of brachial diplegia associated with West Nile virus infection. A 48-year-old man developed severe painless bilateral upper extremity weakness within a few weeks of a flu-like illness. Clinical examination revealed marked periscapular, shoulder girdle, and humeral muscle atrophy and bilateral scapular winging, with near symmetrical bilateral hypotonic upper extremity weakness. This was associated with clinical signs of an encephalomyelopathy without cognitive or sensory deficits. Electrophysiological studies demonstrated a subacute disorder of motor neurons, their axons or both, involving the cervical and thoracic myotomes, with ongoing denervation. Serological studies confirmed recent West Nile virus (WNV) infection. Gradual improvement occurred following conservative supportive therapies. Progressive brachial diplegia is a rare neuromuscular presentation of WNV neuroinvasive disease. This case report adds to the clinical spectrum of WNV-induced neurologic sequelae. Copyright © 2012 Wiley Periodicals, Inc.

  3. Clinical Manifestations and Outcomes of West Nile Virus Infection

    Science.gov (United States)

    Sejvar, James J.

    2014-01-01

    Since the emergence of West Nile virus (WNV) in North America in 1999, understanding of the clinical features, spectrum of illness and eventual functional outcomes of human illness has increased tremendously. Most human infections with WNV remain clinically silent. Among those persons developing symptomatic illness, most develop a self-limited febrile illness. More severe illness with WNV (West Nile neuroinvasive disease, WNND) is manifested as meningitis, encephalitis or an acute anterior (polio) myelitis. These manifestations are generally more prevalent in older persons or those with immunosuppression. In the future, a more thorough understanding of the long-term physical, cognitive and functional outcomes of persons recovering from WNV illness will be important in understanding the overall illness burden. PMID:24509812

  4. Recent progress in West Nile virus diagnosis and vaccination

    Science.gov (United States)

    2012-01-01

    West Nile virus (WNV) is a positive-stranded RNA virus belonging to the Flaviviridae family, a large family with 3 main genera (flavivirus, hepacivirus and pestivirus). Among these viruses, there are several globally relevant human pathogens including the mosquito-borne dengue virus (DENV), yellow fever virus (YFV), Japanese encephalitis virus (JEV) and West Nile virus (WNV), as well as tick-borne viruses such as tick-borne encephalitis virus (TBEV). Since the mid-1990s, outbreaks of WN fever and encephalitis have occurred throughout the world and WNV is now endemic in Africa, Asia, Australia, the Middle East, Europe and the Unites States. This review describes the molecular virology, epidemiology, pathogenesis, and highlights recent progress regarding diagnosis and vaccination against WNV infections. PMID:22380523

  5. Clinical Manifestations and Outcomes of West Nile Virus Infection

    Directory of Open Access Journals (Sweden)

    James J. Sejvar

    2014-02-01

    Full Text Available Since the emergence of West Nile virus (WNV in North America in 1999, understanding of the clinical features, spectrum of illness and eventual functional outcomes of human illness has increased tremendously. Most human infections with WNV remain clinically silent. Among those persons developing symptomatic illness, most develop a self-limited febrile illness. More severe illness with WNV (West Nile neuroinvasive disease, WNND is manifested as meningitis, encephalitis or an acute anterior (polio myelitis. These manifestations are generally more prevalent in older persons or those with immunosuppression. In the future, a more thorough understanding of the long-term physical, cognitive and functional outcomes of persons recovering from WNV illness will be important in understanding the overall illness burden.

  6. West Nile disease in Tunisia: an overview of 60 years.

    Science.gov (United States)

    Hammami, Salah; Hassine, Thameur Ben; Conte, Annamaria; Amdouni, Jihène; De Massis, Fabrizio; Sghaier, Soufiène; Hassen, Sonia Ben

    2017-09-30

    West Nile virus (WNV) is an arthropod borne virus of public health importance. The virus is a member of the genus Flavivirus and belongs to the Japanese encephalitis virus (JEV) antigenic complex under the Flaviviridae family. The WNV is continuously spreading across Tunisia especially in the coastal and Southern area of the country. The first human West Nile disease (WND) epidemic in Tunisia occurred in 1997, since then, the quantity and the extension of spillover effects increased constantly. However, the existing knowledge of factors triggering such events continues to be rather poor. The last epidemic WNV human meningitis and meningoencephalitis recorded in 2012, with 86 cases and 6 deaths, confirmed the failure of the current system in predicting new cases. This review, based on analysis of scientific papers published between 1970 and 2015, summarises the state of knowledge on WNV in Tunisia and highlights the existing knowledge and research gaps that need to be addressed.

  7. West Nile virus infection and diplopia: a case report and review of literature

    Directory of Open Access Journals (Sweden)

    Dahal U

    2013-05-01

    Full Text Available Udip Dahal,1 Neville Mobarakai,1 Dikshya Sharma,2 Bandana Pathak11Department of Medicine, Staten Island University Hospital, Staten Island, New York, NY, USA; 2Department of Medicine, Nepalgunj Medical College, Banke, NepalAbstract: West Nile virus is a neurotropic virus transmitted to humans via an infected mosquito bite. The increase in the incidences and fatalities of West Nile virus disease has made West Nile virus an important pathogen. Here we describe a case of a 65-year-old man with fever and diplopia presenting to the emergency department during a fall season and who was later diagnosed with West Nile virus infection. Diplopia is an uncommon manifestation of West Nile virus and recognition of the different modes of presentation, especially the uncommon ones like diplopia, will aid in the diagnosis of this emerging infectious disease.Keywords: West Nile virus, diplopia, ocular manifestations, infectious disease, Flaviviridae

  8. Ecology of West Nile Virus in North America

    Science.gov (United States)

    Reisen, William K.

    2013-01-01

    The introduction, dispersal and establishment of West Nile virus in North America were reviewed, focusing on factors that may have enhanced receptivity and enabled the invasion process. The overwintering persistence of this tropical virus within temperate latitudes was unexpected, but was key in the transition from invasion to endemic establishment. The cascade of temporal events allowing sporadic amplification to outbreak levels was discussed within a future perspective. PMID:24008376

  9. Prevalence and Incidence of West nile virus in Germany

    OpenAIRE

    Linke, Sonja

    2010-01-01

    West Nile virus (WNV) belongs to the flaviviruses and is transmitted from mosquitoes to vertebrates. Birds represent the natural reservoir. The virus incidentally infects vertebrates like men or other animals. In 1999 the pathogen was imported to the US for the first time and was dispersed over the continent by migrating birds. WNV infections were also observed in Europe since the middle of the last century but the epidemics were time-limited to regions of Southern and Eastern Europe. There w...

  10. West Nile Virus: What You Need to Know Now - August 2012

    Centers for Disease Control (CDC) Podcasts

    2012-08-21

    This podcast lists the states where most of the 2012 West Nile viruses have been reported and explains how people can protect themselves from West Nile virus.  Created: 8/21/2012 by .   Date Released: 8/21/2012.

  11. 78 FR 16505 - Prospective Grant of Exclusive License: Chimeric West Nile/Dengue Viruses

    Science.gov (United States)

    2013-03-15

    ...: Chimeric West Nile/Dengue Viruses AGENCY: Centers for Disease Control and Prevention (CDC), Department of... license, in the field of use of in vitro diagnostics for dengue virus infection, to practice the... Application 61/049,342, filed 4/30/2008, entitled ``Engineered, Chimeric West Nile/Dengue Viruses;'' PCT...

  12. The challenge of west nile virus in Europe: Knowledge gaps and research priorities

    NARCIS (Netherlands)

    A. Rizzoli; M.A. Jiménez-Clavero; L. Barzon; P. Cordioli (Paolo); J. Figuerola; P. Koraka (Penelope); B.E.E. Martina (Byron); A. Moreno; N. Nowotny; N. Pardigon; N. Sanders; S. Ulbert; A. Tenorio

    2015-01-01

    textabstractWest Nile virus (WNV) is continuously spreading across Europe, and other continents, i.e. North and South America and many other regions of the world. Despite the overall sporadic nature of outbreaks with cases of West Nile neuroinvasive disease (WNND) in Europe, the spillover events

  13. West Nile virus meningitis in a patient with human immunodeficiency virus type 1 infection

    Directory of Open Access Journals (Sweden)

    D. Pilalas

    2017-09-01

    Full Text Available The emergence of West Nile virus lineage 2 in central Macedonia, Greece, in 2010 resulted in large outbreaks for 5 consecutive years. We report a case of viral meningitis in an individual infected with human immunodeficiency virus type 1, which preceded the recognition of the outbreak and was confirmed retrospectively as West Nile virus neuroinvasive disease.

  14. Absence of Serological Evidence of West Nile Virus in Blood Donors ...

    African Journals Online (AJOL)

    Background: West Nile virus (WNV) is a mosquito-borne virus that circulates among avians, but can also affect other species, particularly humans and horses. The virus is transmissible via blood transfusion. Objectives: To determine the prevalence of the West Nile virus among blood donors in Nigeria. Materials and ...

  15. Chronic West Nile virus infection in kea (Nestor notabilis).

    Science.gov (United States)

    Bakonyi, Tamás; Gajdon, Gyula K; Schwing, Raoul; Vogl, Wolfgang; Häbich, Annett-Carolin; Thaller, Denise; Weissenböck, Herbert; Rudolf, Ivo; Hubálek, Zdenek; Nowotny, Norbert

    2016-02-01

    Six kea (Nestor notabilis) in human care, naturally infected with West Nile virus (WNV) lineage 2 in Vienna, Austria, in 2008, developed mild to fatal neurological signs. WNV RNA persisted and the virus evolved in the birds' brains, as demonstrated by (phylo)genetic analyses of the complete viral genomes detected in kea euthanized between 2009 and 2014. WNV antibodies persisted in the birds, too. Chronic WNV infection in the brain might contribute to the circulation of the virus through oral transmission to predatory birds. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. The Complex Epidemiological Scenario of West Nile Virusin Italy

    Science.gov (United States)

    Barzon, Luisa; Pacenti, Monia; Franchin, Elisa; Squarzon, Laura; Lavezzo, Enrico; Cattai, Margherita; Cusinato, Riccardo; Palù, Giorgio

    2013-01-01

    Entomological, veterinary, and human surveillance systems for West Nile virus (WNV) infection have been implemented in Italy since the first detection of the virus in 1998. These surveillance activities documented a progressive increase of WNV activity and spread in different regions and the emergence of new WNV lineages and strains. Italy is a paradigmatic example of the complex epidemiology of WNV in Europe, where sporadic cases of WNV infection, clusters, and small outbreaks have been reported in several regions. In addition, different strains of both WNV lineage 1 and lineage 2 have been identified, even co-circulating in the same area. PMID:24084676

  17. Experimental Infection of Cats and Dogs with West Nile Virus

    OpenAIRE

    Austgen, Laura E.; Bowen, Richard A.; Bunning, Michel L.; Davis, Brent S.; Mitchell, Carl J.; Chang, Gwong-Jen J.

    2004-01-01

    Domestic dogs and cats were infected by mosquito bite and evaluated as hosts for West Nile virus (WNV). Viremia of low magnitude and short duration developed in four dogs but they did not display signs of disease. Four cats became viremic, with peak titers ranging from 103.0 to 104.0 PFU/mL. Three of the cats showed mild, non-neurologic signs of disease. WNV was not isolated from saliva of either dogs or cats during the period of viremia. An additional group of four cats were exposed to WNV o...

  18. The first human case of neuroinvasive West Nile virus infection identified in Cyprus.

    Science.gov (United States)

    Paphitou, Niki I; Tourvas, Aristomenis; Floridou, Dora; Richter, Jan; Tryfonos, Christina; Christodoulou, Christina

    West Nile virus infection can pose a diagnostic challenge to clinicians, especially in geographic areas where human cases of this disease have never been encountered before. In August 2016, the first human case of West Nile virus infection was diagnosed in Cyprus. An elderly non immunosuppressed patient with a history of recent travel, presented with a clinical picture of rapidly progressing ascending paralysis mimicking Guillain-Barré syndrome. Neuroinvasive West Nile virus disease was diagnosed by detecting West Nile virus nucleic acid in the patient's cerebrospinal fluid. Public health measures were taken raising awareness regarding this disease and its prevention. Clinical vigilance to consider West Nile virus as a possible emerging pathogen in the appropriate clinical setting is warranted and could benefit individual patients. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Ocular Lesions in Red-Tailed Hawks ( Buteo jamaicensis) With Naturally Acquired West Nile Disease.

    Science.gov (United States)

    Wünschmann, A; Armién, A G; Khatri, M; Martinez, L C; Willette, M; Glaser, A; Alvarez, J; Redig, P

    2017-03-01

    Ocular lesions are common in red-tailed hawks with West Nile (WN) disease. These lesions consist of pectenitis, choroidal or retinal inflammation, or retinal necrosis, but detailed investigation of the ocular lesions is lacking. Postmortem examination of the eyes of 16 red-tailed hawks with naturally acquired WN disease and 3 red-tailed hawks without WN disease was performed using histopathology, immunohistochemistry for West Nile virus (WNV) antigen, glial fibrillary acid protein, cleaved caspase-3, and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling method. Retinal lesions were classified as type I or type II lesions. Type I lesions were characterized by lymphoplasmacytic infiltrates in the subjacent choroid with degeneration limited to the outer retina (type Ia lesion) or with degeneration and necrosis of the outer retina or outer and inner retina (type Ib lesion) while retinal collapse, atrophy, and scarring were hallmarks of type II lesions. Type II retinal lesions were associated with a more pronounced choroiditis. Although not statistically significant, WNV antigen tended to be present in larger quantity in type Ib lesions. Type I lesions are considered acute while type II lesions are chronic. The development of retinal lesions was associated with the presence of an inflammatory infiltrate in the choroid. A breakdown of the blood-retina barrier is suspected to be the main route of infection of the retina. Within the retina, virus appeared to spread via both neuronal and Müller cell processes.

  20. Experimental infection of raccoons (Procyon lotor) with West Nile virus.

    Science.gov (United States)

    Root, J Jeffrey; Bentler, Kevin T; Nemeth, Nicole M; Gidlewski, Thomas; Spraker, Terry R; Franklin, Alan B

    2010-10-01

    To characterize the responses of raccoons to West Nile virus (WNV) infection, we subcutaneously exposed them to WNV. Moderately high viremia titers (≤ 10(4.6) plaque forming units [PFU]/mL of serum) were noted in select individuals; however, peak viremia titers were variable and viremia was detectable in some individuals as late as 10 days post-inoculation (DPI). In addition, fecal shedding was prolonged in some animals (e.g., between 6 and 13 DPI in one individual), with up to 10(5.0) PFU/fecal swab detected. West Nile virus was not detected in tissues collected on 10 or 16 DPI, and no histologic lesions attributable to WNV infection were observed. Overall, viremia profiles suggest that raccoons are unlikely to be important WNV amplifying hosts. However, this species may occasionally shed significant quantities of virus in feces. Considering their behavioral ecology, including repeated use of same-site latrines, high levels of fecal shedding could potentially lead to interspecies fecal-oral WNV transmission.

  1. West Nile Virus workshop: scientific considerations for tissue donors.

    Science.gov (United States)

    Brubaker, Scott A; Robert Rigney, P

    2012-08-01

    This report contains selected excerpts, presented as a summary, from a public workshop sponsored by the American Association of Tissue Banks (AATB) held to discuss West Nile Virus (WNV) and scientific considerations for tissue donors. The daylong workshop was held 9 July 2010 at the Ritz-Carlton Hotel at Tyson's Corner in McLean, Virginia, United States (U.S.). The workshop was designed to determine and discuss scientific information that is known, and what is not known, regarding WNV infection and transmission. The goal is to determine how to fill gaps in knowledge of WNV and tissue donation and transplantation by pursuing relevant scientific studies. This information should ultimately support decisions leading to appropriate tissue donor screening and testing considerations. Discussion topics were related to identifying these gaps and determining possible solutions. Workshop participants included subject-matter experts from the U.S. Food and Drug Administration, the Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Health Canada, the Public Health Agency of Canada, AATB-accredited tissue banks including reproductive tissue banks, accredited eye banks of the Eye Bank Association of America, testing laboratories, and infectious disease and organ transplantation professionals. After all presentations concluded, a panel addressed this question: "What are the scientific considerations for tissue donors and what research could be performed to address those considerations?" The slide presentations from the workshop are available at: http://www.aatb.org/2010-West-Nile-Virus-Workshop-Presentations.

  2. Risk mapping of West Nile virus circulation in Spain, 2015.

    Science.gov (United States)

    Sánchez-Gómez, Amaya; Amela, Carmen; Fernández-Carrión, Eduardo; Martínez-Avilés, Marta; Sánchez-Vizcaíno, José Manuel; Sierra-Moros, María José

    2017-05-01

    West Nile fever is an emergent disease in Europe. The objective of this study was to conduct a predictive risk mapping of West Nile Virus (WNV) circulation in Spain based on historical data of WNV circulation. Areas of Spain with evidence of WNV circulation were mapped based on data from notifications to the surveillance systems and a literature review. A logistic regression-based spatial model was used to assess the probability of WNV circulation. Data were analyzed at municipality level. Mean temperatures of the period from June to October, presence of wetlands and presence of Special Protection Areas for birds were considered as potential predictors. Two predictors of WNV circulation were identified: higher temperature [adjusted odds ratio (AOR) 2.07, 95% CI 1.82-2.35, pSpain. The importance of a comprehensive surveillance for WNF, including human, animal and potential vectors is highlighted, which could additionally result in model refinements. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Indigenous West Nile virus infections in horses in Albania.

    Science.gov (United States)

    Berxholi, K; Ziegler, U; Rexhepi, A; Schmidt, K; Mertens, M; Korro, K; Cuko, A; Angenvoort, J; Groschup, M H

    2013-11-01

    Serum samples collected from 167 equines of 12 districts in Albania were tested for West Nile virus-specific antibodies by enzyme-linked immunosorbent assay and virus neutralization assay, using WNV lineage 1 and 2. In addition, 95 bird serum samples from Albania and 29 horse samples from Kosovo were tested in ELISA. An overall seroprevalence rate of 22% was found in horses from Albania, whereas no specific antibodies were found in the equine samples from Kosovo and the bird samples. This is the first report indicating WNV infections in animals in Albania, and the first reported seroprevalence study conducted for Kosovo. These results provide evidence for widespread infections of WNV in Albania. © 2013 Blackwell Verlag GmbH.

  4. Globalization, land use and the invasion of West Nile virus

    Science.gov (United States)

    Kilpatrick, A. Marm

    2012-01-01

    Many invasive species that have been spread through the globalization of trade and travel are infectious pathogens. A paradigmatic case is the introduction of West Nile virus (WNV) into North America in 1999. A decade of research on the ecology and evolution of WNV includes three findings that provide insight into the outcome of future viral introductions. First, WNV transmission in North America is highest in urbanized and agricultural habitats, in part because the hosts and vectors of WNV are abundant in human-modified areas. Second, after its introduction, the virus quickly adapted to infect local mosquito vectors more efficiently than the originally introduced strain. Third, highly focused feeding patterns of the mosquito vectors of WNV result in unexpected host species being important for transmission. These findings provide a framework for predicting and preventing the emergence of foreign vector-borne pathogens. PMID:22021850

  5. Experimental Infections of Wild Birds with West Nile Virus

    Directory of Open Access Journals (Sweden)

    Elisa Pérez-Ramírez

    2014-02-01

    Full Text Available Avian models of West Nile virus (WNV disease have become pivotal in the study of infection pathogenesis and transmission, despite the intrinsic constraints that represents this type of experimental research that needs to be conducted in biosecurity level 3 (BSL3 facilities. This review summarizes the main achievements of WNV experimental research carried out in wild birds, highlighting advantages and limitations of this model. Viral and host factors that determine the infection outcome are analyzed in detail, as well as recent discoveries about avian immunity, viral transmission, and persistence achieved through experimental research. Studies of laboratory infections in the natural host will help to understand variations in susceptibility and reservoir competence among bird species, as well as in the epidemiological patterns found in different affected areas.

  6. Experimental Infections of Wild Birds with West Nile Virus

    Science.gov (United States)

    Pérez-Ramírez, Elisa; Llorente, Francisco; Jiménez-Clavero, Miguel Ángel

    2014-01-01

    Avian models of West Nile virus (WNV) disease have become pivotal in the study of infection pathogenesis and transmission, despite the intrinsic constraints that represents this type of experimental research that needs to be conducted in biosecurity level 3 (BSL3) facilities. This review summarizes the main achievements of WNV experimental research carried out in wild birds, highlighting advantages and limitations of this model. Viral and host factors that determine the infection outcome are analyzed in detail, as well as recent discoveries about avian immunity, viral transmission, and persistence achieved through experimental research. Studies of laboratory infections in the natural host will help to understand variations in susceptibility and reservoir competence among bird species, as well as in the epidemiological patterns found in different affected areas. PMID:24531334

  7. Current Trends in West Nile Virus Vaccine Development

    Science.gov (United States)

    Amanna, Ian J.; Slifka, Mark K.

    2014-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus that has become endemic in the United States. From 1999-2012, there have been 37,088 reported cases of WNV and 1,549 deaths, resulting in a 4.2% case-fatality rate. Despite development of effective WNV vaccines for horses, there is no vaccine to prevent human WNV infection. Several vaccines have been tested in preclinical studies and to date there have been 8 clinical trials, with promising results in terms of safety and induction of antiviral immunity. Although mass vaccination is unlikely to be cost-effective, implementation of a targeted vaccine program may be feasible if a safe and effective vaccine can be brought to market. Further evaluation of new and advanced vaccine candidates is strongly encouraged. PMID:24689659

  8. West Nile virus infection in horses, Indian ocean.

    Science.gov (United States)

    Cardinale, E; Bernard, C; Lecollinet, S; Rakotoharinome, V M; Ravaomanana, J; Roger, M; Olive, M M; Meenowa, D; Jaumally, M R; Melanie, J; Héraud, J M; Zientara, S; Cêtre-Sossah, C

    2017-08-01

    The circulation of West Nile virus (WNV) in horses was investigated in the Southwest Indian ocean. In 2010, blood samples were collected from a total of 303 horses originating from Madagascar, Mauritius, Reunion and the Seychelles and tested for WNV-specific antibodies. An overall seroprevalence of 27.39% was detected in the Indian Ocean with the highest WNV antibody prevalence of 46.22% (95% CI: [37.4-55.2%]) in Madagascar. The age and origin of the horses were found to be associated with the WNV infection risk. This paper presents the first seroprevalence study investigating WN fever in horses in the Southwest Indian Ocean area and indicates a potential risk of infection for humans and animals. In order to gain a better understanding of WN transmission cycles, WNV surveillance needs to be implemented in each of the countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A Mouse Model of Chronic West Nile Virus Disease.

    Directory of Open Access Journals (Sweden)

    Jessica B Graham

    2016-11-01

    Full Text Available Infection with West Nile virus (WNV leads to a range of disease outcomes, including chronic infection, though lack of a robust mouse model of chronic WNV infection has precluded identification of the immune events contributing to persistent infection. Using the Collaborative Cross, a population of recombinant inbred mouse strains with high levels of standing genetic variation, we have identified a mouse model of persistent WNV disease, with persistence of viral loads within the brain. Compared to lines exhibiting no disease or marked disease, the F1 cross CC(032x013F1 displays a strong immunoregulatory signature upon infection that correlates with restraint of the WNV-directed cytolytic response. We hypothesize that this regulatory T cell response sufficiently restrains the immune response such that a chronic infection can be maintained in the CNS. Use of this new mouse model of chronic neuroinvasive virus will be critical in developing improved strategies to prevent prolonged disease in humans.

  10. The Global Ecology and Epidemiology of West Nile Virus

    Science.gov (United States)

    Rios, Maria

    2015-01-01

    Since its initial isolation in Uganda in 1937 through the present, West Nile virus (WNV) has become an important cause of human and animal disease worldwide. WNV, an enveloped virus of the genus Flavivirus, is naturally maintained in an enzootic cycle between birds and mosquitoes, with occasional epizootic spillover causing disease in humans and horses. The mosquito vectors for WNV are widely distributed worldwide, and the known geographic range of WNV transmission and disease has continued to increase over the past 77 years. While most human infections with WNV are asymptomatic, severe neurological disease may develop resulting in long-term sequelae or death. Surveillance and preventive measures are an ongoing need to reduce the public health impact of WNV in areas with the potential for transmission. PMID:25866777

  11. Innate immune control of West Nile virus infection.

    Science.gov (United States)

    Arjona, Alvaro; Wang, Penghua; Montgomery, Ruth R; Fikrig, Erol

    2011-11-01

    West Nile virus (WNV), from the Flaviviridae family, is a re-emerging zoonotic pathogen of medical importance. In humans, WNV infection may cause life-threatening meningoencephalitis or long-term neurologic sequelae. WNV is transmitted by Culex spp. mosquitoes and both the arthropod vector and the mammalian host are equipped with antiviral innate immune mechanisms sharing a common phylogeny. As far as the current evidence is able to demonstrate, mosquitoes primarily rely on RNA interference, Toll, Imd and JAK-STAT signalling pathways for limiting viral infection, while mammals are provided with these and other more complex antiviral mechanisms involving antiviral effectors, inflammatory mediators, and cellular responses triggered by highly specialized pathogen detection mechanisms that often resemble their invertebrate ancestry. This mini-review summarizes our current understanding of how the innate immune systems of the vector and the mammalian host react to WNV infection and shape its pathogenesis. © 2011 Blackwell Publishing Ltd.

  12. The Global Ecology and Epidemiology of West Nile Virus

    Directory of Open Access Journals (Sweden)

    Caren Chancey

    2015-01-01

    Full Text Available Since its initial isolation in Uganda in 1937 through the present, West Nile virus (WNV has become an important cause of human and animal disease worldwide. WNV, an enveloped virus of the genus Flavivirus, is naturally maintained in an enzootic cycle between birds and mosquitoes, with occasional epizootic spillover causing disease in humans and horses. The mosquito vectors for WNV are widely distributed worldwide, and the known geographic range of WNV transmission and disease has continued to increase over the past 77 years. While most human infections with WNV are asymptomatic, severe neurological disease may develop resulting in long-term sequelae or death. Surveillance and preventive measures are an ongoing need to reduce the public health impact of WNV in areas with the potential for transmission.

  13. Dead Crow Density and West Nile Virus Monitoring, New York

    Science.gov (United States)

    Schmit, Kate; Hagiwara, Yoichiro; Anand, Madhu; Backenson, P. Bryon; Gotham, Ivan; Kramer, Laura

    2005-01-01

    New York State used the health commerce system to monitor the number of West Nile virus (WNV) human disease cases and the density of dead crows. In each year from 2001 to 2003 and for the 3 years combined, persons living in New York counties (excluding New York City) with elevated weekly dead crow densities (above a threshold value of 0.1 dead crows per square mile) had higher risk (2.0–8.6 times) for disease caused by WNV within the next 2 weeks than residents of counties reporting fewer dead crows per square mile. This type of index can offer a real-time, relatively inexpensive window into viral activity in time for prevention and control. Changes in reporting, bird populations, and immunity may require that thresholds other than 0.1 be used in later years or in other areas. PMID:16229764

  14. Diversification of West Nile virus in a subtropical region

    Directory of Open Access Journals (Sweden)

    Mores Christopher N

    2009-07-01

    Full Text Available Abstract Background West Nile virus (WNV has spread across North, Central, and South America since its introduction in 1999. At the start of this spread, Florida was considered a potentially important area with regards to transmission due to its geographic, climatological, and demographic conditions. Curiously, the anticipated high levels of transmission or disease outbreaks have not been observed. As other studies have predicted that the lack of intense WNV transmission is not due to vector incompetence, we sought to evaluate the role of viral strain diversity in WNV transmission in Florida. Therefore, a phylogentic analysis was carried out on several isolates collected from three distinct locations in Florida. Results Contrasting with a positive control collected in Indian River County, Florida during 2003 that contains the original NY99 genotype with valanine at amino acid 159 of the envelope region, all of the isolates collected in 2005 contain the WN02 genotype composed of a substation with alanine at that position indicating the window of introduction of the WN02 genotype occurred between 2003 and 2005. From the eight isolates collected in Duval, Indian River, and Manatee Counties; there is also a silent nucleotide substitution that differentiates the isolates collected on the Atlantic side of the state compared to the isolate collected on the Gulf side, which groups closer to isolates from other locations near the Gulf. Conclusion As a whole, the Florida isolates contained numerous variable nucleotide and amino acid sites from the reference sequences, as well as each other; indicating greater nucleotide diversity within the Florida 2005 isolates than within other regions. Finally, a series of three amino acid substitutions surrounding a set of histidines located in the envelope coding region that hypothesized to play a role in conformational changes was found in the isolate collected in Indian River County, perhaps changing the

  15. West Nile Virus: Seroprevalence in Animals in Palestine and Israel.

    Science.gov (United States)

    Azmi, Kifaya; Tirosh-Levy, Sharon; Manasrah, Mu'taz; Mizrahi, Rotem; Nasereddin, Abed; Al-Jawabreh, Amer; Ereqat, Suheir; Abdeen, Ziad; Lustig, Yaniv; Gelman, Boris; Schvartz, Gili; Steinman, Amir

    2017-08-01

    West Nile virus (WNV) epidemiological situation in Israel and Palestine, due to their unique location, draws attention following to the global spread of West Nile fever (WNF). Although much information is available from Israel on clinical cases and prevalence of WNV, clinical cases are rarely reported in Palestine, and prevalence is not known. The objectives of this study were to determine WNV seroprevalence in various domestic animals in Palestine and to reevaluate current seroprevalence, force of infection, and risk factors for WNV exposure in horses in Israel. Sera samples were collected from 717 animals from Palestine and Israel (460 horses, 124 donkeys, 3 mules, 50 goats, 45 sheep, and 35 camels). Two hundred and ten horses were sampled twice. The level of WNV antibodies was determined using commercial Enzyme-linked Immunosorbent Assay (ELISA) Kit. Seroprevalence in equids was 73%. Seroprevalence in Israel (84.6%) was significantly higher than in Palestine (48.6%). Seroprevalence in horses (82.6%) was significantly higher than in donkeys and mules (39.3%). Multivariable statistical analysis showed that geographical area, landscape features (altitude), environmental factors (land surface temperature during the day [LSTD]), species, and age significantly influenced WNV seroprevalence. Fourteen of 95 (14.7%) sheep and goats and 14/35 camels (40%) sampled in Palestine were seropositive for WNV. Of the horses that were sampled twice, 82.8% were seropositive for WNV at the first sampling, and all remained seropositive. Three of the seronegative horses, all from Palestine, converted to positive when resampled (8.5%). The results indicate that domestic animals in Palestine were infected with WNV in the past, and the seroconversion indicates that WNV was circulating in Palestine in the summer of 2014. Control measures to prevent human infection should be implemented in Palestine. Anti WNV antibodies in domestic animals suggest that those species can be used as

  16. Surveillance of maternal antibodies against West Nile virus in chicken eggs in South-West Germany.

    Science.gov (United States)

    Börstler, Jessica; Engel, Dimitri; Petersen, Mathis; Poggensee, Claudia; Jansen, Stephanie; Schmidt-Chanasit, Jonas; Lühken, Renke

    2016-05-01

    The emergence of West Nile virus (WNV) in several European countries increases the risk of its introduction to Germany. This study evaluated a new method for WNV surveillance by testing for maternal antibodies in chicken eggs. A total of 1,990 eggs were collected in 35 sampling sites in the south-west of Germany and tested for WNV-specific antibodies. The results did not indicate evidence for WNV circulation in the study area. This work serves as a proof-of-concept that such a method is useful and a potential alternative to use of sentinel chicken for regular WNV surveillance. © 2016 John Wiley & Sons Ltd.

  17. Reported Neuroinvasive Cases of West Nile Virus by State, 2002-2014

    Data.gov (United States)

    U.S. Environmental Protection Agency — This map shows the average annual incidence of neuroinvasive West Nile virus disease in each state, which is calculated as the average number of new cases per...

  18. Mapping and analysis of West Nile virus-specific monoclonal antibodies: prospects for vaccine development

    NARCIS (Netherlands)

    Throsby, Mark; ter Meulen, Jan; Geuijen, Cecile; Goudsmit, Jaap; de Kruif, John

    2007-01-01

    Seasonal epidemics of West Nile virus (WNV) infection now occur throughout North America, causing clinical symptoms ranging from fever to encephalitis. There are no specific treatment options or licensed vaccines. Several classically developed vaccine candidates are being evaluated in clinical

  19. Biological and phylogenetic characteristics of West African lineages of West Nile virus.

    Science.gov (United States)

    Fall, Gamou; Di Paola, Nicholas; Faye, Martin; Dia, Moussa; Freire, Caio César de Melo; Loucoubar, Cheikh; Zanotto, Paolo Marinho de Andrade; Faye, Ousmane; Sall, Amadou Alpha

    2017-11-01

    The West Nile virus (WNV), isolated in 1937, is an arbovirus (arthropod-borne virus) that infects thousands of people each year. Despite its burden on global health, little is known about the virus' biological and evolutionary dynamics. As several lineages are endemic in West Africa, we obtained the complete polyprotein sequence from three isolates from the early 1990s, each representing a different lineage. We then investigated differences in growth behavior and pathogenicity for four distinct West African lineages in arthropod (Ap61) and primate (Vero) cell lines, and in mice. We found that genetic differences, as well as viral-host interactions, could play a role in the biological properties in different WNV isolates in vitro, such as: (i) genome replication, (ii) protein translation, (iii) particle release, and (iv) virulence. Our findings demonstrate the endemic diversity of West African WNV strains and support future investigations into (i) the nature of WNV emergence, (ii) neurological tropism, and (iii) host adaptation.

  20. West Nile virus encephalitis in organ transplant recipients: another high-risk group for meningoencephalitis and death.

    Science.gov (United States)

    DeSalvo, Debby; Roy-Chaudhury, Prabir; Peddi, Ram; Merchen, Todd; Konijetti, Krishna; Gupta, Manish; Boardman, Robyn; Rogers, Christin; Buell, Joseph; Hanaway, Michael; Broderick, Joseph; Smith, Roger; Woodle, E Steve

    2004-02-15

    West Nile virus infection has been spreading westward across the continental United States since 1999. Although it often presents as a mild, self-limiting viral illness, it can result in a devastating meningoencephalitis in some patient populations, particularly the elderly. We report in this article on two immunosuppressed transplant patients who developed a severe meningoencephalitis caused by mosquito-borne West Nile virus infection. Suggestions for the prevention, diagnosis, and treatment of West Nile virus infection in this patient population are described.

  1. Characterization of Puerto Rican West Nile Virus isolates in mice.

    Science.gov (United States)

    Caraballo, Elba V; Hunsperger, Elizabeth; Martínez, Idalí

    2015-09-11

    West Nile virus (WNV) is a neurotropic arbovirus that was first isolated in 1937 in the West Nile District of Uganda. The virus emerged in New York in 1999 and is now endemic in North America (2007). The first virus isolates from Puerto Rico were obtained in 2007 from a chicken (PR20wh) and a mosquito pool (PR423). Our study further characterized these viral isolates using in vitro plaque morphology assays and in vivo using a Balb/c mice pathogenesis model. In the in vitro experiments, PR WNV isolates produced significantly smaller plaques in Vero cells compared to the New York 1999 strain (NY99). For the in vivo experiments, PR WNV isolates were propagated in mammalian (Vero) and insect (C6/36) cell lines and then inoculated in Balb/c mice. When WNV was propagated in Vero cells, we observed a trend towards significance in the survival rate with PR20wh compared to NY99 (log rank, p = 0.092). Regardless of whether the viral isolates were propagated in Vero or C6/36 cells, we found a significantly greater survival in mice infected with PR20wh strain, when compared to NY99 (log rank, p = 0.04), while no statistical difference was detected between PR423 and NY99 (p = 0.84). The average survival time (AST) in mice was significantly lower in C6/36-derived PR423 when compared to C6/36-derived NY99 (t-test, p = 0.013), and Vero-derived PR423 (t-test, p Vero-derived PR423 was significantly higher when compared to NY99 and PR20wh. These results suggest that the PR WNV isolate, PR20wh, is a less pathogenic strain in mice than NY99. Moreover, we found that PR423 is a pathogenic isolate that causes faster mortality than NY99, when propagated in C6/36.

  2. European Surveillance for West Nile Virus in Mosquito Populations

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    Nicholas Johnson

    2013-10-01

    Full Text Available A wide range of arthropod-borne viruses threaten both human and animal health either through their presence in Europe or through risk of introduction. Prominent among these is West Nile virus (WNV, primarily an avian virus, which has caused multiple outbreaks associated with human and equine mortality. Endemic outbreaks of West Nile fever have been reported in Italy, Greece, France, Romania, Hungary, Russia and Spain, with further spread expected. Most outbreaks in Western Europe have been due to infection with WNV Lineage 1. In Eastern Europe WNV Lineage 2 has been responsible for human and bird mortality, particularly in Greece, which has experienced extensive outbreaks over three consecutive years. Italy has experienced co-circulation with both virus lineages. The ability to manage this threat in a cost-effective way is dependent on early detection. Targeted surveillance for pathogens within mosquito populations offers the ability to detect viruses prior to their emergence in livestock, equine species or human populations. In addition, it can establish a baseline of mosquito-borne virus activity and allow monitoring of change to this over time. Early detection offers the opportunity to raise disease awareness, initiate vector control and preventative vaccination, now available for horses, and encourage personal protection against mosquito bites. This would have major benefits through financial savings and reduction in equid morbidity/mortality. However, effective surveillance that predicts virus outbreaks is challenged by a range of factors including limited resources, variation in mosquito capture rates (too few or too many, difficulties in mosquito identification, often reliant on specialist entomologists, and the sensitive, rapid detection of viruses in mosquito pools. Surveillance for WNV and other arboviruses within mosquito populations varies between European countries in the extent and focus of the surveillance. This study reviews the

  3. The natural history of West Nile virus infection presenting with West Nile virus meningoencephalitis in a man with a prolonged illness: a case report

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    Wood James B

    2011-05-01

    Full Text Available Abstract Introduction Estimates indicate that West Nile virus infects approximately one and a half million people in the United States of America. Up to 1% may develop West Nile virus neuroinvasive disease, in which infected patients develop any combination of meningitis, encephalitis, or acute paralysis. Case presentation A 56-year-old African-American man presented to our hospital with headache, restlessness, fever, myalgias, decreased appetite, and progressive confusion. A cerebrospinal fluid examination showed mild leukocytosis and an elevated protein level. Testing for routine infections was negative. Brain T2-weighted magnetic resonance imaging scans showed marked enlargement of caudate nuclei and increased intensity within the basal ganglia and thalami. A West Nile virus titer was positive, and serial brain magnetic resonance imaging scans showed resolving abnormalities that paralleled his neurological examination. Conclusion This report is unusual as it portrays the natural history and long-term consequences of West Nile virus meningoencephalitis diagnosed on the basis of serial brain images.

  4. Economic conditions predict prevalence of West Nile virus.

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    Ryan J Harrigan

    Full Text Available Understanding the conditions underlying the proliferation of infectious diseases is crucial for mitigating future outbreaks. Since its arrival in North America in 1999, West Nile virus (WNV has led to population-wide declines of bird species, morbidity and mortality of humans, and expenditures of millions of dollars on treatment and control. To understand the environmental conditions that best explain and predict WNV prevalence, we employed recently developed spatial modeling techniques in a recognized WNV hotspot, Orange County, California. Our models explained 85-95% of the variation of WNV prevalence in mosquito vectors, and WNV presence in secondary human hosts. Prevalence in both vectors and humans was best explained by economic variables, specifically per capita income, and by anthropogenic characteristics of the environment, particularly human population and neglected swimming pool density. While previous studies have shown associations between anthropogenic change and pathogen presence, results show that poorer economic conditions may act as a direct surrogate for environmental characteristics related to WNV prevalence. Low-income areas may be associated with higher prevalence for a number of reasons, including variations in property upkeep, microhabitat conditions conducive to viral amplification in both vectors and hosts, host community composition, and human behavioral responses related to differences in education or political participation. Results emphasize the importance and utility of including economic variables in mapping spatial risk assessments of disease.

  5. West Nile Virus in Resident Birds from Yucatan, Mexico.

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    Chaves, Andrea; Sotomayor-Bonilla, Jesus; Monge, Otto; Ramírez, Abigaíl; Galindo, Francisco; Sarmiento-Silva, Rosa Elena; Gutiérrez-Espeleta, Gustavo A; Suzán, Gerardo

    2016-01-01

    West Nile virus (WNV) in the Americas is thought to be transported at large spatial scales by migratory birds and locally spread and amplified by resident birds. Local processes, including interspecific interactions and dominance of passerine species recognized as competent reservoirs, may boost infection and maintain endemic cycles. Change in species composition has been recognized as an important driver for infection dynamics. Due to migration and changes in species diversity and composition in wintering grounds, changes in infection prevalence are expected. To these changes, we used PCR to estimate the prevalence of WNV in wild resident birds during the dry and rainy seasons of 2012 in Yucatan, Mexico. Serum samples were obtained from 104 wild birds, belonging to six orders and 35 species. We detected WNV in 14 resident birds, representing 11 species and three orders. Prevalences by order was Passeriformes (27%), Columbiformes (6%), and Piciformes (33%). Resident birds positive to WNV from Yucatan may be indicative of local virus circulation and evidence of past virus transmission activity.

  6. Experimental infection of horses with West Nile virus.

    Science.gov (United States)

    Bunning, Michel L; Bowen, Richard A; Cropp, C Bruce; Sullivan, Kevin G; Davis, Brent S; Komar, Nicholas; Godsey, Marvin S; Baker, Dale; Hettler, Danielle L; Holmes, Derek A; Biggerstaff, Brad J; Mitchell, Carl J

    2002-04-01

    A total of 12 horses of different breeds and ages were infected with West Nile virus (WNV) via the bites of infected Aedes albopictus mosquitoes. Half the horses were infected with a viral isolate from the brain of a horse (BC787), and half were infected with an isolate from crow brain (NY99-6625); both were NY99 isolates. Postinfection, uninfected female Ae. albopictus fed on eight of the infected horses. In the first trial, Nt antibody titers reached >1:320, 1:20, 1:160, and 1:80 for horses 1 to 4, respectively. In the second trial, the seven horses with subclinical infections developed Nt antibody titers >1:10 between days 7 and 11 post infection. The highest viremia level in horses fed upon by the recipient mosquitoes was approximately 460 Vero cell PFU/mL. All mosquitoes that fed upon viremic horses were negative for the virus. Horses infected with the NY99 strain of WNV develop low viremia levels of short duration; therefore, infected horses are unlikely to serve as important amplifying hosts for WNV in nature.

  7. Differential Virulence and Pathogenesis of West Nile Viruses

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    Emilie Donadieu

    2013-11-01

    Full Text Available West Nile virus (WNV is a neurotropic flavivirus that cycles between mosquitoes and birds but that can also infect humans, horses, and other vertebrate animals. In most humans, WNV infection remains subclinical. However, 20%–40% of those infected may develop WNV disease, with symptoms ranging from fever to meningoencephalitis. A large variety of WNV strains have been described worldwide. Based on their genetic differences, they have been classified into eight lineages; the pathogenic strains belong to lineages 1 and 2. Ten years ago, Beasley et al. (2002 found that dramatic differences exist in the virulence and neuroinvasion properties of lineage 1 and lineage 2 WNV strains. Further insights on how WNV interacts with its hosts have recently been gained; the virus acts either at the periphery or on the central nervous system (CNS, and these observed differences could help explain the differential virulence and neurovirulence of WNV strains. This review aims to summarize the current state of knowledge on factors that trigger WNV dissemination and CNS invasion as well as on the inflammatory response and CNS damage induced by WNV. Moreover, we will discuss how WNV strains differentially interact with the innate immune system and CNS cells, thus influencing WNV pathogenesis.

  8. West Nile Virus lineage-2 in Culex specimens from Iran.

    Science.gov (United States)

    Shahhosseini, Nariman; Chinikar, Sadegh; Moosa-Kazemi, Seyed Hassan; Sedaghat, Mohammad Mehdi; Kayedi, Mohammad Hassan; Lühken, Renke; Schmidt-Chanasit, Jonas

    2017-10-01

    Screening of mosquitoes for viruses is an important forecasting tool for emerging and re-emerging arboviruses. Iran has been known to harbour medically important arboviruses such as West Nile virus (WNV) and dengue virus (DENV) based on seroepidemiological data. However, there are no data about the potential mosquito vectors for arboviruses in Iran. This study was performed to provide mosquito and arbovirus data from Iran. A total of 32 317 mosquitos were collected at 16 sites in five provinces of Iran in 2015 and 2016. RT-PCR for detection of flaviviruses was performed. The PCR amplicons were sequenced, and 109 WNV sequences, including one obtained in this study, were used for phylogenetic analyses. The 32 317 mosquito specimens belonging to 25 species were morphologically distinguished and distributed into 1222 pools. Culex pipiens s.l. comprised 56.429%. One mosquito pool (0.08%), containing 46 unfed Cx. pipiens pipiens form pipiens (Cpp) captured in August 2015, was positive for flavivirus RNA. Subsequent sequencing and phylogenetic analyses revealed that the detected Iranian WNV strain belongs to lineage 2 and clusters with a strain recently detected in humans. No flaviviruses other than WNV were detected in the mosquito pools. Cpp could be a vector for WNV in Iran. Our findings indicate recent circulation of WNV lineage-2 strain in Iran and provide a solid base for more targeted arbovirus surveillance programs. © 2017 John Wiley & Sons Ltd.

  9. Replication Cycle and Molecular Biology of the West Nile Virus

    Science.gov (United States)

    Brinton, Margo A.

    2013-01-01

    West Nile virus (WNV) is a member of the genus Flavivirus in the family Flaviviridae. Flaviviruses replicate in the cytoplasm of infected cells and modify the host cell environment. Although much has been learned about virion structure and virion-endosomal membrane fusion, the cell receptor(s) used have not been definitively identified and little is known about the early stages of the virus replication cycle. Members of the genus Flavivirus differ from members of the two other genera of the family by the lack of a genomic internal ribosomal entry sequence and the creation of invaginations in the ER membrane rather than double-membrane vesicles that are used as the sites of exponential genome synthesis. The WNV genome 3' and 5' sequences that form the long distance RNA-RNA interaction required for minus strand initiation have been identified and contact sites on the 5' RNA stem loop for NS5 have been mapped. Structures obtained for many of the viral proteins have provided information relevant to their functions. Viral nonstructural protein interactions are complex and some may occur only in infected cells. Although interactions between many cellular proteins and virus components have been identified, the functions of most of these interactions have not been delineated. PMID:24378320

  10. Differential virulence and pathogenesis of West Nile viruses.

    Science.gov (United States)

    Donadieu, Emilie; Bahuon, Céline; Lowenski, Steeve; Zientara, Stéphan; Coulpier, Muriel; Lecollinet, Sylvie

    2013-11-22

    West Nile virus (WNV) is a neurotropic flavivirus that cycles between mosquitoes and birds but that can also infect humans, horses, and other vertebrate animals. In most humans, WNV infection remains subclinical. However, 20%-40% of those infected may develop WNV disease, with symptoms ranging from fever to meningoencephalitis. A large variety of WNV strains have been described worldwide. Based on their genetic differences, they have been classified into eight lineages; the pathogenic strains belong to lineages 1 and 2. Ten years ago, Beasley et al. (2002) found that dramatic differences exist in the virulence and neuroinvasion properties of lineage 1 and lineage 2 WNV strains. Further insights on how WNV interacts with its hosts have recently been gained; the virus acts either at the periphery or on the central nervous system (CNS), and these observed differences could help explain the differential virulence and neurovirulence of WNV strains. This review aims to summarize the current state of knowledge on factors that trigger WNV dissemination and CNS invasion as well as on the inflammatory response and CNS damage induced by WNV. Moreover, we will discuss how WNV strains differentially interact with the innate immune system and CNS cells, thus influencing WNV pathogenesis.

  11. West Nile virus vector Culex modestus established in southern England

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    Golding Nick

    2012-02-01

    Full Text Available Abstract Background The risk posed to the United Kingdom by West Nile virus (WNV has previously been considered low, due to the absence or scarcity of the main Culex sp. bridge vectors. The mosquito Culex modestus is widespread in southern Europe, where it acts as the principle bridge vector of WNV. This species was not previously thought to be present in the United Kingdom. Findings Mosquito larval surveys carried out in 2010 identified substantial populations of Cx. modestus at two sites in marshland in southeast England. Host-seeking-adult traps placed at a third site indicate that the relative seasonal abundance of Cx. modestus peaks in early August. DNA barcoding of these specimens from the United Kingdom and material from southern France confirmed the morphological identification. Conclusions Cx. modestus appears to be established in the North Kent Marshes, possibly as the result of a recent introduction. The addition of this species to the United Kingdom's mosquito fauna may increase the risk posed to the United Kingdom by WNV.

  12. Mechanism of West Nile Virus Neuroinvasion: A Critical Appraisal

    Science.gov (United States)

    Suen, Willy W.; Prow, Natalie A.; Hall, Roy A.; Bielefeldt-Ohmann, Helle

    2014-01-01

    West Nile virus (WNV) is an important emerging neurotropic virus, responsible for increasingly severe encephalitis outbreaks in humans and horses worldwide. However, the mechanism by which the virus gains entry to the brain (neuroinvasion) remains poorly understood. Hypotheses of hematogenous and transneural entry have been proposed for WNV neuroinvasion, which revolve mainly around the concepts of blood-brain barrier (BBB) disruption and retrograde axonal transport, respectively. However, an over‑representation of in vitro studies without adequate in vivo validation continues to obscure our understanding of the mechanism(s). Furthermore, WNV infection in the current rodent models does not generate a similar viremia and character of CNS infection, as seen in the common target hosts, humans and horses. These differences ultimately question the applicability of rodent models for pathogenesis investigations. Finally, the role of several barriers against CNS insults, such as the blood-cerebrospinal fluid (CSF), the CSF-brain and the blood-spinal cord barriers, remain largely unexplored, highlighting the infancy of this field. In this review, a systematic and critical appraisal of the current evidence relevant to the possible mechanism(s) of WNV neuroinvasion is conducted. PMID:25046180

  13. West Nile virus: A re-emerging pathogen revisited

    Science.gov (United States)

    Martín-Acebes, Miguel A; Saiz, Juan-Carlos

    2012-01-01

    West Nile virus (WNV), a flavivirus of the Flaviviridae family, is maintained in nature in an enzootic transmission cycle between avian hosts and ornithophilic mosquito vectors, although the virus occasionally infects other vertebrates. WNV causes sporadic disease outbreaks in horses and humans, which may result in febrile illness, meningitis, encephalitis and flaccid paralysis. Until recently, its medical and veterinary health concern was relatively low; however, the number, frequency and severity of outbreaks with neurological consequences in humans and horses have lately increased in Europe and the Mediterranean basin. Since its introduction in the Americas, the virus spread across the continent with worrisome consequences in bird mortality and a considerable number of outbreaks among humans and horses, which have resulted in the largest epidemics of neuroinvasive WNV disease ever documented. Surprisingly, its incidence in human and animal health is very different in Central and South America, and the reasons for it are not yet understood. Even though great advances have been obtained lately regarding WNV infection, and although efficient equine vaccines are available, no specific treatments or vaccines for human use are on the market. This review updates the most recent investigations in different aspects of WNV life cycle: molecular virology, transmission dynamics, host range, clinical presentations, epidemiology, ecology, diagnosis, control, and prevention, and highlights some aspects that certainly require further research. PMID:24175211

  14. Hydroclimatic Assessment of West Nile Virus Occurrence Across Continental US

    Science.gov (United States)

    Billian, H. E.; Jutla, A.; Colwell, R. R.

    2014-12-01

    West Nile virus (WNV) is the most widely infections from arbovirus in mid-latitudes, having reached the Western Hemisphere in 1999. As a vector-borne disease, WNV is primarily spread by mosquitoes; the disease is predominantly found in tropical and temperate regions of the world, and is now considered an endemic pathogen in the United States, Africa, Asia, Australia, the Middle East, and Europe. Environmental processes play a vital role in the trigger of WNV. Here, using logistical regression models, we quantified relationships between hydroclimatic processes and mosquito abundance for WNV across the continental USA using precipitation and temperature at different spatial and temporal scales. It will be shown that reported cases of this disease are more prevalent during spring and summer months in the entire country, when there is more precipitation and higher surface air temperatures for 2003 to 2013. The key impacts of this research are those related to the improvement of human health, and a means to predict mosquito breeding patterns long term as they relate to the prevalence of vector-borne illnesses.

  15. Does reservoir host mortality enhance transmission of West Nile virus?

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    Foppa Ivo M

    2007-05-01

    Full Text Available Abstract Background Since its 1999 emergence in New York City, West Nile virus (WNV has become the most important and widespread cause of mosquito-transmitted disease in North America. Its sweeping spread from the Atlantic to the Pacific coast was accompanied by widespread mortality among wild birds, especially corvids. Only sporadic avian mortality had previously been associated with this infection in the Old World. Here, we examine the possibility that reservoir host mortality may intensify transmission, both by concentrating vector mosquitoes on remaining hosts and by preventing the accumulation of "herd immunity". Results Inspection of the Ross-Macdonald expression of the basic reproductive number (R0 suggests that this quantity may increase with reservoir host mortality. Computer simulation confirms this finding and indicates that the level of virulence is positively associated with the numbers of infectious mosquitoes by the end of the epizootic. The presence of reservoir incompetent hosts in even moderate numbers largely eliminated the transmission-enhancing effect of host mortality. Local host die-off may prevent mosquitoes to "waste" infectious blood meals on immune host and may thus facilitate perpetuation and spread of transmission. Conclusion Under certain conditions, host mortality may enhance transmission of WNV and similarly maintained arboviruses and thus facilitate their emergence and spread. The validity of the assumptions upon which this argument is built need to be empirically examined.

  16. Syndromic surveillance for West Nile virus using raptors in rehabilitation.

    Science.gov (United States)

    Ana, Alba; Perez Andrés, M; Julia, Ponder; Pedro, Puig; Arno, Wünschmann; Kimberly, Vander Waal; Julio, Alvarez; Michelle, Willette

    2017-11-29

    Wildlife rehabilitation centers routinely gather health-related data from diverse species. Their capability to signal the occurrence of emerging pathogens and improve traditional surveillance remains largely unexplored. This paper assessed the utility for syndromic surveillance of raptors admitted to The Raptor Center (TRC) to signal circulation of West Nile Virus (WNV) in Minnesota between 1990 and 2014. An exhaustive descriptive analysis using grouping time series structures and models of interrupted times series was conducted for indicator subsets. A total of 13,080 raptors were monitored. The most representative species were red-tailed hawks, great horned owls, Cooper's hawks, American kestrels and bald eagles. Results indicated that temporal patterns of accessions at the TRC changed distinctively after the incursion of WNV in 2002. The frequency of hawks showing WNV-like signs increased almost 3 times during July and August, suggesting that monitoring of hawks admitted to TRC with WNV-like signs could serve as an indicator of WNV circulation. These findings were also supported by the results of laboratory diagnosis. This study demonstrates that monitoring of data routinely collected by wildlife rehabilitation centers has the potential to signal the spread of pathogens that may affect wild, domestic animals and humans, thus supporting the early detection of disease incursions in a region and monitoring of disease trends. Ultimately, data collected in rehabilitation centers may provide insights to efficiently allocate financial and human resources on disease prevention and surveillance.

  17. Hydrologic variability and the dynamics of West Nile virus transmission

    Science.gov (United States)

    Shaman, J. L.

    2011-12-01

    West Nile virus (WNV) first emerged in North America in New York City during 1999 and since that time has spread throughout the continent and settled into a pattern of local endemicity in which outbreaks of variable size develop in some years but not others. Predicting where and when these outbreaks will develop is an issue of considerable public health importance. Spillover transmission of WNV to humans typically occurs when infection rates among vector mosquitoes are elevated. Mosquito infection rates are not constant through time but instead increase when newly emergent mosquitoes can more readily acquire WNV by blood-meal feeding on available, infected animal hosts. Such an increase of vector mosquito infection rates is termed amplification and is facilitated for WNV by intense zoonotic transmission of the virus among vector mosquitoes and avian hosts. Theory, observation and model simulations indicate that amplification is favored when mosquito breeding habitats and bird nesting and roosting habitats overlap. Both vector mosquitoes and vertebrate hosts depend on water resources; mosquitoes are critically dependent on the availability of standing water, as the first 3 stages of the mosquito life cycle, egg, larvae, pupae, are aquatic. Here it is shown that hydrologic variability often determines where and when vector mosquitoes and avian hosts congregate together, and when the amplification of WNV is more likely. Measures of land surface wetness and pooling, from ground observation, satellite observation, or numerical modeling, can provide reliable estimates of where and when WNV transmission hotspots will arise. Examples of this linkage between hydrology and WNV activity are given for Florida, Colorado and New York, and an operational system for monitoring and forecasting WNV risk in space and time is presented for Florida.

  18. West Nile virus encephalitis induced opsoclonus-myoclonus syndrome

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    Chad J. Cooper

    2014-04-01

    Full Text Available West Nile virus (WNV is an arthropod borne neurotropic single stranded RNA flavivirus with <1% developing presenting with neurological disease. Immunocompromised and elderly patients are more prone to developing WNV meningitis or encephalitis. Definitive diagnosis of WNV meningoencephalitis is a combination of clinical suspicion and cerebrospinal fluid (CSF serology. Forty-eight year old Caucasian female presented with a sudden onset of altered mental status after being found unresponsive. She was confused with intermittent bouts of alertness/lethargy and unintelligible responses to questioning. Her medical problems included endometrial cancer that was in remission after undergoing a total abdominal hysterectomy with bilateral salpingectomy and postoperative chemotherapy with paclitaxel and carboplatin. Pertinent physical examination revealed muscle strength that was significantly decreased, nuchal rigidity and +2 pitting edema of both lower extremities. Computed tomography and magnetic resonance imaging of the brain were negative for any intracranial pathology. CSF analysis was consistent with aseptic meningitis with all CSF serology being negative except for positive WNV antibody. A few days after being admitted she developed involuntary random movements of her eyes and generalized jerking movements (myoclonus. This was determined to be opsoclonus myoclonus syndrome (OMS induced by the WNV meningoencephalitis. She then received five consecutive days of plasmapheresis with a significant improvement in her neurological status. Opsoclonusmyoclonus syndrome (OMS is a rare neurological disorder associated with chaotic multidirectional eye movements, myoclonus and less frequently cerebellar ataxia. OMS affects as few as 1 in 10,000,000 people per year. The pathogenesis is not fully understood with the majority of cases of opsoclonus-myoclonus syndrome being idiopathic. According to current medical literature there have only been two previous case

  19. Dry weather induces outbreaks of human West Nile virus infections

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    Belant Jerrold L

    2010-02-01

    Full Text Available Abstract Background Since its first occurrence in the New York City area during 1999, West Nile virus (WNV has spread rapidly across North America and has become a major public health concern in North America. By 2002, WNV was reported in 40 states and the District of Columbia with 4,156 human and 14,539 equine cases of infection. Mississippi had the highest human incidence rate of WNV during the 2002 epidemic in the United States. Epidemics of WNV can impose enormous impacts on local economies. Therefore, it is advantageous to predict human WNV risks for cost-effective controls of the disease and optimal allocations of limited resources. Understanding relationships between precipitation and WNV transmission is crucial for predicting the risk of the human WNV disease outbreaks under predicted global climate change scenarios. Methods We analyzed data on the human WNV incidences in the 82 counties of Mississippi in 2002, using standard morbidity ratio (SMR and Bayesian hierarchical models, to determine relationships between precipitation and human WNV risks. We also entertained spatial autocorrelations of human WNV risks with conditional autocorrelative (CAR models, implemented in WinBUGS 1.4.3. Results We observed an inverse relationship between county-level human WNV incidence risk and total annual rainfall during the previous year. Parameters representing spatial heterogeneity in the risk of human exposure to WNV improved model fit. Annual precipitation of the previous year was a predictor of spatial variation of WNV risk. Conclusions Our results have broad implications for risk assessment of WNV and forecasting WNV outbreaks. Assessing risk of vector-born infectious diseases will require understanding of complex ecological relationships. Based on the climatologically characteristic drought occurrence in the past and on climate model predictions for climate change and potentially greater drought occurrence in the future, we suggest that the

  20. Purification and crystallization of dengue and West Nile virus NS2B–NS3 complexes

    Energy Technology Data Exchange (ETDEWEB)

    D’Arcy, Allan, E-mail: allan.darcy@novartis.com; Chaillet, Maxime; Schiering, Nikolaus; Villard, Frederic [Novartis Institutes of Biomedical Research, Protease Platform, Klybeckstrasse 144, CH 4002 Basel (Switzerland); Lim, Siew Pheng [Novartis Institutes of Tropical Diseases (Singapore); Lefeuvre, Peggy [Novartis Institutes of Biomedical Research, Protease Platform, Klybeckstrasse 144, CH 4002 Basel (Switzerland); Erbel, Paul [Novartis Institutes of Biomedical Research, Protease Platform, Klybeckstrasse 144, CH 4002 Basel (Switzerland); Novartis Institutes of Tropical Diseases (Singapore)

    2006-02-01

    Crystals of dengue serotype 2 and West Nile virus NS2B–NS3 protease complexes have been obtained and the crystals of both diffract to useful resolution. Sample homogeneity was essential for obtaining X-ray-quality crystals of the dengue protease. Controlled proteolysis produced a crystallizable fragment of the apo West Nile virus NS2B–NS3 and crystals were also obtained in the presence of a peptidic inhibitor. Both dengue and West Nile virus infections are an increasing risk to humans, not only in tropical and subtropical areas, but also in North America and parts of Europe. These viral infections are generally transmitted by mosquitoes, but may also be tick-borne. Infection usually results in mild flu-like symptoms, but can also cause encephalitis and fatalities. Approximately 2799 severe West Nile virus cases were reported this year in the United States, resulting in 102 fatalities. With this alarming increase in the number of West Nile virus infections in western countries and the fact that dengue virus already affects millions of people per year in tropical and subtropical climates, there is a real need for effective medicines. A possible therapeutic target to combat these viruses is the protease, which is essential for virus replication. In order to provide structural information to help to guide a lead identification and optimization program, crystallizations of the NS2B–NS3 protease complexes from both dengue and West Nile viruses have been initiated. Crystals that diffract to high resolution, suitable for three-dimensional structure determinations, have been obtained.

  1. Ecological complexity and West Nile virus: perspectives on improving public health response.

    Science.gov (United States)

    Rainham, Daniel G C

    2005-01-01

    The emergence of West Nile Virus, as well as other emerging diseases, is linked to complex ecosystem processes such as climate change and constitutes an important threat to population health. Traditional public health intervention activities related to vector surveillance and control tend to be reactive and limited in their ability to deal with multiple epidemics and in their consideration of population health determinants. This paper reviews the current status of West Nile Virus in Canada and describes how complex systems and geographical perspectives help to acknowledge the influence of ecosystem processes on population health. It also provides examples of how these perspectives can be integrated into population-based intervention strategies.

  2. Antibody response of five bird species after vaccination with a killed West Nile virus vaccine.

    Science.gov (United States)

    Okeson, Danelle M; Llizo, Shirley Yeo; Miller, Christine L; Glaser, Amy L

    2007-06-01

    West Nile virus has been associated with numerous bird mortalities in the United States since 1999. Five avian species at three zoological parks were selected to assess the antibody response to vaccination for West Nile virus: black-footed penguins (Spheniscus demersus), little blue penguins (Eudyptula minor), American flamingos (Phoenicopterus ruber), Chilean flamingos (Phoenicopterus chilensis), and Attwater's prairie chickens (Tympanuchus cupido attwateri). All birds were vaccinated intramuscularly at least twice with a commercially available inactivated whole virus vaccine (Innovator). Significant differences in antibody titer over time were detected for black-footed penguins and both flamingo species.

  3. Analysis of YouTube as a source of information for West Nile Virus infection.

    Science.gov (United States)

    Dubey, Divyanshu; Amritphale, Amod; Sawhney, Anshudha; Dubey, Devashish; Srivastav, Nupur

    2014-12-01

    A major outbreak of West Nile Virus was seen last year in different parts of the United States. Adequate dissemination of correct information about the disease would have helped decrease its spread and the associated panic in the general population. In this study, we looked into the use of YouTube as a resource for providing information about West Nile Virus infection. This study aims to identify and evaluate YouTube as resource for providing information on West Nile Virus infection to the general public. YouTube was searched on November 25, 2012, using the keywords West Nile Virus epidemic, West Nile Virus infection, and West Nile Virus prevention for videos uploaded in the past 6 months containing relevant information about the disease. The videos were classified as useful, misleading, or as news updates based on the type of information contained. Total viewership, number of days since upload, total duration of videos, and source of upload were noted. A total of 106 videos with information on West Nile Virus infection were included in the study, with 79.24% having useful information about the disease. Among the useful videos, 51/84 (60.71%) had information on disease prevention, and 29/84 (34.52%) contained information on news and research updates. The majority of these videos were uploaded by individuals (54.6%) or news agencies (41.8 %). Healthcare agencies contributed only 3.4 % of the total videos. Even though the useful videos represented 72% of all videos, there was significantly higher total viewership and viewership per day for the non-useful videos (PYouTube may be a significant resource for dissemination of information on public health issues like West Nile virus infection and should be targeted by healthcare agencies for this use. The major drawback of this medium is lack of verification by authorized healthcare professionals before these videos are made available for viewing by the community. Hence, a strict caution should be exercised in obtaining

  4. The Role of Innate Immunity in Conditioning Mosquito Susceptibility to West Nile Virus

    Directory of Open Access Journals (Sweden)

    Abhishek N. Prasad

    2013-12-01

    Full Text Available Arthropod-borne viruses (arboviruses represent an emerging threat to human and livestock health globally. In particular, those transmitted by mosquitoes present the greatest challenges to disease control efforts. An understanding of the molecular basis for mosquito innate immunity to arbovirus infection is therefore critical to investigations regarding arbovirus evolution, virus-vector ecology, and mosquito vector competence. In this review, we discuss the current state of understanding regarding mosquito innate immunity to West Nile virus. We draw from the literature with respect to other virus-vector pairings to attempt to draw inferences to gaps in our knowledge about West Nile virus and relevant vectors.

  5. Recovery and Identification of West Nile Virus from a Hawk in Winter

    OpenAIRE

    Garmendia, Antonio E.; Van Kruiningen, Herbert J.; French, Richard A.; Anderson, John F.; Andreadis, Theodore G.; Kumar, Asok; West, A. Brian

    2000-01-01

    West Nile virus was recovered from the brain of a red-tailed hawk that died in Westchester County, N.Y., in February 2000. Multiple foci of glial cells, lymphocytes, and a few pyknotic nuclei were observed in the brain. Three to 4 days after inoculation of Vero cells with brain homogenates, cytopathic changes were detected. The presence of West Nile virus antigen in fixed cells or cell lysates was revealed by fluorescent antibody testing or enzyme-linked immunosorbent assay, respectively. Fur...

  6. The role of innate immunity in conditioning mosquito susceptibility to West Nile virus.

    Science.gov (United States)

    Prasad, Abhishek N; Brackney, Doug E; Ebel, Gregory D

    2013-12-13

    Arthropod-borne viruses (arboviruses) represent an emerging threat to human and livestock health globally. In particular, those transmitted by mosquitoes present the greatest challenges to disease control efforts. An understanding of the molecular basis for mosquito innate immunity to arbovirus infection is therefore critical to investigations regarding arbovirus evolution, virus-vector ecology, and mosquito vector competence. In this review, we discuss the current state of understanding regarding mosquito innate immunity to West Nile virus. We draw from the literature with respect to other virus-vector pairings to attempt to draw inferences to gaps in our knowledge about West Nile virus and relevant vectors.

  7. Review of West Nile virus circulation and outbreak risk in Madagascar: Entomological and ornithological perspectives

    OpenAIRE

    Tantely, Micha?l Luciano; Goodman, Steven M.; Rakotondranaivo, Tsirinaina; Boyer, S?bastien

    2016-01-01

    West Nile fever (WNF) is a zoonotic disease, occurring nearly globally. In Madagascar, West Nile virus (WNV) was first detected in 1978 from wild birds and the virus is currently distributed across the island, but no epidemic or epizootic period has been recorded. One fatal human case of WNV infection was reported in 2011, suggesting a “tip of the iceberg” phenomenon of a possible WNF epidemic/epizootic on the island. The main objective of this literature-based survey is to review patterns of...

  8. West nile virus infection in the Mesopotamia region, Syria border of Turkey.

    Science.gov (United States)

    Karakoç, Zehra Çağla; Tüzüner, Bora Mete; Ergonul, Onder; Pierro, Anna; Di Fonzo, Eugenio; Koruk, İbrahim; Sambri, Vittorio

    2013-10-01

    We described the serological prevalence of West Nile Virus (WNV) antibodies among the human population in a historical and strategic region of Turkey. A serologic survey was conducted based on suspected cases in April, 2009, in the Mesopotamia region of Turkey, in the villages that were located alongside the Zergan River. All the sera were tested by enzyme-linked immunosorbent assay ELISA (Euroimmune™), and the positive samples were tested by immunofluorescent assay (IFA; Euroimmune™). As confirmation, neutralizing antibodies against WNV were tested by microneutralization assay (MNTA). In total, 307 individuals were included. The MNTA test was found to be positive among 52 individuals out of 307 (17%). In multivariate analysis, age >50 [odds ratio (OR)=5.2, confidence interval (CI) 2.76-9.97, p<0.001) and being in an occupational risk group (OR=2.02, CI 1.02-4.04, p=0.044) were found to be the risk factors for WNV seropositivity with the MNTA test. The physicians in the region should be aware of the risk of WNV infection and should be alerted to detect the clinical cases.

  9. Larvicidal Activity of Nerium oleander against Larvae West Nile Vector Mosquito Culex pipiens (Diptera: Culicidae)

    Science.gov (United States)

    El-Akhal, Fouad; Guemmouh, Raja; Ez Zoubi, Yassine; El Ouali Lalami, Abdelhakim

    2015-01-01

    Background. Outbreaks of the West Nile virus infection were reported in Morocco in 1996, 2003, and 2010. Culex pipiens was strongly suspected as the vector responsible for transmission. In the North center of Morocco, this species has developed resistance to synthetic insecticides. There is an urgent need to find alternatives to the insecticides as natural biocides. Objective. In this work, the insecticidal activity of the extract of the local plant Nerium oleander, which has never been tested before in the North center of Morocco, was studied on larval stages 3 and 4 of Culex pipiens. Methods. Biological tests were realized according to a methodology inspired from standard World Health Organization protocol. The mortality values were determined after 24 h of exposure and LC50 and LC90 values were calculated. Results. The extract had toxic effects on the larvae of culicid mosquitoes. The ethanolic extract of Nerium oleander applied against the larvae of Culex pipiens has given the lethal concentrations LC50 and LC90 in the order of 57.57 mg/mL and 166.35 mg/mL, respectively. Conclusion. This investigation indicates that N. oleander could serve as a potential larvicidal, effective natural biocide against mosquito larvae, particularly Culex pipiens. PMID:26640701

  10. Two Case Reports of Neuroinvasive West Nile Virus Infection in the Critical Care Unit

    Directory of Open Access Journals (Sweden)

    Edgardo M. Flores Anticona

    2012-01-01

    Full Text Available We describe the clinical course of two cases of neuroinvasive West Nile Virus (WNV infection in the critical care unit. The first case is a 70-year-old man who presented during summer with mental status changes. Cerebrospinal fluid (CSF analysis revealed pleocytosis with lymphocyte predominance. WNV serology was positive in the CSF. His condition worsened with development of left-sided weakness and deterioration of mental status requiring intensive care. The patient gradually improved and was discharged with residual left-sided weakness and near-complete improvement in his mental status. The second case is an 81-year-old man who presented with mental status changes, fever, lower extremity weakness, and difficulty in walking. CSF analysis showed pleocytosis with neutrophil predominance. WNV serology was also positive in CSF. During the hospital stay his mentation worsened, eventually requiring intubation for airway protection and critical care support. The patient gradually improved and was discharged with residual upper and lower extremity paresis. Neuroinvasive WNV infection can lead to significant morbidity, especially in the elderly. These cases should be suspected in patients with antecedent outdoor activities during summer. It is important for critical care providers to be aware of and maintain a high clinical suspicion of this disease process.

  11. Larvicidal Activity of Nerium oleander against Larvae West Nile Vector Mosquito Culex pipiens (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Fouad El-Akhal

    2015-01-01

    Full Text Available Background. Outbreaks of the West Nile virus infection were reported in Morocco in 1996, 2003, and 2010. Culex pipiens was strongly suspected as the vector responsible for transmission. In the North center of Morocco, this species has developed resistance to synthetic insecticides. There is an urgent need to find alternatives to the insecticides as natural biocides. Objective. In this work, the insecticidal activity of the extract of the local plant Nerium oleander, which has never been tested before in the North center of Morocco, was studied on larval stages 3 and 4 of Culex pipiens. Methods. Biological tests were realized according to a methodology inspired from standard World Health Organization protocol. The mortality values were determined after 24 h of exposure and LC50 and LC90 values were calculated. Results. The extract had toxic effects on the larvae of culicid mosquitoes. The ethanolic extract of Nerium oleander applied against the larvae of Culex pipiens has given the lethal concentrations LC50 and LC90 in the order of 57.57 mg/mL and 166.35 mg/mL, respectively. Conclusion. This investigation indicates that N. oleander could serve as a potential larvicidal, effective natural biocide against mosquito larvae, particularly Culex pipiens.

  12. Superiority of West Nile Virus RNA Detection in Whole Blood for Diagnosis of Acute Infection.

    Science.gov (United States)

    Lustig, Yaniv; Mannasse, Batya; Koren, Ravit; Katz-Likvornik, Shiri; Hindiyeh, Musa; Mandelboim, Michal; Dovrat, Sara; Sofer, Danit; Mendelson, Ella

    2016-09-01

    The current diagnosis of West Nile virus (WNV) infection is primarily based on serology, since molecular identification of WNV RNA is unreliable due to the short viremia and absence of detectable virus in cerebrospinal fluid (CSF). Recent studies have shown that WNV RNA can be detected in urine for a longer period and at higher concentrations than in plasma. In this study, we examined the presence of WNV RNA in serum, plasma, whole-blood, CSF, and urine samples obtained from patients diagnosed with acute WNV infection during an outbreak which occurred in Israel in 2015. Our results demonstrate that 33 of 38 WNV patients had detectable WNV RNA in whole blood at the time of diagnosis, a higher rate than in any of the other sample types tested. Overall, whole blood was superior to all other samples, with 86.8% sensitivity, 100% specificity, 100% positive predictive value, and 83.9% negative predictive value. Interestingly, WNV viral load in urine was higher than in whole blood, CSF, serum, and plasma despite the lower sensitivity than that of whole blood. This study establishes the utility of whole blood in the routine diagnosis of acute WNV infection and suggests that it may provide the highest sensitivity for WNV RNA detection in suspected cases. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  13. Serologic survey of West Nile virus in horses from Central-West, Northeast and Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Jaqueline Raymondi Silva

    2013-11-01

    Full Text Available Since the emergence of West Nile virus (WNV in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.

  14. Acute West Nile Virus Meningoencephalitis Diagnosed Via Metagenomic Deep Sequencing of Cerebrospinal Fluid in a Renal Transplant Patient.

    Science.gov (United States)

    Wilson, M R; Zimmermann, L L; Crawford, E D; Sample, H A; Soni, P R; Baker, A N; Khan, L M; DeRisi, J L

    2017-03-01

    Solid organ transplant patients are vulnerable to suffering neurologic complications from a wide array of viral infections and can be sentinels in the population who are first to get serious complications from emerging infections like the recent waves of arboviruses, including West Nile virus, Chikungunya virus, Zika virus, and Dengue virus. The diverse and rapidly changing landscape of possible causes of viral encephalitis poses great challenges for traditional candidate-based infectious disease diagnostics that already fail to identify a causative pathogen in approximately 50% of encephalitis cases. We present the case of a 14-year-old girl on immunosuppression for a renal transplant who presented with acute meningoencephalitis. Traditional diagnostics failed to identify an etiology. RNA extracted from her cerebrospinal fluid was subjected to unbiased metagenomic deep sequencing, enhanced with the use of a Cas9-based technique for host depletion. This analysis identified West Nile virus (WNV). Convalescent serum serologies subsequently confirmed WNV seroconversion. These results support a clear clinical role for metagenomic deep sequencing in the setting of suspected viral encephalitis, especially in the context of the high-risk transplant patient population. © 2016 The Authors. American Journal of Transplantation published by Wiley Periodicals, Inc. on behalf of American Society of Transplant Surgeons.

  15. Evaluating the Use of Commercial West Nile Virus Antigens as Positive Controls in the Rapid Analyte Measurement Platform West Nile Virus Assay.

    Science.gov (United States)

    Burkhalter, Kristen L; Savage, Harry M

    2015-12-01

    We evaluated the utility of 2 types of commercially available antigens as positive controls in the Rapid Analyte Measurement Platform (RAMP®) West Nile virus (WNV) assay. Purified recombinant WNV envelope antigens and whole killed virus antigens produced positive RAMP results and either type would be useful as a positive control. Killed virus antigens provide operational and economic advantages and we recommend their use over purified recombinant antigens. We also offer practical applications for RAMP positive controls and recommendations for preparing them.

  16. Quest for economic development in agrarian localities : Lessons from West Nile, Uganda

    NARCIS (Netherlands)

    W. Enzama (Wilson)

    2008-01-01

    textabstractThis paper describes and analyzes the operational strategy of West Nile region, a typical low local capability community, in pursuit of local economic development. Special emphasis has been placed on the development of groups of survival beekeeping-enterprises and their integration in

  17. Neuroinvasive disease and West Nile virus infection, North Dakota, USA, 1999-2008.

    Science.gov (United States)

    Carson, Paul J; Borchardt, Stephanie M; Custer, Brian; Prince, Harry E; Dunn-Williams, Joan; Winkelman, Valerie; Tobler, Leslie; Biggerstaff, Brad J; Lanciotti, Robert; Petersen, Lyle R; Busch, Michael P

    2012-04-01

    To determine risk for West Nile virus (WNV) neuroinvasive disease in North Dakota, we tested plasma samples from blood donors for WNV IgG and compared infection rates with reported WNV neuroinvasive disease incidence. We estimate that 1 in 244 WNV infections leads to neuroinvasive disease; risk is substantially increased among men and older persons.

  18. Can reconstructed land surface temperature data from space predict a West Nile Virus outbreak?

    NARCIS (Netherlands)

    Andreo, V.; Metz, J.C.M.; Neteler, M.; Rosà, R.; Marcantonio, M.; Billinis, C.; Rizzoli, A.; Papa, Anne-Laure

    2017-01-01

    Temperature is one of the main drivers of ecological processes. The availability of temporally and spatially continuous temperature time series is crucial in different research and application fields, such as epidemiology and control of zoonotic diseases. In 2010, several West Nile virus (WNV)

  19. West nile virus anti-body surveillance in three Sierra Nevada raptors of conservation concern

    Science.gov (United States)

    J.M. Hull; J.J. Keane; L.A. Tell; H.B. Ernest

    2010-01-01

    West Nile virus (WNV) infection has caused high levels of mortality in North American hawks and owls. To investigate the extent of infection among raptors of conservation concern in the Sierra Nevada, we tested 62 Northern Goshawks (Accipiter gentilis), 209 Spotted Owls (Strix occidentalis), and 22 Great Gray Owls (...

  20. The role of Culex pipiens mosquitoes in transmission of West Nile virus in Europe

    NARCIS (Netherlands)

    Vogels, Chantal B.F.

    2017-01-01

    West Nile virus (WNV) is maintained in a natural transmission cycle between mosquito vectors and bird hosts. However, mosquitoes can also transmit WNV to mammals, such as humans and horses, which may result in disease. In Europe, such cases of WNV disease are yearly recurring in southern and central

  1. Projection of Climate Change Influences on U.S. West Nile Virus Vectors

    National Research Council Canada - National Science Library

    Heidi E Brown; Alex Young; Joceline Lega; Theodore G Andreadis; Jessica Schurich; Andrew Comrie

    2015-01-01

    ... to infection, which varies among populations, and pathogen and vector development rates, which are influenced by weather (Hartvigsen et al. 1998; Paz and Semenza 2013). West Nile virus disease (WNV) is now the most common domestic arthropodborne viral disease (Reimann et al. 2008). Presumably introduced from the Middle East, the first WNV case in the...

  2. West Nile virus infection in cats : ABCD guidelines on prevention and management

    NARCIS (Netherlands)

    Egberink, Herman; Addie, Diane D; Boucraut-Baralon, Corine; Frymus, Tadeusz; Gruffydd-Jones, Tim; Hartmann, Katrin; Horzinek, Marian C; Hosie, Margaret J; Marsilio, Fulvio; Lloret, Albert; Lutz, Hans; Pennisi, Maria Grazia; Radford, Alan D; Thiry, Etienne; Truyen, Uwe; Möstl, Karin

    OVERVIEW: West Nile virus (WNV) is a zoonotic mosquito-borne virus with a broad host range that infects mainly birds and mosquitos, but also mammals (including humans), reptiles, amphibians and ticks. It is maintained in a bird-mosquito-bird transmission cycle. The most important vectors are

  3. Importance of bird-to-bird transmission for the establishment of West Nile Virus

    NARCIS (Netherlands)

    Hartemink, N.A.; Davis, S.A.; Reiter, P.; Hubálek, Z.; Heesterbeek, J.A.P.

    2007-01-01

    West Nile virus (WNV) is principally considered to be maintained in a mosquito–bird transmission cycle. Under experimental conditions, several other transmission routes have been observed, but the significance of these additional routes in nature is unknown. Here, we derive an expression for the

  4. Seroprevalence of West Nile Virus specific IgG and IgM antibodies ...

    African Journals Online (AJOL)

    Background: West Nile Virus (WNV) infection has been reported worldwide, including in Africa but its existence in Zambia is unknown. Symptoms for the virus include headache, myalgia, arthralgia and rash. Objectives: This study aimed to determine the seroprevalence of WNV and its correlates. Methods: A cross sectional ...

  5. Spatiotemporal modeling of ecological and sociological predictors of West Nile virus in Suffolk County, NY, mosquitoes

    Science.gov (United States)

    Suffolk County, New York, is a locus for West Nile virus (WNV) infection in the American northeast that includes the majority of Long Island to the east of New York City. The county has a system of light and gravid traps used for mosquito collection and disease monitoring. In ord...

  6. Spatially explicit West Nile virus risk modeling in Santa Clara County, California

    Science.gov (United States)

    A previously created Geographic Information Systems model designed to identify regions of West Nile virus (WNV) transmission risk is tested and calibrated in Santa Clara County, California. American Crows that died from WNV infection in 2005 provide the spatial and temporal ground truth. Model param...

  7. Case report: West-Nile virus infection in two Dutch travellers returning from Israel

    NARCIS (Netherlands)

    N. Aboutaleb; M.F.C. Beersma (Thijs); H.F. Wunderink; A.C.Th.M. Vossen (Ann); L.G. Visser (Leo)

    2010-01-01

    textabstractWe report about West Nile virus (WNV) infections in a symptomatic traveller returning from Israel and in her asymptomatic travel companion. Knowledge of the current epidemiological situation in Israel from where WNV cases were reported recently enabled a rapid diagnosis. The described

  8. Mutation in West Nile Virus Structural Protein prM during Human Infection.

    Science.gov (United States)

    Lustig, Yaniv; Lanciotti, Robert S; Hindiyeh, Musa; Keller, Nathan; Milo, Ron; Mayan, Shlomo; Mendelson, Ella

    2016-09-01

    A mutation leading to substitution of a key amino acid in the prM protein of West Nile virus (WNV) occurred during persistent infection of an immunocompetent patient. WNV RNA persisted in the patient's urine and serum in the presence of low-level neutralizing antibodies. This case demonstrates active replication of WNV during persistent infection.

  9. Mosquito and West Nile virus surveillance in northeast Montana, U.S.A., 2005-2006

    Science.gov (United States)

    Mosquito and West Nile virus surveillance was conducted on a National Wildlife Refuge in northeast Montana, 2005-2006, during which outbreaks of WNV in a colony of American white pelicans (Pelecanus erythrorhynchos Gmelin) resulted in juvenile mortality rates of 30 and 31%. During both years, flood...

  10. No evidence of West Nile virus infection in Dutch blood donors

    NARCIS (Netherlands)

    Koppelman, M. H. G. M.; Sjerps, M. S.; de Waal, M.; Reesink, H. W.; Cuypers, H. T. M.

    2006-01-01

    BACKGROUND AND OBJECTIVES: West Nile virus (WNV) can be transmitted by transfusion through infected blood components. This study aimed to determine the prevalence of WNV infection among Dutch blood donors to assess whether WNV is a possible threat for the Dutch blood supply. MATERIALS AND METHODS:

  11. Characterization of the functional requirements of West Nile virus membrane fusion

    NARCIS (Netherlands)

    Moesker, Bastiaan; Rodenhuis-Zybert, Izabela A.; Meijerhof, Tjarko; Wilschut, Jan; Smit, Jolanda M.

    Flaviviruses infect their host cells by a membrane fusion reaction. In this study, we performed a functional analysis of the membrane fusion properties of West Nile virus (WNV) with liposomal target membranes. Membrane fusion was monitored continuously using a lipid mixing assay involving the

  12. Spatially Explicit West Nile Virus Risk Modeling in Santa Clara County, CA

    Science.gov (United States)

    A geographic information systems model designed to identify regions of West Nile virus (WNV) transmission risk was tested and calibrated with data collected in Santa Clara County, California. American Crows that died from WNV infection in 2005, provided spatial and temporal ground truth. When the mo...

  13. prM-antibody renders immature West Nile virus infectious in vivo

    NARCIS (Netherlands)

    Colpitts, Tonya M.; Rodenhuis-Zybert, Izabela; Moesker, Bastiaan; Wang, Penghua; Fikrig, Erol; Smit, Jolanda M.

    2011-01-01

    West Nile virus (WNV) is a member of the family Flaviviridae and is a neurotropic pathogen responsible for severe human disease. Flavivirus-infected cells release virus particles that contain variable numbers of precursor membrane (prM) protein molecules at the viral surface. Consequently,

  14. Domestic goose as a model for West Nile virus vaccine efficacy

    Science.gov (United States)

    West Nile virus (WNV) is an emergent pathogen in the Americas, first reported in New York during 1999, and has since spread across the United States (USA), Central and South America causing neurological disease in humans, horses and some bird species, including domestic geese. No WNV vaccines are li...

  15. Long-term Death Rates, West Nile Virus Epidemic, Israel, 2000

    OpenAIRE

    Green, Manfred S.; Weinberger, Miriam; Ben-Ezer, Judith; Bin, Hanna; Mendelson, Ella; Gandacu, Dan; Kaufman, Zalman; Dichtiar, Rita; Sobel, Annette; Cohen, Dani; Chowers, Michal Y.

    2005-01-01

    We studied the 2-year death rate of 246 adults discharged from hospital after experiencing acute West Nile Virus infection in Israel during 2000. The age- and sex-adjusted death rates were significantly higher than in the general population. This excess was greater for men. Significant adverse prognostic factors were age, male sex, diabetes mellitus, and dementia.

  16. First Case of West Nile Fever in a Child in Autonomous Republic of Crimea

    Directory of Open Access Journals (Sweden)

    N.V. Rymarenko

    2014-09-01

    Full Text Available The article shows a case report of West Nile fever in 11-year-old boy taken from own clinical experience. The duration of the diseases was typical, with fever, meningism, lymphadenitis, hyperemic of facial and chest skin, conjunctivitis, pain in muscles of low extremities.

  17. Recovery and identification of West Nile virus from a hawk in winter.

    Science.gov (United States)

    Garmendia, A E; Van Kruiningen, H J; French, R A; Anderson, J F; Andreadis, T G; Kumar, A; West, A B

    2000-08-01

    West Nile virus was recovered from the brain of a red-tailed hawk that died in Westchester County, N.Y., in February 2000. Multiple foci of glial cells, lymphocytes, and a few pyknotic nuclei were observed in the brain. Three to 4 days after inoculation of Vero cells with brain homogenates, cytopathic changes were detected. The presence of West Nile virus antigen in fixed cells or cell lysates was revealed by fluorescent antibody testing or enzyme-linked immunosorbent assay, respectively. Furthermore, Reverse transcriptase-PCR with primers specific for the NS3 gene of West Nile virus resulted in an amplicon of the expected size (470 bp). Electron microscopy of thin sections of infected Vero cells revealed the presence of viral particles approximately 40 nm in diameter, within cytoplasmic vesicles. The demonstration of infection with the West Nile virus in the dead of the winter, long after mosquitoes ceased to be active, is significant in that it testifies to the survival of the virus in the region beyond mosquito season and suggests another route of transmission: in this case, prey to predator.

  18. Entomological studies along the Colorado Front Range during a period of intense West Nile virus activity.

    Science.gov (United States)

    Bolling, B G; Moore, C G; Anderson, S L; Blair, C D; Beaty, B J

    2007-03-01

    To better understand the ecology of West Nile virus transmission in Northern Colorado, field studies were conducted in Larimer and Weld counties from September 2003 through March 2005. During summer studies, 18,540 adult mosquitoes were collected using light traps and gravid traps. West Nile virus RNA was detected in 24 of the 2,140 mosquito pools tested throughout the study area in 2003 and 2004. Culex tarsalis had the highest minimum infection rate (MIR) in both 2003 (MIR = 34.48) and in 2004 (MIR = 8.74). During winter studies, 9,391 adult mosquitoes were collected by aspirator from various overwintering sites including bridges and storm drains. The most frequently collected species was Culex pipiens. West Nile virus was not detected in our overwintering collections. The relationship between spring adult emergence and temperature inside and outside overwintering sites is described. Species composition of collections as well as the spatial and temporal distribution of West Nile virus detections are presented.

  19. West Nile Virus Outbreak in Houston and Harris County, Texas, USA, 2014.

    Science.gov (United States)

    Martinez, Diana; Murray, Kristy O; Reyna, Martin; Arafat, Raouf R; Gorena, Roberto; Shah, Umair A; Debboun, Mustapha

    2017-08-01

    Since 2002, West Nile virus (WNV) has been detected every year in Houston and the surrounding Harris County, Texas. In 2014, the largest WNV outbreak to date occurred, comprising 139 cases and causing 2 deaths. Additionally, 1,286 WNV-positive mosquito pools were confirmed, the most reported in a single mosquito season.

  20. Performance of elite grain sorghum varieties in the West Nile Agro ...

    African Journals Online (AJOL)

    ACSS

    Grain Sorghum (Sorghum bicolor (L.) Moench) is the fifth most important cereal in the world and third most important cereal crop in Uganda. In the West Nile region of Uganda, it is the most important cereal crop. Ten pre-released sorghum varieties, acquired from the National Semi-. Arid Resources Research Institute, were ...

  1. West Nile Virus positive blood donation and subsequent entomological investigation, Austria, 2014

    Czech Academy of Sciences Publication Activity Database

    Kolodziejek, J.; Seidel, B.; Jungbauer, C.; Dimmel, K.; Kolodziejek, M.; Rudolf, Ivo; Hubálek, Zdeněk; Allerberger, F.; Nowotny, N.

    2015-01-01

    Roč. 10, č. 5 (2015), e0126381 E-ISSN 1932-6203 EU Projects: European Commission(XE) 261504 - EDENEXT Institutional support: RVO:68081766 Keywords : West Nile virus * Austria Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.057, year: 2015

  2. Noncoding subgenomic flavivirus RNA: multiple functions in West Nile virus pathogenesis and modulation of host responses

    NARCIS (Netherlands)

    Roby, J.A.; Pijlman, G.P.; Wilusz, J.; Khromykh, A.A.

    2014-01-01

    Flaviviruses are a large group of positive strand RNA viruses transmitted by arthropods that include many human pathogens such as West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus, dengue virus, and tick-borne encephalitis virus. All members in this genus tested so far are

  3. Human Monoclonal Antibodies against West Nile Virus Induced by Natural Infection Neutralize at a Postattachment Step

    NARCIS (Netherlands)

    Vogt, Matthew R.; Moesker, Bastiaan; Goudsmit, Jaap; Jongeneelen, Mandy; Austin, S. Kyle; Oliphant, Theodore; Nelson, Steevenson; Pierson, Theodore C.; Wilschut, Jan; Throsby, Mark; Diamond, Michael S.

    West Nile virus (WNV) is a neurotropic flavivirus that is now a primary cause of epidemic encephalitis in North America. Studies of mice have demonstrated that the humoral immune response against WNV limits primary infection and protects against a secondary challenge. The most-potent neutralizing

  4. West Nile Virus RNA in Tissues from Donor Associated with Transmission to Organ Transplant Recipients

    Centers for Disease Control (CDC) Podcasts

    2013-11-19

    William Hale reads an abridged version of the Emerging Infectious Diseases’ dispatch, West Nile Virus RNA in Tissues from Donor Associated with Transmission to Organ Transplant Recipients.  Created: 11/19/2013 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 11/21/2013.

  5. Prevalence of West Nile virus in Mashhad, Iran: A population-based study.

    Science.gov (United States)

    Meshkat, Zahra; Chinikar, Sadegh; Shakeri, MohammadTaghi; Manavifar, Lida; Moradi, Maryam; Mirshahabi, Hessam; Jalali, Tahmineh; Khakifirouz, Sahar; Shahhosseini, Nariman

    2015-03-01

    To evaluate the prevalence of West Nile virus seropositivity in the general population of Mashhad, Northeast of Iran. One hundred and eighty two individuals living in the city of Mashhad were studied using cluster sampling method. Both IgM and IgG antibodies against WNV were detected by ELISA method. In this study, the overall IgG seroprevalence of positive West Nile virus was 11%; however, IgM antibody was not found in the participants. Our study suggested that the prevalence rate of West virus is considerable in Mashhad city. It seems necessary for clinicians and health care workers to be aware of WNV infection in the Northeast Iran. Copyright © 2015 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.

  6. Potential Reservoir and Associated Factors for West Nile Virus in Three Distinct Climatological Zones.

    Science.gov (United States)

    DeCarlo, Christine; Omar, Anwar H; Haroun, Mohammod I; Bigler, Laura; Bin Rais, Mohamad N; Abu, Jalila; Omar, Abdul Rahman; Mohammed, Hussni O

    2017-10-01

    West Nile virus (WNV) is a zoonotic single-strand RNA arbovirus (family Flaviviridae: Flavivirus), transmitted among avian hosts in enzootic cycles by a mosquito vector. The virus has a significant disease effect on humans and equines when it bridges into a cycle with various sequelae with epidemic potential. This study was carried out to identify the potential spectrum of WNV hosts in three geographic areas with climatologically distinct features: Malaysia, Qatar, and the United States of America (U.S.). Serum samples were collected from avian and mammal species suspected to be reservoirs for the virus at these areas in a cross-sectional epidemiologic study. The samples were tested for the presence of antibodies against the virus using an enzyme-linked immunosorbent assay. Data on putative risk factors were also collected and analyzed for significance of association with seropositivity using the logistic regression analysis. Among the tested avian and mammalian species, raccoons had the highest seroconversion rate (54%) followed by crows (30%), horses (27%), camels (10%), other avian species (7%), and canine species (3%). It was almost twice as likely to detect seroconversion among these mammalian and avian species in the fall in comparison to other seasons of the year. Only mammalian and avian species and seasons of the year were significantly associated with the likelihood of seroconversion to WNV when we controlled for other factors in the multivariate analysis. Our data from the U.S. showed that raccoons and camels are susceptible to infection by the virus and may play a role in the perpetuation of endemic foci for the disease.

  7. Inactivation of West Nile Virus in Serum with Heat, Ionic Detergent, and Reducing Agent for Proteomic Applications

    Science.gov (United States)

    2017-06-14

    Inactivation of West Nile virus in serum with heat, ionic detergent, and reducing agent for proteomic applications Louis A. Altamura1§, Lisa H...Infectious Diseases, Fort Detrick, MD 21702 3DOD Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced...of West Nile virus in serum with heat, detergent, and reducing agent for proteomic applications Abstract Research involving biosafety level 3

  8. Clinical and pathologic features of lineage 2 West Nile virus infections in birds of prey in Hungary.

    Science.gov (United States)

    Erdélyi, Károly; Ursu, Krisztina; Ferenczi, Emöke; Szeredi, Levente; Rátz, Ferenc; Skáre, József; Bakonyi, Tamás

    2007-01-01

    In the southeast of Hungary a sparrow hawk (Accipiter nisus) and several goshawk (Accipiter gentilis) fledglings succumbed to encephalitis manifesting as an acute neurological disease during the summers of 2004 and 2005. Both years the causative agent was identified as a lineage 2 West Nile virus. This is the first description of clinical, pathological and immunohistochemical findings of infection caused by a neuroinvasive, lineage 2 West Nile virus and the first evidence of its circulation in continental Europe.

  9. Molecular Epidemiology and Evolution of West Nile Virus in North America

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    Alan D. T. Barrett

    2013-10-01

    Full Text Available West Nile virus (WNV was introduced to New York in 1999 and rapidly spread throughout North America and into parts of Central and South America. Displacement of the original New York (NY99 genotype by the North America/West Nile 2002 (NA/WN02 genotype occurred in 2002 with subsequent identification of a novel genotype in 2003 in isolates collected from the southwestern Unites States region (SW/WN03 genotype. Both genotypes co-circulate to date. Subsequent WNV surveillance studies have confirmed additional genotypes in the United States that have become extinct due to lack of a selective advantage or stochastic effect; however, the dynamic emergence, displacement, and extinction of multiple WNV genotypes in the US from 1999–2012 indicates the continued evolution of WNV in North America.

  10. THE PASSAGE AND DURATION OF ANTIBODIES TO WEST NILE VIRUS IN HUMBOLDT PENGUINS (SPHENISCUS HUMBOLDTI).

    Science.gov (United States)

    Cushing, Andrew C; Dubovi, Edward; Erb, Hollis N; Georoff, Timothy A; Abou-Madi, Noha

    2017-03-01

    West Nile virus (genus Flavivirus) outbreaks and mortality events have been documented in both wild and captive avian species, including penguins. Serologic response to vaccination in avian species has varied and appears to be largely species dependent; however, Humboldt penguins ( Spheniscus humboldti ) previously showed excellent rates of seroconversion. The goal of this study was to determine virus neutralization titers of 17 Humboldt penguin hens and their subsequent eggs, chicks, or both following vaccination with a killed West Nile vaccine. Chicks were also vaccinated at 56, 70, and 84 days old. Titers were measured from 10-346 days prior to lay as well as serially in seven chicks. Data collected showed positive rank correlation between maternal titers and yolk titers (ρ = 0.90, P penguin chicks based on a time-dependent decline in maternal antibody titers. Cell-mediated immunity and experimental challenge following vaccination have not yet been investigated in this species.

  11. Incidence of West Nile Virus in Birds Arriving in Wildlife Rehabilitation Centers in Southern Spain

    OpenAIRE

    López, Guillermo; Jiménez-Clavero, Miguel A.; Vázquez, Ana; Soriguer, Ramón C.; Gómez-Tejedor, Concha; Tenorio, Antonio; Figuerola, Jordi

    2011-01-01

    West Nile virus (WNV) is a neurotropic mosquito-transmitted flavivirus that in Eurasia, Africa, and the Americas primarily affects birds and secondarily other vertebrates. WNV has caused frequent massive episodes of wild bird mortality during its expansion throughout the Americas, and has become a regulating factor in the population dynamics of many wild bird species. On the other hand, WNV-related mortalities in wild birds have rarely been reported in the Medite...

  12. The Importance of Haematological and Biochemical Findings in Patients with West Nile Virus Neuroinvasive Disease

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    Urošević Aleksandar

    2016-10-01

    Full Text Available Background: West Nile virus neuroinvasive disease (WNND occurs in less than 1% of infected people. Leukocytosis with lymphocytopenia, mild anaemia, thrombocytopenia, elevated liver and muscle enzymes and hyponatremia are occasionally present in patients with WNND. Cerebrospinal fluid (CSF findings resemble other viral neuroinfections. The purpose of this study is to present some of the most important laboratory findings of our patients with WNND and to evaluate their correlation with fatal outcome.

  13. Field Methods and Sample Collection Techniques for the Surveillance of West Nile Virus in Avian Hosts.

    Science.gov (United States)

    Wheeler, Sarah S; Boyce, Walter M; Reisen, William K

    2016-01-01

    Avian hosts play an important role in the spread, maintenance, and amplification of West Nile virus (WNV). Avian susceptibility to WNV varies from species to species thus surveillance efforts can focus both on birds that survive infection and those that succumb. Here we describe methods for the collection and sampling of live birds for WNV antibodies or viremia, and methods for the sampling of dead birds. Target species and study design considerations are discussed.

  14. Interferon-λ restricts West Nile virus neuroinvasion by tightening the blood-brain barrier.

    Science.gov (United States)

    Lazear, Helen M; Daniels, Brian P; Pinto, Amelia K; Huang, Albert C; Vick, Sarah C; Doyle, Sean E; Gale, Michael; Klein, Robyn S; Diamond, Michael S

    2015-04-22

    Although interferon-λ [also known as type III interferon or interleukin-28 (IL-28)/IL-29] restricts infection by several viruses, its inhibitory mechanism has remained uncertain. We used recombinant interferon-λ and mice lacking the interferon-λ receptor (IFNLR1) to evaluate the effect of interferon-λ on infection with West Nile virus, an encephalitic flavivirus. Cell culture studies in mouse keratinocytes and dendritic cells showed no direct antiviral effect of exogenous interferon-λ, even though expression of interferon-stimulated genes was induced. We observed no differences in West Nile virus burden between wild-type and Ifnlr1(-/-) mice in the draining lymph nodes, spleen, or blood. We detected increased West Nile virus infection in the brain and spinal cord of Ifnlr1(-/-) mice, yet this was not associated with a direct antiviral effect in mouse neurons. Instead, we observed an increase in blood-brain barrier permeability in Ifnlr1(-/-) mice. Treatment of mice with pegylated interferon-λ2 resulted in decreased blood-brain barrier permeability, reduced West Nile virus infection in the brain without affecting viremia, and improved survival against lethal virus challenge. An in vitro model of the blood-brain barrier showed that interferon-λ signaling in mouse brain microvascular endothelial cells increased transendothelial electrical resistance, decreased virus movement across the barrier, and modulated tight junction protein localization in a protein synthesis- and signal transducer and activator of transcription 1 (STAT1)-independent manner. Our data establish an indirect antiviral function of interferon-λ in which noncanonical signaling through IFNLR1 tightens the blood-brain barrier and restricts viral neuroinvasion and pathogenesis. Copyright © 2015, American Association for the Advancement of Science.

  15. Reported Neuroinvasive Cases of West Nile Virus by State, 2002-2014

    Science.gov (United States)

    This map shows the average annual incidence of neuroinvasive West Nile virus disease in each state, which is calculated as the average number of new cases per 100,000 people per year from 2002 to 2014. The map is based on cases that local and state health departments report to CDC??s national disease tracking system. Neuroinvasive cases are those that affect the brain or cause neurologic dysfunction. For more information: www.epa.gov/climatechange/science/indicators

  16. Animal viral diseases and global change: Bluetongue and West Nile fever as paradigms

    Directory of Open Access Journals (Sweden)

    Miguel Angel eJimenez-Clavero

    2012-06-01

    Full Text Available Environmental changes have an undoubted influence on the appearance, distribution and evolution of infectious diseases, and notably on those transmitted by vectors. Global change refers to environmental changes arising from human activities affecting the fundamental mechanisms operating in the biosphere. This paper discusses the changes observed in recent times with regard to some important arboviral (arthropod-borne viral diseases of animals, and the role global change could have played in these variations. Two of the most important arboviral diseases of animals, bluetongue and West Nile fever/encephalitis, have been selected as models. In both cases, in the last 15 years an important leap forward has been observed, which has lead to considering them emerging diseases in different parts of the world. Bluetongue, affecting domestic ruminants, has recently afflicted livestock in Europe in an unprecedented epizootic, causing enormous economic losses. West Nile fever/encephalitis affects wildlife (birds, domestic animals (equines and humans, thus, beyond the economic consequences of its occurrence, as a zoonotic disease, it poses an important public health threat. West Nile virus has expanded in the last 12 years worldwide, and particularly in the Americas, where it first occurred in 1999, extending throughout the Americas relentlessly since then, causing a severe epidemic of disastrous consequences for public health, wildlife and livestock. In Europe, West Nile virus is known long time ago, but it is since the last years of the XXth century that its incidence has risen substantially. Circumstances such as global warming, changes in land use and water management, increase in travel, trade of animals, and others, can have an important influence in the observed changes in both diseases. The following question is raised: What is the contribution of global changes to the current increase of these diseases in the world?

  17. Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs

    OpenAIRE

    Ana Belen Blazquez; Martín-Acebes, Miguel A; Juan-Carlos eSaiz

    2016-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral ...

  18. Reduced Avian Virulence and Viremia of West Nile Virus Isolates from Mexico and Texas

    OpenAIRE

    Brault, Aaron C.; Langevin, Stanley A.; Ramey, Wanichaya N.; Fang, Ying; Beasley, David W. C.; Barker, Christopher M.; Sanders, Todd A.; Reisen, William K.; Barrett, Alan D. T.; Bowen, Richard A.

    2011-01-01

    A West Nile virus (WNV) isolate from Mexico (TM171-03) and BIRD1153, a unique genotype from Texas, have exhibited reduced murine neuroinvasive phenotypes. To determine if murine neuroinvasive capacity equates to avian virulence potential, American crow (Corvus brachyrhynchos) and house sparrows (Passer domesticus) were experimentally inoculated with representative murine neuroinvasive/non-neuroinvasive strains. In both avian species, a plaque variant from Mexico that was E-glycosylation compe...

  19. An Update on the Potential of North American Mosquitoes (Diptera: Culicidae) to Transmit West Nile Virus

    Science.gov (United States)

    2004-09-22

    Say), and Psorophora ferox (Von Humboldt). Mosquito larvae and pupae (Ae. vexans, Oc. canadensis, and Oc. cantator) were collected in Westport...Scott. 2002. Vector competence of California mosquitoes for West Nile virus. Emerg. Infect. Dis. 8: 1385Ð1391. Hardy, J. L. 1988. Susceptibility and... California . Am. J. Trop. Med. Hyg. 14: 170Ð177. Turell, M. J., T. P. Gargan, I. I., and C. L. Bailey. 1984. Replication anddissemination ofRift Valley

  20. Clinical pathology results from cranes with experimental West Nile Virus infection

    Science.gov (United States)

    Olsen, Glenn H.

    2011-01-01

    Sandhill cranes (Grus canadensis) were vaccinated for and then challenged with West Nile virus. Resulting titers demonstrated protection in the vaccinated-challenged cranes as compared to the unvaccinated-challenged cranes. Clinical pathology results showed challenged cranes, whether vaccinated or not, had a decrease in their hematocrits and an elevation of 2.5-fold in their white blood cell counts as compared to unchallenged control sandhill cranes. No differences were apparent in the differential counts of heterophils and lymphocytes.

  1. Reduced West Nile Virus Transmission Around Communal Roosts of Great-Tailed Grackle (Quiscalus mexicanus).

    Science.gov (United States)

    Komar, Nicholas; Colborn, James M; Horiuchi, Kalanthe; Delorey, Mark; Biggerstaff, Brad; Damian, Dan; Smith, Kirk; Townsend, John

    2015-03-01

    West Nile virus has caused several outbreaks among humans in the Phoenix metropolitan area (Arizona, southwest USA) within the last decade. Recent ecologic studies have implicated Culex quinquefasciatus and Culex tarsalis as the mosquito vectors and identified three abundant passerine birds-great-tailed grackle (Quiscalus mexicanus), house sparrow (Passer domesticus), and house finch (Haemorhous mexicanus)-as key amplifiers among vertebrates. Nocturnal congregations of certain species have been suggested as critical for late summer West Nile virus amplification. We evaluated the hypothesis that house sparrow (P. domesticus) and/or great-tailed grackle (Q. mexicanus) communal roost sites (n = 22 and n = 5, respectively) in a primarily suburban environment were spatially associated with West Nile virus transmission indices during the 2010 outbreak of human neurological disease in metropolitan Phoenix. Spatial associations between human case residences and communal roosts were non-significant for house sparrows, and were negative for great-tailed grackle. Several theories that explain these observations are discussed, including the possibility that grackle communal roosts are protective.

  2. West Nile virus circulation in South-Eastern Romania, 2011 to 2013.

    Science.gov (United States)

    Dinu, S; Cotar, A I; Pănculescu-Gătej, I R; Fălcuţă, E; Prioteasa, F L; Sîrbu, A; Oprişan, G; Bădescu, D; Reiter, P; Ceianu, C S

    2015-05-21

    Lineage 2 West Nile virus (WNV), previously found only in sub-Saharan Africa and Madagascar, was identified in Hungary in 2004 and has rapidly expanded in Europe in the past decade. Following a significant outbreak of West Nile fever with neurological cases caused by lineage 1 WNV in Romania in 1996, scattered cases have been recorded in the south-east of the country in each transmission season. Another outbreak, affecting a larger area and caused by lineage 2 WNV, was recorded in 2010. We analysed human sera from neuroinvasive West Nile fever cases and mosquitoes, sampled in south-eastern Romania between 2011 and 2013, for the presence of WNV genome, and obtained partial NS5 and envelope glycoprotein sequences. Human- and mosquito-derived WNV sequences were highly similar (99%) to Volgograd 2007 lineage 2 WNV and differed from isolates previously detected in central and southern Europe. WNV was detected in one pool of Culex pipiens s.l. males, documenting vertical transmission. Lineage 4 WNV, of unknown pathogenicity to mammals, was found in the amphibian-feeding mosquito Uranotaenia unguiculata from the Danube Delta. Our results present molecular evidence for the maintenance of the same isolates of Volgograd 2007-like lineage 2 WNV in south-eastern Romania between 2011 and 2013.

  3. Proteomic Profiling and Neurodegeneration in West-Nile-Virus-Infected Neurons

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    V. Dhingra

    2005-01-01

    Full Text Available West Nile virus, a mosquito-borne flavivirus, is a human, equine, and avian pathogen. High-resolution two-dimensional differential-gel electrophoresis (2D-DIGE was used to characterize protein expression in primary rat neurons and to examine the proteomic profiling to understand the pathogenesis of West-Nile-associated meningoencephalitis. Three pH ranges, 3–10, 4–7, and 5–6, were used to analyze the protein spots. The proteins are labeled with fluorescent dyes Cy3 and Cy5 before being separated on the basis of charge and size respectively on a two-dimensional platform. About 55 proteins showed altered expression levels. These were then subsequently digested and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS analysis using peptide mass fingerprinting and database searching. These cellular proteins could represent distinct roles during infection related to apoptosis. Our findings show that two-dimensional differential gel electrophoresis combined with mass spectrometry is a powerful approach that permits the identification of proteins whose expression was altered due to West Nile virus infection.

  4. A nano-view of West Nile virus-induced cellular changes during infection

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    Ng Mah-Lee

    2004-06-01

    Full Text Available Abstract Background Microscopic imaging of viruses and their interactions with and effects on host cells are frequently held back by limitations of the microscope's resolution or the invasive nature of the sample preparation procedures. It is also difficult to have a technique that would allow simultaneous imaging of both surface and sub-surface on the same cell. This has hampered endeavours to elucidate virus-host interactions. Atomic Force Microscopy (AFM, which is commonly used in the physical sciences, is now becoming a good correlative form of microscopy used to complement existing optical, confocal and electron microscopy for biological applications Results In this study, the West Nile (Sarafend virus-infected Vero cell model was used. The atomic force microscope was found to be useful in producing high resolution images of virus-host events with minimal sample processing requirements. The AFM was able to image the budding of the West Nile (Sarafend virus at the infected cell surface. Proliferation of the filopodia and thickening of clusters of actin filaments accompanied West Nile virus replication. Conclusions The study shows that the AFM is useful for virus-host interaction studies. The technique provides morphological information on both the virus and the host cell during the infection stages.

  5. OAS1 polymorphisms are associated with susceptibility to West Nile encephalitis in horses.

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    Jonathan J Rios

    Full Text Available West Nile virus, first identified within the United States in 1999, has since spread across the continental states and infected birds, humans and domestic animals, resulting in numerous deaths. Previous studies in mice identified the Oas1b gene, a member of the OAS/RNASEL innate immune system, as a determining factor for resistance to West Nile virus (WNV infection. A recent case-control association study described mutations of human OAS1 associated with clinical susceptibility to WNV infection. Similar studies in horses, a particularly susceptible species, have been lacking, in part, because of the difficulty in collecting populations sufficiently homogenous in their infection and disease states. The equine OAS gene cluster most closely resembles the human cluster, with single copies of OAS1, OAS3 and OAS2 in the same orientation. With naturally occurring susceptible and resistant sub-populations to lethal West Nile encephalitis, we undertook a case-control association study to investigate whether, similar to humans (OAS1 and mice (Oas1b, equine OAS1 plays a role in resistance to severe WNV infection. We identified naturally occurring single nucleotide mutations in equine (Equus caballus OAS1 and RNASEL genes and, using Fisher's Exact test, we provide evidence that mutations in equine OAS1 contribute to host susceptibility. Virtually all of the associated OAS1 polymorphisms were located within the interferon-inducible promoter, suggesting that differences in OAS1 gene expression may determine the host's ability to resist clinical manifestations associated with WNV infection.

  6. Identifying the environmental conditions favouring West Nile Virus outbreaks in Europe.

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    Matteo Marcantonio

    Full Text Available West Nile Virus (WNV is a globally important mosquito borne virus, with significant implications for human and animal health. The emergence and spread of new lineages, and increased pathogenicity, is the cause of escalating public health concern. Pinpointing the environmental conditions that favour WNV circulation and transmission to humans is challenging, due both to the complexity of its biological cycle, and the under-diagnosis and reporting of epidemiological data. Here, we used remote sensing and GIS to enable collation of multiple types of environmental data over a continental spatial scale, in order to model annual West Nile Fever (WNF incidence across Europe and neighbouring countries. Multi-model selection and inference were used to gain a consensus from multiple linear mixed models. Climate and landscape were key predictors of WNF outbreaks (specifically, high precipitation in late winter/early spring, high summer temperatures, summer drought, occurrence of irrigated croplands and highly fragmented forests. Identification of the environmental conditions associated with WNF outbreaks is key to enabling public health bodies to properly focus surveillance and mitigation of West Nile virus impact, but more work needs to be done to enable accurate predictions of WNF risk.

  7. Large Human Outbreak of West Nile Virus Infection in North-Eastern Italy in 2012

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    Luisa Barzon

    2013-11-01

    Full Text Available Human cases of West Nile virus (WNV disease have been reported in Italy since 2008. So far, most cases have been identified in north-eastern Italy, where, in 2012, the largest outbreak of WNV infection ever recorded in Italy occurred. Most cases of the 2012 outbreak were identified in the Veneto region, where a special surveillance plan for West Nile fever was in place. In this outbreak, 25 cases of West Nile neuroinvasive disease and 17 cases of fever were confirmed. In addition, 14 WNV RNA-positive blood donors were identified by screening of blood and organ donations and two cases of asymptomatic infection were diagnosed by active surveillance of subjects at risk of WNV exposure. Two cases of death due to WNND were reported. Molecular testing demonstrated the presence of WNV lineage 1 in all WNV RNA-positive patients and, in 15 cases, infection by the novel Livenza strain was ascertained. Surveillance in other Italian regions notified one case of neuroinvasive disease in the south of Italy and two cases in Sardinia. Integrated surveillance for WNV infection remains a public health priority in Italy and vector control activities have been strengthened in areas of WNV circulation.

  8. Usutu virus persistence and West Nile virus inactivity in the Emilia-Romagna region (Italy) in 2011.

    Science.gov (United States)

    Calzolari, Mattia; Bonilauri, Paolo; Bellini, Romeo; Albieri, Alessandro; Defilippo, Francesco; Tamba, Marco; Tassinari, Massimo; Gelati, Antonio; Cordioli, Paolo; Angelini, Paola; Dottori, Michele

    2013-01-01

    The circulation of West Nile virus and Usutu virus was detected in the Emilia-Romagna region in 2008 and 2009. To evaluate the extent of circulation of both viruses, environmental surveillance, based on bird and mosquito testing, was conducted in 2008 and gradually improved over the years. In February-March 2009-2011, 5,993 hibernating mosquitoes were manually sampled, out of which 80.1% were Culex pipiens; none tested positive for the viruses. From 2008 to 2011, 946,213 mosquitoes, sampled between May and October, were tested; 86.5% were Cx. pipiens. West Nile virus was detected in 32 Cx. pipiens pools, and Usutu virus was detected in 229 mosquito pools (217 Cx. pipiens, 10 Aedes albopictus, one Anopheles maculipennis s.l., and one Aedes caspius). From 2009 to 2011, of 4,546 birds collected, 42 tested positive for West Nile virus and 48 for Usutu virus. West Nile virus and Usutu virus showed different patterns of activity during the 2008-2011 surveillance period. West Nile virus was detected in 2008, 2009, and 2010, but not in 2011. Usutu virus, however, was continuously active throughout 2009, 2010, and 2011. The data strongly suggest that both viruses overwinter in the surveyed area rather than being continually reintroduced every season. The lack of hibernating mosquitoes testing positive for the viruses and the presence of positive birds sampled early in the season support the hypothesis that the viruses overwinter in birds rather than in mosquitoes. Herd immunity in key bird species could explain the decline of West Nile virus observed in 2011, while the persistence of Usutu virus may be explained by not yet identified reservoirs. Reported results are comparable with a peri-Mediterranean circulation of the West Nile virus lineage 1 related strain, which became undetectable in the environment after two to three years of obvious circulation.

  9. West Nile virus 'circulation' in Vojvodina, Serbia: Mosquito, bird, horse and human surveillance.

    Science.gov (United States)

    Petrić, Dušan; Petrović, Tamaš; Hrnjaković Cvjetković, Ivana; Zgomba, Marija; Milošević, Vesna; Lazić, Gospava; Ignjatović Ćupina, Aleksandra; Lupulović, Diana; Lazić, Sava; Dondur, Dragan; Vaselek, Slavica; Živulj, Aleksandar; Kisin, Bratislav; Molnar, Tibor; Janku, Djordje; Pudar, Dubravka; Radovanov, Jelena; Kavran, Mihaela; Kovačević, Gordana; Plavšić, Budimir; Jovanović Galović, Aleksandra; Vidić, Milan; Ilić, Svetlana; Petrić, Mina

    2017-02-01

    Efforts to detect West Nile virus (WNV) in the Vojvodina province, northern Serbia, commenced with human and mosquito surveillance in 2005, followed by horse (2009) and wild bird (2012) surveillance. The knowledge obtained regarding WNV circulation, combined with the need for timely detection of virus activity and risk assessment resulted in the implementation of a national surveillance programme integrating mosquito, horse and bird surveillance in 2014. From 2013, the system showed highly satisfactory results in terms of area specificity (the capacity to indicate the spatial distribution of the risk for human cases of West Nile neuroinvasive disease - WNND) and sensitivity to detect virus circulation even at the enzootic level. A small number (n = 50) of Culex pipiens (pipiens and molestus biotypes, and their hybrids) females analysed per trap/night, combined with a high number of specimens in the sample, provided variable results in the early detection capacity at different administrative levels (NUTS2 versus NUTS3). The clustering of infected mosquitoes, horses, birds and human cases of WNND in 2014-2015 was highly significant, following the south-west to north-east direction in Vojvodina (NUTS2 administrative level). Human WNND cases grouped closest with infected mosquitoes in 2014, and with wild birds/mosquitoes in 2015. In 2014, sentinel horses showed better spatial correspondence with human WNND cases than sentinel chickens. Strong correlations were observed between the vector index values and the incidence of human WNND cases recorded at the NUTS2 and NUTS3 levels. From 2010, West Nile virus was detected in mosquitoes sampled at 43 different trap stations across Vojvodina. At 14 stations (32.56%), WNV was detected in two different (consecutive or alternate) years, at 2 stations in 3 different years, and in 1 station during 5 different years. Based on these results, integrated surveillance will be progressively improved to allow evidence-based adoption of

  10. Measles vaccine expressing the secreted form of West Nile virus envelope glycoprotein induces protective immunity in squirrel monkeys, a new model of West Nile virus infection.

    Science.gov (United States)

    Brandler, Samantha; Marianneau, Philippe; Loth, Philippe; Lacôte, Sandra; Combredet, Chantal; Frenkiel, Marie-Pascale; Desprès, Philippe; Contamin, Hugues; Tangy, Frédéric

    2012-07-15

    West Nile virus (WNV) is a mosquito-borne flavivirus that emerged in North America and caused numerous cases of human encephalitis, thus urging the development of a vaccine. We previously demonstrated the efficacy of a recombinant measles vaccine (MV) expressing the secreted form of the envelope glycoprotein from WNV to prevent WNV encephalitis in mice. In the present study, we investigated the capacity of this vaccine candidate to control WNV infection in a primate model. We first established experimental WNV infection of squirrel monkeys (Saimiri sciureus). A high titer of virus was detected in plasma on day 2 after infection, and viremia persisted for 5 days. A single immunization of recombinant MV-WNV vaccine elicited anti-WNV neutralizing antibodies that strongly reduced WNV viremia at challenge. This study demonstrates for the first time the capacity of a recombinant live attenuated measles vector to protect nonhuman primates from a heterologous infectious challenge.

  11. Antibodies to West Nile Virus in Wild and Farmed Crocodiles in Southeastern Mexico

    Science.gov (United States)

    Machain-Williams, Carlos; Padilla-Paz, Sergio E.; Weber, Manuel; Cetina-Trejo, Rosa; Juarez-Ordaz, José Alfredo; Loroño-Pino, María Alba; Ulloa, Armando; Wang, Chong; Garcia-Rejon, Julián; Blitvich, Bradley J.

    2013-01-01

    Surveillance for evidence of West Nile virus (WNV) infection in Morelet’s crocodiles (Crocodylus moreletii) was conducted in Campeche State, Mexico, in 2007. Sera from 62 crocodiles (32 free-ranging and 30 captive) were assayed for antibodies to WNV by epitope-blocking enzyme-linked immunosorbent assay. Antibodies to WNV were detected in 13 (41%) wild and nine (30%) captive crocodiles, and the overall antibody prevalence was 35%. Although evidence of WNV infection in captive crocodiles has been reported in Mexico, we provide the first evidence of WNV exposure in wild crocodiles in Mexico. PMID:23778623

  12. Estimated cumulative incidence of West Nile virus infection in US adults, 1999-2010.

    Science.gov (United States)

    Petersen, L R; Carson, P J; Biggerstaff, B J; Custer, B; Borchardt, S M; Busch, M P

    2013-03-01

    West Nile virus (WNV) was first recognized in the USA in 1999. We estimated the cumulative incidence of WNV infection in the USA from 1999 to 2010 using recently derived age- and sex-stratified ratios of infections to WNV neuroinvasive disease (WNND) and the number of WNND cases reported to national surveillance. We estimate that over 3 million persons have been infected with WNV in the USA, with the highest incidence rates in the central plains states. These 3 million infections would have resulted in about 780 000 illnesses. A substantial number of WNV infections and illnesses have occurred during the virus' first decade in the USA.

  13. West Nile Virus (WNV seroprevalence in a blood donors group of Milan

    Directory of Open Access Journals (Sweden)

    Giovanna Lunghi

    2012-09-01

    Full Text Available A seroprevalence study for anti West Nile virus was carried out among 864 healthy blood donors living in the metropolitan area of Milan by using a commercially available ELISA method. In addition, the performance of a novel ELISA assay for WNV antibodies was assessed. The sero-prevalence rate of WNV antibodies was 0.57% thus showing that WNV is likely circulating also in this up to now unknown area. The overall sensitivity and specificity of the novel ELISA were 99.9% and 45.4%, respectively, well comparable with that of the chosen reference immunoenzimatic method.

  14. West Nile Virus Infection in the Central Nervous System [version 1; referees: 3 approved

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    Evandro R. Winkelmann

    2016-01-01

    Full Text Available West Nile virus (WNV, a neurotropic single-stranded flavivirus has been the leading cause of arboviral encephalitis worldwide.  Up to 50% of WNV convalescent patients in the United States were reported to have long-term neurological sequelae.  Neither antiviral drugs nor vaccines are available for humans.  Animal models have been used to investigate WNV pathogenesis and host immune response in humans.  In this review, we will discuss recent findings from studies in animal models of WNV infection, and provide new insights on WNV pathogenesis and WNV-induced host immunity in the central nervous system.

  15. Serosurvey for West Nile Virus Antibodies in Steller's Jays ( Cyanocitta stelleri ) Captured in Coastal California, USA.

    Science.gov (United States)

    West, Elena; Hofmeister, Erik; Peery, M Zach

    2017-07-01

    West Nile virus (WNV) was first detected in New York in 1999 and, during its expansion across the continental US, southern Canada, and Mexico, members of the Corvidae (ravens, crows, magpies, and jays) were frequently infected and highly susceptible to the virus. As part of a behavioral study of Steller's Jays ( Cyanocitta stelleri ) conducted from 2011-14 in the coastal California counties of San Mateo and Santa Cruz, 380 Steller's Jays were captured and tested for antibodies to WNV. Using the wild bird immunoglobulin G enzyme linked immunoassay, we failed to detect antibodies to WNV, indicating either that there was no previous exposure to the virus or that exposed birds had died.

  16. West Nile virus lineage 2 infection in a blood donor from Vienna, Austria, August 2014.

    Science.gov (United States)

    Jungbauer, C; Hourfar, M K; Stiasny, K; Aberle, S W; Cadar, D; Schmidt-Chanasit, J; Mayr, W R

    2015-03-01

    Eastern Austria is neighbouring regions with ongoing West Nile virus (WNV) transmissions. Three human WNV infections had been diagnosed during the past decade in Austria. The Austrian Red Cross Blood Service (ARC-BS) started a first voluntary screening for WNV in blood donors from Eastern Austria by Nucleic Acid Testing (NAT) in June 2014. This is also the most extensive WNV surveillance programme in humans in Austria so far. In August 2014, one autochthonous WNV infection was detected in a blood donor from Vienna. By now, one in 67,800 whole blood donations was found to be positive for WNV RNA. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil

    Science.gov (United States)

    Melandri, Vanessa; Guimarães, Anthony Érico; Komar, Nicholas; Nogueira, Maurício L; Mondini, Adriano; Fernandez-Sesma, Ana; Alencar, Jeronimo; Bosch, Irene

    2016-01-01

    In an effort to detect West Nile virus (WNV) in Brazil, we sampled serum from horses and chickens from the Pantanal region of the state of Mato Grosso and tested for flavivirus-reactive antibodies by blocking ELISA. The positive samples were further confirmed for serological evidence of WNV infection in three (8%) of the 38 horses and one (3.2%) of the 31 chickens using an 80% plaque-reduction neutralisation test (PRNT80). These results provide evidence of the circulation of WNV in chickens and horses in Pantanal. PMID:23295763

  18. Immune Responses to West Nile Virus Infection in the Central Nervous System

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    Hyelim Cho

    2012-12-01

    Full Text Available West Nile virus (WNV continues to cause outbreaks of severe neuroinvasive disease in humans and other vertebrate animals in the United States, Europe, and other regions of the world. This review discusses our understanding of the interactions between virus and host that occur in the central nervous system (CNS, the outcome of which can be protection, viral pathogenesis, or immunopathogenesis. We will focus on defining the current state of knowledge of WNV entry, tropism, and host immune response in the CNS, all of which affect the balance between injury and successful clearance.

  19. Immune Responses to West Nile Virus Infection in the Central Nervous System

    Science.gov (United States)

    Cho, Hyelim; Diamond, Michael S.

    2012-01-01

    West Nile virus (WNV) continues to cause outbreaks of severe neuroinvasive disease in humans and other vertebrate animals in the United States, Europe, and other regions of the world. This review discusses our understanding of the interactions between virus and host that occur in the central nervous system (CNS), the outcome of which can be protection, viral pathogenesis, or immunopathogenesis. We will focus on defining the current state of knowledge of WNV entry, tropism, and host immune response in the CNS, all of which affect the balance between injury and successful clearance. PMID:23247502

  20. West Nile Virus Lineage 2 Associated with Human Case in Republic of Serbia.

    Science.gov (United States)

    Jovanović Galović, Aleksandra; Weyer, Jacqueline; Jansen van Vuren, Petrus; Paweska, Janusz T; Radovanov, Jelena; Kovačević, Gordana; Hrnjaković Cvjetković, Ivana; Petrović, Vladimir; Blumberg, Lucille H; Milošević, Vesna

    2017-11-01

    A suspicion on West Nile virus (WNV) in Serbia was first reported in 1972 by a seroprevalence study, after which no data were available for four decades. We report full sequence of the isolate obtained for the first time from a human sample in Serbia. The closest clustering was obtained with lineage 2 WNV identified in Greece in 2010. Since WNV lineage 2 emerged in Europe in 2004, a cocirculation of lineages 1 and 2-as observed in Hungary and Italy-cannot be excluded. The reinforcement of surveillance will be required to investigate the possible cocirculation of the two lineages and the burden of WNV in the local population.

  1. Serological Survey of West Nile Virus in Pet Dogs from Saskatchewan, Canada.

    Science.gov (United States)

    Gaunt, M Casey; Waldner, Cheryl; Taylor, Susan M

    2015-12-01

    Serum samples collected from 143 dogs from Saskatchewan, Canada, between 2008 and 2010 were evaluated for seroprevalence of West Nile virus (WNV). WNV antibodies were identified in 40/143 dogs (28%). Dogs that were primarily housed in the yard were 6.2 times (95% confidence interval [CI] 2.6-14.5) more likely to have antibodies than dogs housed in the house or garage. Dogs were more likely to be positive with increasing time spent outside. The results of this study document WNV seroprevalence in dogs from Saskatchewan and suggest that pet dogs might be useful as a sentinel species for WNV surveillance.

  2. Equine Immunoglobulin and Equine Neutralizing F(ab')₂ Protect Mice from West Nile Virus Infection.

    Science.gov (United States)

    Cui, Jiannan; Zhao, Yongkun; Wang, Hualei; Qiu, Boning; Cao, Zengguo; Li, Qian; Zhang, Yanbo; Yan, Feihu; Jin, Hongli; Wang, Tiecheng; Sun, Weiyang; Feng, Na; Gao, Yuwei; Sun, Jing; Wang, Yanqun; Perlman, Stanley; Zhao, Jincun; Yang, Songtao; Xia, Xianzhu

    2016-12-18

    West Nile virus (WNV) is prevalent in Africa, Europe, the Middle East, West Asia, and North America, and causes epidemic encephalitis. To date, no effective therapy for WNV infection has been developed; therefore, there is urgent need to find an efficient method to prevent WNV disease. In this study, we prepared and evaluated the protective efficacy of immune serum IgG and pepsin-digested F(ab')₂ fragments from horses immunized with the WNV virus-like particles (VLP) expressing the WNV M and E proteins. Immune equine F(ab')₂ fragments and immune horse sera efficiently neutralized WNV infection in tissue culture. The passive transfer of equine immune antibodies significantly accelerated the virus clearance in the spleens and brains of WNV infected mice, and reduced mortality. Thus, equine immunoglobulin or equine neutralizing F(ab')₂ passive immunotherapy is a potential strategy for the prophylactic or therapeutic treatment of patients infected with WNV.

  3. Detection of West Nile virus in wild birds in Tana River and Garissa Counties, Kenya.

    Science.gov (United States)

    Nyamwaya, Doris; Wang'ondu, Virginia; Amimo, Joshua; Michuki, George; Ogugo, Moses; Ontiri, Enoch; Sang, Rosemary; Lindahl, Johanna; Grace, Delia; Bett, Bernard

    2016-11-23

    West Nile fever virus is a zoonotic arboviral infection maintained in a sylvatic cycle involving mosquito vectors and birds. It is one the arboviruses whose geographical range is expanding because of climate and land use changes that enhance the densities of mosquitoes and promote mosquito-bird-human interactions. We carried out a survey to determine the reservoirs of WNV among wild birds in Tana River and Garissa counties, Kenya. Blood samples were obtained from 361 randomly trapped wild birds. Using real-time polymerase chain reaction (PCR), all samples were screened for WNV using gene specific primer sets amplifying a portion of the E region of the genome encoding the envelope protein. Sixty five (65) out of 361 birds screened tested positive for WNV on real-time PCR assay. Sequencing of the selected positive samples reveals that the isolated WNV were most closely related to strains isolated from China (2011). A regression analysis indicated that sampling location influenced the occurrence of WNV while species, age, weight and sex of the birds did not have any effect. This study provides baseline information on the existing circulation of WNV in this region among wild bird reservoirs that could spill over to the human population and points to the need for implementation of surveillance programs to map the distribution of the virus among reservoirs. Awareness creation about West Nile fever in this region is important to improve its detection and management.

  4. Impact of Climate and Environmental Factors on West Nile Virus Circulation in Iran

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    Farzaneh Ahmadnejad

    2016-01-01

    Full Text Available Background: Geographic distribution of West Nile virus (WNV is heterogeneous in Iran by a high circulation in the southern-western areas. The objective of our study was to determine environmental and climatic factors associ­ated with the risk of WNV equine seropositivity in Iran.Methods: Serological data were obtained from a serosurvey conducted in equine population in 260 districts in Iran. The climate and environmental parameters included in the models were distance to the nearest wetland area, type of stable, Normalized Difference Vegetation Index (NDVI, annual mean temperature, humidity and precipitation.Results: The important risk factors included annual mean temperature, distance to wetlands, local and seasonal NDVI differences. The effect of local NDVI differences in spring was particularly notable. This was a normalized difference of average NDVI between two areas: a 5 km radius area centered on the stable and the 5–10 km sur­rounding area.Conclusion: The model indicated that local NDVI’s contrast during spring is a major risk factor of the transmission of West-Nile virus in Iran. This so-called oasis effect consistent with the seasonal production of vegetation in spring, and is associated to the attractiveness of the local NDVI environment for WNV vectors and hosts.  

  5. Association of West Nile virus illness and urban landscapes in Chicago and Detroit

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    Haramis Linn D

    2007-03-01

    Full Text Available Abstract Background West Nile virus infection in humans in urban areas of the Midwestern United States has exhibited strong spatial clustering during epidemic years. We derived urban landscape classes from the physical and socio-economic factors hypothesized to be associated with West Nile Virus (WNV transmission and compared those to human cases of illness in 2002 in Chicago and Detroit. The objectives were to improve understanding of human exposure to virus-infected mosquitoes in the urban context, and to assess the degree to which environmental factors found to be important in Chicago were also found in Detroit. Results Five urban classes that partitioned the urban space were developed for each city region. The classes had many similarities in the two settings. In both regions, the WNV case rate was considerably higher in the urban class associated with the Inner Suburbs, where 1940–1960 era housing dominates, vegetation cover is moderate, and population density is moderate. The land cover mapping approach played an important role in the successful and consistent classification of the urban areas. Conclusion The analysis demonstrates how urban form and past land use decisions can influence transmission of a vector-borne virus. In addition, the results are helpful to develop hypotheses regarding urban landscape features and WNV transmission, they provide a structured method to stratify the urban areas to locate representative field study sites specifically for WNV, and this analysis contributes to the question of how the urban environment affects human health.

  6. Inhibition of West Nile virus multiplication in cell culture by anti-parkinsonian drugs

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    Ana Belen Blazquez

    2016-03-01

    Full Text Available West Nile virus (WNV is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin and Amantadine, that are used as therapy for Parkinson´s disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection.

  7. West Nile virus surveillance in Europe: moving towards an integrated animal-human-vector approach.

    Science.gov (United States)

    Gossner, Céline M; Marrama, Laurence; Carson, Marianne; Allerberger, Franz; Calistri, Paolo; Dilaveris, Dimitrios; Lecollinet, Sylvie; Morgan, Dilys; Nowotny, Norbert; Paty, Marie-Claire; Pervanidou, Danai; Rizzo, Caterina; Roberts, Helen; Schmoll, Friedrich; Van Bortel, Wim; Gervelmeyer, Andrea

    2017-05-04

    This article uses the experience of five European countries to review the integrated approaches (human, animal and vector) for surveillance and monitoring of West Nile virus (WNV) at national and European levels. The epidemiological situation of West Nile fever in Europe is heterogeneous. No model of surveillance and monitoring fits all, hence this article merely encourages countries to implement the integrated approach that meets their needs. Integration of surveillance and monitoring activities conducted by the public health authorities, the animal health authorities and the authorities in charge of vector surveillance and control should improve efficiency and save resources by implementing targeted measures. The creation of a formal interagency working group is identified as a crucial step towards integration. Blood safety is a key incentive for public health authorities to allocate sufficient resources for WNV surveillance, while the facts that an effective vaccine is available for horses and that most infected animals remain asymptomatic make the disease a lesser priority for animal health authorities. The examples described here can support other European countries wishing to strengthen their WNV surveillance or preparedness, and also serve as a model for surveillance and monitoring of other (vector-borne) zoonotic infections. This article is copyright of The Authors, 2017.

  8. Prevalence of West Nile virus in migratory birds during spring and fall migration

    Science.gov (United States)

    Dusek, Robert J.; McLean, R.G.; Kramer, L.D.; Ubico, S.R.; Dupuis, A.P.; Ebel, G.D.; Guptill, S.C.

    2009-01-01

    To investigate the role of migratory birds in the dissemination of West Nile virus (WNV), we measured the prevalence of infectious WNV and specific WNV neutralizing antibodies in birds, principally Passeriformes, during spring and fall migrations in the Atlantic and Mississippi flyways from 2001-2003. Blood samples were obtained from 13,403 birds, representing 133 species. Specific WNV neutralizing antibody was detected in 254 resident and migratory birds, representing 39 species, and was most commonly detected in northern cardinals (Cardinalis cardinalis) (9.8%, N = 762) and gray catbirds (Dumetella carolinensis) (3.2%,N = 3188). West Nile virus viremias were detected in 19 birds, including 8 gray catbirds, and only during the fall migratory period. These results provide additional evidence that migratory birds may have been a principal agent for the spread of WNV in North America and provide data on the occurrence of WNV in a variety of bird species. Copyright ?? 2009 by The American Society of Tropical Medicine and Hygiene.

  9. Epidemiology of West Nile Disease in Europe and in the Mediterranean Basin from 2009 to 2013

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    Daria Di Sabatino

    2014-01-01

    Full Text Available West Nile virus (WNV transmission has been confirmed in the last four years in Europe and in the Mediterranean Basin. An increasing concern towards West Nile disease (WND has been observed due to the high number of human and animal cases reported in these areas confirming the importance of this zoonosis. A new epidemiological scenario is currently emerging: although new introductions of the virus from abroad are always possible, confirming the epidemiological role played by migratory birds, the infection endemisation in some European territories today is a reality supported by the constant reoccurrence of the same strains across years in the same geographical areas. Despite the WND reoccurrence in the Old World, the overwintering mechanisms are not well known, and the role of local resident birds or mosquitoes in this context is poorly understood. A recent new epidemiological scenario is the spread of lineage 2 strain across European and Mediterranean countries in regions where lineage 1 strain is still circulating creating favourable conditions for genetic reassortments and emergence of new strains. This paper summarizes the main epidemiological findings on WNV occurrence in Europe and in the Mediterranean Basin from 2009 to 2013, considering potential future spread patterns.

  10. Identification of Suitable Areas for West Nile Virus Circulation in Tunisia.

    Science.gov (United States)

    Ben Hassine, T; Conte, A; Calistri, P; Candeloro, L; Ippoliti, C; De Massis, F; Danzetta, M L; Bejaoui, M; Hammami, S

    2017-04-01

    West Nile virus (WNV) is a mosquito-transmitted Flavivirus belonging to the Japanese encephalitis antigenic complex of the Flaviviridae family. It is transmitted primarily by the bite of infected mosquitoes, particularly Culex spp. and Aedes/Ochlerotatus spp., which acquire the virus by feeding on viraemic birds. Humans, horses and other mammals are regarded as incidental or dead-end hosts. In the last decades, an increasing number of cases of WNV infection in horses and humans have been notified in the Mediterranean basin. In Tunisia, human cases of WNV-related meningoencephalitis were detected in 1997, 2003, 2007, 2010, 2011 and 2012. Based on the analysis of climatic and environmental conditions found in the locations where human cases have been reported in 2012, the aim of this study was to identify similar areas in Tunisia potentially at risk of disease occurrence. Data related to 85 neuroinvasive West Nile fever (WNF) human cases were georeferenced and a set of environmental and climatic variables (wetlands and humid areas, normalized difference vegetation index (NDVI), temperatures and elevation, migratory bird settlements) were used in the analysis. Areas, ecologically similar to those where human cases were detected, were identified using the Mahalanobis distance statistic. A leave-one-out cross-validation was performed to validate the sensitivity of the model, and 78 of 85 points were correctly classified. © 2015 Blackwell Verlag GmbH.

  11. A continental risk assessment of West Nile virus under climate change.

    Science.gov (United States)

    Harrigan, Ryan J; Thomassen, Henri A; Buermann, Wolfgang; Smith, Thomas B

    2014-08-01

    Since first introduced to North America in 1999, West Nile virus (WNV) has spread rapidly across the continent, threatening wildlife populations and posing serious health risks to humans. While WNV incidence has been linked to environmental factors, particularly temperature and rainfall, little is known about how future climate change may affect the spread of the disease. Using available data on WNV infections in vectors and hosts collected from 2003-2011 and using a suite of 10 species distribution models, weighted according to their predictive performance, we modeled the incidence of WNV under current climate conditions at a continental scale. Models were found to accurately predict spatial patterns of WNV that were then used to examine how future climate may affect the spread of the disease. Predictions were accurate for cases of human WNV infection in the following year (2012), with areas reporting infections having significantly higher probability of presence as predicted by our models. Projected geographic distributions of WNV in North America under future climate for 2050 and 2080 show an expansion of suitable climate for the disease, driven by warmer temperatures and lower annual precipitation that will result in the exposure of new and naïve host populations to the virus with potentially serious consequences. Our risk assessment identifies current and future hotspots of West Nile virus where mitigation efforts should be focused and presents an important new approach for monitoring vector-borne disease under climate change. © 2014 John Wiley & Sons Ltd.

  12. Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs.

    Science.gov (United States)

    Blázquez, Ana B; Martín-Acebes, Miguel A; Saiz, Juan-Carlos

    2016-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin, and Amantadine), that are used as therapy for Parkinson's disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection.

  13. West Nile Virus in the United States — A Historical Perspective

    Directory of Open Access Journals (Sweden)

    John T. Roehrig

    2013-12-01

    Full Text Available Prior to 1999, West Nile virus (WNV was a bit player in the screenplay of global vector-borne viral diseases. First discovered in the West Nile District of Uganda in 1937, this Culex sp.-transmitted virus was known for causing small human febrile outbreaks in Africa and the Middle East. Prior to 1995, the last major human WNV outbreak was in the 1950s in Israel. The epidemiology and ecology of WNV began to change in the mid-1990s when an epidemic of human encephalitis occurred in Romania. The introduction of WNV into Eastern Europe was readily explained by bird migration between Africa and Europe. The movement of WNV from Africa to Europe could not, however, predict its surprising jump across the Atlantic Ocean to New York City and the surrounding areas of the United States (U.S.. This movement of WNV from the Eastern to Western Hemisphere in 1999, and its subsequent dissemination throughout two continents in less than ten years is widely recognized as one of the most significant events in arbovirology during the last two centuries. This paper documents the early events of the introduction into and the spread of WNV in the Western Hemisphere.

  14. Changes in West Nile virus seroprevalence and antibody titers among Wisconsin mesopredators 2003-2006.

    Science.gov (United States)

    Docherty, Douglas E; Samuel, Michael D; Egstad, Kristina F; Griffin, Kathryn M; Nolden, Cherrie A; Karwal, Lovkesh; Ip, Hon S

    2009-07-01

    After the 2001 occurrence of West Nile virus (WNV) in Wisconsin (WI), we collected sera, during 2003-2006, from south-central WI mesopredators. We tested these sera to determine WNV antibody prevalence and geometric mean antibody titer (GMAT). Four-fold higher antibody prevalence and 2-fold higher GMAT in 2003-2004 indicated greater exposure of mesopredators to WNV during the apparent epizootic phase. The period 2005-2006 was likely the enzootic phase because WNV antibody prevalence fell to a level similar to other flaviviruses. Our results suggest that, in mesopredators, vector-borne transmission is the primary route of infection and WNV antibodies persist for < 1 year. Mesopredators may be sensitive indicators of West Nile virus spill-over into humans and horses. Mesopredator sero-surveys may complement dead crow surveillance by providing additional data for the timing of public health interventions. Research is needed to clarify the dynamics of WNV infection in these mammals and their role as potential WNV amplifiers.

  15. Review of West Nile virus circulation and outbreak risk in Madagascar: Entomological and ornithological perspectives

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    Tantely Michaël Luciano

    2016-01-01

    Full Text Available West Nile fever (WNF is a zoonotic disease, occurring nearly globally. In Madagascar, West Nile virus (WNV was first detected in 1978 from wild birds and the virus is currently distributed across the island, but no epidemic or epizootic period has been recorded. One fatal human case of WNV infection was reported in 2011, suggesting a “tip of the iceberg” phenomenon of a possible WNF epidemic/epizootic on the island. The main objective of this literature-based survey is to review patterns of WNV circulation in Madagascar from the entomological and ornithological points of view. Among the 235 mosquito species described from Madagascar, 29 species are widely associated with WNV infection; 16 of them are found naturally infected with WNV on the island and categorized into major, candidate, and potential vectors of WNV according to their vector capacity. This study upholds the hypothesis that WNV enzooticity is independent of annual movements of migratory birds passing through Madagascar. Moreover, the lack of regular migratory bird flux between Africa and Madagascar would reduce the probability of transmission and the subsequent reintroduction of the virus into locally occurring mosquito species. Given that Palearctic migratory birds are strongly implicated in the transmission of WNV, we highlight notable differences in the movements and species diversity of these birds in Madagascar as compared to eastern and northern Africa. Risk factors from this two-pronged approach are presented for the emergence of WNF outbreak.

  16. Review of West Nile virus circulation and outbreak risk in Madagascar: Entomological and ornithological perspectives.

    Science.gov (United States)

    Tantely, Michaël Luciano; Goodman, Steven M; Rakotondranaivo, Tsirinaina; Boyer, Sébastien

    2016-01-01

    West Nile fever (WNF) is a zoonotic disease, occurring nearly globally. In Madagascar, West Nile virus (WNV) was first detected in 1978 from wild birds and the virus is currently distributed across the island, but no epidemic or epizootic period has been recorded. One fatal human case of WNV infection was reported in 2011, suggesting a "tip of the iceberg" phenomenon of a possible WNF epidemic/epizootic on the island. The main objective of this literature-based survey is to review patterns of WNV circulation in Madagascar from the entomological and ornithological points of view. Among the 235 mosquito species described from Madagascar, 29 species are widely associated with WNV infection; 16 of them are found naturally infected with WNV on the island and categorized into major, candidate, and potential vectors of WNV according to their vector capacity. This study upholds the hypothesis that WNV enzooticity is independent of annual movements of migratory birds passing through Madagascar. Moreover, the lack of regular migratory bird flux between Africa and Madagascar would reduce the probability of transmission and the subsequent reintroduction of the virus into locally occurring mosquito species. Given that Palearctic migratory birds are strongly implicated in the transmission of WNV, we highlight notable differences in the movements and species diversity of these birds in Madagascar as compared to eastern and northern Africa. Risk factors from this two-pronged approach are presented for the emergence of WNF outbreak. © M.L. Tantely et al., published by EDP Sciences, 2016.

  17. Declining mortality in American crow (Corvus brachyrhynchos) following natural West Nile virus infection.

    Science.gov (United States)

    Reed, Lisa M; Johansson, Michael A; Panella, Nicholas; McLean, Robert; Creekmore, Terry; Puelle, Rose; Komar, Nicholas

    2009-09-01

    The American crow (Corvus brachyrhynchos) is known to suffer 100% mortality from infection with the New York 1999 strain of West Nile virus (WNV). Following the initial detection of WNV in North America in 1999, we measured prevalence of WNV-reactive antibodies ("seroprevalence") in free-ranging American and fish crows (Corvus ossifragus) of central New Jersey after each transmission season through 2005. In 2002, seroprevalence in American crow juveniles increased to 14% from the 5% of the previous year, potentially indicating increased survival in this species. Using the annual seroprevalence measurements and the number of human West Nile neuroinvasive disease cases as a surrogate for WNV transmission intensity, we developed a model to estimate the annual WNV-associated mortality rates among both of these crow species. Our model supports the hypothesis that mortality is changing over time; the WNV-associated mortality rate declined over time by 1.5% for American crow and by 1.1% for fish crow. The probability that the trend in mortality was negative was 90% for the American crow and 60% for the fish crow.

  18. Dynamics of West Nile virus persistence in House Sparrows (Passer domesticus).

    Science.gov (United States)

    Wheeler, Sarah S; Vineyard, Meighan P; Woods, Leslie W; Reisen, William K

    2012-01-01

    West Nile Virus (WNV) is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi) when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13) positive at 3 weeks post-infection (pi) to 12.5% (n = 8) at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle.

  19. The impact of West Nile virus on the abundance of selected North American birds

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    Beard Raphaelle H

    2011-08-01

    Full Text Available Abstract Background The emergence of West Nile virus (WNV in North America has been associated with high mortality in the native avifauna and has raised concerns about the long-term impact of WNV on bird populations. Here, we present results from a longitudinal analysis of annual counts of six bird species, using North American Breeding Bird Survey data from ten states (1994 to 2010. We fit overdispersed Poisson models to annual counts. Counts from successive years were linked by an autoregressive process that depended on WNV transmission intensity (annual West Nile neuroinvasive disease reports and was adjusted by El Niño Southern Oscillation events. These models were fit using a Markov chain Monte Carlo algorithm. Results Model fit was mostly excellent, especially for American Crows, for which our models explained between 26% and 81% of the observed variance. The impact of WNV on bird populations was quantitatively evaluated by contrasting hypothetical count trajectories (omission of WNV with observed counts. Populations of American crows were most consistently affected with a substantial cumulative impact in six of ten states. The largest negative impact, almost 60%, was found in Illinois. A regionally substantial decline was also seen for American Robins and House Sparrows, while the other species appeared unaffected. Conclusions Our results confirm findings from previous studies that single out American Crows as the species most vulnerable to WNV infection. We discuss strengths and limitations of this and other methods for quantifying the impact of WNV on bird populations.

  20. Dynamics of West Nile virus persistence in House Sparrows (Passer domesticus.

    Directory of Open Access Journals (Sweden)

    Sarah S Wheeler

    Full Text Available West Nile Virus (WNV is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13 positive at 3 weeks post-infection (pi to 12.5% (n = 8 at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle.

  1. Ecology of West Nile Fever across four European countries: Review of weather profiles, vector population dynamics and vector control response

    Science.gov (United States)

    West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause large unforeseen epidemics. Until 2004, only lineage 1 and 3 WNV strains had been found in Europe. Lineage 2 strains were initially isolated in 2004 (Hungary), again in 2008 (Austria), and f...

  2. Comparison of assays for the detection of West Nile virus antibodies in equine serum after natural infection or vaccination

    Czech Academy of Sciences Publication Activity Database

    Joó, K.; Bakonyi, T.; Szenci, O.; Ferenczi, E.; Barna, M.; Malik, P.; Hubálek, Zdeněk; Fehér, O.; Kutasi, O.

    2017-01-01

    Roč. 183, č. 1 (2017), s. 1-6 ISSN 0165-2427 Institutional support: RVO:68081766 Keywords : West Nile virus * Haemagglutination-inhibition test * Enzymelinked immunosorbent assay * Plaque reduction neutralization test * Vaccination * Natural infection Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 1.718, year: 2016

  3. Vector competence of northern European Culex pipiens biotypes and hybrids for West Nile virus is differentially affected by temperature

    NARCIS (Netherlands)

    Vogels, Chantal B.F.; Fros, Jelke J.; Goertz, Giel; Pijlman, Gorben P.; Koenraadt, Sander

    2016-01-01

    Background: Outbreaks of West Nile virus (WNV) have not occurred in northern Europe despite nearby circulation of WNV in the southern part of the continent. The main vector for WNV, the mosquito Culex (Cx.) pipiens, consists of two behaviorally distinct biotypes, pipiens and molestus, which can

  4. Winter Activity and Aboveground Hybridization Between the Two Biotypes of the West Nile Virus Vector Culex pipiens

    NARCIS (Netherlands)

    Vogels, C.B.F.; Peppel, van de L.J.J.; Vliet, van A.J.H.; Westenberg, M.; Ibanez-Justicia, A.; Stroo, A.; Buijs, J.A.; Visser, T.M.; Koenraadt, C.J.M.

    2015-01-01

    Culex (Cx.) pipiens mosquitoes are important vectors of West Nile virus (WNV). In Europe, the species Cx. pipiens consists of two biotypes, pipiens and molestus, which are morphologically identical, but differ in behavior. Typical behavior of the molestus biotype is the ability to remain active

  5. West Nile virus and hemoparasites in captive snowy owls (Bubo scandiacus)--management strategies to optimize survival.

    Science.gov (United States)

    Harasym, Carol A

    2008-11-01

    In August 2005, 2 members of a group of 6 captive snowy owls (Bubo scandiacus) in central Saskatchewan died of West Nile virus infection. One of these owls and 3 of the remaining owls had significant numbers of circulating hemoparasites. Management strategies are suggested to reduce morbidity and mortality.

  6. West Nile virus and hemoparasites in captive snowy owls (Bubo scandiacus) — management strategies to optimize survival

    Science.gov (United States)

    Harasym, Carol A.

    2008-01-01

    In August 2005, 2 members of a group of 6 captive snowy owls (Bubo scandiacus) in central Saskatchewan died of West Nile virus infection. One of these owls and 3 of the remaining owls had significant numbers of circulating hemoparasites. Management strategies are suggested to reduce morbidity and mortality. PMID:19183740

  7. West Nile virus and hemoparasites in captive snowy owls (Bubo scandiacus) — management strategies to optimize survival

    OpenAIRE

    Harasym, Carol A.

    2008-01-01

    In August 2005, 2 members of a group of 6 captive snowy owls (Bubo scandiacus) in central Saskatchewan died of West Nile virus infection. One of these owls and 3 of the remaining owls had significant numbers of circulating hemoparasites. Management strategies are suggested to reduce morbidity and mortality.

  8. Immunogenicity and protective efficacy of recombinant Modified Vaccinia virus Ankara candidate vaccines delivering West Nile virus envelope antigens

    NARCIS (Netherlands)

    Volz, Asisa; Lim, Stephanie; Kaserer, Martina; Pijlman, Gorben P.

    2016-01-01

    West Nile virus (WNV) cycles between insects and wild birds, and is transmitted via mosquito vectors to horses and humans, potentially causing severe neuroinvasive disease. Modified Vaccinia virus Ankara (MVA) is an advanced viral vector for developing new recombinant vaccines against infectious

  9. Climatic, ecological, and socioeconomic factors associated with West Nile virus incidence in Atlanta, Georgia, U.S.A.

    Science.gov (United States)

    Graeme Lockaby; Navideh Noori; Wayde Morse; Wayne Zipperer; Latif Kalin; Robin Governo; Rajesh Sawant; Matthew Ricker

    2016-01-01

    The integrated effects of the many risk factors associated with West Nile virus (WNV) incidence are complex and notwell understood. We studied an array of risk factors in and around Atlanta, GA, that have been shown to be linked with WNV inother locations. This array was comprehensive and included climate and meteorological metrics, vegetation...

  10. A spatiotemporal model of ecological and sociological predictors of West Nile virus in Suffolk County, NY mosquitoes

    Science.gov (United States)

    Background/Question/Methods Suffolk County, New York is a locus for West Nile virus (WNV) infection in the American northeast that includes the majority of Long Island to the east of New York City. The county has a robust system of light and gravid traps used for mosquito collect...

  11. Pathogenicity of West Nile virus and response to vaccination in sandhill cranes (Grus canadensis) using a killed vaccine

    Science.gov (United States)

    Olsen, Glenn H.; Miller, Kimberli J.; Docherty, Douglas E.; Shearn-Bochsler, Valerie I.; Sileo, Louis

    2009-01-01

    West Nile virus was introduced into the United States in the vicinity of New York, New York, USA in 1999. The virus has since killed large numbers of birds nationwide, especially, but not limited to, crows (Corvus brachyrhinchos). One sandhill crane (Grus canadensis) at the Bridgeport Zoo (Bridgeport, Connecticut, USA) reportedly died from West Nile virus, so sandhill cranes and endangered whooping cranes (Grus americana), both in the wild and in captive breeding colonies at United States Geological Service (USGS) Patuxent Wildlife Research Center (Laurel, Maryland, USA) were considered at risk. A killed vaccine in sandhill cranes was evaluated by vaccinating and then challenging these cranes with live West Nile virus. No sandhill cranes inoculated with the killed vaccine developed significant titers when compared with unvaccinated controls. No sandhill cranes inoculated with the vaccine and challenged with the virus died from West Nile virus infection. In addition, no unvaccinated challenged sandhill cranes died. However, 2 days postchallenge, vaccinated cranes had significantly less viremia (P virus (P < 0.05) than unvaccinated cranes and significantly less weight loss (P < 0.05) as compared with unvaccinated cranes. Vaccinated sandhill cranes developed significantly higher titers 14 days postchallenge and were viremic for shorter periods of time after challenge than unvaccinated individuals. Unvaccinated challenged cranes had glial cell aggregates in both the brain and brain stem areas, and this was not observed in vaccinated challenged cranes or in vaccinated unchallenged cranes.

  12. Assessing human risk of illness with West Nile virus mosquito surveillance data to improve public health preparedness

    Science.gov (United States)

    Surveillance for West Nile virus (WNV) and other mosquito-borne pathogens involves costly and time-consuming collection and testing of mosquito samples. One difficulty faced by public health personnel is how to interpret mosquito data relative to human risk, thus leading to a failure to fully exploi...

  13. Safety and efficacy in geese of a PER.C6-based inactivated West Nile virus vaccine

    NARCIS (Netherlands)

    Samina, Itzchak; Havenga, Menzo; Koudstaal, Wouter; Khinich, Yevgeny; Koldijk, Martin; Malkinson, Mertyn; Simanov, Michael; Perl, Shmuel; Gijsbers, Linda; Weverling, Gerrit Jan; Uytdehaag, Fons; Goudsmit, Jaap

    2007-01-01

    Studies were performed with an inactivated vaccine against the mosquito-borne flavivirus, West Nile virus (WNV). The mammalian cell line, PER.C6, was selected as the platform for WNV growth since both the neurovirulent strains NY99 and ISR98 that cause epidemics in humans and high mortality in

  14. Infection with non-lethal West Nile virus Eg101 strain induces immunity that protects mice against the lethal West Nile virus NY99 strain.

    Science.gov (United States)

    Kumar, Mukesh; O'Connell, Maile; Namekar, Madhuri; Nerurkar, Vivek R

    2014-06-06

    Herein we demonstrate that infection of mice with West Nile virus (WNV) Eg101 provides protective immunity against lethal challenge with WNV NY99. Our data demonstrated that WNV Eg101 is largely non-virulent in adult mice when compared to WNV NY99. By day 6 after infection, WNV-specific IgM and IgG antibodies, and neutralizing antibodies were detected in the serum of all WNV Eg101 infected mice. Plaque reduction neutralization test data demonstrated that serum from WNV Eg101 infected mice neutralized WNV Eg101 and WNV NY99 strains with similar efficiency. Three weeks after infection, WNV Eg101 immunized mice were challenged subcutaneously or intracranially with lethal dose of WNV NY99 and observed for additional three weeks. All the challenged mice were protected against disease and no morbidity and mortality was observed in any mice. In conclusion, our data for the first time demonstrate that infection of mice with WNV Eg101 induced high titers of WNV specific IgM and IgG antibodies, and cross-reactive neutralizing antibodies, and the resulting immunity protected all immunized animals from both subcutaneous and intracranial challenge with WNV NY99. These observations suggest that WNV Eg101 may be a suitable strain for the development of a vaccine in humans against virulent strains of WNV.

  15. Potential for Waterborne and Invertebrate Transmission of West Nile Virus in the Great Salt Lake, Utah.

    Science.gov (United States)

    Lund, Melissa; Shearn-Bochsler, Valerie; Dusek, Robert J; Shivers, Jan; Hofmeister, Erik

    2017-07-15

    In November and December of 2013, a large mortality event involving 15,000 to 20,000 eared grebes ( Podiceps nigricollis ) occurred at the Great Salt Lake (GSL), UT. The onset of the outbreak in grebes was followed by a mortality event in >86 bald eagles ( Haliaeetus leucocephalus ). During the die-off, West Nile virus (WNV) was detected by reverse transcription-PCR (RT-PCR) or viral culture in the carcasses of grebes and eagles submitted to the National Wildlife Health Center. However, no activity of mosquitoes, the primary vectors of WNV, was detected by the State of Utah's WNV monitoring program. The transmission of WNV has rarely been reported during the winter in North America in the absence of known mosquito activity; however, the size of this die-off, the habitat in which it occurred, and the species involved are unique. We experimentally investigated whether WNV could survive in water with a high salt content, as found at the GSL, and whether brine shrimp, the primary food of migrating eared grebes on the GSL, could have played a role in the transmission of WNV to feeding birds. We found that WNV can survive up to 72 h at 4°C in water containing 30 to 150 ppt NaCl, and brine shrimp incubated with WNV in 30 ppt NaCl may adsorb WNV to their cuticle and, through feeding, infect epithelial cells of their gut. Both mechanisms may have potentiated the WNV die-off in migrating eared grebes on the GSL. IMPORTANCE Following a major West Nile virus die-off of eared grebes and bald eagles at the Great Salt Lake (GSL), UT, in November to December 2013, this study assessed the survival of West Nile virus (WNV) in water as saline as that of the GSL and whether brine shrimp, the major food for migrating grebes, could have played a role as a vector for the virus. While mosquitoes are the major vector of WNV, under certain circumstances, transmission may occur through contaminated water and invertebrates as food. Copyright © 2017 American Society for Microbiology.

  16. An outbreak of West Nile Virus infection in the region of Monastir, Tunisia, 2003

    Science.gov (United States)

    Riabi, Samira; Gaaloul, Imed; Mastouri, Maha; Hassine, Mohsen; Aouni, Mahjoub

    2014-01-01

    Background A West Nile (WN) fever epidemic occurred in the region of Monastir, Tunisia, between August and October 2003. Aim of the study We attempt to describe the epidemiology, clinical presentation, and outcome of patients with confirmed West Nile virus (WNV) infection. Methods Three groups of specimens were prepared. One was made up of serum only (n  =  43), the other of cerebrospinal fluid (CSF) only (n  =  30), and the third group was made up of both (n  =  40). These specimens were obtained from 113 patients. A serological diagnosis and evidence of WNV genome by nested reverse-transcriptase polymerase chain reaction (nRT-PCR) and TaqMan reverse transcription-polymerase chain reaction (RT-PCR) were carried out. Results Thirty-eight cases (33.6%) were serologically positive. Results of nRT-PCR showed a total of 10 positive cases of WNV (8.8%) detected in group 1 (n  =  1/43), group 2 (n  =  5/30), and group 3 (n  =  4/40) whereas the PCR TaqMan showed 18 positive samples (15.9%) found in group 1 (n  =  3/43), group 2 (n  =  9/30), and group 3 (n  =  6/40). All TaqMan PCR positive cases were nRT-PCR positive. In addition, four serologically probable cases were confirmed by TaqMan PCR. The attempts to isolate WNV by cell culture were unsuccessful. Considering the results of TaqMan assay and the serological diagnosis, WNV infection was confirmed in a total of 42 patients. The main clinical presentations were meningoencephalitis (40%), febrile disease (95%), and meningitis (36%). Eight patients (19%) died. The highest case-fatality rates occurred among patients aged ≧55 years. The phylogenetic analysis revealed that isolates of WNV were closely related to the Tunisian strain 1997 (PAH001) and the Israeli one (Is-98). Conclusions West Nile virus is a reemerging global pathogen that remains an important public health challenge in the next decade. PMID:24766339

  17. Identification of Climatic Factors Affecting the Epidemiology of Human West Nile Virus Infections in Northern Greece.

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    Nikolaos I Stilianakis

    Full Text Available Climate can affect the geographic and seasonal patterns of vector-borne disease incidence such as West Nile Virus (WNV infections. We explore the association between climatic factors and the occurrence of West Nile fever (WNF or West Nile neuro-invasive disease (WNND in humans in Northern Greece over the years 2010-2014. Time series over a period of 30 years (1979-2008 of climatic data of air temperature, relative humidity, soil temperature, volumetric soil water content, wind speed, and precipitation representing average climate were obtained utilising the ECMWF's (European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim system allowing for a homogeneous set of data in time and space. We analysed data of reported human cases of WNF/WNND and Culex mosquitoes in Northern Greece. Quantitative assessment resulted in identifying associations between the above climatic variables and reported human cases of WNF/WNND. A substantial fraction of the cases was linked to the upper percentiles of the distribution of air and soil temperature for the period 1979-2008 and the lower percentiles of relative humidity and soil water content. A statistically relevant relationship between the mean weekly value climatic anomalies of wind speed (negative association, relative humidity (negative association and air temperature (positive association over 30 years, and reported human cases of WNF/WNND during the period 2010-2014 could be shown. A negative association between the presence of WNV infected Culex mosquitoes and wind speed could be identified. The statistically significant associations could also be confirmed for the week the WNF/WNND human cases appear and when a time lag of up to three weeks was considered. Similar statistically significant associations were identified with the weekly anomalies of the maximum and minimum values of the above climatic factors. Utilising the ERA-Interim re-analysis methodology it could be shown that besides

  18. Use of laboratory reports as predictors of West Nile virus disease cases, Texas, 2008-2012.

    Science.gov (United States)

    Yendell, S J; Taylor, J; Biggerstaff, B J; Tabony, L; Staples, J E; Fischer, M

    2015-01-01

    We evaluated laboratory reports as early indicators of West Nile virus (WNV) disease cases in Texas. We compared WNV laboratory results in the National Electronic Disease Surveillance System Base System (NBS) to WNV disease cases reported to the state health department from 2008 to 2012. We calculated sensitivity and positive predictive value (PPV) of NBS reports, estimated the number of disease cases expected per laboratory report, and determined lead and lag times. The sensitivity and PPV of NBS laboratory reports were 86% and 77%, respectively. For every 10 positive laboratory reports, we expect 9·0 (95% confidence interval 8·9-9·2) reported disease cases. Laboratory reports preceded case reports with a lead time of 7 days. Electronic laboratory reports provided longer lead times than manually entered reports (P < 0·01). NBS laboratory reports are useful estimates of future reported WNV disease cases and may provide timely information for planning public health interventions.

  19. Innate immune evasion by hepatitis C virus and West Nile virus

    Science.gov (United States)

    Keller, Brian C; Johnson, Cynthia L.; Erickson, Andrea Kaup; Gale, Michael

    2009-01-01

    Antiviral immunity in mammals involves several levels of surveillance and effector actions by host factors to detect viral pathogens, trigger α/β interferon production, and to mediate innate defenses within infected cells. Our studies have focused on understanding how these processes are regulated during infection by hepatitis C virus (HCV) and West Nile virus (WNV). Both viruses are members of the Flaviviridae and are human pathogens but they each mediate a very different disease and course of infection. Our results demonstrate common and unique innate immune interactions of each virus that govern antiviral immunity, and demonstrate the central role of α/β interferon immune defenses in controlling the outcome of infection. PMID:17702639

  20. Severe neuroinvasive West Nile virus infection in a child with undiagnosed Addison's disease

    Directory of Open Access Journals (Sweden)

    Kevin Messacar

    2014-01-01

    Full Text Available This report describes a case of West Nile virus (WNV meningoencephalitis in a child who presented with fever, headache, seizures, and altered mental status, as well as hyponatremia and bronzing of the skin. Findings that led to the diagnosis of WNV included plasma-cell pleocytosis of the cerebrospinal fluid (CSF and linear chorioretinitis on ophthalmologic exam. The diagnosis was confirmed by a positive serum and CSF WNV IgM. The acute WNV infection triggered an adrenal crisis which uncovered a new diagnosis of underlying Addison's disease. This is the first case report of severe neuroinvasive WNV disease in a pediatric patient with primary adrenal insufficiency. Neuroinvasive WNV disease is uncommon in children, but may have a more severe presentation in those with certain underlying medical conditions.

  1. Low Seroprevalence of West Nile Virus in Blood Donors from Catalonia, Spain.

    Science.gov (United States)

    Piron, Maria; Plasencia, Antoni; Fleta-Soriano, Eric; Martinez, Ana; Martinez, Javier P; Torner, Nuria; Sauleda, Silvia; Meyerhans, Andreas; Escalé, Josefina; Trilla, Antoni; Pumarola, Tomás; Martinez, Miguel Julian

    2015-12-01

    West Nile virus (WNV) is an emerging arbovirus first recognized in Europe in the 1950s. Since then, outbreaks have been reported in several European countries. In 2010, the first WNV outbreak was recorded in Spain, affecting the southern part of the country. We conducted a seroprevalence study in the Catalonia region (northeastern Spain), an area considered at high risk of arbovirus transmission. A total of 800 serum samples from blood donors were collected and screened for antibodies against WNV by enzyme-linked immunosorbent assay (ELISA) and confirmed by a microneutralization assay. More than 50 samples tested positive by ELISA, but only one sample contained neutralizing antibodies against WNV and was obtained from a donor native of Pakistan. The low seroprevalence detected may serve as reference baseline data for monitoring WNV activity in our region in future years.

  2. Experimental infection of North American birds with the New York 1999 strain of West Nile virus.

    Science.gov (United States)

    Komar, Nicholas; Langevin, Stanley; Hinten, Steven; Nemeth, Nicole; Edwards, Eric; Hettler, Danielle; Davis, Brent; Bowen, Richard; Bunning, Michel

    2003-03-01

    To evaluate transmission dynamics, we exposed 25 bird species to West Nile virus (WNV) by infectious mosquito bite. We monitored viremia titers, clinical outcome, WNV shedding (cloacal and oral), seroconversion, virus persistence in organs, and susceptibility to oral and contact transmission. Passeriform and charadriiform birds were more reservoir competent (a derivation of viremia data) than other species tested. The five most competent species were passerines: Blue Jay (Cyanocitta cristata), Common Grackle (Quiscalus quiscula), House Finch (Carpodacus mexicanus), American Crow (Corvus brachyrhynchos), and House Sparrow (Passer domesticus). Death occurred in eight species. Cloacal shedding of WNV was observed in 17 of 24 species, and oral shedding in 12 of 14 species. We observed contact transmission among four species and oral in five species. Persistent WNV infections were found in tissues of 16 surviving birds. Our observations shed light on transmission ecology of WNV and will benefit surveillance and control programs.

  3. First Isolation of West Nile virus from a patient with encephalitis in the United States.

    Science.gov (United States)

    Huang, Cinnia; Slater, Brett; Rudd, Robert; Parchuri, Nandakishore; Hull, Rene; Dupuis, Michelle; Hindenburg, Alexander

    2002-12-01

    West Nile virus (WNV) was isolated from a patient who developed encephalitis while undergoing treatment with CHOP (cyclophosphamide, hydroxydoxorubicin, vincristine [Oncovin], predisone) and rituximab for a non-Hodgkin B-cell lymphoma. Both standard reverse transcription-polymerase chain reaction (RT-PCR) and Taqman RT-PCR established the diagnosis of WNV infection from cerebrospinal fluid (CSF). Several whole blood samples and one serum sample underwent further testing. CSF and serum samples were negative for WNV antibody; however, all samples were positive by both RT-PCR assays. Infectious virus was recovered from a blood sample, and its identity was confirmed by using a WNV-specific immunofluorescence assay. The complete WNV genomes determined from CSF and from the virus isolate adapted from cell culture were the same. The results represent the first complete WNV genome sequence obtained directly from human CSF and the first time that infectious WNV has been recovered from a patient with encephalitis in North America.

  4. Further circulation of West Nile and Usutu viruses in wild birds in Italy.

    Science.gov (United States)

    Llopis, Isis Victoriano; Rossi, Luca; Di Gennaro, Annapia; Mosca, Andrea; Teodori, Liana; Tomassone, Laura; Grego, Elena; Monaco, Federica; Lorusso, Alessio; Savini, Giovanni

    2015-06-01

    Usutu virus (USUV) and West Nile virus (WNV) are emerging pathogens that can cause neurological disease in humans. From March 2012 to June 2013, a sero-survey on wild birds was carried out to investigate the circulation of both viruses in Northwest (NW) Italy. Samples belonging to 47 different bird species have been collected using a volunteer based network and a wildlife rehabilitation center. Four of 297 serum samples had neutralizing antibodies against USUV (P=1.34%, IC 95% 0.36-3.4), while 10 of 233 samples tested positive for WNV (P=4.29%, IC 95% 2.07-7.75). Neutralizing antibodies for WNV were significantly more prevalent (pbirds, but no migratory habit-related differences were found for USUV. Antibodies in resident bird species suggest that both viruses are circulating in NW Italy. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Characterization of West Nile viruses isolated form captive American flamingoes (Phoenicopterus ruber) in Medellin, Colombia.

    Science.gov (United States)

    Osorio, Jorge E.; Ciuoderis, Karl A.; Lopera, Juan G.; Piedrahita, Leidy D.; Murphy, Darby; LeVasseur, James; Carrillo, Lina; Ocampo, Martha C.; Hofmeister, Erik

    2012-01-01

    Serum samples from a total of 71 healthy captive birds belonging to 18 species were collected in July of 2008 in Medellin (Colombia) and tested for flaviviruses. Eighteen of 29 samples from American Flamingoes (Phoenicopterus ruber) were positive for West Nile virus (WNV) by reverse transcription-polymerase chain reaction. Selected positive samples were serially passaged and WNV was confirmed by immunofluorescence. Two isolates (524/08, 9835/08) were characterized in vitro and in vivo. Sequence analysis revealed WNV with 16 nucleotide substitutions resulting in six amino acid changes when compared with the NY99 strain. Colombian (COL) viruses were more closely related to Louisiana isolates from 2001. When compared with attenuated strains isolated from Texas, COL isolates differed in their plaque size and temperature sensitivity phenotype. The COL viruses were pathogenic in embryonated chicken eggs and Balb/c mice.

  6. Culex Flavivirus During West Nile Virus Epidemic and Interepidemic Years in Chicago, United States.

    Science.gov (United States)

    Newman, Christina M; Krebs, Bethany L; Anderson, Tavis K; Hamer, Gabriel L; Ruiz, Marilyn O; Brawn, Jeffrey D; Brown, William M; Kitron, Uriel D; Goldberg, Tony L

    2017-08-01

    Culex flavivirus (CxFV) is an insect-specific flavivirus infecting Culex mosquitoes, which are important vectors of West Nile virus (WNV). CxFV and WNV cocirculate in nature and coinfect Culex mosquitoes, including in a WNV "hotspot" in suburban Chicago. We previously identified a positive association between CxFV and WNV in mosquito pools collected from suburban Chicago in 2006. To further investigate this phenomenon, we compared the spatial and temporal distribution of CxFV during an interepidemic year (2011) and an epidemic year (2012) for WNV. Both viruses were more prevalent in mosquito pools in 2012 compared to 2011. During both years, the CxFV infection status of mosquito pools was associated with environmental factors such as habitat type and precipitation frequency rather than coinfection with WNV. These results support the idea that WNV and CxFV are ecologically associated, perhaps because both viruses respond to similar environmental drivers of mosquito populations.

  7. Occurrence of West Nile virus infection in raptors at the Salton Sea, California

    Science.gov (United States)

    Dusek, Robert J.; Iko, William M.; Hofmeister, Erik K.

    2010-01-01

    We investigated the prevalence of West Nile virus (WNV)-neutralizing antibodies and infectious virus, and the occurrence of overwinter transmission in two raptor species during January and March 2006 at the Salton Sea, Imperial County, California. We captured 208 American Kestrels (Falco sparverius) (January, n=100; March, n=108) and 116 Burrowing Owls (Athene cunicularia) (January, n=52; March, n=64). Laboratory analysis revealed that 83% of American Kestrels and 31% of Burrowing Owls were positive for WNV-neutralizing antibodies. Additionally, two seroconversions were detected in Burrowing Owls between January and March. Infectious WNV, consistent with acute infection, was not detected in any bird.

  8. Crystallization and preliminary X-ray diffraction analysis of West Nile virus

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    Kaufmann, Barbel; Plevka, Pavel; Kuhn, Richard J.; Rossmann, Michael G. (Purdue)

    2010-05-25

    West Nile virus, a human pathogen, is closely related to other medically important flaviviruses of global impact such as dengue virus. The infectious virus was purified from cell culture using polyethylene glycol (PEG) precipitation and density-gradient centrifugation. Thin amorphously shaped crystals of the lipid-enveloped virus were grown in quartz capillaries equilibrated by vapor diffusion. Crystal diffraction extended at best to a resolution of about 25 {angstrom} using synchrotron radiation. A preliminary analysis of the diffraction images indicated that the crystals had unit-cell parameters a {approx_equal} b {approx_equal} 480 {angstrom}, {gamma} = 120{sup o}, suggesting a tight hexagonal packing of one virus particle per unit cell.

  9. The use of early summer mosquito surveillance to predict late summer West Nile virus activity

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    Ginsberg, Howard S.; Rochlin, Ilia; Campbell, Scott R.

    2010-01-01

    Utility of early-season mosquito surveillance to predict West Nile virus activity in late summer was assessed in Suffolk County, NY. Dry ice-baited CDC miniature light traps paired with gravid traps were set weekly. Maximum-likelihood estimates of WNV positivity, minimum infection rates, and % positive pools were generally well correlated. However, positivity in gravid traps was not correlated with positivity in CDC light traps. The best early-season predictors of WNV activity in late summer (estimated using maximum-likelihood estimates of Culex positivity in August and September) were early date of first positive pool, low numbers of mosquitoes in July, and low numbers of mosquito species in July. These results suggest that early-season entomological samples can be used to predict WNV activity later in the summer, when most human cases are acquired. Additional research is needed to establish which surveillance variables are most predictive and to characterize the reliability of the predictions.

  10. Seroprevalence of West Nile Virus in feral horses on Sheldon National Wildlife Refuge, Nevada, United States

    Science.gov (United States)

    Franson, J. Christian; Hofmeister, Erik K.; Collins, Gail H.; Dusek, Robert J.

    2011-01-01

    We screened 1,397 feral horses (Equus caballus) on Sheldon National Wildlife Refuge, Nevada, United States, for IgM and IgG against flavivirus during 2004–2006, 2008, and 2009. Positive serum samples were tested for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis virus (SLEV). One animal was positive for antibody against WNV in 2004, but all others tested in 2004–2006 were negative. In 2008 and 2009, we found evidence of increasing seropositive horses with age, whereas seroprevalence of WNV decreased from 19% in 2008 to 7.2% in 2009. No horses were positive for antibody against SLEV. Being unvaccinated, feral horses can be useful for WNV surveillance.

  11. Serosurvey for West Nile virus antibodies in Steller's Jays (Cyanocitta stelleri) captured in coastal California

    Science.gov (United States)

    West, Elena; Hofmeister, Erik K.; Peery, M. Zach

    2017-01-01

    West Nile virus (WNV) was first detected in New York in 1999 and, during its expansion across the continental US, southern Canada, and Mexico, members of the Corvidae (ravens, crows, magpies, and jays) were frequently infected and highly susceptible to the virus. As part of a behavioral study of Steller's Jays (Cyanocitta stelleri) conducted from 2011–2014 in the coastal California counties of San Mateo and Santa Cruz, 380 Steller's Jays were captured and tested for antibodies to WNV. Using the wild bird IgG enzyme linked immunoassay, we failed to detect antibodies to WNV, indicating either that there was no previous exposure to the virus or that exposed birds had died.

  12. Role of Natural Killer and Gamma-Delta T cells in West Nile Virus Infection

    Directory of Open Access Journals (Sweden)

    Thomas Welte

    2013-09-01

    Full Text Available Natural Killer (NK cells and Gamma-delta T cells are both innate lymphocytes that respond rapidly and non-specifically to viral infection and other pathogens. They are also known to form a unique link between innate and adaptive immunity. Although they have similar immune features and effector functions, accumulating evidence in mice and humans suggest these two cell types have distinct roles in the control of infection by West Nile virus (WNV, a re-emerging pathogen that has caused fatal encephalitis in North America over the past decade. This review will discuss recent studies on these two cell types in protective immunity and viral pathogenesis during WNV infection.

  13. Prevalence and effects of West Nile virus on wild American kestrel (Falco sparverius) populations in Colorado

    Science.gov (United States)

    Dusek, Robert J.; Iko, William M.; Hofmeister, Erik K.; Paul, Ellen

    2012-01-01

    To assess the potential impacts of West Nile virus (WNV) on a wild population of free-ranging raptors, we investigated the prevalence and effects of WNV on American Kestrels (Falco sparverius) breeding along the Front Range of the Rocky Mountains in northern Colorado. We monitored kestrel nesting activity at 131 nest boxes from March to August 2004. Of 81 nest attempts, we obtained samples from 111 adults and 250 young. We did not detect WNV in sera; however, 97.3% (108/111) of adults tested positive for WNV neutralizing antibodies, which possibly represented passive transfer of maternal antibodies. Clutch size, hatching, and fledging success in our study did not differ from that previously reported for this species, suggesting that previous WNV exposure in kestrels did not have an effect on reproductive parameters measured in the breeding populations we studied in 2004.

  14. Continued Evolution of West Nile Virus, Houston, Texas, USA, 2002–2012

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    Mann, Brian R.; McMullen, Allison R.; Swetnam, Daniele M.; Salvato, Vence; Reyna, Martin; Guzman, Hilda; Bueno, Rudy; Dennett, James A.; Tesh, Robert B.

    2013-01-01

    We investigated the genetics and evolution of West Nile virus (WNV) since initial detection in the United States in 1999 on the basis of continual surveillance studies in the Houston, Texas, USA, metropolitan area (Harris County) as a surrogate model for WNV evolution on a national scale. Full-length genomic sequencing of 14 novel 2010–2012 WNV isolates collected from resident birds in Harris County demonstrates emergence of 4 independent genetic groups distinct from historical strains circulating in the greater Houston region since 2002. Phylogenetic and geospatial analyses of the 2012 WNV isolates indicate closer genetic relationship with 2003–2006 Harris County isolates than more recent 2007–2011 isolates. Inferred monophyletic relationships of these groups with several 2006–2009 northeastern US isolates supports potential introduction of a novel WNV strain in Texas since 2010. These results emphasize the need to maintain WNV surveillance activities to better understand WNV transmission dynamics in the United States. PMID:23965756

  15. Chikungunya virus and West Nile virus infections imported into Belgium, 2007-2012.

    Science.gov (United States)

    VAN DEN Bossche, D; Cnops, L; Meersman, K; Domingo, C; VAN Gompel, A; VAN Esbroeck, M

    2015-07-01

    Arboviral infections are emerging among tourists travelling to (sub)tropical regions. This study aims to describe the importation of chikungunya virus (CHIKV) and West Nile virus (WNV) into Belgium over a 6-year period from 2007 to 2012. Clinical samples were obtained from travellers presenting at the outpatient clinic of the Institute of Tropical Medicine (ITM), Antwerp, Belgium or submitted to the Central Laboratory for Clinical Biology of the ITM. Testing was performed by serology and/or by real-time reverse transcriptase-polymerase chain reaction. A total of 1288 returning travellers were investigated for CHIKV infection resulting in 34 confirmed and two probable diagnoses (2·80%). Out of 899 patients, four confirmed and one probable imported WNV infections were diagnosed (0·55%). No locally acquired cases have been registered in Belgium until now and the geographical origin of the imported infections reflects the global locations where the viruses are circulating.

  16. Flaviviruses, an expanding threat in public health: focus on Dengue, West Nile, and Japanese encephalitis virus

    Science.gov (United States)

    Daep, Carlo Amorin; Muñoz-Jordán, Jorge L.; Eugenin, Eliseo Alberto

    2014-01-01

    The flaviviruses Dengue, West Nile, and Japanese encephalitis represent three major mosquito-borne viruses worldwide. These pathogens impact the lives of millions of individuals and potentially could affect non-endemic areas already colonized by mosquito vectors. Unintentional transport of infected vectors (Aedes and Culex sp), traveling within endemic areas, rapid adaptation of the insects into new geographic locations, climate change, and lack of medical surveillance have greatly contributed to the increase in flaviviral infections worldwide. The mechanisms by which flaviviruses alter the immune and the central nervous system have only recently been examined despite the alarming number of infections, related deaths, and increasing global distribution. In this review, we will discuss the expansion of the geographic areas affected by flaviviruses, the potential threats to previously unaffected countries, the mechanisms of pathogenesis, and the potential therapeutic interventions to limit the devastating consequences of these viruses. PMID:25287260

  17. Flaviviruses, an expanding threat in public health: focus on dengue, West Nile, and Japanese encephalitis virus.

    Science.gov (United States)

    Daep, Carlo Amorin; Muñoz-Jordán, Jorge L; Eugenin, Eliseo Alberto

    2014-12-01

    The flaviviruses dengue, West Nile, and Japanese encephalitis represent three major mosquito-borne viruses worldwide. These pathogens impact the lives of millions of individuals and potentially could affect non-endemic areas already colonized by mosquito vectors. Unintentional transport of infected vectors (Aedes and Culex spp.), traveling within endemic areas, rapid adaptation of the insects into new geographic locations, climate change, and lack of medical surveillance have greatly contributed to the increase in flaviviral infections worldwide. The mechanisms by which flaviviruses alter the immune and the central nervous system have only recently been examined despite the alarming number of infections, related deaths, and increasing global distribution. In this review, we will discuss the expansion of the geographic areas affected by flaviviruses, the potential threats to previously unaffected countries, the mechanisms of pathogenesis, and the potential therapeutic interventions to limit the devastating consequences of these viruses.

  18. Effects of weather and landscape on the equine West Nile virus infection risk in Mississippi, USA

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    Guiming Wang

    2015-11-01

    Full Text Available The West Nile virus (WNv continues to be a public health concern in North America. Dry weather appears to increase human WNv infection risks, but it is uncertain whether dry weather conditions exert similar effects on the corresponding equine WNv infection. This study assessed the effects of precipitation of the previous year and land cover diversity on the equine WNv risk of Mississippi, USA, at the county level in the year 2002 using Bayesian hierarchical models. The risk estimated for 2002 was found to be inversely related to annual precipitation of the preceding year. Equine WNv risks were lower with greater land cover diversity probably due to the diluting effects of biodiversity. Correlation between the equine and human WNv risks was positive but relatively low. Dry weather conditions of the previous year might reduce mosquito competitors and predators and subsequently increase mosquito abundances and equine WNv risks in agricultural areas with low biodiversity.

  19. West Nile virus finally debuts in British Columbia 10 years after its introduction to North America.

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    Morshed, Muhammad; Tang, Patrick; Petric, Martin; Krajden, Mel; Roth, David; Henry, Bonnie; Isaac-Renton, Judith

    2011-08-01

    Since its first detection in New York (1999), West Nile virus (WNv) has spread across the United States and Canada with the first activity reported in Canada in 2001. By 2004, WNv had been detected almost in every province of Canada and the contiguous regions of the United States with the exception of British Columbia (BC), this despite being detected in Alberta in 2003 and Washington as early as 2002. In August 2009, two human cases were serologically found to have WNv infection. They reported mosquito bites and had only traveled in the South and Central Okanagan areas of BC before their presentation. On the basis of clinical, laboratory, and epidemiological data, these two human cases have been confirmed as the first locally acquired WNv cases in BC. Various factors may have contributed to the 10-year delay in the spread of WNv to BC, including regional weather conditions and unique topography.

  20. Evidence for co-evolution of West Nile Virus and house sparrows in North America.

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    Nisha K Duggal

    2014-10-01

    Full Text Available West Nile virus (WNV has been maintained in North America in enzootic cycles between mosquitoes and birds since it was first described in North America in 1999. House sparrows (HOSPs; Passer domesticus are a highly competent host for WNV that have contributed to the rapid spread of WNV across the U.S.; however, their competence has been evaluated primarily using an early WNV strain (NY99 that is no longer circulating. Herein, we report that the competence of wild HOSPs for the NY99 strain has decreased significantly over time, suggesting that HOSPs may have developed resistance to this early WNV strain. Moreover, recently isolated WNV strains generate higher peak viremias and mortality in contemporary HOSPs compared to NY99. These data indicate that opposing selective pressures in both the virus and avian host have resulted in a net increase in the level of host competence of North American HOSPs for currently circulating WNV strains.

  1. Evidence for co-evolution of West Nile Virus and house sparrows in North America.

    Science.gov (United States)

    Duggal, Nisha K; Bosco-Lauth, Angela; Bowen, Richard A; Wheeler, Sarah S; Reisen, William K; Felix, Todd A; Mann, Brian R; Romo, Hannah; Swetnam, Daniele M; Barrett, Alan D T; Brault, Aaron C

    2014-10-01

    West Nile virus (WNV) has been maintained in North America in enzootic cycles between mosquitoes and birds since it was first described in North America in 1999. House sparrows (HOSPs; Passer domesticus) are a highly competent host for WNV that have contributed to the rapid spread of WNV across the U.S.; however, their competence has been evaluated primarily using an early WNV strain (NY99) that is no longer circulating. Herein, we report that the competence of wild HOSPs for the NY99 strain has decreased significantly over time, suggesting that HOSPs may have developed resistance to this early WNV strain. Moreover, recently isolated WNV strains generate higher peak viremias and mortality in contemporary HOSPs compared to NY99. These data indicate that opposing selective pressures in both the virus and avian host have resulted in a net increase in the level of host competence of North American HOSPs for currently circulating WNV strains.

  2. West Nile virus envelope proteins: nucleotide sequence analysis of strains differing in mouse neuroinvasiveness.

    Science.gov (United States)

    Chambers, T J; Halevy, M; Nestorowicz, A; Rice, C M; Lustig, S

    1998-10-01

    Several neuroinvasive and non-neuroinvasive West Nile (WN) viruses were characterized by nucleotide sequencing of their envelope (E) protein regions. Prolonged passage in mosquito cells caused loss of neuroinvasiveness and acquisition of an N-linked glycosylation site, which is utilized. Limited passage in cell culture also caused glycosylation but not attenuation, suggesting that glycosylation may not be directly responsible for attenuation and that a second mutation (L68 --> P) may also be involved. A monoclonal antibody-neutralization escape mutant with a substitution at residue 307, a site common to other flavivirus escape mutants, was also attenuated. A partially neuroinvasive revertant regained the parental E sequence, implying that determinants outside of the E region may also influence attenuation. Data suggest that the neuroinvasive determinants may be similar to those for other flaviviruses. Also, sequence comparison with the WN virus (Nigeria) strain revealed considerable divergence of the E protein at the nucleotide and amino acid levels.

  3. Is initial preservation of deep tendon reflexes in West Nile Virus paralysis a good prognostic sign?

    Science.gov (United States)

    Mojumder, Deb Kumar; Agosto, Melina; Wilms, Henrik; Kim, Jongyeol

    2014-03-01

    Typical West Nile virus paralysis is characterized by muscle weakness, decreased tone, and loss of deep tendon reflexes attributed to destruction of anterior horn cells. Two cases in which deep tendon reflexes were initially preserved in the presence of profound and persistent muscle weakness are presented here. In both cases, deep tendon reflexes were later severely attenuated or lost, while weakness of the involved muscles remained profound and unchanged. Both patients showed good motor recovery at 6 months. Initial preservation of deep tendon reflexes in the presence of persistent muscle weakness indicates that in the early stages of disease, the muscle weakness in these two cases was not caused by destruction of anterior horn cells. Pathology involving anterior horns preceding AHC destruction could potentially disrupt upper motor neuron pathways to anterior horn cells, causing weakness with initial preserved deep tendon reflexes.

  4. Experimental susceptibility of Wood Ducks (Aix sponsa) for West Nile virus

    Science.gov (United States)

    Hofmeister, Erik K.; Porter, Robert E.; Franson, J. Christian

    2015-01-01

    Detection of West Nile virus (WNV) has been reported in a variety of wild ducks in the US, but little is known about the pathogenesis and outcome of exposure of the disease in these species. Previous experimental studies of WNV in ducks either have challenged a small number of ducks with WNV or have tested domesticated ducks. To determine susceptibility and immune response, we challenged 7-wk-old Wood Ducks (Aix sponsa) with a 1999 American Crow (Corvus brachyrhynchos) isolate of WNV. Wood Ducks were susceptible to infection with the virus, and, although clinical signs or mortality were not observed, microscopic lesions were noted, particularly in the heart and brain. West Nile virus viremia peaked on day 2 postinfection (pi) at 104.54 plaque-forming units (PFU) of virus/mL serum and WNV was shed orally (between 102and 102.9 PFU per swab) and cloacally. Specific anti-WNV antibody response was rapid, with anti-WNV IgM detected on day 3 pi followed on day 5 pi by anti-WNV IgG. Neutralizing antibodies were detected by plaque-reduction neutralization assay in one duck on day 4 pi, and in all sampled ducks on day 5. These results indicate that Wood Ducks are susceptible to WNV, but it is unlikely that significant WNV mortality events occur in Wood Ducks or that ducks play a significant role in transmission. However, WNV viremia was sufficient, in theory, to infect mosquitoes, and oral and cloacal shedding of the virus may increase the risk of infection to other waterbirds.

  5. Transmission of West Nile virus by Culex quinquefasciatus say infected with Culex Flavivirus Izabal.

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    Rebekah J Kent

    Full Text Available BACKGROUND: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV from Guatemala. METHODS AND FINDINGS: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05. However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014. Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva. CONCLUSIONS: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with

  6. Experimental susceptibility of wood ducks (Aix sponsa) for West Nile virus.

    Science.gov (United States)

    Hofmeister, Erik; Porter, Robert E; Franson, J Christian

    2015-04-01

    Detection of West Nile virus (WNV) has been reported in a variety of wild ducks in the US, but little is known about the pathogenesis and outcome of exposure of the disease in these species. Previous experimental studies of WNV in ducks either have challenged a small number of ducks with WNV or have tested domesticated ducks. To determine susceptibility and immune response, we challenged 7-wk-old Wood Ducks (Aix sponsa) with a 1999 American Crow (Corvus brachyrhynchos) isolate of WNV. Wood Ducks were susceptible to infection with the virus, and, although clinical signs or mortality were not observed, microscopic lesions were noted, particularly in the heart and brain. West Nile virus viremia peaked on day 2 postinfection (pi) at 10(4.54) plaque-forming units (PFU) of virus/mL serum and WNV was shed orally (between 10(2) and 10(2.9) PFU per swab) and cloacally. Specific anti-WNV antibody response was rapid, with anti-WNV IgM detected on day 3 pi followed on day 5 pi by anti-WNV IgG. Neutralizing antibodies were detected by plaque-reduction neutralization assay in one duck on day 4 pi, and in all sampled ducks on day 5. These results indicate that Wood Ducks are susceptible to WNV, but it is unlikely that significant WNV mortality events occur in Wood Ducks or that they play a significant role in transmission. However, WNV viremia was sufficient, in theory, to infect mosquitoes, and oral and cloacal shedding of the virus may increase the risk of infection to other waterbirds.

  7. The role of temperature on the spatiotemporal distribution of West Nile virus in the United States

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    Horton, D. E.; Kilpatrick, A. M.; Ruybal, J.; Diffenbaugh, N. S.

    2012-12-01

    Determining the relationship between climatological factors and vector-borne pathogens remains a critical challenge. The recent arrival of the West Nile virus (WNV) to the Americas, coupled with an extensive climatological and disease observation network, offers the potential to improve our mechanistic understanding of climate's influence on vector-borne disease transmission. Since its introduction to the Americas in the summer of 1999, the West Nile Virus (WNV) has rapidly spread from coastal New York State, across the North American continent, and into Central and South America. To date, 13,385 cases of WNV-induced human neuroinvasive disease have been reported to the U.S. Centers for Disease Control, with approximately 1,267 fatalities attributed to viral infection (as of 31 July 2012). Of those infected, severe symptoms develop in only ~1 in 150 people, suggesting that the total U.S. population infected with WNV is on the order of 2 million. The transmission of WNV is predominantly vector-borne, with three mosquitoes of the Culex genus, pipiens, tarsalis, and quinquefasciatus, largely responsible for the spread of the pathogen between avian and human hosts and across the contiguous United States. In this contribution, we synthesize laboratory and local-scale field studies of the Culex vectors with observed and modeled climatological data in an attempt to determine the mechanistic influence of temperature on the spatiotemporal distribution of WNV incidence across the United States. Our preliminary results suggest that many of the physiological factors that determine the transmission intensity of WNV, including mosquito biting rate, vector competence, infection transition rate, and mosquito mortality rate, demonstrate direct temperature dependencies. Based on these results, we utilize bias-corrected outputs from late-20th and mid-21st century CMIP5 simulations to examine the influence of temperature on the distribution of WNV relative to other factors and to

  8. Geographic variations of the bird-borne structural risk of West Nile virus circulation in Europe.

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    Benoit Durand

    Full Text Available The structural risk of West Nile Disease results from the usual functioning of the socio-ecological system, which may favour the introduction of the pathogen, its circulation and the occurrence of disease cases. Its geographic variations result from the local interactions between three components: (i reservoir hosts, (ii vectors, both characterized by their diversity, abundance and competence, (iii and the socio-economic context that impacts the exposure of human to infectious bites. We developed a model of bird-borne structural risk of West Nile Virus (WNV circulation in Europe, and analysed the association between the geographic variations of this risk and the occurrence of WND human cases between 2002 and 2014. A meta-analysis of WNV serosurveys conducted in wild bird populations was performed to elaborate a model of WNV seropositivity in European bird species, considered a proxy for bird exposure to WNV. Several eco-ethological traits of bird species were linked to seropositivity and the statistical model adequately fitted species-specific seropositivity data (area under the ROC curve: 0.85. Combined with species distribution maps, this model allowed deriving geographic variations of the bird-borne structural risk of WNV circulation. The association between this risk, and the occurrence of WND human cases across the European Union was assessed. Geographic risk variations of bird-borne structural risk allowed predicting WND case occurrence in administrative districts of the EU with a sensitivity of 86% (95% CI: 0.79-0.92, and a specificity of 68% (95% CI: 0.66-0.71. Disentangling structural and conjectural health risks is important for public health managers as risk mitigation procedures differ according to risk type. The results obtained show promise for the prevention of WND in Europe. Combined with analyses of vector-borne structural risk, they should allow designing efficient and targeted prevention measures.

  9. Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa

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    June H. Williams

    2014-02-01

    Full Text Available Since 2007, West Nile virus (WNV has been reported in South African horses, causing severe neurological signs. All cases were of lineage 2, except for one case that clustered with lineage 1 viruses. In the present study, gross and microscopic lesions of six South African lineage 2-infected horses and the one lineage 1 case are described. Diagnoses were confirmed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR of central nervous system (CNS tissue and one by RT-PCR of a brain virus isolate. The CNS of all cases was negative by RT-PCR or immunohistochemistry (IHC for African horse sickness (AHS, equine encephalosis virus, equine herpes viruses 1 and 4, other zoonotic flaviviruses, alphaviruses, and shunivirus, and either by immunofluorescence or IHC for rabies. Gross visceral lesions were nonspecific but often mimicked those of AHS. The CNS histopathology of WNV lineage 2 cases resembled the nonsuppurative polioencephalomyelitis reported in the Northern Hemisphere lineage 1 and recent Hungarian lineage 2 cases. Occasional meningitis, focal spinal ventral horn poliomalacia, dorsal and lateral horn poliomyelitis, leucomyelitis, asymmetrical ventral motor spinal neuritis and frequent olfactory region involvement were also seen. Lineage 2 cases displayed marked variations in CNS lesion severity, type and distribution, and suggested various viral entry routes into the CNS, based on findings in experimental mice and hamsters. Lineage 1 lesions were comparable to the milder lineage 2 cases. West Nile virus IHC on CNS sections with marked lesions from all cases elicited only two antigen-positive cells in the olfactory cortex of one case. The presence in the CNS of T-lymphocytes, B-lymphocytes, plasma cells and macrophage-monocytes was confirmed by cluster of differentiation (CD 3, CD20, multiple myeloma oncogene 1 (MUM1 and macrophage (MAC 387 IHC.

  10. A thiopurine drug inhibits West Nile virus production in cell culture, but not in mice.

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    Pei-Yin Lim

    Full Text Available Many viruses within the Flavivirus genus cause significant disease in humans; however, effective antivirals against these viruses are not currently available. We have previously shown that a thiopurine drug, 6-methylmercaptopurine riboside (6MMPr, inhibits replication of distantly related viruses within the Flaviviridae family in cell culture, including bovine viral diarrhea virus and hepatitis C virus replicon. Here we further examined the potential antiviral effect of 6MMPr on several diverse flaviviruses. In cell culture, 6MMPr inhibited virus production of yellow fever virus, dengue virus-2 (DENV-2 and West Nile virus (WNV in a dose-dependent manner, and DENV-2 was significantly more sensitive to 6MMPr treatment than WNV. We then explored the use of 6MMPr as an antiviral against WNV in an immunocompetent mouse model. Once a day treatment of mice with 0.5 mg 6MMPr was just below the toxic dose in our mouse model, and this dose was used in subsequent studies. Mice were treated with 6MMPr immediately after subcutaneous inoculation with WNV for eight consecutive days. Treatment with 6MMPr exacerbated weight loss in WNV-inoculated mice and did not significantly affect mortality. We hypothesized that 6MMPr has low bioavailability in the central nervous system (CNS and examined the effect of pre-treatment with 6MMPr on viral loads in the periphery and CNS. Pre-treatment with 6MMPr had no significant effect on viremia or viral titers in the periphery, but resulted in significantly higher viral loads in the brain, suggesting that the effect of 6MMPr is tissue-dependent. In conclusion, despite being a potent inhibitor of flaviviruses in cell culture, 6MMPr was not effective against West Nile disease in mice; however, further studies are warranted to reduce the toxicity and/or improve the bioavailability of this potential antiviral drug.

  11. Animal viral diseases and global change: bluetongue and West Nile fever as paradigms.

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    Jiménez-Clavero, Miguel Á

    2012-01-01

    Environmental changes have an undoubted influence on the appearance, distribution, and evolution of infectious diseases, and notably on those transmitted by vectors. Global change refers to environmental changes arising from human activities affecting the fundamental mechanisms operating in the biosphere. This paper discusses the changes observed in recent times with regard to some important arboviral (arthropod-borne viral) diseases of animals, and the role global change could have played in these variations. Two of the most important arboviral diseases of animals, bluetongue (BT) and West Nile fever/encephalitis (WNF), have been selected as models. In both cases, in the last 15 years an important leap forward has been observed, which has lead to considering them emerging diseases in different parts of the world. BT, affecting domestic ruminants, has recently afflicted livestock in Europe in an unprecedented epizootic, causing enormous economic losses. WNF affects wildlife (birds), domestic animals (equines), and humans, thus, beyond the economic consequences of its occurrence, as a zoonotic disease, it poses an important public health threat. West Nile virus (WNV) has expanded in the last 12 years worldwide, and particularly in the Americas, where it first occurred in 1999, extending throughout the Americas relentlessly since then, causing a severe epidemic of disastrous consequences for public health, wildlife, and livestock. In Europe, WNV is known long time ago, but it is since the last years of the twentieth century that its incidence has risen substantially. Circumstances such as global warming, changes in land use and water management, increase in travel, trade of animals, and others, can have an important influence in the observed changes in both diseases. The following question is raised: What is the contribution of global changes to the current increase of these diseases in the world?

  12. Seroprevalence of West Nile virus in Saskatchewan's Five Hills Health Region, 2003.

    Science.gov (United States)

    Schellenberg, Tara L; Anderson, Maureen E; Drebot, Michael A; Vooght, Mark T R; Findlater, A Ross; Curry, Phillip S; Campbell, C Alexia; Osei, William D

    2006-01-01

    The Five Hills Health Region of Saskatchewan reported the highest West Nile virus (WNV) case rates in the 2003 outbreak. A serologic and telephone survey was undertaken to assess the seroprevalence of the virus and the knowledge, attitudes and behaviours of the residents. Respondents had to be at least 18 years of age, and residents of the Five Hills Health Region between July 1st and September 15th, 2003. Blood samples of respondents were tested at the National Microbiology Laboratory for flavivirus immunoglobulin using a WNV IgG ELISA and plaque reduction neutralization test. Descriptive analyses performed related to respondents' demographics, knowledge, attitudes, behaviours, and seropositivity. WNV infection risk was assessed using odds ratio. There were 619 questionnaire respondents, of whom 501 donated a blood sample. The seroprevalence of WNV in the Five Hills Health Region was 9.98% (95% CI 7.37-12.59%). Seropositivity of rural areas was 16.8% and urban was 3.2%. Most (97%) of participants thought WNV was an important health issue. Forty-eight percent of the participants used insect repellents containing DEET most of the time. There was good knowledge regarding WNV transmission and prevention of the spread of WNV. Rural compared to urban residents were six times more likely to be positive for WNV (OR=6.13, 95% CI 2.82-13.34). This is the highest seroprevalence rate of West Nile virus recorded in North America thus far. Many factors could have influenced this outbreak, such as eco-region, early prolonged hot weather, level of mosquito control programs, urban and rural community differences, and personal protective behaviours.

  13. Antecedent avian immunity limits tangential transmission of West Nile virus to humans.

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    Jennifer L Kwan

    Full Text Available West Nile virus (WNV is a mosquito-borne flavivirus maintained and amplified among birds and tangentially transmitted to humans and horses which may develop terminal neuroinvasive disease. Outbreaks typically have a three-year pattern of silent introduction, rapid amplification and subsidence, followed by intermittent recrudescence. Our hypothesis that amplification to outbreak levels is contingent upon antecedent seroprevalence within maintenance host populations was tested by tracking WNV transmission in Los Angeles, California from 2003 through 2011.Prevalence of antibodies against WNV was monitored weekly in House Finches and House Sparrows. Tangential or spillover transmission was measured by seroconversions in sentinel chickens and by the number of West Nile neuroinvasive disease (WNND cases reported to the Los Angeles County Department of Public Health.Elevated seroprevalence in these avian populations was associated with the subsidence of outbreaks and in the antecedent dampening of amplification during succeeding years. Dilution of seroprevalence by recruitment resulted in the progressive loss of herd immunity following the 2004 outbreak, leading to recrudescence during 2008 and 2011. WNV appeared to be a significant cause of death in these avian species, because the survivorship of antibody positive birds significantly exceeded that of antibody negative birds. Cross-correlation analysis showed that seroprevalence was negatively correlated prior to the onset of human cases and then positively correlated, peaking at 4-6 weeks after the onset of tangential transmission. Antecedent seroprevalence during winter (Jan - Mar was negatively correlated with the number of WNND cases during the succeeding summer (Jul-Sep.Herd immunity levels within after hatching year avian maintenance host populations <10% during the antecedent late winter and spring period were followed on three occasions by outbreaks of WNND cases during the succeeding summer

  14. Absence of humoral response in flamingos and red-tailed hawks to experimental vaccination with a killed West Nile virus vaccine.

    Science.gov (United States)

    Nusbaum, Kenneth E; Wright, James C; Johnston, William B; Allison, Andrew B; Hilton, Clayton D; Staggs, Lydia A; Stallknecht, David E; Shelnutt, Joseph L

    2003-01-01

    Sixteen Chilean flamingos, Phoenicopterus chiles, and 10 red-tailed hawks, Buteo jamacensis, were vaccinated in the pectoral muscle with 0.2 ml of a commercially produced killed West Nile virus vaccine intended for use in horses. Half the birds of each species received a booster vaccination 3 weeks after the first injection. Three weeks after the booster vaccination, none of 13 birds surveyed had detectable antibody to West Nile virus.

  15. A GIS-driven integrated real-time surveillance pilot system for national West Nile virus dead bird surveillance in Canada

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    Aramini Jeff

    2006-04-01

    Full Text Available Abstract Background An extensive West Nile virus surveillance program of dead birds, mosquitoes, horses, and human infection has been launched as a result of West Nile virus first being reported in Canada in 2001. Some desktop and web GIS have been applied to West Nile virus dead bird surveillance. There have been urgent needs for a comprehensive GIS services and real-time surveillance. Results A pilot system was developed to integrate real-time surveillance, real-time GIS, and Open GIS technology in order to enhance West Nile virus dead bird surveillance in Canada. Driven and linked by the newly developed real-time web GIS technology, this integrated real-time surveillance system includes conventional real-time web-based surveillance components, integrated real-time GIS components, and integrated Open GIS components. The pilot system identified the major GIS functions and capacities that may be important to public health surveillance. The six web GIS clients provide a wide range of GIS tools for public health surveillance. The pilot system has been serving Canadian national West Nile virus dead bird surveillance since 2005 and is adaptable to serve other disease surveillance. Conclusion This pilot system has streamlined, enriched and enhanced national West Nile virus dead bird surveillance in Canada, improved productivity, and reduced operation cost. Its real-time GIS technology, static map technology, WMS integration, and its integration with non-GIS real-time surveillance system made this pilot system unique in surveillance and public health GIS.

  16. A Fatal Neuroinvasive West Nile Virus Infection in a Traveler Returning from Madagascar: Clinical, Epidemiological and Veterinary Investigations

    Science.gov (United States)

    Larrieu, Sophie; Cardinale, Eric; Ocquidant, Philippe; Roger, Matthieu; Lepec, Richard; Delatte, Hélène; Camuset, Guillaume; Desprès, Philippe; Brottet, Elise; Charlin, Cyril; Michault, Alain

    2013-01-01

    A 58-year-old woman living in Reunion Island and returning from Madagascar was hospitalized for neuroinvasive encephalitis and died 1 month later. West Nile virus (WNV) infection was biologically confirmed by detection of immunoglobulin M (IgM) reactive with WNV antigens in both cerebrospinal fluid and serum, and weak neutralizing activity was also detected. A veterinary survey performed in her traveling area showed a seroprevalence of WNV of 28.7% (95% confidence interval [CI] = 21.1–36.3) in adult poultry, confirming an active circulation of the virus. Development of a severe form could be related to a weak antibody response, because the patient presented low IgM and IgG titers. This case report underlines the constant risk of emergence of West Nile in Indian Ocean territories, including Reunion Island where competent vectors are widely present during the whole year. PMID:23751400

  17. Passive transfer of maternal antibodies to West Nile virus in flamingo chicks (Phoenicopterus chilensis and Phoenicopterus ruber ruber).

    Science.gov (United States)

    Baitchman, Eric J; Tlusty, Michael F; Murphy, Hayley W

    2007-06-01

    Passive transfer of maternal antibodies against West Nile virus (WNV) was studied in a captive population of Chilean (Phoenicopterus chilensis) and Caribbean flamingos (Phoenicopterus ruber ruber). Transfer of WNV antibodies from hens to chicks was documented and measured by plaque-reduction neutralization test. Hen titers were significantly correlated to chick titers. Mean half-life of maternal WNV antibodies was 13.4 days in chicks for which half-life was measurable.

  18. Mosquito cell-derived West Nile virus replicon particles mimic arbovirus inoculum and have reduced spread in mice.

    Science.gov (United States)

    Boylan, Brendan T; Moreira, Fernando R; Carlson, Tim W; Bernard, Kristen A

    2017-02-01

    Half of the human population is at risk of infection by an arthropod-borne virus. Many of these arboviruses, such as West Nile, dengue, and Zika viruses, infect humans by way of a bite from an infected mosquito. This infectious inoculum is insect cell-derived giving the virus particles distinct qualities not present in secondary infectious virus particles produced by infected vertebrate host cells. The insect cell-derived particles differ in the glycosylation of virus structural proteins and the lipid content of the envelope, as well as their induction of cytokines. Thus, in order to accurately mimic the inoculum delivered by arthropods, arboviruses should be derived from arthropod cells. Previous studies have packaged replicon genome in mammalian cells to produce replicon particles, which undergo only one round of infection, but no studies exist packaging replicon particles in mosquito cells. Here we optimized the packaging of West Nile virus replicon genome in mosquito cells and produced replicon particles at high concentration, allowing us to mimic mosquito cell-derived viral inoculum. These particles were mature with similar genome equivalents-to-infectious units as full-length West Nile virus. We then compared the mosquito cell-derived particles to mammalian cell-derived particles in mice. Both replicon particles infected skin at the inoculation site and the draining lymph node by 3 hours post-inoculation. The mammalian cell-derived replicon particles spread from the site of inoculation to the spleen and contralateral lymph nodes significantly more than the particles derived from mosquito cells. This in vivo difference in spread of West Nile replicons in the inoculum demonstrates the importance of using arthropod cell-derived particles to model early events in arboviral infection and highlights the value of these novel arthropod cell-derived replicon particles for studying the earliest virus-host interactions for arboviruses.

  19. West Nile Virus Lineage 2 in Horses and Other Animals with Neurologic Disease, South Africa, 2008-2015.

    Science.gov (United States)

    Venter, Marietjie; Pretorius, Marthi; Fuller, James A; Botha, Elizabeth; Rakgotho, Mpho; Stivaktas, Voula; Weyer, Camilla; Romito, Marco; Williams, June

    2017-12-01

    During 2008-2015 in South Africa, we conducted West Nile virus surveillance in 1,407 animals with neurologic disease and identified mostly lineage 2 cases in horses (7.4%, 79/1,069), livestock (1.5%, 2/132), and wildlife (0.5%, 1/206); 35% were fatal. Geographic correlation of horse cases with seropositive veterinarians suggests disease in horses can predict risk in humans.

  20. Testing a West Nile virus vaccine in sandhill cranes (Grus canadensis)

    Science.gov (United States)

    Olsen, G.H.; Miller, K.; Docherty, D.; Sileo, L.; Chavez-Ramirez, Felipe

    2005-01-01

    Eight sandhill cranes (Grus canadensis) were vaccinated with a commercial equine West Nile virus vaccine (Fort Dodge Animal Health, Fort Dodge, Iowa, USA) at the USGS Patuxent Wildlife Research Center, Laurel, Maryland, USA. Three doses of the vaccine were given, the first dose (day 0) was followed by a second 21 days later and the third dose 7 days after the second day 28 after the first dose). All doses were 0.50 ml. In addition, 5 sandhill cranes were given injections of similar amounts of sterile water on the same schedule. Blood for complete blood counts, serum chemistries, and serological testing was collected at weekly intervals. Ten weeks after the first injection of the vaccine and 6 weeks after the last of the 3 injections of the vaccine, the cranes were shipped to the USGS National Wildlife Heath Center, Madison, Wisconsin, USA. After a two-week adjustment period, 11 of these cranes were injected intramuscularly with one mosquito dose of West Nile virus. Two of the vaccinated cranes were not challenged and acted as uninfected controls. One week post challenge the only abnormal findings were slight weight loss (average 6% loss since the time of challenge with West Nile virus) and elevated white blood cell counts (heterophilic leukocytosis). There were no deaths and no clinically ill cranes (unvaccinated or vaccinated cranes) among the 11 challenged birds. All cranes were euthanized 6 weeks post challenge, and necropsies were performed. Pre-challenge titers showed no titer response to the vaccinations. However, when challenged, vaccinated cranes developed titers more quickly (within 7-10 days), and were viremic and shed virus via the cloaca for a shorter period of time than the unvaccinated cranes (2-7 days for vaccinated cranes versus 2-10 days for unvaccinated cranes). No remarkable lesions were noted in any of the cranes during the necropsy examinations. Histopathological findings are available for only four of the cranes at this time. Three of those

  1. Detection of West Nile Virus and other common equine viruses in three locations from the Leeward Islands, West Indies.

    Science.gov (United States)

    Bolfa, Pompei; Jeon, Isaac; Loftis, Amanda; Leslie, Teresa; Marchi, Silvia; Sithole, Fortune; Beck, Cecile; Lecollinet, Sylvie; Zientara, Stephan; Hans, Aymeric; Issel, Charles J

    2017-10-01

    Equines in the West Indies are used for recreational purposes, tourism industry, racing and agriculture or can be found in feral populations. Little is known in the Caribbean basin about the prevalence of some major equine infectious diseases, some with zoonotic potential, listed as reportable by the OIE. Our objective was to study the prevalence of antibodies for West Nile Virus (WNV), Equine Herpes Virus-1 and 4 (EHV-1 and EHV-4), Equine Influenza (EI), Equine Viral Arteritis (EVA) and Equine Infectious Anemia Virus (EIAV) using a retrospective serological convenience study. We used 180 equine serum samples, 140 from horses and 40 from donkeys in St. Kitts, Nevis, and Sint Eustatius, collected between 2006 and 2015 that were tested with ELISA kits and virus neutralization (for WNV and EVA). Combining ELISA with virus neutralization testing, 25 (13.8%) equine sera were WNV positive (a mixture of indigenous and imported equines) and 3 sera (1.6%) showed doubtful results. For EHV-1, 41 equines (23.7%), mean age 6.7 years, were seropositive. For EHV-4, 138 equines were found seropositive (82.8%), mean age 6.3 years. For EI, 49 equines (27.2%), mean age 7.5 years, were seropositive on ELISA, some previously vaccinated horses. No antibodies against EAV were found on virus neutralization testing, although one animal (0.6%), was EAV positive on ELISA. All samples were EIAV negative. The seroprevalence for EHV-1 and EHV-4 is similar to other parts of the world. For the first time in the study location serologic evidence of antibodies against WNV and EI is reported. This was found in both indigenous and imported animals, highlighting the need for developing proper surveillance plans based on complementary methods of virus detection. Further studies will be needed to define the prevalence, rates of transmission, characterize local virus strains, and study their impact on these populations. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. The seroprevalence of West Nile Virus in Israel: A nationwide cross sectional study.

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    Ravit Bassal

    Full Text Available West Nile Virus (WNV is endemic in Israel, affecting yearly 40-160 individuals. Israel is located on a central migratory path between Africa and Eurasia and most West Nile Fever (WNF cases reported in recent years were among residents of the coastal plain. The aim of the study was to evaluate the seroprevalence of WNV among the Israeli population and to assess correlates for WNV infection. A cross-sectional nationwide serologic survey was conducted using 3,145 serum samples collected by the national Israeli serum bank during 2011-2014, representing all age and population groups in Israel. Prevalence rates of WNV IgG antibodies were determined. Logistic regressions models were applied to assess the associations between demographic characteristics and WNV seropositivity. 350 samples were positive to WNV (11.1%; 95%CI: 10.0-12.3%. In the multivariable analysis, there was a significant association between seropositivity and the Arab population group vs. Jews and others (OR = 1.86, 95%CI: 1.37-2.52, the time lived in Israel [50-59 years vs. 0-9 years; OR = 10.80 (95%CI: 1.03-113.46 and ≥60 years vs. 0-9 years; OR = 14.00 (1.32-148.31] residence area] Coastal Plain, Inland Plain (Shfela and Great Rift Valley vs. Upper Galilee; OR = 2.24 (95%CI: 1.37-3.65, OR = 2.18 (95%CI: 1.18-4.03, OR = 1.90 (95%CI: 1.10-3.30, respectively [and rural vs. urban settlement (OR = 1.65, 95%CI: 1.26-2.16. People, who reside in the Coastal Plain, Inland Plain and Great Rift Valley, should be aware of the risk of contracting WNV and reduce exposure to mosquito bites, using insect repellents, and wearing protective clothing. The Ministry of Environmental Protection should be active in reducing the mosquito population by eliminating sources of standing water, a breeding ground for mosquitoes.

  3. Recovery of West Nile Virus Envelope Protein Domain III Chimeras with Altered Antigenicity and Mouse Virulence.

    Science.gov (United States)

    McAuley, Alexander J; Torres, Maricela; Plante, Jessica A; Huang, Claire Y-H; Bente, Dennis A; Beasley, David W C

    2016-05-01

    Flaviviruses are positive-sense, single-stranded RNA viruses responsible for millions of human infections annually. The envelope (E) protein of flaviviruses comprises three structural domains, of which domain III (EIII) represents a discrete subunit. The EIII gene sequence typically encodes epitopes recognized by virus-specific, potently neutralizing antibodies, and EIII is believed to play a major role in receptor binding. In order to assess potential interactions between EIII and the remainder of the E protein and to assess the effects of EIII sequence substitutions on the antigenicity, growth, and virulence of a representative flavivirus, chimeric viruses were generated using the West Nile virus (WNV) infectious clone, into which EIIIs from nine flaviviruses with various levels of genetic diversity from WNV were substituted. Of the constructs tested, chimeras containing EIIIs from Koutango virus (KOUV), Japanese encephalitis virus (JEV), St. Louis encephalitis virus (SLEV), and Bagaza virus (BAGV) were successfully recovered. Characterization of the chimeras in vitro and in vivo revealed differences in growth and virulence between the viruses, within vivo pathogenesis often not being correlated within vitro growth. Taken together, the data demonstrate that substitutions of EIII can allow the generation of viable chimeric viruses with significantly altered antigenicity and virulence. The envelope (E) glycoprotein is the major protein present on the surface of flavivirus virions and is responsible for mediating virus binding and entry into target cells. Several viable West Nile virus (WNV) variants with chimeric E proteins in which the putative receptor-binding domain (EIII) sequences of other mosquito-borne flaviviruses were substituted in place of the WNV EIII were recovered, although the substitution of several more divergent EIII sequences was not tolerated. The differences in virulence and tissue tropism observed with the chimeric viruses indicate a

  4. The seroprevalence of West Nile Virus in Israel: A nationwide cross sectional study.

    Science.gov (United States)

    Bassal, Ravit; Shohat, Tamy; Kaufman, Zalman; Mannasse, Batya; Shinar, Eilat; Amichay, Doron; Barak, Mira; Ben-Dor, Anat; Bar Haim, Adina; Cohen, Daniel; Mendelson, Ella; Lustig, Yaniv

    2017-01-01

    West Nile Virus (WNV) is endemic in Israel, affecting yearly 40-160 individuals. Israel is located on a central migratory path between Africa and Eurasia and most West Nile Fever (WNF) cases reported in recent years were among residents of the coastal plain. The aim of the study was to evaluate the seroprevalence of WNV among the Israeli population and to assess correlates for WNV infection. A cross-sectional nationwide serologic survey was conducted using 3,145 serum samples collected by the national Israeli serum bank during 2011-2014, representing all age and population groups in Israel. Prevalence rates of WNV IgG antibodies were determined. Logistic regressions models were applied to assess the associations between demographic characteristics and WNV seropositivity. 350 samples were positive to WNV (11.1%; 95%CI: 10.0-12.3%). In the multivariable analysis, there was a significant association between seropositivity and the Arab population group vs. Jews and others (OR = 1.86, 95%CI: 1.37-2.52), the time lived in Israel [50-59 years vs. 0-9 years; OR = 10.80 (95%CI: 1.03-113.46) and ≥60 years vs. 0-9 years; OR = 14.00 (1.32-148.31)] residence area] Coastal Plain, Inland Plain (Shfela) and Great Rift Valley vs. Upper Galilee; OR = 2.24 (95%CI: 1.37-3.65), OR = 2.18 (95%CI: 1.18-4.03), OR = 1.90 (95%CI: 1.10-3.30), respectively [and rural vs. urban settlement (OR = 1.65, 95%CI: 1.26-2.16). People, who reside in the Coastal Plain, Inland Plain and Great Rift Valley, should be aware of the risk of contracting WNV and reduce exposure to mosquito bites, using insect repellents, and wearing protective clothing. The Ministry of Environmental Protection should be active in reducing the mosquito population by eliminating sources of standing water, a breeding ground for mosquitoes.

  5. Identification of risk factors for plague in the West Nile Region of Uganda.

    Science.gov (United States)

    Eisen, Rebecca J; MacMillan, Katherine; Atiku, Linda A; Mpanga, Joseph T; Zielinski-Gutierrez, Emily; Graham, Christine B; Boegler, Karen A; Enscore, Russell E; Gage, Kenneth L

    2014-06-01

    Plague is an often fatal, primarily flea-borne rodent-associated zoonosis caused by Yersinia pestis. We sought to identify risk factors for plague by comparing villages with and without a history of human plague cases within a model-defined plague focus in the West Nile Region of Uganda. Although rat (Rattus rattus) abundance was similar inside huts within case and control villages, contact rates between rats and humans (as measured by reported rat bites) and host-seeking flea loads were higher in case villages. In addition, compared with persons in control villages, persons in case villages more often reported sleeping on reed or straw mats, storing food in huts where persons sleep, owning dogs and allowing them into huts where persons sleep, storing garbage inside or near huts, and cooking in huts where persons sleep. Compared with persons in case villages, persons in control villages more commonly reported replacing thatch roofing, and growing coffee, tomatoes, onions, and melons in agricultural plots adjacent to their homesteads. Rodent and flea control practices, knowledge of plague, distance to clinics, and most care-seeking practices were similar between persons in case villages and persons in control villages. Our findings reinforce existing plague prevention recommendations and point to potentially advantageous local interventions. © The American Society of Tropical Medicine and Hygiene.

  6. Evaluation of antibody response to vaccination against West Nile virus in thick billed parrots (Rhynchopsitta pachyrhyncha).

    Science.gov (United States)

    Glavis, Jennifer; Larsen, R Scott; Lamberski, Nadine; Gaffney, Patricia; Gardner, Ian

    2011-09-01

    West Nile virus (WNV) was first documented in North America in New York City in 1999. Several deaths attributable to WNV have been reported in captive thick-billed parrots (Rhynchopsitta pachyrhyncha), an endangered psittacine native to North America. The serologic responses in 12 captive adult thick-billed parrots after a series of three initial WNV vaccine injections with annual boosters over 6 yr was evaluated. In addition, the serologic responses of 11 thick-billed parrot chicks following an initial vaccination series to determine if there were seroconversions were also reported. Most adults (67%) had seroconverted after 5 yr of annual vaccination, with a median titer of 1:80 (range 1:40-1:160) for those that seroconverted. After the first year, birds were likely naturally exposed to WNV, which limited interpretation of titers. None of the chicks seroconverted during the initial three-vaccine series; only two of four chicks (50%) had seroconverted when tested at the 1-yr yearly booster, and at 2 yr, three of four chicks had seroconverted. Although some birds had detectable antibody titers, it is unclear whether this vaccine can reliably provide protection against WNV in thick-billed parrots.

  7. Land cover variation and West Nile virus prevalence: Patterns, processes, and implications for disease control

    Science.gov (United States)

    Ezenwa, V.O.; Milheim, L.E.; Coffey, M.F.; Godsey, M.S.; King, R.J.; Guptill, S.C.

    2007-01-01

    Identifying links between environmental variables and infectious disease risk is essential to understanding how human-induced environmental changes will effect the dynamics of human and wildlife diseases. Although land cover change has often been tied to spatial variation in disease occurrence, the underlying factors driving the correlations are often unknown, limiting the applicability of these results for disease prevention and control. In this study, we described associations between land cover composition and West Nile virus (WNV) infection prevalence, and investigated three potential processes accounting for observed patterns: (1) variation in vector density; (2) variation in amplification host abundance; and (3) variation in host community composition. Interestingly, we found that WNV infection rates among Culex mosquitoes declined with increasing wetland cover, but wetland area was not significantly associated with either vector density or amplification host abundance. By contrast, wetland area was strongly correlated with host community composition, and model comparisons suggested that this factor accounted, at least partially, for the observed effect of wetland area on WNV infection risk. Our results suggest that preserving large wetland areas, and by extension, intact wetland bird communities, may represent a valuable ecosystem-based approach for controlling WNV outbreaks. ?? Mary Ann Liebert, Inc.

  8. Inhibition of West Nile virus by calbindin-D28k.

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    Venkatraman Siddharthan

    Full Text Available Evidence indicates that West Nile virus (WNV employs Ca(2+ influx for its replication. Moreover, calcium buffer proteins, such as calbindin D28k (CB-D28k, may play an important role mitigating cellular destruction due to disease processes, and more specifically, in some neurological diseases. We addressed the hypothesis that CB-D28k inhibits WNV replication in cell culture and infected rodents. WNV envelope immunoreactivity (ir was not readily co-localized with CB-D28k ir in WNV-infected Vero 76 or motor neuron-like NSC34 cells that were either stably or transiently transfected with plasmids coding for CB-D28k gene. This was confirmed in cultured cells fixed on glass coverslips and by flow cytometry. Moreover, WNV infectious titers were reduced in CB-D28k-transfected cells. As in cell culture studies, WNV env ir was not co-localized with CB-D28k ir in the cortex of an infected WNV hamster, or in the hippocampus of an infected mouse. Motor neurons in the spinal cord typically do not express CB-D28k and are susceptible to WNV infection. Yet, CB-D28k was detected in the surviving motor neurons after the initial phase of WNV infection in hamsters. These data suggested that induction of CB-D28k elicit a neuroprotective response to WNV infection.

  9. The effect of exogenous corticosterone on West Nile virus infection in Northern Cardinals (Cardinalis cardinalis

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    Owen Jennifer C

    2012-04-01

    Full Text Available Abstract The relationship between stress and disease is thought to be unambiguous: chronic stress induces immunosuppression, which likely increases the risk of infection. However, this link has not been firmly established in wild animals, particularly whether stress hormones affect host responses to zoonotic pathogens, which can be transmitted to domesticated animal, wildlife and human populations. Due to the dynamic effects of stress hormones on immune functions, stress hormones may make hosts better or poorer amplifying hosts for a pathogen contingent on context and the host species evaluated. Using an important zoonotic pathogen, West Nile virus (WNV and a competent host, the Northern Cardinal (Cardinalis cardinalis, we tested the effects of exogenous corticosterone on response to WNV infection. Corticosterone was administered at levels that individuals enduring chronic stressors (i.e., long-term inclement weather, food shortage, anthropogenic pollution might experience in the wild. Corticosterone greatly impacted mortality: half of the corticosterone-implanted cardinals died between five - 11 days post-inoculation whereas only one of nine empty-implanted (control birds died. No differences were found in viral titer between corticosterone- and empty-implanted birds. However, cardinals that survived infections had significantly higher average body temperatures during peak infection than individuals that died. In sum, this study indicates that elevated corticosterone could affect the survival of WNV-infected wild birds, suggesting that populations may be disproportionately at-risk to disease in stressful environments.

  10. West nile virus and its theories, a big puzzle in Mexico and latin america.

    Science.gov (United States)

    Elizondo-Quiroga, Darwin; Elizondo-Quiroga, Armando

    2013-10-01

    It has been 13 years since the first outbreak of West Nile Virus (WNV) occurred in the Americas. Since then, thousands of human cases have been reported in the United States. In contrast, there has not yet been an outbreak of WNV in any Latin American countries, including Mexico where database. Furthermore, we present on-line published information from Mexico. We found that researchers have tried to explain this phenomenon using several theories, like pre-existing antibodies against a heterotypical virus that have conferred cross protection in the population. Another explanation is that the strains circulating in Latin America are attenuated or that they came from a different origin of introduction in the continent. Another theory is that a conclusive diagnostic in regions where more than one Flavivirus is circulating results in cross-reaction in serological tests. Probably the sum of factors described by researchers in these theories in order to explain the behavior of the virus has resulted in the low number of reported cases in Latin America.

  11. Use of Competition ELISA for Monitoring of West Nile Virus Infections in Horses in Germany

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    Martin H. Groschup

    2013-07-01

    Full Text Available West Nile virus (WNV is a mosquito-borne viral pathogen of global importance and is considered to be the most widespread flavivirus in the World. Horses, as dead-end hosts, can be infected by bridge mosquito vectors and undergo either subclinical infections or develop severe neurological diseases. The aim of this study was to detect WNV specific antibodies in horses in Germany as an indicator for an endemic circulation of WNV. Sera from more than 5,000 horses (primarily fallen stock animals were collected in eight different federal states of Germany from 2010 to 2012. Sera were screened by a competitive ELISA and positive reactions were verified by an indirect IgM ELISA and/or by virus neutralization tests (VNT for WNV and Tick-borne encephalitis virus (TBEV in order to exclude cross-reacting antibody reactions. In essence WNV specific antibodies could not be detected in any of the horse sera. Not surprisingly, a small number of sera contained antibodies against TBEV. It is noteworthy that equine sera were often collected from horse carcasses and therefore were of poor quality. Nonetheless, these sera were still suitable for WNV ELISA testing, i.e., they did not produce a high background reaction which is a frequently observed phenomenon. According to these data there is no evidence for indigenous WNV infections in horses in Germany at present.

  12. Use of competition ELISA for monitoring of West Nile virus infections in horses in Germany.

    Science.gov (United States)

    Ziegler, Ute; Angenvoort, Joke; Klaus, Christine; Nagel-Kohl, Uschi; Sauerwald, Claudia; Thalheim, Sabine; Horner, Steffen; Braun, Bettina; Kenklies, Susanne; Tyczka, Judith; Keller, Markus; Groschup, Martin H

    2013-07-24

    West Nile virus (WNV) is a mosquito-borne viral pathogen of global importance and is considered to be the most widespread flavivirus in the World. Horses, as dead-end hosts, can be infected by bridge mosquito vectors and undergo either subclinical infections or develop severe neurological diseases. The aim of this study was to detect WNV specific antibodies in horses in Germany as an indicator for an endemic circulation of WNV. Sera from more than 5,000 horses (primarily fallen stock animals) were collected in eight different federal states of Germany from 2010 to 2012. Sera were screened by a competitive ELISA and positive reactions were verified by an indirect IgM ELISA and/or by virus neutralization tests (VNT) for WNV and Tick-borne encephalitis virus (TBEV) in order to exclude cross-reacting antibody reactions. In essence WNV specific antibodies could not be detected in any of the horse sera. Not surprisingly, a small number of sera contained antibodies against TBEV. It is noteworthy that equine sera were often collected from horse carcasses and therefore were of poor quality. Nonetheless, these sera were still suitable for WNV ELISA testing, i.e., they did not produce a high background reaction which is a frequently observed phenomenon. According to these data there is no evidence for indigenous WNV infections in horses in Germany at present.

  13. A CRISPR-Based Screen Identifies Genes Essential for West-Nile-Virus-Induced Cell Death.

    Science.gov (United States)

    Ma, Hongming; Dang, Ying; Wu, Yonggan; Jia, Gengxiang; Anaya, Edgar; Zhang, Junli; Abraham, Sojan; Choi, Jang-Gi; Shi, Guojun; Qi, Ling; Manjunath, N; Wu, Haoquan

    2015-07-28

    West Nile virus (WNV) causes an acute neurological infection attended by massive neuronal cell death. However, the mechanism(s) behind the virus-induced cell death is poorly understood. Using a library containing 77,406 sgRNAs targeting 20,121 genes, we performed a genome-wide screen followed by a second screen with a sub-library. Among the genes identified, seven genes, EMC2, EMC3, SEL1L, DERL2, UBE2G2, UBE2J1, and HRD1, stood out as having the strongest phenotype, whose knockout conferred strong protection against WNV-induced cell death with two different WNV strains and in three cell lines. Interestingly, knockout of these genes did not block WNV replication. Thus, these appear to be essential genes that link WNV replication to downstream cell death pathway(s). In addition, the fact that all of these genes belong to the ER-associated protein degradation (ERAD) pathway suggests that this might be the primary driver of WNV-induced cell death. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Seroconversion for west Nile and St. Louis encephalitis viruses among sentinel horses in Colombia

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    Salim Mattar

    2011-12-01

    Full Text Available We prospectively sampled flavivirus-naïve horses in northern Colombia to detect West Nile virus (WNV and St. Louis encephalitis virus (SLEV seroconversion events, which would indicate the current circulation of these viruses. Overall, 331 (34.1% of the 971 horses screened were positive for past infection with flaviviruses upon initial sampling in July 2006. During the 12-month study from July 2006-June 2007, 33 WNV seroconversions and 14 SLEV seroconversions were detected, most of which occurred in the department of Bolivar. The seroconversion rates of horses in Bolivar for the period of March-June 2007 reached 12.4% for WNV and 6.7% for SLEV. These results comprise the first serologic evidence of SLEV circulation in Colombia. None of the horses sampled developed symptoms of encephalitis within three years of initial sampling. Using seroconversions in sentinel horses, we demonstrated an active circulation of WNV and SLEV in northern Colombia, particularly in the department of Bolivar. The absence of WNV-attributed equine or human disease in Colombia and elsewhere in the Caribbean Basin remains a topic of debate and speculation.

  15. WEST NILE VIRUS ANTIBODY DECAY RATE IN FREE-RANGING BIRDS.

    Science.gov (United States)

    McKee, Eileen M; Walker, Edward D; Anderson, Tavis K; Kitron, Uriel D; Brawn, Jeffrey D; Krebs, Bethany L; Newman, Christina; Ruiz, Marilyn O; Levine, Rebecca S; Carrington, Mary E; McLean, Robert G; Goldberg, Tony L; Hamer, Gabriel L

    2015-07-01

    Antibody duration, following a humoral immune response to West Nile virus (WNV) infection, is poorly understood in free-ranging avian hosts. Quantifying antibody decay rate is important for interpreting serologic results and for understanding the potential for birds to serorevert and become susceptible again. We sampled free-ranging birds in Chicago, Illinois, US, from 2005 to 2011 and Atlanta, Georgia, US, from 2010 to 2012 to examine the dynamics of antibody decay following natural WNV infection. Using serial dilutions in a blocking enzyme-linked immunosorbent assay, we quantified WNV antibody titer in repeated blood samples from individual birds over time. We quantified a rate of antibody decay for 23 Northern Cardinals (Cardinalis cardinalis) of 0.198 natural log units per month and 24 individuals of other bird species of 0.178 natural log units per month. Our results suggest that juveniles had a higher rate of antibody decay than adults, which is consistent with nonlinear antibody decay at different times postexposure. Overall, most birds had undetectable titers 2 yr postexposure. Nonuniform WNV antibody decay rates in free-ranging birds underscore the need for cautious interpretation of avian serology results in the context of arbovirus surveillance and epidemiology.

  16. Characteristics of antibody responses in West Nile virus-seropositive blood donors.

    Science.gov (United States)

    Carson, Paul J; Prince, Harry E; Biggerstaff, Brad J; Lanciotti, Robert; Tobler, Leslie H; Busch, Michael

    2014-01-01

    West Nile virus (WNV) is now endemic in the United States. Protection against infection is thought to be conferred in part by humoral immunity. An understanding of the durability and specificity of the humoral response is not well established. We studied the magnitude and specificity of antibody responses in 370 WNV-seropositive blood donors. We also recalled 18 donors who were infected in 2005 to compare their antibody responses at 6 months following infection versus at 5 years postinfection. There were no significant differences in IgG antibody levels based on age, sex, or recent infection (as evidenced by IgM positivity). Specific antibody responses by viral plaque reduction neutralization testing (PRNT) were seen in 51/54 subjects evaluated. All donors who were seropositive in 2005 remained seropositive at 5 years and maintained neutralizing antibodies. IgG levels at 5 years postinfection showed fairly minimal decreases compared with the paired levels at 6 months postinfection (mean of paired differences,-0.54 signal-to-cutoff ratio (S/CO) units [95% confidence interval {CI}, -0.86 to -0.21 S/CO units]) and only minimal decreases in PRNT titers. WNV induces a significant antibody response that remains present even 5 years after infection.

  17. Effect of aerial insecticide spraying on West Nile virus disease--north-central Texas, 2012.

    Science.gov (United States)

    Ruktanonchai, Duke J; Stonecipher, Shelley; Lindsey, Nicole; McAllister, Janet; Pillai, Satish K; Horiuchi, Kalanthe; Delorey, Mark; Biggerstaff, Brad J; Sidwa, Tom; Zoretic, James; Nasci, Roger; Fischer, Marc; Hills, Susan L

    2014-08-01

    During 2012, four north-central Texas counties experienced high West Nile virus (WNV) disease incidence. Aerial insecticide spraying was conducted in two counties. To evaluate the effect of spraying on WNV disease, we calculated incidence rate ratios (IRRs) in treated and untreated areas by comparing incidence before and after spraying; for unsprayed areas, before and after periods were defined by using dates from a corresponding sprayed area. In treated areas, WNV neuroinvasive disease incidence before and after spraying was 7.31/100,000 persons and 0.28/100,000 persons, respectively; the IRR was 26.42 (95% confidence interval [CI]: 12.42-56.20). In untreated areas, the before and after incidence was 4.80/100,000 persons and 0.45/100,000 persons, respectively; the IRR was 10.57 (95% CI: 6.11-18.28). The ratio of IRRs was 2.50 (95% CI: 0.98-6.35). Disease incidence decreased in both areas, but the relative change was greater in aerial-sprayed areas. © The American Society of Tropical Medicine and Hygiene.

  18. Effect of Aerial Insecticide Spraying on West Nile Virus Disease—North-Central Texas, 2012

    Science.gov (United States)

    Ruktanonchai, Duke J.; Stonecipher, Shelley; Lindsey, Nicole; McAllister, Janet; Pillai, Satish K.; Horiuchi, Kalanthe; Delorey, Mark; Biggerstaff, Brad J.; Sidwa, Tom; Zoretic, James; Nasci, Roger; Fischer, Marc; Hills, Susan L.

    2014-01-01

    During 2012, four north-central Texas counties experienced high West Nile virus (WNV) disease incidence. Aerial insecticide spraying was conducted in two counties. To evaluate the effect of spraying on WNV disease, we calculated incidence rate ratios (IRRs) in treated and untreated areas by comparing incidence before and after spraying; for unsprayed areas, before and after periods were defined by using dates from a corresponding sprayed area. In treated areas, WNV neuroinvasive disease incidence before and after spraying was 7.31/100,000 persons and 0.28/100,000 persons, respectively; the IRR was 26.42 (95% confidence interval [CI]: 12.42–56.20). In untreated areas, the before and after incidence was 4.80/100,000 persons and 0.45/100,000 persons, respectively; the IRR was 10.57 (95% CI: 6.11–18.28). The ratio of IRRs was 2.50 (95% CI: 0.98–6.35). Disease incidence decreased in both areas, but the relative change was greater in aerial-sprayed areas. PMID:24778196

  19. Isolation and characterization of human monoclonal antibodies from individuals infected with West Nile Virus.

    Science.gov (United States)

    Throsby, Mark; Geuijen, Cecile; Goudsmit, Jaap; Bakker, Arjen Q; Korimbocus, Jehanara; Kramer, R Arjen; Clijsters-van der Horst, Marieke; de Jong, Maureen; Jongeneelen, Mandy; Thijsse, Sandra; Smit, Renate; Visser, Therese J; Bijl, Nora; Marissen, Wilfred E; Loeb, Mark; Kelvin, David J; Preiser, Wolfgang; ter Meulen, Jan; de Kruif, John

    2006-07-01

    Monoclonal antibodies (MAbs) neutralizing West Nile Virus (WNV) have been shown to protect against infection in animal models and have been identified as a correlate of protection in WNV vaccine studies. In the present study, antibody repertoires from three convalescent WNV-infected patients were cloned into an scFv phage library, and 138 human MAbs binding to WNV were identified. One hundred twenty-one MAbs specifically bound to the viral envelope (E) protein and four MAbs to the premembrane (prM) protein. Enzyme-linked immunosorbent assay-based competitive-binding assays with representative E protein-specific MAbs demonstrated that 24/51 (47%) bound to domain II while only 4/51 (8%) targeted domain III. In vitro neutralizing activity was demonstrated for 12 MAbs, and two of these, CR4374 and CR4353, protected mice from lethal WNV challenge at 50% protective doses of 12.9 and 357 mug/kg of body weight, respectively. Our data analyzing three infected individuals suggest that the human anti-WNV repertoire after natural infection is dominated by nonneutralizing or weakly neutralizing MAbs binding to domain II of the E protein, while domain III-binding MAbs able to potently neutralize WNV in vitro and in vivo are rare.

  20. West Nile Virus and Usutu Virus Monitoring of Wild Birds in Germany

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    Friederike Michel

    2018-01-01

    Full Text Available By systematically setting up a unique nation-wide wild bird surveillance network, we monitored migratory and resident birds for zoonotic arthropod-borne virus infections, such as the flaviviruses West Nile virus (WNV and Usutu virus (USUV. More than 1900 wild bird blood samples, from 20 orders and 136 different bird species, were collected between 2014 and 2016. Samples were investigated by WNV and USUV-specific real-time polymerase chain reactions as well as by differentiating virus neutralization tests. Dead bird surveillance data, obtained from organ investigations in 2016, were also included. WNV-specific RNA was not detected, whereas four wild bird blood samples tested positive for USUV-specific RNA. Additionally, 73 USUV-positive birds were detected in the 2016 dead bird surveillance. WNV neutralizing antibodies were predominantly found in long-distance, partial and short-distance migrants, while USUV neutralizing antibodies were mainly detected in resident wild bird species, preferentially with low seroprevalences. To date, WNV-specific RNA has neither been detected in wild birds, nor in mosquitoes, thus, we conclude that WNV is not yet present in Germany. Continued wild bird and mosquito monitoring studies are essential to detect the incursion of zoonotic viruses and to allow risk assessments for zoonotic pathogens.

  1. Enhanced West Nile Virus Surveillance in a Dengue-Endemic Area—Puerto Rico, 2007

    Science.gov (United States)

    Torres-Aponte, Jomil M.; Luce, Richard R.; Hunsperger, Elizabeth; Muñoz-Jordan, Jorge L.; Beltrán, Manuela; Vergne, Edgardo; Argüello, D. Fermín; García, Enid J.; Sun, Wellington; Tomashek, Kay M.

    2013-01-01

    In June of 2007, West Nile virus (WNV) was detected in sentinel chickens and blood donors in Puerto Rico, where dengue virus (DENV) is hyperendemic. Enhanced human surveillance for acute febrile illness (AFI) began in eastern Puerto Rico on July 1, 2007. Healthcare providers submitted specimens from AFI cases for WNV and DENV virology and serology testing. Over 6 months, 385 specimens were received from 282 cases; 115 (41%) specimens were DENV laboratory-positive, 86 (31%) specimens were laboratory-indeterminate, and 32 (11%) specimens were laboratory-negative for WNV and DENV. One WNV infection was detected by anti-WNV immunoglobulin M (IgM) antibody and confirmed by a plaque reduction neutralization test. DENV and WNV infections could not be differentiated in 27 cases (10%). During a period of active WNV transmission, enhanced human surveillance identified one case of symptomatic WNV infection. Improved diagnostic methods are needed to allow differentiation of WNV and DENV in dengue-endemic regions. PMID:23478583

  2. Using Undergraduate Researchers to Build Vector and West Nile Virus Surveillance Capacity

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    Daniel T. Kinsey

    2013-07-01

    Full Text Available Vector surveillance for infectious diseases is labor intensive and constantly threatened by budget decisions. We report on outcomes of an undergraduate research experience designed to build surveillance capacity for West Nile Virus (WNV in Montana (USA. Students maintained weekly trapping stations for mosquitoes and implemented assays to test for WNV in pools of Culex tarsalis. Test results were verified in a partnership with the state health laboratory and disseminated to the ArboNET Surveillance System. Combined with prior surveillance data, Cx. tarsalis accounted for 12% of mosquitoes with a mean capture rate of 74 (±SD = 118 Cx. tarsalis females per trap and a minimum infection rate of 0.3 infected mosquitoes per 1000 individuals. However, capture and infection rates varied greatly across years and locations. Infection rate, but not capture rate, was positively associated with the number of WNV human cases (Spearman’s rho = 0.94, p < 0.001. In most years, detection of the first positive mosquito pool occurred at least a week prior to the first reported human case. We suggest that undergraduate research can increase vector surveillance capacity while providing effective learning opportunities for students.

  3. West Nile virus infection induces depletion of IFNAR1 protein levels.

    Science.gov (United States)

    Evans, Jared D; Crown, Rachel A; Sohn, Ji A; Seeger, Christoph

    2011-08-01

    Productive virus infection requires evasion, inhibition, or subversion of innate immune responses. West Nile virus (WNV), a human pathogen that can cause symptomatic infections associated with meningitis and encephalitis, inhibits the interferon (IFN) signal transduction pathway by preventing phosphorylation of Janus kinases and STAT transcription factors. Inhibition of the IFN signal cascade abrogates activation of IFN-induced genes, thus attenuating an antiviral response. We investigated the mechanism responsible for this inhibition and found that WNV infection prevents accumulation of the IFN-α receptor subunit 1 (IFNAR1). The WNV-induced depletion of IFNAR1 was conserved across multiple cell types. Our results indicated that expression of WNV nonstructural proteins resulted in activated lysosomal and proteasomal protein degradation pathways independent of the unfolded protein response (UPR). Furthermore, WNV infection did not induce serine phosphorylation, a modification on IFNAR1 that precedes its natural turnover. These data demonstrate that WNV infection results in a reduction of IFNAR1 protein through a non-canonical protein degradation pathway, and may participate in the inhibition of the IFN response.

  4. Transcriptional response to West Nile virus infection in the zebra finch (Taeniopygia guttata)

    Science.gov (United States)

    Newhouse, Daniel J.; Hofmeister, Erik K.; Balakrishnan, Christopher N.

    2017-01-01

    West Nile virus (WNV) is a widespread arbovirus that imposes a significant cost to both human and wildlife health. WNV exists in a bird-mosquito transmission cycle in which passerine birds act as the primary reservoir host. As a public health concern, the mammalian immune response to WNV has been studied in detail. Little, however, is known about the avian immune response to WNV. Avian taxa show variable susceptibility to WNV and what drives this variation is unknown. Thus, to study the immune response to WNV in birds, we experimentally infected captive zebra finches (Taeniopygia guttata). Zebra finches provide a useful model, as like many natural avian hosts they are moderately susceptible to WNV and thus provide sufficient viremia to infect mosquitoes. We performed RNAseq in spleen tissue during peak viremia to provide an overview of the transcriptional response. In general, we find strong parallels with the mammalian immune response to WNV, including upregulation of five genes in the Rig-I-like receptor signalling pathway, and offer insights into avian-specific responses. Together with complementary immunological assays, we provide a model of the avian immune response to WNV and set the stage for future comparative studies among variably susceptible populations and species.

  5. Targeting Host Factors to Treat West Nile and Dengue Viral Infections

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    Manoj N. Krishnan

    2014-02-01

    Full Text Available West Nile (WNV and Dengue (DENV viruses are major arboviral human pathogens belonging to the genus Flavivirus. At the current time, there are no approved prophylactics (e.g., vaccines or specific therapeutics available to prevent or treat human infections by these pathogens. Due to their minimal genome, these viruses require many host molecules for their replication and this offers a therapeutic avenue wherein host factors can be exploited as treatment targets. Since several host factors appear to be shared by many flaviviruses the strategy may result in pan-flaviviral inhibitors and may also attenuate the rapid emergence of drug resistant mutant viruses. The scope of this strategy is greatly enhanced by the recent en masse identification of host factors impacting on WNV and DENV infection. Excellent proof-of-principle experimental demonstrations for host-targeted control of infection and infection-induced pathogenesis have been reported for both WNV and DENV. These include exploiting not only those host factors supporting infection, but also targeting host processes contributing to pathogenesis and innate immune responses. While these early studies validated the host-targeting approach, extensive future investigations spanning a range of aspects are needed for a successful deployment in humans.

  6. West Nile virus genetic diversity is maintained during transmission by Culex pipiens quinquefasciatus mosquitoes.

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    Doug E Brackney

    Full Text Available Due to error-prone replication, RNA viruses exist within hosts as a heterogeneous population of non-identical, but related viral variants. These populations may undergo bottlenecks during transmission that stochastically reduce variability leading to fitness declines. Such bottlenecks have been documented for several single-host RNA viruses, but their role in the population biology of obligate two-host viruses such as arthropod-borne viruses (arboviruses in vivo is unclear, but of central importance in understanding arbovirus persistence and emergence. Therefore, we tracked the composition of West Nile virus (WNV; Flaviviridae, Flavivirus populations during infection of the vector mosquito, Culex pipiens quinquefasciatus to determine whether WNV populations undergo bottlenecks during transmission by this host. Quantitative, qualitative and phylogenetic analyses of WNV sequences in mosquito midguts, hemolymph and saliva failed to document reductions in genetic diversity during mosquito infection. Further, migration analysis of individual viral variants revealed that while there was some evidence of compartmentalization, anatomical barriers do not impose genetic bottlenecks on WNV populations. Together, these data suggest that the complexity of WNV populations are not significantly diminished during the extrinsic incubation period of mosquitoes.

  7. West Nile Virus State of the Art Report of MALWEST Project

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    Andriani Marka

    2013-12-01

    Full Text Available During the last three years Greece is experiencing the emergence of West Nile virus (WNV epidemics. Within this framework, an integrated surveillance and control programme (MALWEST project with thirteen associate partners was launched aiming to investigate the disease and suggest appropriate interventions. One out of seven work packages of the project is dedicated to the State of the Art report for WNV. Three expert working groups on humans, animals and mosquitoes were established. Medical databases (PubMed, Scopus were searched together with websites: e.g., WHO, CDC, ECDC. In total, 1,092 relevant articles were initially identified and 258 of them were finally included as references regarding the current knowledge about WNV, along with 36 additional sources (conference papers, reports, book chapters. The review is divided in three sections according to the fields of interest: (1 WNV in humans (epidemiology, molecular characteristics, transmission, diagnosis, treatment, prevention, surveillance; (2 WNV in animals (epidemiological and transmission characteristics concerning birds, horses, reptiles and other animal species and (3 WNV in mosquitoes (control, surveillance. Finally, some examples of integrated surveillance programmes are presented. The introduction and establishment of the disease in Greece and other European countries further emphasizes the need for thorough research and broadening of our knowledge on this viral pathogen.

  8. Identification of Risk Factors for Plague in the West Nile Region of Uganda

    Science.gov (United States)

    Eisen, Rebecca J.; MacMillan, Katherine; Atiku, Linda A.; Mpanga, Joseph T.; Zielinski-Gutierrez, Emily; Graham, Christine B.; Boegler, Karen A.; Enscore, Russell E.; Gage, Kenneth L.

    2014-01-01

    Plague is an often fatal, primarily flea-borne rodent-associated zoonosis caused by Yersinia pestis. We sought to identify risk factors for plague by comparing villages with and without a history of human plague cases within a model-defined plague focus in the West Nile Region of Uganda. Although rat (Rattus rattus) abundance was similar inside huts within case and control villages, contact rates between rats and humans (as measured by reported rat bites) and host-seeking flea loads were higher in case villages. In addition, compared with persons in control villages, persons in case villages more often reported sleeping on reed or straw mats, storing food in huts where persons sleep, owning dogs and allowing them into huts where persons sleep, storing garbage inside or near huts, and cooking in huts where persons sleep. Compared with persons in case villages, persons in control villages more commonly reported replacing thatch roofing, and growing coffee, tomatoes, onions, and melons in agricultural plots adjacent to their homesteads. Rodent and flea control practices, knowledge of plague, distance to clinics, and most care-seeking practices were similar between persons in case villages and persons in control villages. Our findings reinforce existing plague prevention recommendations and point to potentially advantageous local interventions. PMID:24686743

  9. Incidence of West Nile virus in birds arriving in wildlife rehabilitation centers in southern Spain.

    Science.gov (United States)

    López, Guillermo; Jiménez-Clavero, Miguel Ángel; Vázquez, Ana; Soriguer, Ramón; Gómez-Tejedor, Concha; Tenorio, Antonio; Figuerola, Jordi

    2011-03-01

    West Nile virus (WNV) is a neurotropic mosquito-transmitted flavivirus that in Eurasia, Africa, and the Americas primarily affects birds and secondarily other vertebrates. WNV has caused frequent massive episodes of wild bird mortality during its expansion throughout the Americas, and has become a regulating factor in the population dynamics of many wild bird species. On the other hand, WNV-related mortalities in wild birds have rarely been reported in the Mediterranean Basin despite its well-documented circulation, and only sporadic outbreaks in horses have been documented. The causes underlying this contrasting epidemiological pattern have never been properly described. An initial suggestion is that Mediterranean and American strains possess different pathogenicities, whereas an alternative view proposes that WNV-related disease and mortalities may have been overlooked in Europe. To test these hypotheses, between 2004 and 2006 in southern Spain we sampled tissue from 119 wild bird carcasses to detect WNV and other flaviviruses, as well as blood from 227 wild birds arriving in wildlife rehabilitation centers to test for WNV seroprevalence. No flavivirus was found in the tissue samples. The prevalence of WNV-neutralizing antibodies was 2.2%, similar to that of 800 healthy birds of the same species that were captured in the field. Our results suggest that WNV circulation during the study period did not result in any detectable effects in terms of bird morbidity or mortality.

  10. Genotype-specific variation in West Nile virus dispersal in California.

    Science.gov (United States)

    Duggal, Nisha K; Reisen, William K; Fang, Ying; Newman, Ruchi M; Yang, Xiao; Ebel, Gregory D; Brault, Aaron C

    2015-11-01

    West Nile virus (WNV) is an arbovirus that was first reported in North America in New York in 1999 and, by 2003, had spread more than 4000 km to California. However, variation in viral genetics associated with spread is not well understood. Herein, we report sequences for more than 100 WNV isolates made from mosquito pools that were collected from 2003 to 2011 as part of routine surveillance by the California Mosquito-borne Virus Surveillance System. We performed phylogeographic analyses and demonstrated that 5 independent introductions of WNV (1 WN02 genotype strain and 4 SW03 genotype strains) occurred in California. The SW03 genotype of WNV was constrained to the southwestern U.S. and had a more rapid rate of spread. In addition, geographic constraint of WNV strains within a single region for up to 6 years suggest viral maintenance has been driven by resident, rather than migratory, birds and overwintering in mosquitoes. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Prospective investigation of the impact of West Nile Virus infections in renal diseases.

    Science.gov (United States)

    Ergunay, Koray; Karagul, Aydan; Abudalal, Ayman; Hacioglu, Sabri; Us, Durdal; Erdem, Yunus; Ozkul, Aykut

    2015-10-01

    An increased incidence of chronic kidney disease (CKD) after West Nile Virus (WNV) infections has been suggested but the association of WNV infections with renal damage remain inconclusive. This study was undertaken to characterize WNV infections in individuals with acute kidney injury (AKI) and CKD, and to evaluate hemodialysis as a probable transmission route. A total of 463 plasma and urine samples were collected from 45 AKI and 77 CKD patients. Nested and real-time polymerase chain reaction (PCR) assays were employed for viral RNA detection. Specific immunoglobulins were investigated via immunofluorescence and plaque reduction neutralization assays. Consecutive pre and post-dialysis samples were evaluated in CKD cases. WNV RNA and specific immunoglobulins were detected in 7 (5.7%) and 5 (4.1%) individuals, respectively. The AKI patients with WNV RNA in blood and urine had underlying diseases requiring immunosuppressive therapy and demonstrated moderate to high viral loads. No clinical symptom related to WNV infection were observed in CKD cases with detectable viral nucleic acids. All WNV sequences were characterized as lineage 1 clade 1a and several amino acid substitutions with unknown impact were noted. Detailed epidemiologic investigation of WNV RNA positive CKD cases revealed probable vector-borne virus exposure, without the evidence for transmission via hemodialysis. © 2015 Wiley Periodicals, Inc.

  12. Experimental infection of cliff swallows (Petrochelidon pyrrhonota) with varying doses of West Nile virus

    Science.gov (United States)

    Oesterle, P.T.; Nemeth, N.M.; VanDalen, Kaci K.; Sullivan, H.; Bentler, K.T.; Young, G.R.; McLean, R.G.; Clark, L.; Smeraski, C.; Hall, Jeffrey S.

    2009-01-01

    Cliff swallows (Petrochelidon pyrrhonota) were inoculated with differing doses of West Nile virus (WNV) to evaluate their potential role as reservoir hosts in nature. Swallows often nest in large colonies in habitats and months associated with high mosquito abundance and early WNV transmission in North America. Additionally, cliff swallow diet consists of insects, including mosquitoes, leading to an additional potential route of WNV infection. The average peak viremia titer among infected cliff swallows was 106.3 plaque-forming units (PFU)/mL serum and the reservoir competence index was 0.34. There was no correlation between dose and probability of becoming infected or viremia peak and duration. Oral shedding was detected from 2 to 14 days post-inoculation with an average peak titer of 1044 PFU/swab. These results suggest that cliff swallows are competent reservoir hosts of WNV and therefore, they may play a role in early seasonal amplification and maintenance of WNV. Copyright ?? 2009 by The American Society of Tropical Medicine and Hygiene.

  13. Surveillance potential of non-native Hawaiian birds for detection of West Nile Virus

    Science.gov (United States)

    Hofmeister, Erik K.; Dusek, Robert J.; Brand, Christopher J.

    2015-01-01

    West Nile virus (WNV) was first detected in North America in 1999. Alaska and Hawaii (HI) remain the only U.S. states in which transmission of WNV has not been detected. Dead bird surveillance has played an important role in the detection of the virus geographically, as well as temporally. In North America, corvids have played a major role in WNV surveillance; however, the only corvid in HI is the endangered Hawaiian crow that exists only in captivity, thus precluding the use of this species for WNV surveillance in HI. To evaluate the suitability of alternate avian species for WNV surveillance, we experimentally challenged seven abundant non-native bird species present in HI with WNV and compared mortality, viremia, oral shedding of virus, and seroconversion. For detection of WNV in oral swabs, we compared viral culture, reverse-transcriptase polymerase chain reaction, and the RAMP® test. For detection of antibodies to WNV, we compared an indirect and a competitive enzyme-linked immunoassay. We found four species (house sparrow, house finch, Japanese white-eye, and Java sparrow) that may be useful in dead bird surveillance for WNV; while common myna, zebra dove, and spotted dove survived infection and may be useful in serosurveillance.

  14. West Nile virus infection causes endocytosis of a specific subset of tight junction membrane proteins.

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    Zaikun Xu

    Full Text Available West Nile virus (WNV is a blood-borne pathogen that causes systemic infections and serious neurological disease in human and animals. The most common route of infection is mosquito bites and therefore, the virus must cross a number of polarized cell layers to gain access to organ tissue and the central nervous system. Resistance to trans-cellular movement of macromolecules between epithelial and endothelial cells is mediated by tight junction complexes. While a number of recent studies have documented that WNV infection negatively impacts the barrier function of tight junctions, the intracellular mechanism by which this occurs is poorly understood. In the present study, we report that endocytosis of a subset of tight junction membrane proteins including claudin-1 and JAM-1 occurs in WNV infected epithelial and endothelial cells. This process, which ultimately results in lysosomal degradation of the proteins, is dependent on the GTPase dynamin and microtubule-based transport. Finally, infection of polarized cells with the related flavivirus, Dengue virus-2, did not result in significant loss of tight junction membrane proteins. These results suggest that neurotropic flaviviruses such as WNV modulate the host cell environment differently than hemorrhagic flaviviruses and thus may have implications for understanding the molecular basis for neuroinvasion.

  15. Generation of West Nile virus infectious clones containing amino acid insertions between capsid and capsid anchor.

    Science.gov (United States)

    Vandergaast, Rianna; Hoover, Lisa I; Zheng, Kang; Fredericksen, Brenda L

    2014-04-09

    West Nile virus (WNV) is a positive-sense RNA arbovirus responsible for recent outbreaks of severe neurological disease within the US and Europe. Large-scale analyses of antiviral compounds that inhibit virus replication have been limited due to the lack of an adequate WN reporter virus. Previous attempts to insert a reporter into the 3' untranslated region of WNV generated unstable viruses, suggesting that this region does not accommodate additional nucleotides. Here, we engineered two WNV infectious clones containing insertions at the Capsid (C)/Capsid Anchor (CA) junction of the viral polyprotein. Recombinant viruses containing a TAT(1-67) or Gaussia Luciferase (GLuc) gene at this location were successfully recovered. However, rapid loss of most, if not all, of the reporter sequence occurred for both viruses, indicating that the reporter viruses were not stable. While the GLuc viruses predominantly reverted back to wild-type WNV length, the TAT viruses retained up to 75 additional nucleotides of the reporter sequence. These additional nucleotides were stable over at least five passages and did not significantly alter WNV fitness. Thus, the C/CA junction of WNV can tolerate additional nucleotides, though insertions are subject to certain constraints.

  16. West Nile virus experimental evolution in vivo and the trade-off hypothesis.

    Directory of Open Access Journals (Sweden)

    Eleanor R Deardorff

    2011-11-01

    Full Text Available In nature, arthropod-borne viruses (arboviruses perpetuate through alternating replication in vertebrate and invertebrate hosts. The trade-off hypothesis proposes that these viruses maintain adequate replicative fitness in two disparate hosts in exchange for superior fitness in one host. Releasing the virus from the constraints of a two-host cycle should thus facilitate adaptation to a single host. This theory has been addressed in a variety of systems, but remains poorly understood. We sought to determine the fitness implications of alternating host replication for West Nile virus (WNV using an in vivo model system. Previously, WNV was serially or alternately passed 20 times in vivo in chicks or mosquitoes and resulting viruses were characterized genetically. In this study, these test viruses were competed in vivo in fitness assays against an unpassed marked reference virus. Fitness was assayed in chicks and in two important WNV vectors, Culex pipiens and Culex quinquefasciatus. Chick-specialized virus displayed clear fitness gains in chicks and in Cx. pipiens but not in Cx. quinquefasciatus. Cx. pipiens-specialized virus experienced reduced fitness in chicks and little change in either mosquito species. These data suggest that when fitness is measured in birds the trade-off hypothesis is supported; but in mosquitoes it is not. Overall, these results suggest that WNV evolution is driven by alternate cycles of genetic expansion in mosquitoes, where purifying selection is weak and genetic diversity generated, and restriction in birds, where purifying selection is strong.

  17. Spreading and vanishing in a West Nile virus model with expanding fronts

    Science.gov (United States)

    Tarboush, Abdelrazig K.; Lin, ZhiGui; Zhang, MengYun

    2017-05-01

    In this paper, we study a simplified version of a West Nile virus model discussed by Lewis et al. [28], which was considered as a first approximation for the spatial spread of WNv. The basic reproduction number $R_0$ for the non-spatial epidemic model is defined and a threshold parameter $R_0 ^D$ for the corresponding problem with null Dirichlet boundary condition is introduced. We consider a free boundary problem with coupled system, which describes the diffusion of birds by a PDE and the movement of mosquitoes by a ODE. The risk index $R_0^F (t)$ associated with the disease in spatial setting is represented. Sufficient conditions for the WNv to eradicate or to spread are given. The asymptotic behavior of the solution to system when the spreading occurs are considered. It is shown that the initial number of infected populations, the diffusion rate of birds and the length of initial habitat exhibit important impacts on the vanishing or spreading of the virus. Numerical simulations are presented to illustrate the analytical results.

  18. Plant-made vaccines against West Nile virus are potent, safe, and economically feasible.

    Science.gov (United States)

    Chen, Qiang

    2015-05-01

    The threat of West Nile virus (WNV) epidemics with increasingly severe neuroinvasive infections demands the development and licensing of effective vaccines. To date, vaccine candidates based on inactivated, live-attenuated, or chimeric virus, and viral DNA and WNV protein subunits have been developed. Some have been approved for veterinary use or are under clinical investigation, yet no vaccine has been licensed for human use. Reaching the milestone of a commercialized human vaccine, however, may largely depend on the economics of vaccine production. Analysis suggests that currently only novel low-cost production technologies would allow vaccination to outcompete the cost of surveillance and clinical treatment. Here, we review progress using plants to address the economic challenges of WNV vaccine production. The advantages of plants as hosts for vaccine production in cost, speed and scalability, especially those of viral vector-based transient expression systems, are discussed. The progress in developing WNV subunit vaccines in plants is reviewed within the context of their expression, characterization, downstream processing, and immunogenicity in animal models. The development of vaccines based on enveloped and non-enveloped virus-like particles is also discussed. These advancements suggest that plants may provide a production platform that offers potent, safe and affordable human vaccines against WNV. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Survey for West Nile virus antibodies in wild ducks, 2004-06, USA

    Science.gov (United States)

    Hofmeister, Erik K.; Jankowski, Mark D.; Goldberg, Diana R.; Franson, J. Christian

    2016-01-01

    Detection of West Nile virus (WNV) in ducks has been reported in North America in isolated cases of mortality in wild waterbirds and following outbreaks in farmed ducks. Although the virus has been noted as an apparent incidental finding in several species of ducks, little is known about the prevalence of exposure or the outcome of infection with WNV in wild ducks in North America. From 2004–06, we collected sera from 1,406 wild-caught American Wigeon (Anas americana), Mallard (Anas platyrhynchos), and Northern Pintail (Anas acuta) ducks at national wildlife refuges (NWRs) in North Dakota and Wood Ducks (Aix sponsa) at NWRs in South Carolina and Tennessee. We measured the prevalence of previous exposure to WNV in these ducks by measuring WNV antibodies and evaluated variation in exposure among species, age, and year. Additionally, we evaluated the performance of a commercial antibody to wild bird immunoglobulin in duck species that varied in their phylogenetic relatedness to the bird species the antibody was directed against. As determined by a screening immunoassay and a confirmatory plaque reduction neutralization assay, the prevalence of WNV antibody was 10%. In light of experimental studies that show ducks to be relatively resistant to mortality caused by WNV, the antibody prevalence we detected suggests that wild ducks may be less-frequently exposed to WNV than expected for birds inhabiting wetlands where they may acquire infection from mosquitoes.

  20. Susceptibility of Carrion Crows to Experimental Infection with Lineage 1 and 2 West Nile Viruses.

    Science.gov (United States)

    Lim, Stephanie M; Brault, Aaron C; van Amerongen, Geert; Bosco-Lauth, Angela M; Romo, Hannah; Sewbalaksing, Varsha D; Bowen, Richard A; Osterhaus, Albert D M E; Koraka, Penelope; Martina, Byron E E

    2015-08-01

    West Nile virus (WNV) outbreaks in North America have been characterized by substantial die-offs of American crows (Corvus brachyrhynchos). In contrast, a low incidence of bird deaths has been observed during WNV epidemic activity in Europe. To examine the susceptibility of the western European counterpart of American crows, we inoculated carrion crows (Corvus corone) with WNV strains isolated in Greece (Gr-10), Italy (FIN and Ita09), and Hungary (578/10) and with the highly virulent North American genotype strain (NY99). We also inoculated American crows with a selection of these strains to examine the strains' virulence in a highly susceptible bird species. Infection with all strains, except WNV FIN, resulted in high rates of death and high-level viremia in both bird species and virus dissemination to several organs. These results suggest that carrion crows are highly susceptible to WNV and may potentially be useful as part of dead bird surveillance for early warning of WNV activity in Europe.

  1. West Nile Virus State of the Art Report of MALWEST Project

    Science.gov (United States)

    Marka, Andriani; Diamantidis, Alexandros; Papa, Anna; Valiakos, George; Chaintoutis, Serafeim C.; Doukas, Dimitrios; Tserkezou, Persefoni; Giannakopoulos, Alexios; Papaspyropoulos, Konstantinos; Patsoula, Eleni; Badieritakis, Evangelos; Baka, Agoritsa; Tseroni, Maria; Pervanidou, Danai; Papadopoulos, Nikos T.; Koliopoulos, George; Tontis, Dimitrios; Dovas, Chrysostomos I.; Billinis, Charalambos; Tsakris, Athanassios; Kremastinou, Jenny; Hadjichristodoulou, Christos

    2013-01-01

    During the last three years Greece is experiencing the emergence of West Nile virus (WNV) epidemics. Within this framework, an integrated surveillance and control programme (MALWEST project) with thirteen associate partners was launched aiming to investigate the disease and suggest appropriate interventions. One out of seven work packages of the project is dedicated to the State of the Art report for WNV. Three expert working groups on humans, animals and mosquitoes were established. Medical databases (PubMed, Scopus) were searched together with websites: e.g., WHO, CDC, ECDC. In total, 1,092 relevant articles were initially identified and 258 of them were finally included as references regarding the current knowledge about WNV, along with 36 additional sources (conference papers, reports, book chapters). The review is divided in three sections according to the fields of interest: (1) WNV in humans (epidemiology, molecular characteristics, transmission, diagnosis, treatment, prevention, surveillance); (2) WNV in animals (epidemiological and transmission characteristics concerning birds, horses, reptiles and other animal species) and (3) WNV in mosquitoes (control, surveillance). Finally, some examples of integrated surveillance programmes are presented. The introduction and establishment of the disease in Greece and other European countries further emphasizes the need for thorough research and broadening of our knowledge on this viral pathogen. PMID:24317379

  2. Mosquitoes Transmit Unique West Nile Virus Populations during Each Feeding Episode.

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    Grubaugh, Nathan D; Fauver, Joseph R; Rückert, Claudia; Weger-Lucarelli, James; Garcia-Luna, Selene; Murrieta, Reyes A; Gendernalik, Alex; Smith, Darci R; Brackney, Doug E; Ebel, Gregory D

    2017-04-25

    Arthropod-borne viruses (arboviruses), such as Zika virus, chikungunya virus, and West Nile virus (WNV), pose continuous threats to emerge and cause large epidemics. Often, these events are associated with novel virus variants optimized for local transmission that first arise as minorities within a host. Thus, the conditions that regulate the frequency of intrahost variants are important determinants of emergence. Here, we describe the dynamics of WNV genetic diversity during its transmission cycle. By temporally sampling saliva from individual mosquitoes, we demonstrate that virus populations expectorated by mosquitoes are highly diverse and unique to each feeding episode. After transmission to birds, however, most genetic diversity is removed by strong purifying selection. Further, transmission of potentially mosquito-adaptive WNV variants is strongly influenced by genetic drift in mosquitoes. These results highlight the complex evolutionary forces a novel virus variant must overcome to alter infection phenotypes at the population level. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  3. Spatial spreading model and dynamics of West Nile virus in birds and mosquitoes with free boundary.

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    Lin, Zhigui; Zhu, Huaiping

    2017-12-01

    In this paper, a reaction-diffusion system is proposed to model the spatial spreading of West Nile virus in vector mosquitoes and host birds in North America. Transmission dynamics are based on a simplified model involving mosquitoes and birds, and the free boundary is introduced to model and explore the expanding front of the infected region. The spatial-temporal risk index [Formula: see text], which involves regional characteristic and time, is defined for the simplified reaction-diffusion model with the free boundary to compare with other related threshold values, including the usual basic reproduction number [Formula: see text]. Sufficient conditions for the virus to vanish or to spread are given. Our results suggest that the virus will be in a scenario of vanishing if [Formula: see text], and will spread to the whole region if [Formula: see text] for some [Formula: see text], while if [Formula: see text], the spreading or vanishing of the virus depends on the initial number of infected individuals, the area of the infected region, the diffusion rate and other factors. Moreover, some remarks on the basic reproduction numbers and the spreading speeds are presented and compared.

  4. Noncoding Subgenomic Flavivirus RNA: Multiple Functions in West Nile Virus Pathogenesis and Modulation of Host Responses

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    Justin A. Roby

    2014-01-01

    Full Text Available Flaviviruses are a large group of positive strand RNA viruses transmitted by arthropods that include many human pathogens such as West Nile virus (WNV, Japanese encephalitis virus (JEV, yellow fever virus, dengue virus, and tick-borne encephalitis virus. All members in this genus tested so far are shown to produce a unique subgenomic flavivirus RNA (sfRNA derived from the 3' untranslated region (UTR. sfRNA is a product of incomplete degradation of genomic RNA by the cell 5'–3' exoribonuclease XRN1 which stalls at highly ordered secondary RNA structures at the beginning of the 3'UTR. Generation of sfRNA results in inhibition of XRN1 activity leading to an increase in stability of many cellular mRNAs. Mutant WNV deficient in sfRNA generation was highly attenuated displaying a marked decrease in cytopathicity in cells and pathogenicity in mice. sfRNA has also been shown to inhibit the antiviral activity of IFN-α/β by yet unknown mechanism and of the RNAi pathway by likely serving as a decoy substrate for Dicer. Thus, sfRNA is involved in modulating multiple cellular pathways to facilitate viral pathogenicity; however the overlying mechanism linking all these multiple functions of sfRNA remains to be elucidated.

  5. An Overview of Current Approaches Toward the Treatment and Prevention of West Nile Virus Infection.

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    Acharya, Dhiraj; Bai, Fengwei

    2016-01-01

    The persistence of West Nile virus (WNV) infections throughout the USA since its inception in 1999 and its continuous spread throughout the globe calls for an urgent need of effective treatments and prevention measures. Although the licensing of several WNV vaccines for veterinary use provides a proof of concept, similar efforts on the development of an effective vaccine for humans remain still unsuccessful. Increased understanding of biology and pathogenesis of WNV together with recent technological advancements have raised hope that an effective WNV vaccine may be available in the near future. In addition, rapid progress in the structural and functional characterization of WNV and other flaviviral proteins have provided a solid base for the design and development of several classes of inhibitors as potential WNV therapeutics. Moreover, the therapeutic monoclonal antibodies demonstrate an excellent efficacy against WNV in animal models and represent a promising class of WNV therapeutics. However, there are some challenges as to the design and development of a safe and efficient WNV vaccine or therapeutic. In this chapter, we discuss the current approaches, progress, and challenges toward the development of WNV vaccines, therapeutic antibodies, and antiviral drugs.

  6. West nile virus in American white pelican chicks: transmission, immunity, and survival

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    Sovada, Marsha A.; Pietz, Pamela J.; Hofmeister, Erik K.; Bartos, Alisa J.

    2013-01-01

    West Nile virus (WNV) causes significant mortality of American White Pelican chicks at northern plains colonies. We tested oropharyngeal/cloacal swabs from moribund chicks for shed WNV. Such shedding could enable chick-to-chick transmission and help explain why WNV spreads rapidly in colonies. WNV was detected on swabs from 11% of chicks in 2006 and 52% of chicks in 2007; however, viral titers were low. Before onset of WNV mortality, we tested blood from < 3-week-old chicks for antibodies to WNV; 5% of chicks were seropositive, suggesting passive transfer of maternal antibodies. Among near-fledged chicks, 41% tested positive for anti-WNV antibodies, indicating that they survived infection. Among years and colonies, cumulative incidence of WNV in chicks varied from 28% to 81%, whereas the proportion of chicks surviving WNV (i.e., seropositive) was 64–75%. Our data revealed that WNV kills chicks that likely would fledge in the absence of WNV, that infection of chicks is pervasive, and that significant numbers of chicks survive infection.

  7. Oral and parenteral immunization of chickens (Gallus gallus) against West Nile virus with recombinant envelope protein

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    Fassbinder-Orth, C. A.; Hofmeister, Erik K.; Weeks-Levy, C.; Karasov, W.H.

    2009-01-01

    West Nile virus (WNV) causes morbidity and mortality in humans, horses, and in more than 315 bird species in North America. Currently approved WNV vaccines are designed for parenteral administration and, as yet, no effective oral WNV vaccines have been developed. WNV envelope (E) protein is a highly antigenic protein that elicits the majority of virus-neutralizing antibodies during a WNV immune response. Leghorn chickens were given three vaccinations (each 2 wk apart) of E protein orally (20 ??g or 100 ??g/dose), of E protein intramuscularly (IM, 20 ??g/dose), or of adjuvant only (control group) followed by a WNV challenge. Viremias were measured post-WNV infection, and three new enzyme-linked immunosorbent assays were developed for quantifying IgM, IgY, and IgA-mediated immune response of birds following WNV infection. WNV viremia levels were significantly lower in the IM group than in both oral groups and the control group. Total WNV E protein-specific IgY production was significantly greater, and WNV nonstructural 1-specific IgY was significantly less, in the IM group compared to all other treatment groups. The results of this study indicate that IM vaccination of chickens with E protein is protective against WNV infection and results in a significantly different antibody production profile as compared to both orally vaccinated and nonvaccinated birds. ?? 2009 American Association of Avian Pathologists.

  8. IFN-Dependent and -Independent Reduction in West Nile Virus Infectivity in Human Dermal Fibroblasts

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    Hoover, Lisa I.; Fredericksen, Brenda L.

    2014-01-01

    Although dermal fibroblasts are one of the first cell types exposed to West Nile virus (WNV) during a blood meal by an infected mosquito, little is known about WNV replication within this cell type. Here, we demonstrate that neuroinvasive, WNV-New York (WNV-NY), and nonneuroinvasive, WNV-Australia (WNV-AUS60) strains are able to infect and replicate in primary human dermal fibroblasts (HDFs). However, WNV-AUS60 replication and spread within HDFs was reduced compared to that of WNV-NY due to an interferon (IFN)-independent reduction in viral infectivity early in infection. Additionally, replication of both strains was constrained late in infection by an IFN-β-dependent reduction in particle infectivity. Overall, our data indicates that human dermal fibroblasts are capable of supporting WNV replication; however, the low infectivity of particles produced from HDFs late in infection suggests that this cell type likely plays a limited role as a viral reservoir in vivo. PMID:24662674

  9. Occurrence of avian Plasmodium and West Nile virus in culex species in Wisconsin

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    Hughes, T.; Irwin, P.; Hofmeister, E.; Paskewitz, S.M.

    2010-01-01

    The occurrence of multiple pathogens in mosquitoes and birds could affect the dynamics of disease transmission. We collected adult Culex pipiens and Cx. restuans (Cx. pipiens/restuans hereafter) from sites in Wisconsin and tested them for West Nile virus (WNV) and for avian malaria (Plasmodium). Gravid Cx. pipiens/restuans were tested for WNV using a commercial immunoassay, the RAMP?? WNV test, and positive results were verified by reverse transcriptasepolymerase chain reaction. There were 2 WNV-positive pools of Cx. pipiens/restuans in 2006 and 1 in 2007. Using a bias-corrected maximum likelihood estimation, the WNV infection rate for Cx. pipiens/restuans was 5.48/1,000 mosquitoes in 2006 and 1.08/1,000 mosquitoes in 2007. Gravid Cx. pipiens or Cx. restuans were tested individually for avian Plasmodium by a restriction enzymebased assay. Twelve mosquitoes were positive for avian Plasmodium (10.0), 2 were positive for Haemoproteus, and 3 were positive for Leucocytozoon. There were 4 mixed infections, with mosquitoes positive for >1 of the hemosporidian parasites. This work documents a high rate of hemosporidian infection in Culex spp. and illustrates the potential for co-infections with other arboviruses in bird-feeding mosquitoes and their avian hosts. In addition, hemosporidian infection rates may be a useful tool for investigating the ecological dynamics of Culex/avian interactions. ?? 2010 by The American Mosquito Control Association, Inc.

  10. Real time PCR assay for detection of all known lineages of West Nile virus.

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    Vázquez, Ana; Herrero, Laura; Negredo, Anabel; Hernández, Lourdes; Sánchez-Seco, María Paz; Tenorio, Antonio

    2016-10-01

    West Nile virus (WNV) is one of the most widespread arbovirus and a large variety of WNV strains and lineages have been described. The molecular methods for the diagnosis of WNV target mainly lineages 1 and 2, which have caused outbreaks in humans, equines and birds. But the last few years new and putative WNV lineages of unknown pathogenicity have been described. Here we describe a new sensitive and specific real-time PCR assay for the detection and quantification of all the WNV lineages described until now. Primers and probe were designed in the 3'-untranslated region (3'-UTR) of the WNV genome and were designed to match all sequenced WNV strains perfectly. The sensitivity of the assay ranged from 1,5 to 15 copies per reaction depending on the WNV lineage tested. The method was validated for WNV diagnosis using different viral strains, human samples (cerebrospinal fluid, biopsies, serum and plasma) and mosquito pools. The assay did not amplify any other phylogenetically or symptomatically related viruses. All of the above make it a very suitable tool for the diagnosis of WNV and for surveillance studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Sequence-Specific Fidelity Alterations Associated with West Nile Virus Attenuation in Mosquitoes.

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    Greta A Van Slyke

    2015-06-01

    Full Text Available High rates of error-prone replication result in the rapid accumulation of genetic diversity of RNA viruses. Recent studies suggest that mutation rates are selected for optimal viral fitness and that modest variations in replicase fidelity may be associated with viral attenuation. Arthropod-borne viruses (arboviruses are unique in their requirement for host cycling and may necessitate substantial genetic and phenotypic plasticity. In order to more thoroughly investigate the correlates, mechanisms and consequences of arbovirus fidelity, we selected fidelity variants of West Nile virus (WNV; Flaviviridae, Flavivirus utilizing selection in the presence of a mutagen. We identified two mutations in the WNV RNA-dependent RNA polymerase associated with increased fidelity, V793I and G806R, and a single mutation in the WNV methyltransferase, T248I, associated with decreased fidelity. Both deep-sequencing and in vitro biochemical assays confirmed strain-specific differences in both fidelity and mutational bias. WNV fidelity variants demonstrated host-specific alterations to replicative fitness in vitro, with modest attenuation in mosquito but not vertebrate cell culture. Experimental infections of colonized and field populations of Cx. quinquefaciatus demonstrated that WNV fidelity alterations are associated with a significantly impaired capacity to establish viable infections in mosquitoes. Taken together, these studies (i demonstrate the importance of allosteric interactions in regulating mutation rates, (ii establish that mutational spectra can be both sequence and strain-dependent, and (iii display the profound phenotypic consequences associated with altered replication complex function of flaviviruses.

  12. Supramolecular peptide hydrogel adjuvanted subunit vaccine elicits protective antibody responses against West Nile virus.

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    Friedrich, Brian M; Beasley, David W C; Rudra, Jai S

    2016-11-04

    A crucial issue in vaccine development is to balance safety with immunogenicity. The low immunogenicity of most subunit antigens warrants a search for adjuvants able to stimulate both cell-mediated and humoral immunity. In recent years, successful applications of nanotechnology and bioengineering in the field of vaccine development have enabled the production of novel adjuvant technologies. In this work, we investigated totally synthetic and supramolecular peptide hydrogels as novel vaccine adjuvants in conjunction with the immunoprotective envelope protein domain III (EIII) of West Nile virus as an immunogen in a mouse model. Our results indicate that, compared to the clinically approved adjuvant alum, peptide hydrogel adjuvanted antigen elicited stronger antibody responses and conferred significant protection against mortality after virus challenge. The high chemical definition and biocompatibility of self-assembling peptide hydrogels makes them attractive as immune adjuvants for the production of subunit vaccines against viral and bacterial infections where antibody-mediated protection is desirable. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Vector-Virus Interactions and Transmission Dynamics of West Nile Virus

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    Ciota, Alexander T.; Kramer, Laura D.

    2013-01-01

    West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission. PMID:24351794

  14. Alterations in the Aedes aegypti transcriptome during infection with West Nile, dengue and yellow fever viruses.

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    Tonya M Colpitts

    2011-09-01

    Full Text Available West Nile (WNV, dengue (DENV and yellow fever (YFV viruses are (reemerging, mosquito-borne flaviviruses that cause human disease and mortality worldwide. Alterations in mosquito gene expression common and unique to individual flaviviral infections are poorly understood. Here, we present a microarray analysis of the Aedes aegypti transcriptome over time during infection with DENV, WNV or YFV. We identified 203 mosquito genes that were ≥ 5-fold differentially up-regulated (DUR and 202 genes that were ≥ 10-fold differentially down-regulated (DDR during infection with one of the three flaviviruses. Comparative analysis revealed that the expression profile of 20 DUR genes and 15 DDR genes was quite similar between the three flaviviruses on D1 of infection, indicating a potentially conserved transcriptomic signature of flaviviral infection. Bioinformatics analysis revealed changes in expression of genes from diverse cellular processes, including ion binding, transport, metabolic processes and peptidase activity. We also demonstrate that virally-regulated gene expression is tissue-specific. The overexpression of several virally down-regulated genes decreased WNV infection in mosquito cells and Aedes aegypti mosquitoes. Among these, a pupal cuticle protein was shown to bind WNV envelope protein, leading to inhibition of infection in vitro and the prevention of lethal WNV encephalitis in mice. This work provides an extensive list of targets for controlling flaviviral infection in mosquitoes that may also be used to develop broad preventative and therapeutic measures for multiple flaviviruses.

  15. Natural and experimental West Nile virus infection in five raptor species.

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    Nemeth, Nicole; Gould, Daniel; Bowen, Richard; Komar, Nicholas

    2006-01-01

    We studied the effects of natural and/or experimental infections of West Nile virus (WNV) in five raptor species from July 2002 to March 2004, including American kestrels (Falco sparverius), golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), barn owls (Tyto alba), and great horned owls (Bubo virginianus). Birds were infected per mosquito bite, per os, or percutaneously by needle. Many experimentally infected birds developed mosquito-infectious levels of viremia (>10(5) WNV plaque forming units per ml serum) within 5 days postinoculation (DPI), and/ or shed virus per os or per cloaca. Infection of organs 15-27 days postinoculation was infrequently detected by virus isolation from spleen, kidney, skin, heart, brain, and eye in convalescent birds. Histopathologic findings varied among species and by method of infection. The most common histopathologic lesions were subacute myocarditis and encephalitis. Several birds had a more acute, severe disease condition represented by arteritis and associated with tissue degeneration and necrosis. This study demonstrates that raptor species vary in their response to WNV infection and that several modes of exposure (e.g., oral) may result in infection. Wildlife managers should recognize that, although many WNV infections are sublethal to raptors, subacute lesions could potentially reduce viability of populations. We recommend that raptor handlers consider raptors as a potential source of WNV contamination due to oral and cloacal shedding.

  16. Serologic evidence of West Nile virus infection in three wild raptor populations.

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    Stout, William E; Cassini, Andrew G; Meece, Jennifer K; Papp, Joseph M; Rosenfield, Robert N; Reed, Kurt D

    2005-09-01

    We assayed for West Nile virus (WNV) antibodies to determine the presence and prevalence of WNV infection in three raptor populations in southeast Wisconsin during 2003-04. This study was conducted in the framework of ongoing population studies that started before WNV was introduced to the study area. For 354 samples, 88% of 42 adult Cooper's hawks (Accipiter cooperii), 2.1% of 96 nestling Cooper's hawks, 9.2% of 141 nestling red-tailed hawks (Buteo jamaicensis), and 12% of 73 nestling great horned owls (Bubo virginianus) tested positive for WNV antibodies by the constant virus-serum dilution neutralization test. Samples that tested positive for WNV antibodies were collected across a wide variety of habitat types, including urban habitats (both high and low density), roads, parking areas, recreational areas, croplands, pastures, grasslands, woodlands, and wetlands. Based on the increased prevalence and significantly higher WNV antibody titers in adults compared with nestlings, we suggest that nestlings with detectable antibody levels acquired these antibodies through passive transmission from the mother during egg production. Low levels of WNV antibodies in nestlings could serve as a surrogate marker of exposure in adult raptor populations. Based on breeding population densities and reproductive success over the past 15 yr, we found no apparent adverse effects of WNV infections on these wild raptor populations.

  17. Raptor mortality due to West Nile virus in the United States, 2002.

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    Saito, Emi K; Sileo, Louis; Green, D Earl; Meteyer, Carol U; McLaughlin, Grace S; Converse, Kathryn A; Docherty, Douglas E

    2007-04-01

    West Nile virus (WNV) has affected many thousands of birds since it was first detected in North America in 1999, but the overall impact on wild bird populations is unknown. In mid-August 2002, wildlife rehabilitators and local wildlife officials from multiple states began reporting increasing numbers of sick and dying raptors, mostly red-tailed hawks (Buteo jamaicensis) and great horned owls (Bubo virginianus). Commonly reported clinical signs were nonspecific and included emaciation, lethargy, weakness, inability to perch, fly or stand, and nonresponse to danger. Raptor carcasses from 12 states were received, and diagnostic evaluation of 56 raptors implicated WNV infection in 40 (71%) of these cases. Histologically, nonsuppurative encephalitis and myocarditis were the salient lesions (79% and 61%, respectively). Other causes of death included lead poisoning, trauma, aspergillosis, and Salmonella spp. and Clostridium spp. infections. The reason(s) for the reported increase in raptor mortality due to WNV in 2002 compared with the previous WNV seasons is unclear, and a better understanding of the epizootiology and pathogenesis of the virus in raptor populations is needed.

  18. Pre-clinical development of a hydrogen peroxide-inactivated West Nile virus vaccine.

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    Poore, Elizabeth A; Slifka, Dawn K; Raué, Hans-Peter; Thomas, Archana; Hammarlund, Erika; Quintel, Benjamin K; Torrey, Lindsay L; Slifka, Ariel M; Richner, Justin M; Dubois, Melissa E; Johnson, Lawrence P; Diamond, Michael S; Slifka, Mark K; Amanna, Ian J

    2017-01-05

    West Nile virus (WNV) is a mosquito-transmitted pathogen with a wide geographical range that can lead to long-term disability and death in some cases. Despite the public health risk posed by WNV, including an estimated 3 million infections in the United States alone, no vaccine is available for use in humans. Here, we present a scaled manufacturing approach for production of a hydrogen peroxide-inactivated whole virion WNV vaccine, termed HydroVax-001WNV. Vaccination resulted in robust virus-specific neutralizing antibody responses and protection against WNV-associated mortality in mice or viremia in rhesus macaques (RM). A GLP-compliant toxicology study performed in rats demonstrated an excellent safety profile with clinical findings limited to minor and transient irritation at the injection site. An in vitro relative potency (IVRP) assay was developed and shown to correlate with in vivo responses following forced degradation studies. Long-term in vivo potency comparisons between the intended storage condition (2-8°C) and a thermally stressed condition (40±2°C) demonstrated no loss in vaccine efficacy or protective immunity over a 6-month span of time. Together, the positive pre-clinical findings regarding immunogenicity, safety, and stability indicate that HydroVax-001WNV is a promising vaccine candidate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. West Nile virus and its theories, a big puzzle in Mexico and Latin America

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    Darwin Elizondo-Quiroga

    2013-01-01

    Full Text Available It has been 13 years since the first outbreak of West Nile Virus (WNV occurred in the Americas. Since then, thousands of human cases have been reported in the United States. In contrast, there has not yet been an outbreak of WNV in any Latin American countries, including Mexico where <20 cases have been reported. We aimed to review publications to gather the main theories related to the fact that not all the countries of the continent reported human cases or that they have reported few cases since the introduction of WNV in the Western Hemisphere. We identified relevant publications using the PubMed database. Furthermore, we present on-line published information from Mexico. We found that researchers have tried to explain this phenomenon using several theories, like pre-existing antibodies against a heterotypical virus that have conferred cross protection in the population. Another explanation is that the strains circulating in Latin America are attenuated or that they came from a different origin of introduction in the continent. Another theory is that a conclusive diagnostic in regions where more than one Flavivirus is circulating results in cross-reaction in serological tests. Probably the sum of factors described by researchers in these theories in order to explain the behavior of the virus has resulted in the low number of reported cases in Latin America.

  20. West Nile virus envelope protein inhibits dsRNA-induced innate immune responses.

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    Arjona, Alvaro; Ledizet, Michel; Anthony, Karen; Bonafé, Nathalie; Modis, Yorgo; Town, Terrence; Fikrig, Erol

    2007-12-15

    The immune response against viral infection relies on the early production of cytokines that induce an antiviral state and trigger the activation of immune cells. This response is initiated by the recognition of virus-associated molecular patterns such as dsRNA, a viral replication intermediate recognized by TLR3 and certain RNA helicases. Infection with West Nile virus (WNV) can lead to lethal encephalitis in susceptible individuals and constitutes an emerging health threat. In this study, we report that WNV envelope protein (WNV-E) specifically blocks the production of antiviral and proinflammatory cytokines induced by dsRNA in murine macrophages. This immunosuppressive effect was not dependent on TLR3 or its adaptor molecule Trif. Instead, our experiments show that WNV-E acts at the level of receptor-interacting protein 1. Our results also indicate that WNV-E requires a certain glycosylation pattern, specifically that of dipteran cells, to inhibit dsRNA-induced cytokine production. In conclusion, these data show that the major structural protein of WNV impairs the innate immune response and suggest that WNV exploits differential vector/host E glycosylation profiles to evade antiviral mechanisms.

  1. Abrogation of macrophage migration inhibitory factor decreases West Nile virus lethality by limiting viral neuroinvasion.

    Science.gov (United States)

    Arjona, Alvaro; Foellmer, Harald G; Town, Terrence; Leng, Lin; McDonald, Courtney; Wang, Tian; Wong, Susan J; Montgomery, Ruth R; Fikrig, Erol; Bucala, Richard

    2007-10-01

    The flavivirus West Nile virus (WNV) is an emerging pathogen that causes life-threatening encephalitis in susceptible individuals. We investigated the role of the proinflammatory cytokine macrophage migration inhibitory factor (MIF), which is an upstream mediator of innate immunity, in WNV immunopathogenesis. We found that patients suffering from acute WNV infection presented with increased MIF levels in plasma and in cerebrospinal fluid. MIF expression also was induced in WNV-infected mice. Remarkably, abrogation of MIF action by 3 distinct approaches (antibody blockade, small molecule pharmacologic inhibition, and genetic deletion) rendered mice more resistant to WNV lethality. Mif(-/-) mice showed a reduced viral load and inflammatory response in the brain when compared with wild-type mice. Our results also indicate that MIF favors viral neuroinvasion by compromising the integrity of the blood-brain barrier. In conclusion, the data obtained from this study provide direct evidence for the involvement of MIF in viral pathogenesis and suggest that pharmacotherapeutic approaches targeting MIF may hold promise for the treatment of WNV encephalitis.

  2. Seroprevalence and risk factors associated to West Nile virus in horses from Andalusia, Southern Spain.

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    García-Bocanegra, Ignacio; Arenas-Montes, Antonio; Napp, Sebastián; Jaén-Téllez, Juan A; Fernández-Morente, Manuel; Fernández-Molera, Vicente; Arenas, Antonio

    2012-12-07

    West Nile virus (WNV) is recognized as an emerging zoonotic pathogen, whose incidence in horses, humans and birds has increased significantly in different European countries in the last decade. A serosurvey study was carried out in non vaccinated horses to determine the geographical distribution of WNV in Andalusia (Southern Spain), and to assess the factors that influence the risk of WNV infection in horses. Antibodies to WNV were detected in 54 out of 510 horses analyzed by a blocking ELISA, of which 36 were confirmed by micro virus neutralization test (7.1%; CI(95%): 4.9-9.3). A total of 28 out of the 348 equine herds (8.3%; CI(95%): 5.4-11.2) had at least one seropositive animal. A generalized estimating equations model showed that the main risk factors associated to WNV seroprevalence were: number of horses within the holding (low), transport of the horse within the last six months (Yes) and presence of mosquitoes in the holding (Yes). The results demonstrated that WNV circulation in Andalusia was more widespread than previously reported. Besides, the distribution of WNV infections was not homogeneous as significant differences among provinces were observed. The results show the need to improve the active surveillance in Spain, so that the early detection of WNV circulation allows the establishment control measures such as vaccination and implementation of vector control programs during the risk period. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Acute flaccid paralysis due to West nile virus infection in adults: A paradigm shift entity

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    Boby Varkey Maramattom

    2014-01-01

    Full Text Available Three cases of acute flaccid paralysis (AFP with preceding fever are described. One patient had a quadriparesis with a florid meningoencephalitic picture and the other two had asymmetric flaccid paralysis with fasciculations at the onset of illness. Magnetic resonance imaging in two cases showed prominent hyperintensitities in the spinal cord and brainstem with prominent involvement of the grey horn (polio-myelitis. Cerebrospinal fluid (CSF polymerase chain reaction was positive for West Nile virus (WNV in the index patient. All three cases had a positive WNV immunoglobulin M antibody in serum/CSF and significantly high titer of WNV neutralizing antibody in serum, clearly distinguishing the infection from other Flaviviridae such as Japanese encephalitis. WNV has been recognized in India for many decades; however, AFP has not been adequately described. WNV is a flavivirus that is spread by Culex mosquitoes while they take blood meals from humans and lineage 1 is capable of causing a devastating neuro-invasive disease with fatal consequences or severe morbidity. We describe the first three laboratory confirmed cases of WNV induced AFP from Kerala and briefly enumerate the salient features of this emerging threat.

  4. Serological evidence of West Nile virus infection in the horse population of northern Serbia.

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    Medić, Strahinja; van den Hoven, Rene; Petrović, Tamaš; Lupulović, Diana; Nowotny, Norbert

    2014-07-14

    This study was conducted to evaluate the seroprevalence of West Nile virus (WNV) in the horse population of northern Serbia. Furthermore, it aimed to provide insight and an updated overview on the circulation of this re-emerging pathogen in this part of southeastern Europe. At the time of manuscript preparation, no clinical cases of WNV infection in horses were reported in this area. Between 2007 and 2011, a total of 252 equine serum samples were collected from seven different locations in northern Serbia. The presence of WNV-reactive IgG antibodies was examined by using commercial and in-house ELISAs. Selected ELISA-positive samples were re-tested by a WNV lineage 2 plaque reduction neutralization test 90% (PRNT-90). In 28.6% of the 252 tested equine serum samples antibodies against WNV were detected. The results obtained with the in-house ELISA corresponded to the outcome of the commercial kit in 90% of the samples. All selected WNV antibody ELISA-positive samples were confirmed by PRNT-90 with neutralizing antibody titers of 1:23 to > 1:512. This study confirms the circulation of WNV in northern Serbia. No striking regional differences in seroprevalences were identified suggesting WNV circulation also in other parts of Serbia. Distances between wetlands or forests and stud farms do not appear to have an influence on WNV seroprevalence.

  5. Negotiated Peace, Denied Justice? The Case of West Nile (Northern Uganda

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    Artur Bogner

    2013-01-01

    Full Text Available “Reconciliation” and “justice” are key concepts used by practitioners as well as authors of conflict-management and peacebuilding textbooks. While it is often recognized that there may be contradictions between the implementation of justice and truth-telling, on the one hand, and an end to organized violence, on the other, the ideal of a seamless fusion of these diverse goals is widely upheld by, among other things, reference to the rather utopian concept of “positive peace” (Galtung. One difficulty arises from the fact that discourses usually focus on (post-conflict settings that resemble a victory of one conflict party, whereas peace settlements are often negotiated in a context more similar to a military or political stalemate – a more ambiguous and complicated scenario. This essay discusses these problems against the background of an empirical case study of the peace accord between the government and the rebels in the West Nile region in north-western Uganda.

  6. Osteopontin facilitates West Nile virus neuroinvasion via neutrophil "Trojan horse" transport.

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    Paul, Amber M; Acharya, Dhiraj; Duty, Laurel; Thompson, E Ashley; Le, Linda; Stokic, Dobrivoje S; Leis, A Arturo; Bai, Fengwei

    2017-07-05

    West Nile virus (WNV) can cause severe human neurological diseases including encephalitis and meningitis. The mechanisms by which WNV enters the central nervous system (CNS) and host-factors that are involved in WNV neuroinvasion are not completely understood. The proinflammatory chemokine osteopontin (OPN) is induced in multiple neuroinflammatory diseases and is responsible for leukocyte recruitment to sites of its expression. In this study, we found that WNV infection induced OPN expression in both human and mouse cells. Interestingly, WNV-infected OPN deficient (Opn -/- ) mice exhibited a higher survival rate (70%) than wild type (WT) control mice (30%), suggesting OPN plays a deleterious role in WNV infection. Despite comparable levels of viral load in circulating blood cells and peripheral organs in the two groups, WNV-infected polymorphonuclear neutrophil (PMN) infiltration and viral burden in brain of Opn -/- mice were significantly lower than in WT mice. Importantly, intracerebral administration of recombinant OPN into the brains of Opn -/- mice resulted in increased WNV-infected PMN infiltration and viral burden in the brain, which was coupled to increased mortality. The overall results suggest that OPN facilitates WNV neuroinvasion by recruiting WNV-infected PMNs into the brain.

  7. First report on entomological field activities for the surveillance of West Nile disease in Italy

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    Maria Goffredo

    2008-09-01

    Full Text Available West Nile virus (WNV is neuropathogenic for birds, horses and humans and is maintained in natural cycles between birds and mosquitoes, particularly the Culex genus; horses and humans are considered to be incidental hosts. A surveillance plan was implemented in Italy in 1998, following a limited outbreak of WNV equine encephalomyelitis and a WNV outbreak in France very close to the Italian border. This plan to assess the risks of the virus being introduced again included entomological surveillance performed in 15 study areas considered ‘at risk’ of WNV introduction in the country. Entomological surveys conducted in Italy from 2003 to 2007 resulted in the capture of a total of 28 798 mosquitoes, of which there were 14 765 adults and 14 033 larvae belonging to 22 species. According to the literature, eight of the species identified have been found to be naturally infected with WNV or were successfully infected in the laboratory in some parts of Europe and in the United States, namely: Aedes albopictus (Skuse, 1897 (= Stegomiya albopicta, Aedes vexans (Meigen, 1830, Anopheles maculipennis Meigen, 1818, Coquillettidia richiardii (Ficalbi, 1889, Culex modestus Ficalbi, 1889, Culex pipiens Linnaeus, 1758, Culex theileri Theobald, 1903 and Ochlerotatus caspius (Pallas, 1771 (= Aedes caspius.

  8. Blood group A and Rh(D)-negativity are associated with symptomatic West Nile virus infection

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    Kaidarova, Zhanna; Bravo, Marjorie D.; Kamel, Hany T.; Custer, Brian S; Busch, Michael P.; Lanteri, Marion C.

    2016-01-01

    Background West Nile virus (WNV) infection is mostly asymptomatic but 20% of subjects report WNV fever and 1% of patients experience neurological diseases with higher rates in elderly and immunosuppressed persons. With no treatment and no vaccine to prevent the development of symptomatic infections, it is essential to understand prognostic factors influencing symptomatic disease outcome. Host genetic background has been linked to the development of WNV neuroinvasive disease. The present study investigates the association between the ABO and Rh(D) blood group status and WNV disease outcome. Study Design and Methods The distribution of blood groups was investigated within a cohort of 374 WNV+ blood donors including 244 asymptomatic (AS) and 130 symptomatic (S) WNV+ blood donors. Logistic regression analyses were used to examine associations between A, B, O and Rh(D) blood groups and WNV clinical disease outcome. Results Symptomatic WNV+ donors exhibited increased frequencies of blood group A (S 47.6% AS 36.8%, P=0.04, OR [95%CI] 1.56 [1.01–2.40]) and Rh(D)-negative individuals (S 21.5% AS 13.1%, P=0.03, OR [95%CI] 1.82 [1.04–3.18]). Conclusion The findings suggest a genetic susceptibility placing blood group A and Rh(D)-negative individuals at risk for the development of symptomatic disease outcome after WNV infection. PMID:27189860

  9. Importance of Wetlands Management for West Nile Virus Circulation Risk, Camargue, Southern France

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    Sophie Pradier

    2014-08-01

    Full Text Available To assess environmental and horse-level risk factors associated with West Nile Virus (WNV circulation in Camargue, Southern France, a serosurvey was conducted on non-vaccinated horses (n = 1159 from 134 stables in 2007 and 2008. Fifteen Landsat images were examined to quantify areas with open water and flooded vegetation around sampled horses. Mean percentages of areas of open water and flooded vegetation, as well as variations in these percentages between 3 periods (November to February = NOT, March to July = END and August to October = EPI, were calculated for buffers of 2 km radius around the stables. Results of the final logistic regression showed that the risk of WNV seropositivity in horses decreased with their date of acquisition and age. Results also demonstrated the significant role of environmental variables. Horse serological status was associated with variations of open water areas between the NOT (November to February and END (March to July periods, as well as between END and EPI (August to October. WNV spillover was found more intense in areas where water level decreased strongly from winter to spring and from spring to summer.

  10. Stress hormones predict a host superspreader phenotype in the West Nile virus system

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    Gervasi, Stephanie; Burgan, Sarah; Hofmeister, Erik K.; Unnasch, Thomas R.; Martin, Lynn B.

    2017-01-01

    Glucocorticoid stress hormones, such as corticosterone (CORT), have profound effects on the behaviour and physiology of organisms, and thus have the potential to alter host competence and the contributions of individuals to population- and community-level pathogen dynamics. For example, CORT could alter the rate of contacts among hosts, pathogens and vectors through its widespread effects on host metabolism and activity levels. CORT could also affect the intensity and duration of pathogen shedding and risk of host mortality during infection. We experimentally manipulated songbird CORT, asking how CORT affected behavioural and physiological responses to a standardized West Nile virus (WNV) challenge. Although all birds became infected after exposure to the virus, only birds with elevated CORT had viral loads at or above the infectious threshold. Moreover, though the rate of mortality was faster in birds with elevated CORT compared with controls, most hosts with elevated CORT survived past the day of peak infectiousness. CORT concentrations just prior to inoculation with WNV and anti-inflammatory cytokine concentrations following viral exposure were predictive of individual duration of infectiousness and the ability to maintain physical performance during infection (i.e. tolerance), revealing putative biomarkers of competence. Collectively, our results suggest that glucocorticoid stress hormones could directly and indirectly mediate the spread of pathogens.

  11. First Serological Evidence of West Nile Virus in Horses and Dogs from Corsica Island, France.

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    Maquart, Marianne; Dahmani, Mustapha; Marié, Jean-Lou; Gravier, Patrick; Leparc-Goffart, Isabelle; Davoust, Bernard

    2017-04-01

    West Nile virus (WNV) is widely distributed over the world, including Europe, Africa, and Asia and spread over the past two decades to North and South America. In the south of France, sporadic cases are frequently described and the virus is endemic in Italy with frequent cases and outbreaks. The aim of this study was to identify a possible WNV circulation in Corsica (French island in the Mediterranean Sea) in sheep, horses, and dogs as sentinel animals for the virus surveillance. In 2014, 386 blood samples were collected from 219 sheep, 96 horses, and 71 dogs, in 12 localities in Corsica, in the oriental coast of Corsica. Each sample was systematically tested for WNV immunoglobulin G using an in-house enzyme-linked immunosorbent assay (ELISA) with inactivated WNV as antigen. The result of the ELISA for the WNV antibody test on the sheep sera was all negative, whereas 9 of 96 horses (9.4%) and 6 of 71 dogs (8.4%) presented WNV antibodies. All the positive samples from horses and dogs were confirmed by serum neutralization test. Although no clinical case in humans and horses was reported to date, this report highlights the necessity to improve WNV surveillance in animals and humans, as well as in blood donors in Corsica.

  12. Absence of indigenous specific West Nile virus antibodies in Tyrolean blood donors.

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    Sonnleitner, S T; Simeoni, J; Schmutzhard, E; Niedrig, M; Ploner, F; Schennach, H; Dierich, M P; Walder, G

    2012-01-01

    In the last several years, West Nile virus (WNV) was proven to be present especially in the neighboring countries of Austria, such as Italy, Hungary, and the Czech Republic, as well as in eastern parts of Austria, where it was detected in migratory and domestic birds. In summer 2010, infections with WNV were reported from Romania and northern Greece with about 150 diseased and increasingly fatal cases. We tested the sera of 1,607 blood donors from North Tyrol (Austria) and South Tyrol (Italy) for antibodies against WNV by using IgG enzyme-linked immunosorbent assay (ELISA). Initial results of the ELISA tests showed seroprevalence rates of 46.2% in North Tyrol and 0.5% in South Tyrol, which turned out to be false-positive cross-reactions with antibodies against tick-borne encephalitis virus (TBEV) by adjacent neutralization assays. These results indicate that seropositivity against WNV requires confirmation by neutralization assays, as cross-reactivity with TBEV is frequent and because, currently, WNV is not endemic in the study area.

  13. Avian diversity and West Nile virus: testing associations between biodiversity and infectious disease risk.

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    Ezenwa, V.O.; Godsey, M.S.; King, R.J.; Guptill, S.C.

    2006-01-01

    The emergence of several high profile infectious diseases in recent years has focused attention on our need to understand the ecological factors contributing to the spread of infectious diseases. West Nile virus (WNV) is a mosquito-borne zoonotic disease that was first detected in the United States in 1999. The factors accounting for variation in the prevalence of WNV are poorly understood, but recentideas suggesting links between high biodiversity and reduced vector-borne disease risk may help account for distribution patterns of this disease. Since wild birds are the primary reservoir hosts for WNV, we tested associations between passerine (Passeriform) bird diversity, non-passerine (all other orders) bird diversity and virus infection rates in mosquitoes and humans to examine the extent to which bird diversity is associated with WNV infection risk. We found t h at non-passerine species richness (number of non-passerine species) was significantly negatively correlated with both mosquito and human infection rates, whereas there was no significant association between passerine species richness and any measure of infection risk. Our findings suggest that non-passerine diversity may play a role in dampening WNV amplification rates in mosquitoes, minimizing human disease risk.

  14. Monoclonal antibody produced in plants efficiently treats West Nile virus infection in mice.

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    Lai, Huafang; Engle, Michael; Fuchs, Anja; Keller, Thomas; Johnson, Syd; Gorlatov, Sergey; Diamond, Michael S; Chen, Qiang

    2010-02-09

    Over the past decade, West Nile virus (WNV) has spread to all 48 of the lower United States as well as to parts of Canada, Mexico, the Caribbean, and South America, with outbreaks of neuroinvasive disease occurring annually. At present, no therapeutic or vaccine is available for human use. Epidemics of WNV and other emerging infectious disease threats demand cost-efficient and scalable production technologies that can rapidly transfer effective therapeutics into the clinical setting. We have previously reported that Hu-E16, a humanized anti-WNV mAb, binds to a highly conserved epitope on the envelope protein, blocks viral fusion, and shows promising postexposure therapeutic activity. Herein, we generated a plant-derived Hu-E16 mAb that can be rapidly scaled up for commercial production. Plant Hu-E16 was expressed at high levels within 8 days of infiltration in Nicotiana benthamiana plants and retained high-affinity binding and potent neutralizing activity in vitro against WNV. A single dose of plant Hu-E16 protected mice against WNV-induced mortality even 4 days after infection at rates that were indistinguishable from mammalian-cell-produced Hu-E16. This study demonstrates the efficacy of a plant-produced mAb against a potentially lethal infection several days after exposure in an animal challenge model and provides a proof of principle for the development of plant-derived mAbs as therapy against emerging infectious diseases.

  15. Prevalence and pathology of West Nile virus in naturally infected house sparrows, western Nebraska, 2008.

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    O'Brien, Valerie A; Meteyer, Carol U; Reisen, William K; Ip, Hon S; Brown, Charles R

    2010-05-01

    Nestling birds are rarely sampled in the field for most arboviruses, yet they may be important in arbovirus amplification cycles. We sampled both nestling and adult house sparrows (Passer domesticus) in western Nebraska for West Nile virus (WNV) or WNV-specific antibodies throughout the summer of 2008 and describe pathology in naturally infected nestlings. Across the summer, 4% of nestling house sparrows were WNV-positive; for the month of August alone, 12.3% were positive. Two WNV-positive nestlings exhibited encephalitis, splenomegaly, hepatic necrosis, nephrosis, and myocarditis. One nestling sparrow had large mural thrombi in the atria and ventricle and immunohistochemical staining of WNV antigen in multiple organs including the wall of the aorta and pulmonary artery; cardiac insufficiency thus may have been a cause of death. Adult house sparrows showed an overall seroprevalence of 13.8% that did not change significantly across the summer months. The WNV-positive nestlings and the majority of seropositive adults were detected within separate spatial clusters. Nestling birds, especially those reared late in the summer when WNV activity is typically greatest, may be important in virus amplification.

  16. Antibody responses in humans infected with newly emerging strains of West Nile Virus in Europe.

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    Stefan Chabierski

    Full Text Available Infection with West Nile Virus (WNV affects an increasing number of countries worldwide. Although most human infections result in no or mild flu-like symptoms, the elderly and those with a weakened immune system are at higher risk for developing severe neurological disease. Since its introduction into North America in 1999, WNV has spread across the continental United States and caused annual outbreaks with a total of 36,000 documented clinical cases and ∼1,500 deaths. In recent years, outbreaks of neuroinvasive disease also have been reported in Europe. The WNV strains isolated during these outbreaks differ from those in North America, as sequencing has revealed that distinct phylogenetic lineages of WNV concurrently circulate in Europe, which has potential implications for the development of vaccines, therapeutics, and diagnostic tests. Here, we studied the human antibody response to European WNV strains responsible for outbreaks in Italy and Greece in 2010, caused by lineage 1 and 2 strains, respectively. The WNV structural proteins were expressed as a series of overlapping fragments fused to a carrier-protein, and binding of IgG in sera from infected persons was analyzed. The results demonstrate that, although the humoral immune response to WNV in humans is heterogeneous, several dominant peptides are recognized.

  17. Antibody responses in humans infected with newly emerging strains of West Nile Virus in Europe.

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    Chabierski, Stefan; Makert, Gustavo R; Kerzhner, Alexandra; Barzon, Luisa; Fiebig, Petra; Liebert, Uwe G; Papa, Anna; Richner, Justin M; Niedrig, Matthias; Diamond, Michael S; Palù, Giorgio; Ulbert, Sebastian

    2013-01-01

    Infection with West Nile Virus (WNV) affects an increasing number of countries worldwide. Although most human infections result in no or mild flu-like symptoms, the elderly and those with a weakened immune system are at higher risk for developing severe neurological disease. Since its introduction into North America in 1999, WNV has spread across the continental United States and caused annual outbreaks with a total of 36,000 documented clinical cases and ∼1,500 deaths. In recent years, outbreaks of neuroinvasive disease also have been reported in Europe. The WNV strains isolated during these outbreaks differ from those in North America, as sequencing has revealed that distinct phylogenetic lineages of WNV concurrently circulate in Europe, which has potential implications for the development of vaccines, therapeutics, and diagnostic tests. Here, we studied the human antibody response to European WNV strains responsible for outbreaks in Italy and Greece in 2010, caused by lineage 1 and 2 strains, respectively. The WNV structural proteins were expressed as a series of overlapping fragments fused to a carrier-protein, and binding of IgG in sera from infected persons was analyzed. The results demonstrate that, although the humoral immune response to WNV in humans is heterogeneous, several dominant peptides are recognized.

  18. Epidemiology and spatio-temporal analysis of West Nile virus in horses in Spain between 2010 and 2016.

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    García-Bocanegra, I; Belkhiria, J; Napp, S; Cano-Terriza, D; Jiménez-Ruiz, S; Martínez-López, B

    2017-10-16

    During the last decade, West Nile virus (WNV) outbreaks have increased sharply in both horses and human in Europe. The aims of this study were to evaluate characteristics and spatio-temporal distribution of WNV outbreaks in horses in Spain between 2010 and 2016 in order to identify the environmental variables most associated with WNV occurrence and to generate high-resolution WNV suitability maps to inform risk-based surveillance strategies in this country. Between August 2010 and November 2016, a total of 403 WNV suspected cases were investigated, of which, 177 (43.9%) were laboratory confirmed. Mean values of morbidity, mortality and case fatality rates were 7.5%, 1.6% and 21.2%, respectively. The most common clinical symptoms were as follows: tiredness/apathy, recumbency, muscular tremor, ataxia, incoordination and hyperaesthesia. The outbreaks confirmed during the last 7 years, with detection of WNV RNA lineage 1 in 2010, 2012, 2013, 2015 and 2016, suggest an endemic circulation of the virus in Spain. The spatio-temporal distribution of WNV outbreaks in Spain was not homogeneous, as most of them (92.7%) were concentrated in western part of Andalusia (southern Spain) and significant clusters were detected in this region in two non-consecutive years. These findings were supported by the results of the space-time scan statistics permutation model. A presence-only MaxEnt ecological niche model was used to generate a suitability map for WNV occurrence in Andalusia. The most important predictors selected by the Ecological Niche Modeling were as follows: mean annual temperature (49.5% contribution), presence of Culex pipiens (19.5% contribution), mean annual precipitation (16.1% contribution) and distance to Ramsar wetlands (14.9% contribution). Our results constitute an important step for understanding WNV emergence and spread in Spain and will provide valuable information for the development of more cost-effective surveillance and control programmes and improve the

  19. Role of bird movements in the epidemiology of West Nile and avian influenza virus

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    Muzaffar, Sabir Bin; Hill, Nichola J.; Takekawa, John Y.; Perry, William M.; Smith, Lacy M.; Boyce, Walter M.

    2012-01-01

    Avian infl uenza virus (AIV) is infl uenced by site fi delity and movements of bird hosts. We examined the movement ecology of American crows (Corvus brachyrhynchos) as potential hosts for West Nile virus (WNV) and greater white-fronted geese (Anser albifrons frontalis) as potential hosts for AIVs. Research was based on radio-telemetry studies conducted in the Central Valley of California, USA. While crows were restricted to a small area of only a few square kilometers, the distribution of the geese encompassed the northern Central Valley. The crows used 1.5 to 3.5 different roosting areas monthly from February through October, revealing lower roost fi delity than the geese that used 1.1 to 1.5 roosting areas each month from November through March. The crows moved a mean distance of 0.11 to 0.49 km/month between their roosting sites and 2.5 to 3.9 km/month between roosting and feeding sites. In contrast, the geese moved 4.2 to 19.3 km/month between roosting areas, and their feeding range varied from 13.2 to 19.0 km/month. Our comparison of the ecological characteristics of bird movements suggests that the limited local movements of crows coupled with frequent turnover of roosts may result in persistence of focal areas for WNV infection. In contrast, widespread areas used by geese will provide regular opportunities for intermixing of AIVs over a much greater geographic area.

  20. Population seroprevalence study after a West Nile virus lineage 2 epidemic, Greece, 2010.

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    Georgia A F Ladbury

    Full Text Available INTRODUCTION: During summer 2010, 262 human cases including 35 deaths from West Nile virus (WNV infection were reported from Central Macedonia, Greece. Evidence from mosquitoes, birds and blood donors demonstrated that the epidemic was caused by WNV lineage 2, which until recently was considered of low virulence. We conducted a household seroprevalence study to estimate the spread of infection in the population during the epidemic, ascertain the relationship of infection to clinical disease, and identify risk factors for infection. METHODS: We used a two-stage cluster design to select a random sample of residents aged ≥18 years in the outbreak epicentre. We collected demographic, medical, and risk factor data using standard questionnaires and environmental checklists, and tested serum samples for presence of WNV IgG and IgM antibodies using ELISA. RESULTS: Overall, 723 individuals participated in the study, and 644 blood samples were available. Weighted seropositivity for IgG antibodies was 5.8% (95% CI: 3.8-8.6; n=41. We estimated that about 1 in 130 (1:141 to 1:124 infected individuals developed WNV neuroinvasive disease, and approximately 18% had clinical manifestations attributable to their infection. Risk factors for infection reflected high exposure to mosquitoes; rural residents were particularly at risk (prevalence ratio: 8.2, 95% CI: 1.1-58.7. DISCUSSION: This study adds to the evidence that WNV lineage 2 strains can cause significant illness, demonstrating ratios of infection to clinical disease similar to those found previously for WNV lineage 1.

  1. Culex flavivirus and West Nile virus in Culex quinquefasciatus populations in the southeastern United States.

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    Crockett, Rebekah Kent; Burkhalter, Kristen; Mead, Daniel; Kelly, Rosmarie; Brown, Jeffrey; Varnado, Wendy; Roy, Alma; Horiuchi, Kalanthe; Biggerstaff, Brad J; Miller, Barry; Nasci, Roger

    2012-01-01

    Little is known of the interactions between insect-only flaviviruses and other arboviruses in their mosquito hosts, or the potential public health significance of these associations. The specific aims of this study were to describe the geographic distribution, prevalence, and seasonal infection rates of Culex flavivirus (CxFV) and West Nile virus (WNV) in Culex quinquefasciatus Say in the Southeastern United States, investigate the potential association between CxFV and WNV prevalence in Cx. quinquefasciatus and describe the phylogenetic relationship among CxFV and WNV isolates from the Southeastern United States and around the world. Using ArboNET records, 11 locations were selected across Georgia, Mississippi, and Louisiana that represented a range of WNV human case incidence levels. Cx. quinquefasciatus were trapped weekly throughout the summer of 2009 and pools were screened for flavivirus RNA by reverse transcriptase polymerase chain reaction. Cx. quinquefasciatus from Georgia had significantly higher CxFV infection rates than either Mississippi or Louisiana. CxFV was not detected in Mississippi after July, and no CxFV was detected in Cx. quinquefasciatus in Louisiana. In Georgia, CxFV infection rates were variable between and within counties and over time. WNV infection rates were not significantly different across states or months, and WNV sequences from all three states were identical to each other in the envelope and NS5 gene regions. Phylogenetically, NS5 and E gene sequences from Georgia CxFV isolates clustered with CxFV from Japan, Iowa, and Texas. Multiple CxFV genetic variants were found circulating simultaneously in Georgia. No evidence was found supporting an association between WNV and CxFV infection prevalence in Cx. quinquefasciatus.

  2. Respiratory insufficiency correlated strongly with mortality of rodents infected with West Nile virus.

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    Morrey, John D; Siddharthan, Venkatraman; Wang, Hong; Hall, Jeffery O

    2012-01-01

    West Nile virus (WNV) disease can be fatal for high-risk patients. Since WNV or its antigens have been identified in multiple anatomical locations of the central nervous system of persons or rodent models, one cannot know where to investigate the actual mechanism of mortality without careful studies in animal models. In this study, depressed respiratory functions measured by plethysmography correlated strongly with mortality. This respiratory distress, as well as reduced oxygen saturation, occurred beginning as early as 4 days before mortality. Affected medullary respiratory control cells may have contributed to the animals' respiratory insufficiency, because WNV antigen staining was present in neurons located in the ventrolateral medulla. Starvation or dehydration would be irrelevant in people, but could cause death in rodents due to lethargy or loss of appetite. Animal experiments were performed to exclude this possibility. Plasma ketones were increased in moribund infected hamsters, but late-stage starvation markers were not apparent. Moreover, daily subcutaneous administration of 5% dextrose in physiological saline solution did not improve survival or other disease signs. Therefore, infected hamsters did not die from starvation or dehydration. No cerebral edema was apparent in WNV- or sham-infected hamsters as determined by comparing wet-to-total weight ratios of brains, or by evaluating blood-brain-barrier permeability using Evans blue dye penetration into brains. Limited vasculitis was present in the right atrium of the heart of infected hamsters, but abnormal electrocardiograms for several days leading up to mortality did not occur. Since respiratory insufficiency was strongly correlated with mortality more than any other pathological parameter, it is the likely cause of death in rodents. These animal data and a poor prognosis for persons with respiratory insufficiency support the hypothesis that neurological lesions affecting respiratory function may be the

  3. In vitro effects of selenium deficiency on West Nile virus replication and cytopathogenicity

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    Cropp Bruce

    2008-05-01

    Full Text Available Abstract Background Selenium (Se deficiency plays an important role in viral pathogenesis. To understand the effects of Se deficiency on West Nile virus (WNV infection, we analyzed cytopathogenicity, apoptosis and viral replication kinetics, using a newly developed Se-deficient cell culture system. Results Both Vero and SK-N-SH cells grown in Se-deficient media exhibited a gradual loss of glutathione peroxidase (GPx1 activity without any significant effect on cell growth and viability. In SK-N-SH cells, Se deficiency had no effect on the expression of key antioxidant enzymes, including manganese- and copper-zinc superoxide dismutase (MnSOD and CuZnSOD, catalase and inducible nitric oxide synthase, whereas Vero cells demonstrated a significant increase in the expression of MnSOD and an overall increase in oxidative stress (OS at day 7 post-induction of Se deficiency. At 2 days after infection with WNV, CPE and cell death were significantly higher in WNV-infected Se-deficient Vero cells, compared to WNV-infected control cells. Furthermore, WNV-induced apoptosis was significantly heightened in Se-deficient cells and was contributed by loss of mitochondrial membrane potential and increased caspase activity. However, no significant difference was found in WNV copy numbers between control, Se-adequate and Se-deficient cell cultures. Conclusion Overall results demonstrate that the in vitro Se-deficient model can be used to study responses of WNV to this essential nutrient. Although Se deficiency has no in vitro effect on WNV replication kinetics, adequate Se is presumably critical to protect WNV-infected cells against virus-induced cell death.

  4. Altered protein networks and cellular pathways in severe west nile disease in mice.

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    Christophe Fraisier

    Full Text Available BACKGROUND: The recent West Nile virus (WNV outbreaks in developed countries, including Europe and the United States, have been associated with significantly higher neuropathology incidence and mortality rate than previously documented. The changing epidemiology, the constant risk of (re-emergence of more virulent WNV strains, and the lack of effective human antiviral therapy or vaccines makes understanding the pathogenesis of severe disease a priority. Thus, to gain insight into the pathophysiological processes in severe WNV infection, a kinetic analysis of protein expression profiles in the brain of WNV-infected mice was conducted using samples prior to and after the onset of clinical symptoms. METHODOLOGY/PRINCIPAL FINDINGS: To this end, 2D-DIGE and gel-free iTRAQ labeling approaches were combined, followed by protein identification by mass spectrometry. Using these quantitative proteomic approaches, a set of 148 proteins with modified abundance was identified. The bioinformatics analysis (Ingenuity Pathway Analysis of each protein dataset originating from the different time-point comparisons revealed that four major functions were altered during the course of WNV-infection in mouse brain tissue: i modification of cytoskeleton maintenance associated with virus circulation; ii deregulation of the protein ubiquitination pathway; iii modulation of the inflammatory response; and iv alteration of neurological development and neuronal cell death. The differential regulation of selected host protein candidates as being representative of these biological processes were validated by western blotting using an original fluorescence-based method. CONCLUSION/SIGNIFICANCE: This study provides novel insights into the in vivo kinetic host reactions against WNV infection and the pathophysiologic processes involved, according to clinical symptoms. This work offers useful clues for anti-viral research and further evaluation of early biomarkers for the diagnosis

  5. West Nile virus outbreak in Israel in 2015: phylogenetic and geographic characterization in humans and mosquitoes.

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    Lustig, Y; Kaufman, Z; Mannasse, B; Koren, R; Katz-Likvornik, S; Orshan, L; Glatman-Freedman, A; Mendelson, E

    2017-12-01

    West Nile Virus (WNV) is endemic in Israel and was responsible for several outbreaks in the past 16 years. The aim of the present study was to investigate the spatial distribution of WNV acute infections from an outbreak that occurred in 2015 in Israel and report the molecular and geographic characterization of WNV isolates from human cases and mosquito pools obtained during this outbreak. Using a geographical layer comprising 51 continuous areas of Israel, the number of WNV infection cases per 100 000 people in each area and the locations of WNV-infected mosquitoes in 2015 were analysed. Sequencing and phylogenetic analyses followed by geographic localization were performed on 13 WNV human isolates and 19 WNV-infected mosquito pools. Substantial geographical variation in the prevalence of acute WNV in patients in Israel was found and an overall correlation with WNV-infected mosquitoes. All human patients sequenced were infected only with the Mediterranean subtype of WNV Lineage 1 and resided primarily in the coastal regions in central Israel. In contrast, mosquitoes were infected with both the Mediterranean and Eastern European subtypes of WNV lineage 1; however, only the Mediterranean subtype was found in mosquitoes from the coastal region in central Israel. These results demonstrate differential geographic dispersion in Israel of the two WNV subtypes and may also point to a differential pattern of human infections. As a geographical bridge between Europe, Asia and Africa, analysis of WNV circulation in humans and mosquitoes in Israel provides information relevant to WNV infections in Eurasia. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  6. A Hierarchical Approach Embedding Hydrologic and Population Modeling for a West Nile Virus Vector Prediction

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    Jian, Y.; Silvestri, S.; Marani, M.; Saltarin, A.; Chillemi, G.

    2012-12-01

    We applied a hierarchical state space model to predict the abundance of Cx.pipiens (a West Nile Virus vector) in the Po River Delta Region, Northeastern Italy. The study area has large mosquito abundance, due to a favorable environment and climate as well as dense human population. Mosquito data were collected on a weekly basis at more than 20 sites from May to September in 2010 and 2011. Cx.pipiens was the dominant species in our samples, accounting for about 90% of the more than 300,000 total captures. The hydrological component of the model accounted for evapotranspiration, infiltration and deep percolation to infer, in a 0D context, the local dynamics of soil moisture as a direct exogenous forcing of mosquito dynamics. The population model had a Gompertz structure, which included exogenous meteorological forcings and delayed internal dynamics. The models were coupled within a hierarchical statistical structure to overcome the relatively short length of the samples by exploiting the large number of concurrent observations available. The results indicated that Cx.pipiens abundance had significant density dependence at 1 week lag, which approximately matched its development time from larvae to adult. Among the exogenous controls, temperature, daylight hours, and soil moisture explained most of the dynamics. Longer daylight hours and lower soil moisture values resulted in higher abundance. The negative correlation of soil moisture and mosquito population can be explained with the abundance of water in the region (e.g. due to irrigation) and the preference for eutrophic habitats by Cx.pipien. Variations among sites were explained by land use factors as represented by distance to the nearest rice field and NDVI values: the carrying capacity decreased with increased distance to the nearest rice filed, while the maximum growth rate was positively related with NDVI. The model shows a satisfactory performance in predicting (potentially one week in advance) mosquito

  7. Generation and characterization of West Nile pseudo-infectious reporter virus for antiviral screening.

    Science.gov (United States)

    Zhang, Hong-Lei; Ye, Han-Qing; Deng, Cheng-Lin; Liu, Si-Qing; Shi, Pei-Yong; Qin, Cheng-Feng; Yuan, Zhi-Ming; Zhang, Bo

    2017-05-01

    West Nile virus (WNV), a mosquito-borne flavivirus, is an important neurotropic human pathogen. As a biosafety level-3 (BSL-3) agent, WNV is strictly to BSL-3 laboratories for experimentations, thus greatly hindering the development of vaccine and antiviral drug. Here, we developed a novel pseudo-infectious WNV reporter virus expressing the Gaussia luciferase (Gluc). A stable 293T NS1 cell line expressing NS1 was selected for trans-supplying NS1 protein to support the replication of WNV-ΔNS1 virus and WNV-ΔNS1-Gluc reporter virus with large-fragment deletion of NS1. WNV-ΔNS1 virus and WNV-Gluc-ΔNS1 reporter virus were confined to complete their replication cycle in this 293T NS1 cell line, displaying nearly identical growth kinetics to WT WNV although the viral titers were lower than those of WT WNV. The reporter gene was stably maintained in virus genome at least within three rounds of passage in 293T NS1 cell line. Using a known flaviviruses inhibitor, NITD008, we demonstrated that the pseudo-infectious WNV-Gluc-ΔNS1 could be used for antiviral screening. Furthermore, a high-throughput screening (HTS) assay in a 96-well format was optimized and validated using several known WNV inhibitors, indicating that the optimized HTS assay was suitable for high-throughput screening WNV inhibitors. Our work provides a stable and safe tool to handle WNV outside of a BSL-3 facility and facilitates high throughput screening for anti-WNV drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression

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    Shives, Katherine D.; Massey, Aaron R.; May, Nicholas A.; Morrison, Thomas E.; Beckham, J. David

    2016-01-01

    West Nile virus (WNV) is a (+) sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7GpppNm 5′ cap with 2′-O-methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1) for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K) and eukaryotic translation initiation factor 4E-binding protein (4EBP) pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E) interaction and eukaryotic initiation factor 4F (eIF4F) complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6) and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome. PMID:27763553

  9. Susceptibility and antibody response of the laboratory model zebra finch (Taeniopygia guttata) to West Nile Virus

    Science.gov (United States)

    Hofmeister, Erik K.; Lund, Melissa; Shearn-Bochsler, Valerie I.; Balakrishnan, Christopher N.

    2017-01-01

    Since the introduction of West Nile virus (WNV) into North America in 1999 a number of passerine bird species have been found to play a role in the amplification of the virus. Arbovirus surveillance, observational studies and experimental studies have implicated passerine birds (songbirds, e.g., crows, American robins, house sparrows, and house finches) as significant reservoirs of WNV in North America, yet we lack a tractable passerine animal model for controlled studies of the virus. The zebra finch (Taeniopygia guttata) serves as a model system across a diversity of fields, and here we develop the zebra finch a songbird model for WNV. Like many natural hosts of WNV, we found that zebra finches developed sufficient viremia to serve as a competent host, yet in general resisted mortality from infection. In the Australian zebra finch (AZF) T. g. castanotis, we detected WNV in the majority of sampled tissues by 4 days post injection (dpi). However, WNV was not detected in tissues of sacrificed birds at 14 dpi, shortly after the development of detectable anti-WNV antibodies in the majority of birds indicating successful viral clearance. We compared susceptibility between the two zebra finch subspecies AZF and Timor zebra finch (TZF) T. g. guttata. Compared to AZF, WNV RNA was detected in a larger proportion of challenged TZF and molecular detection of virus in the serum of TZF was significantly higher than in AZF. Given the observed moderate host competence and disease susceptibility, we suggest that zebra finches are appropriate as models for the study of WNV and although underutilized in this respect, may be ideal models for the study of the many diseases carried and transmitted by songbirds.

  10. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression

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    Katherine D. Shives

    2016-10-01

    Full Text Available West Nile virus (WNV is a (+ sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7GpppNm 5′ cap with 2′-O-methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1 for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K and eukaryotic translation initiation factor 4E-binding protein (4EBP pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E interaction and eukaryotic initiation factor 4F (eIF4F complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6 and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  11. Seroepizootiological-epidemiological investigation and mapping of West Nile infection in the Republic of Serbia

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    Đuričić Bosiljka

    2013-01-01

    Full Text Available The disease caused by the West Nile virus (WNV has been known since 1937 when it was described for the first time in Uganda. After spreading to Europe and the Middle East, the disease has changed its primary location. Today WN infection is a significant health problem in the world. As a result of the current epizootiological and epidemiological situation in Europe studies on the occurrence of WND were introduced in Serbia, also. The investigation on the presence of WNV antibodies was intensified in the period from 2008 to 2012. In this period a total of 3618 serum samples were tested from 18 localities (2736 animal sera from 8 different species and 882 human sera samples. The method applied was gel immunodiffusion and the representative samples were confirmed by the plaque reduction test (PRNT-90. Out of the total number of samples WNV antibodies were present in 3.97% horses, 0.93% dogs, 0.31% poultry and 1.36% man. In one horse serum sample there was a positive reaction with a positive control serum, thus indicating the presence of WNV antigen. The results have confirmed that WNV antibodies are present in 9 out of 18 tested locations in the Republic of Serbia. The percentage of seropositive samples varies from 0.42% in Pozarevac (horses and humans up to 6.45% in Novi Pazar (dogs. Out of the investigated species the highest seropositivity was recorded in horses (3.97%, and lowest in poultry (0.31%. WNV is present and widespread in the Republic of Serbia, thus enabling distribution mapping. [Projekat Ministarstva nauke Republike Srbije, br. TR 21047 i br. TR 37015

  12. Spatio-temporal patterns of distribution of West Nile virus vectors in eastern Piedmont Region, Italy

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    Bisanzio Donal

    2011-12-01

    Full Text Available Abstract Background West Nile Virus (WNV transmission in Italy was first reported in 1998 as an equine outbreak near the swamps of Padule di Fucecchio, Tuscany. No other cases were identified during the following decade until 2008, when horse and human outbreaks were reported in Emilia Romagna, North Italy. Since then, WNV outbreaks have occurred annually, spreading from their initial northern foci throughout the country. Following the outbreak in 1998 the Italian public health authority defined a surveillance plan to detect WNV circulation in birds, horses and mosquitoes. By applying spatial statistical analysis (spatial point pattern analysis and models (Bayesian GLMM models to a longitudinal dataset on the abundance of the three putative WNV vectors [Ochlerotatus caspius (Pallas 1771, Culex pipiens (Linnaeus 1758 and Culex modestus (Ficalbi 1890] in eastern Piedmont, we quantified their abundance and distribution in space and time and generated prediction maps outlining the areas with the highest vector productivity and potential for WNV introduction and amplification. Results The highest abundance and significant spatial clusters of Oc. caspius and Cx. modestus were in proximity to rice fields, and for Cx. pipiens, in proximity to highly populated urban areas. The GLMM model showed the importance of weather conditions and environmental factors in predicting mosquito abundance. Distance from the preferential breeding sites and elevation were negatively associated with the number of collected mosquitoes. The Normalized Difference Vegetation Index (NDVI was positively correlated with mosquito abundance in rice fields (Oc. caspius and Cx. modestus. Based on the best models, we developed prediction maps for the year 2010 outlining the areas where high abundance of vectors could favour the introduction and amplification of WNV. Conclusions Our findings provide useful information for surveillance activities aiming to identify locations where the

  13. IL-1β Signaling Promotes CNS-Intrinsic Immune Control of West Nile Virus Infection

    Science.gov (United States)

    Ramos, Hilario J.; Lanteri, Marion C.; Blahnik, Gabriele; Negash, Amina; Suthar, Mehul S.; Brassil, Margaret M.; Sodhi, Khushbu; Treuting, Piper M.; Busch, Michael P.; Norris, Philip J.; Gale, Michael

    2012-01-01

    West Nile virus (WNV) is an emerging flavivirus capable of infecting the central nervous system (CNS) and mediating neuronal cell death and tissue destruction. The processes that promote inflammation and encephalitis within the CNS are important for control of WNV disease but, how inflammatory signaling pathways operate to control CNS infection is not defined. Here, we identify IL-1β signaling and the NLRP3 inflammasome as key host restriction factors involved in viral control and CNS disease associated with WNV infection. Individuals presenting with acute WNV infection displayed elevated levels of IL-1β in their plasma over the course of infection, suggesting a role for IL-1β in WNV immunity. Indeed, we found that in a mouse model of infection, WNV induced the acute production of IL-1β in vivo, and that animals lacking the IL-1 receptor or components involved in inflammasome signaling complex exhibited increased susceptibility to WNV pathogenesis. This outcome associated with increased accumulation of virus within the CNS but not peripheral tissues and was further associated with altered kinetics and magnitude of inflammation, reduced quality of the effector CD8+ T cell response and reduced anti-viral activity within the CNS. Importantly, we found that WNV infection triggers production of IL-1β from cortical neurons. Furthermore, we found that IL-1β signaling synergizes with type I IFN to suppress WNV replication in neurons, thus implicating antiviral activity of IL-1β within neurons and control of virus replication within the CNS. Our studies thus define the NLRP3 inflammasome pathway and IL-1β signaling as key features controlling WNV infection and immunity in the CNS, and reveal a novel role for IL-1β in antiviral action that restricts virus replication in neurons. PMID:23209411

  14. Mapping the serological prevalence rate of West Nile fever in equids, Tunisia.

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    Bargaoui, R; Lecollinet, S; Lancelot, R

    2015-02-01

    West Nile fever (WNF) is a viral disease of wild birds transmitted by mosquitoes. Humans and equids can also be affected and suffer from meningoencephalitis. In Tunisia, two outbreaks of WNF occurred in humans in 1997 and 2003; sporadic cases were reported on several other years. Small-scale serological surveys revealed the presence of antibodies against WN virus (WNV) in equid sera. However, clinical cases were never reported in equids, although their population is abundant in Tunisia. This study was achieved to characterize the nationwide serological status of WNV in Tunisian equids. In total, 1189 sera were collected in 2009 during a cross-sectional survey. Sera were tested for IgG antibodies, using ELISA and microneutralization tests. The estimated overall seroprevalence rate was 28%, 95% confidence interval [22; 34]. The highest rates were observed (i) in the north-eastern governorates (Jendouba, 74%), (ii) on the eastern coast (Monastir, 64%) and (iii) in the lowlands of Chott El Jerid and Chott el Gharsa (Kebili, 58%; Tozeur, 52%). Environmental risk factors were assessed, including various indicators of wetlands, wild avifauna, night temperature and chlorophyllous activity (normalized difference vegetation index: NDVI). Multimodel inference showed that lower distance to ornithological sites and wetlands, lower night-time temperature, and higher NDVI in late spring and late fall were associated with higher serological prevalence rate. The model-predicted nationwide map of WNF seroprevalence rate in Tunisian equids highlighted different areas with high seroprevalence probability. These findings are discussed in the perspective of implementing a better WNF surveillance system in Tunisia. This system might rely on (i) a longitudinal survey of sentinel birds in high-risk areas and time periods for WNV transmission, (ii) investigations of bird die-offs and (iii) syndromic surveillance of equine meningoencephalitis. © 2013 Blackwell Verlag GmbH.

  15. Pathology and epidemiology of natural West Nile viral infection of raptors in Georgia.

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    Ellis, Angela E; Mead, Daniel G; Allison, Andrew B; Stallknecht, David E; Howerth, Elizabeth W

    2007-04-01

    Carcasses from 346 raptors found between August 2001 and December 2004 were tested for West Nile virus (WNV) using virus isolation and immunohistochemistry; 40 were positive for WNV by one or both methods. Of these 40 birds, 35 had histologic lesions compatible with WNV infection, one had lesions possibly attributable to WNV, and four had no histologic evidence of WNV. The most common histologic lesions associated with WNV infection were myocardial inflammation, necrosis, and fibrosis; skeletal muscle degeneration, inflammation, and fibrosis; and lymphoplasmacytic encephalitis. Other lesions included hepatitis, lymphoid depletion in spleen and bursa, splenic and hepatic hemosiderosis, pancreatitis, and ganglioneuritis. Gross lesions included calvarial and leptomeningeal hemorrhage, myocardial pallor, and splenomegaly. Red-tailed hawks (Buteo jamaicensis) (10/56), sharp-shinned hawks (Accipiter striatus) (8/40), and Cooper's hawks (Accipiter cooperii) (10/103) were most commonly affected. Also affected were red-shouldered hawks (Buteo lineatus) (2/43), an osprey (Pandion haliaetus) (1/5), barred owls (Strix varia) (4/27), a great horned owl (Bubo virginianus) (1/18), and eastern screech owls (Megascops asio) (4/42). Although birds were examined throughout the year, positive cases occurred only during the summer and late fall (June-December). Yearly WNV mortality rates ranged from 7-15% over the four years of the study. This study indicates trends in infection rates of WNV in raptorial species over a significant time period and supports the available information regarding pathology of WNV infection in Strigiformes and Falconiformes. Although many species tested were positive for WNV infection, severity of lesions varied among species.

  16. West Nile virus in raptors from Virginia during 2003: clinical, diagnostic, and epidemiologic findings.

    Science.gov (United States)

    Joyner, Priscilla H; Kelly, Sean; Shreve, Allison A; Snead, Sarah E; Sleeman, Jonathan M; Pettit, Denise A

    2006-04-01

    Sixty-one birds of prey admitted to The Wildlife Center of Virginia (WCV; Waynesboro, Virginia, USA) from June to November 2003 were tested for West Nile virus (WNV) infection. Choanal and/or cloacal swabs were obtained and submitted to Virginia's Division of Consolidated Laboratory Services (Richmond, Virginia, USA) for analysis with real-time reverse transcriptase polymerase chain reaction (RT-PCR). Forty birds of prey were positive for WNV by RT-PCR. Five avian families and nine species of raptors were represented, with great horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) most frequently affected. Presenting clinical signs were consistent with previous reports of WNV infection in raptors; however, these differed between species. Of WNV positive birds, nonspecific signs of illness were the most common clinical findings, particularly in red-tailed hawks; signs included dehydration (n = 20), emaciation (n = 18), and depression (n = 15). Neurologic abnormalities were frequently identified, especially in great horned owls, and included head tremors (n = 17), ataxia (n = 13), head incoordination (n = 7), torticollis (n = 3), nystagmus (n = 3), and head tilt (n = 3). Great horned owls exhibited anemia and leukocytosis with heterophilia, eosinophilia, and monocytosis consistent with chronic inflammation. Red-tailed hawks were anemic with a heterophilic leukocytosis and regenerative left shift. The majority of WNV cases occurred during August and September; there was a marked increase in the number of raptors admitted to WCV during these months followed by a marked decrease during October, November, and December. This pattern differed from mean monthly admissions during the previous 10 years and suggests a negative impact on local raptor populations. The effects of WNV on avian populations are largely unknown; however, because of their ecological importance, further investigation of the effects of WNV on raptor populations is warranted.

  17. Assessing Interventions to Manage West Nile Virus Using Multi-Criteria Decision Analysis with Risk Scenarios.

    Science.gov (United States)

    Hongoh, Valerie; Campagna, Céline; Panic, Mirna; Samuel, Onil; Gosselin, Pierre; Waaub, Jean-Philippe; Ravel, André; Samoura, Karim; Michel, Pascal

    2016-01-01

    The recent emergence of West Nile virus (WNV) in North America highlights vulnerability to climate sensitive diseases and stresses the importance of preventive efforts to reduce their public health impact. Effective prevention involves reducing environmental risk of exposure and increasing adoption of preventive behaviours, both of which depend on knowledge and acceptance of such measures. When making operational decisions about disease prevention and control, public health must take into account a wide range of operational, environmental, social and economic considerations in addition to intervention effectiveness. The current study aimed to identify, assess and rank possible risk reduction measures taking into account a broad set of criteria and perspectives applicable to the management of WNV in Quebec under increasing transmission risk scenarios, some of which may be related to ongoing warming in higher-latitude regions. A participatory approach was used to collect information on categories of concern to relevant stakeholders with respect to WNV prevention and control. Multi-criteria decision analysis was applied to examine stakeholder perspectives and their effect on strategy rankings under increasing transmission risk scenarios. Twenty-three preventive interventions were retained for evaluation using eighteen criteria identified by stakeholders. Combined evaluations revealed that, at an individual-level, inspecting window screen integrity, wearing light colored, long clothing, eliminating peridomestic larval sites and reducing outdoor activities at peak times were top interventions under six WNV transmission scenarios. At a regional-level, the use of larvicides was a preferred strategy in five out of six scenarios, while use of adulticides and dissemination of sterile male mosquitoes were found to be among the least favoured interventions in almost all scenarios. Our findings suggest that continued public health efforts aimed at reinforcing individual

  18. West Nile virus serosurveillance in pigs, wild boars, and roe deer in Serbia.

    Science.gov (United States)

    Escribano-Romero, Estela; Lupulović, Diana; Merino-Ramos, Teresa; Blázquez, Ana-Belén; Lazić, Gospava; Lazić, Sava; Saiz, Juan-Carlos; Petrović, Tamaš

    2015-04-17

    West Nile virus (WNV) is maintained in nature in an enzootic transmission cycle between birds and mosquitoes, but it also infects many other vertebrates, including humans and horses, in which it can induce severe neurological diseases; however, data about virus circulation in other mammals is scarce. WNV has a history of recent outbreaks in Europe, including Serbia, where it was identified for the first time in 2010 in mosquitoes and in 2012 in birds and humans, being responsible for over 300 confirmed human cases and 35 deaths there along 2013. To assess WNV circulation among mammals in the country, 688 samples obtained from 279 farm pigs, 318 wild boars, and 91 roe deer were investigated for the presence of antibodies to WNV by enzyme-linked immunosorbent assay (ELISA) and viral neutralization test (VNT), and the specificity of their reactivity was assayed against Usutu virus (USUV). ELISA-reactive sera were identified in 43 (15.4%) pigs, 56 (17.6%) wild boars, and 17 (18.7%) roe deer. Of these, 6 (14%), 33 (59%), and 4 (23.5%) respectively, neutralized WNV. One out of the 45 ELISA negative sera tested, from a roe deer, neutralized WNV. Cross-reactivity neutralization test indicated that all deer and pigs neutralizing sera were WNV specific, while in 5 (15.2%) of the wild boar samples the specificity could not be established. Four wild boar sera showed USUV specificity. All these data confirm the circulation of both flaviviruses in Serbia, and highlight the need for the implementation of global coordinated surveillance programs in the region. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Parasitic Cowbirds have increased immunity to West Nile and other mosquitoborne encephalitis viruses

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    Reisen, W.K.; Hahn, D.C.

    2006-01-01

    The rapid geographic spread of West Nile Virus [WNV, Flaviviridae, Flavivirus] across the United States has stimulated interest in comparative host infection studies of avian species to delineate competent reservoir hosts critical for viral amplification. Striking taxonomic differences in avian susceptibility have been noted, offering the opportunity to strategically select species on the basis of life history traits to examine aspects of pathogen virulence or host immunity. We hypothesized that avian brood parasites would show increased resistance to pathogens compared to related taxa, because they have been exposed in their evolutionary history to a wide array of infectious organisms from their different parenting species. The Brown-headed Cowbird (Molothrus ater) is a generalist brood parasite that parasitizes 200+ North American species. Elevated exposure to other species? parasites may have created an unusual degree of pathogen resistance. We compared the relative susceptibility of adult cowbirds to three closely-related non-parasitic species, Red-winged blackbirds, Tricolored blackbirds and Brewer?s blackbirds, to invading NY99 strain of WNV that is highly virulent for many passeriform birds. Previously we had experimentally infected these species with two North American mosquitoborne encephalitis viruses, western equine encephalomyelitis virus [WEEV, Togaviridae, Alphavirus] and St. Louis encephalitis virus [SLEV, Flaviviridae, Flavivirus]. Our results showed that cowbirds exhibited significantly lower viremia responses against all three viruses as well as after co-infection with both WEEV and WNV than did the three related, non-parasitic species. These data supported our hypothesis and indicated that cowbirds were more resistant to infection to both native and introduced viruses.

  20. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression.

    Science.gov (United States)

    Shives, Katherine D; Massey, Aaron R; May, Nicholas A; Morrison, Thomas E; Beckham, J David

    2016-10-18

    West Nile virus (WNV) is a (+) sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7GpppNm 5' cap with 2'-O-methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1) for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K) and eukaryotic translation initiation factor 4E-binding protein (4EBP) pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E) interaction and eukaryotic initiation factor 4F (eIF4F) complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6) and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  1. Risk factors associated with West Nile virus mortality in American Crow populations in Southern Quebec.

    Science.gov (United States)

    Ludwig, Antoinette; Bigras-Poulin, Michel; Michel, Pascal; Bélanger, Denise

    2010-01-01

    Soon after the appearance of West Nile virus (WNV) in North America, a number of public health authorities designated the American Crow (Corvus brachyrhynchos) a sentinel for WNV detection. Although preliminary studies have suggested a positive association between American Crow mortality and increased risk of WNV infection in humans, we still know little about dynamic variation in American Crow mortality, both baseline levels and mortality associated with WNV. We hypothesized that the complex social behavior of American Crows, which is shaped by age and seasonal factors, influences both baseline mortality and WNV mortality in American Crow populations. We examined American Crow mortality data from Quebec for the 2005 WNV surveillance year, which lasted from 5 June to 17 September 2005. The variables of interest were age, gender, body condition index, time of year, and land cover. We used a log-linear model to examine baseline mortality. Logistic regression and general linear regression models were constructed to examine variables associated with mortality due to WNV. We found that both age and time of year were key variables in explaining baseline mortality. These two variables were also risk factors for WNV mortality. The probability that a carcass tested positive for WNV increased with the age of the dead bird and as summer progressed. WNV-positive carcasses also had a lower body condition index than WNV-negative carcasses. We believe that the first major wave of American Crow mortality observed in the early summer of 2005 was the result of natural mortality among young American Crows. Because this mortality was not linked to WNV, it appears that American Crow may not be a good species for early detection of WNV activity. Our data also suggest that second-year American Crows play a major role in propagating WNV during their movements to urban land covers during midsummer.

  2. Identification of class I HLA T cell control epitopes for West Nile virus.

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    Saghar Kaabinejadian

    Full Text Available The recent West Nile virus (WNV outbreak in the United States underscores the importance of understanding human immune responses to this pathogen. Via the presentation of viral peptide ligands at the cell surface, class I HLA mediate the T cell recognition and killing of WNV infected cells. At this time, there are two key unknowns in regards to understanding protective T cell immunity: 1 the number of viral ligands presented by the HLA of infected cells, and 2 the distribution of T cell responses to these available HLA/viral complexes. Here, comparative mass spectroscopy was applied to determine the number of WNV peptides presented by the HLA-A*11:01 of infected cells after which T cell responses to these HLA/WNV complexes were assessed. Six viral peptides derived from capsid, NS3, NS4b, and NS5 were presented. When T cells from infected individuals were tested for reactivity to these six viral ligands, polyfunctional T cells were focused on the GTL9 WNV capsid peptide, ligands from NS3, NS4b, and NS5 were less immunogenic, and two ligands were largely inert, demonstrating that class I HLA reduce the WNV polyprotein to a handful of immune targets and that polyfunctional T cells recognize infections by zeroing in on particular HLA/WNV epitopes. Such dominant HLA/peptide epitopes are poised to drive the development of WNV vaccines that elicit protective T cells as well as providing key antigens for immunoassays that establish correlates of viral immunity.

  3. Land cover, landscape structure, and West Nile virus circulation in southern France.

    Science.gov (United States)

    Pradier, S; Leblond, A; Durand, B

    2008-04-01

    The transmission of West Nile virus (WNV) is strongly influenced by environmental factors. In France, two endemic areas for WNV have been identified: Camargue and Var. The objective of our study was to test whether landscape characteristics could be associated with the risk of endemic circulation of WNV in these two ecologically different areas. Equine serological data collected during outbreaks in Var (2003) and Camargue (2004) were used. Both areas were marked out in cells of 5 km(2), and data were aggregated for each cell. Sixteen cells, classified as "high" level viral circulation, and 28 cells, classified as "low" level viral circulation were used for the analysis. The Corine Land Cover database (European Environment Agency) was used to evaluate, for each geographic cell, the area covered by 12 land cover classes, as well as the value of 5 landscape metrics (patch richness and density, edge density, the Shannon's diversity index, and interspersion and juxtaposition index (IJI). Multivariate linear generalized regression showed that IJI as well as the surface covered by heterogeneous agricultural areas were significantly higher in high level WNV circulation cells than in low level ones (p = 0.01 and 0.05 respectively). Both variables are indicators of a complex spatial biotope configuration that may favor the co-existence of competent vectors and reservoir hosts: the structure of the landscape thus appeared as a key element in WNV circulation. An internal validation was performed and the model was used to compute a risk map for the French Mediterranean coast. Cells with a probability > 0.8 of having a high level of viral circulation were found near Aix-en-Provence, Beziers, and Perpignan, areas where no serological study has yet been conducted. Equine cases reported in 2006 were all located in the neighborhood of cells having a > 0.8 probability for high WNV circulation status.

  4. Susceptibility and Antibody Response of the Laboratory Model Zebra Finch (Taeniopygia guttata to West Nile Virus.

    Directory of Open Access Journals (Sweden)

    Erik K Hofmeister

    Full Text Available Since the introduction of West Nile virus (WNV into North America in 1999 a number of passerine bird species have been found to play a role in the amplification of the virus. Arbovirus surveillance, observational studies and experimental studies have implicated passerine birds (songbirds, e.g., crows, American robins, house sparrows, and house finches as significant reservoirs of WNV in North America, yet we lack a tractable passerine animal model for controlled studies of the virus. The zebra finch (Taeniopygia guttata serves as a model system across a diversity of fields, and here we develop the zebra finch a songbird model for WNV. Like many natural hosts of WNV, we found that zebra finches developed sufficient viremia to serve as a competent host, yet in general resisted mortality from infection. In the Australian zebra finch (AZF T. g. castanotis, we detected WNV in the majority of sampled tissues by 4 days post injection (dpi. However, WNV was not detected in tissues of sacrificed birds at 14 dpi, shortly after the development of detectable anti-WNV antibodies in the majority of birds indicating successful viral clearance. We compared susceptibility between the two zebra finch subspecies AZF and Timor zebra finch (TZF T. g. guttata. Compared to AZF, WNV RNA was detected in a larger proportion of challenged TZF and molecular detection of virus in the serum of TZF was significantly higher than in AZF. Given the observed moderate host competence and disease susceptibility, we suggest that zebra finches are appropriate as models for the study of WNV and although underutilized in this respect, may be ideal models for the study of the many diseases carried and transmitted by songbirds.

  5. Improved reliability of serological tools for the diagnosis of West Nile fever in horses within Europe.

    Science.gov (United States)

    Beck, Cécile; Lowenski, Steeve; Durand, Benoit; Bahuon, Céline; Zientara, Stéphan; Lecollinet, Sylvie

    2017-09-01

    West Nile Fever is a zoonotic disease caused by a mosquito-borne flavivirus, WNV. By its clinical sensitivity to the disease, the horse is a useful sentinel of infection. Because of the virus' low-level, short-term viraemia in horses, the primary tools used to diagnose WNV are serological tests. Inter-laboratory proficiency tests (ILPTs) were held in 2010 and 2013 to evaluate WNV serological diagnostic tools suited for the European network of National Reference Laboratories (NRLs) for equine diseases. These ILPTs were designed to evaluate the laboratories' and methods' performances in detecting WNV infection in horses through serology. The detection of WNV immunoglobulin G (IgG) antibodies by ELISA is widely used in Europe, with 17 NRLs in 2010 and 20 NRLs in 2013 using IgG WNV assays. Thanks to the development of new commercial IgM capture kits, WNV IgM capture ELISAs were rapidly implemented in NRLs between 2010 (4 NRLs) and 2013 (13 NRLs). The use of kits allowed the quick standardisation of WNV IgG and IgM detection assays in NRLs with more than 95% (20/21) and 100% (13/13) of satisfactory results respectively in 2013. Conversely, virus neutralisation tests (VNTs) were implemented in 33% (7/21) of NRLs in 2013 and their low sensitivity was evidenced in 29% (2/7) of NRLs during this ILPT. A comparison of serological diagnostic methods highlighted the higher sensitivity of IgG ELISAs compared to WNV VNTs. They also revealed that the low specificity of IgG ELISA kits meant that it could detect animals infected with other flaviviruses. In contrast VNT and IgM ELISA assays were highly specific and did not detect antibodies against related flaviviruses. These results argue in favour of the need for and development of new, specific serological diagnostic assays that could be easily transferred to partner laboratories.

  6. Serosurvey Reveals Exposure to West Nile Virus in Asymptomatic Horse Populations in Central Spain Prior to Recent Disease Foci.

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    Abad-Cobo, A; Llorente, F; Barbero, M Del Carmen; Cruz-López, F; Forés, P; Jiménez-Clavero, M Á

    2017-10-01

    West Nile fever/encephalitis (WNF) is an infectious disease affecting horses, birds and humans, with a cycle involving birds as natural reservoirs and mosquitoes as transmission vectors. It is a notifiable disease, re-emerging in Europe. In Spain, it first appeared in horses in the south (Andalusia) in 2010, where outbreaks occur every year since. However, in 2014, an outbreak was declared in horses in central Spain, approximately 200 km away from the closest foci in Andalusia. Before that, evidence of West Nile virus (WNV) circulation in central Spain had been obtained only from wildlife, but never in horses. The purpose of this work was to perform a serosurvey to retrospectively detect West Nile virus infections in asymptomatic horses in central Spain from 2011 to 2013, that is before the occurrence of the first outbreaks in the area. For that, serum samples from 369 horses, collected between September 2011 and November 2013 in central Spain, were analysed by ELISA (blocking and IgM) and confirmed by virus neutralization, proving its specificity using parallel titration with another flavivirus (Usutu virus). As a result, 10 of 369 horse serum samples analysed gave positive results by competitive ELISA, 5 of which were confirmed as positive to WNV by virus neutralization (seropositivity rate: 1.35%). One of these WNV seropositive samples was IgM-positive. Chronologically, the first positive samples, including the IgM-positive, corresponded to sera collected in 2012 in Madrid province. From these results, we concluded that WNV circulated in asymptomatic equine populations of central Spain at least since 2012, before the first disease outbreak reported in this area. © 2016 Blackwell Verlag GmbH.

  7. Sentinel birds in wild-bird resting sites as potential indicators for West Nile virus infections in Germany.

    Science.gov (United States)

    Ziegler, Ute; Seidowski, Diana; Globig, Anja; Fereidouni, Sasan R; Ulrich, Rainer G; Groschup, Martin H

    2010-06-01

    West Nile virus (WNV) is a mosquito-transmitted flavivirus with wild birds as its natural hosts. Ravens, falcons and jays are highly susceptible for WNV and develop deadly encephalitis, while other bird species undergo only subclinical infections. Migratory birds are efficient vectors for geographic spreading of WNV. Until now, WNV infections have not been diagnosed in Germany, but infections in humans and horses have occurred recently in Austria, Hungary and Italy. To investigate potential WNV introduction by infected wild birds, we have monitored the serological status of ducks in three national sentinel stations. No WNV-positive reactions were found, whereas sera from coots from northern Iran were positive.

  8. Detection of West Nile virus and tick-borne encephalitis virus in birds in Slovakia, using a universal primer set.

    Science.gov (United States)

    Csank, Tomáš; Bhide, Katarína; Bencúrová, Elena; Dolinská, Saskia; Drzewnioková, Petra; Major, Peter; Korytár, Ľuboš; Bocková, Eva; Bhide, Mangesh; Pistl, Juraj

    2016-06-01

    West Nile virus (WNV) is a mosquito-borne neurotropic pathogen that presents a major public health concern. Information on WNV prevalence and circulation in Slovakia is insufficient. Oral and cloacal swabs and bird brain samples were tested for flavivirus RNA by RT-PCR using newly designed generic primers. The species designation was confirmed by sequencing. WNV was detected in swab and brain samples, whereas one brain sample was positive for tick-borne encephalitis virus (TBEV). The WNV sequences clustered with lineages 1 and 2. These results confirm the circulation of WNV in birds in Slovakia and emphasize the risk of infection of humans and horses.

  9. Blood donor screening for West Nile virus (WNV) revealed acute Usutu virus (USUV) infection, Germany, September 2016.

    Science.gov (United States)

    Cadar, Daniel; Maier, Philipp; Müller, Susanne; Kress, Julia; Chudy, Michael; Bialonski, Alexandra; Schlaphof, Alexander; Jansen, Stephanie; Jöst, Hanna; Tannich, Egbert; Runkel, Stefan; Hitzler, Walter E; Hutschenreuter, Gabriele; Wessiepe, Martina; Schmidt-Chanasit, Jonas

    2017-04-06

    Between 1 June and 31 December 2016, 13,023 blood donations from the University Hospital Aachen in Germany were routinely screened for West Nile virus (WNV) RNA using the cobas TaqScreen WNV Test. On 28 September 2016, one blood donor was tested positive. Subsequent analysis revealed an acute Usutu virus (USUV) infection. During the ongoing USUV epizootics in Germany, blood transfusion services, public health authorities and clinicians should be aware of increased human USUV infections. This article is copyright of The Authors, 2017.

  10. Examination of West Nile Virus Neuroinvasion and Neuropathogenesis in the Central Nervous System of a Murine Model.

    Science.gov (United States)

    Sultana, Hameeda

    2016-01-01

    West Nile virus (WNV) is a neurotropic virus that causes inflammation and neuronal loss in the Central Nervous System leading to encephalitis and death. In this chapter, detailed methods to detect WNV in the murine brain tissue by quantitative real-time polymerase chain reaction and viral plaque assays are described. Determination of WNV neuropathogenesis by Hematoxylin and Eosin staining and immunohistochemical procedures are provided. In addition, TUNEL assays to determine neuronal loss during WNV neuropathogenesis are discussed in detail. Collectively, the methods mentioned in this chapter provide an overview to understand neuroinvasion and neuropathogenesis in a murine model of WNV infection.

  11. A Risk Factor Analysis of West Nile Virus: Extraction of Relationships from a Neural-Network Model

    Science.gov (United States)

    Ghosh, Debarchana; Guha, Rajarshi

    The West Nile Virus (WNV) is an infectious disease spreading rapidly throughout the United States, causing illness among thousands of birds, animals, and humans. The broad categories of risk factors underlying WNV incidences are: environmental, socioeconomic, built-environment, and existing mosquito abatement policies. Computational neural network (CNN) model was developed to understand the occurrence of WNV infected dead birds because of their ability to capture complex relationships with higher accuracy than linear models. In this paper, we describe a method to interpret a CNN model by considering the final optimized weights. The research was conducted in the Metropolitan area of Minnesota, which had experienced significant outbreaks from 2002 till present.

  12. Toll-like Receptor 7 Mitigates Lethal West Nile Encephalitis via Interleukin 23-Dependent Immune Cell Infiltration and Homing

    OpenAIRE

    Town, Terrence; Bai, Fengwei; Wang, Tian; Kaplan, Amber T.; Qian, Feng; Montgomery, Ruth R.; Anderson, John F.; Flavell, Richard A.; Fikrig, Erol

    2009-01-01

    West Nile virus (WNV), a mosquito-transmitted single-stranded RNA (ssRNA) flavivirus, causes human disease of variable severity. We investigated Toll-like receptor 7-deficient (Tlr7−/−) and myeloid differentiation factor 88-deficient (Myd88−/−) mice, which both have defective recognition of ssRNA, and found increased viremia and susceptibility to lethal WNV infection. Despite increased tissue concentrations of most innate cytokines, CD45+ leukocytes and CD11b+ macrophages failed to home to WN...

  13. A review of the epidemiological and clinical aspects of West Nile virus

    Directory of Open Access Journals (Sweden)

    Gray TJ

    2014-04-01

    Full Text Available Timothy J Gray,1 Cameron E Webb2,31Department of Infectious Diseases, St Vincent's Hospital, Darlinghurst, NSW, Australia; 2Department of Medical Entomology, Centre for Infectious Diseases and Microbiology and Pathology West - Institute of Clinical Pathology and Medical Research, Westmead, NSW, Australia; 3Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, NSW, AustraliaAbstract: The resurgence of West Nile virus (WNV in North America and Europe in recent years has raised the concerns of local authorities and highlighted that mosquito-borne disease is not restricted to tropical regions of the world. WNV is maintained in enzootic cycles involving, primarily, Culex spp. mosquitoes and avian hosts, with epizootic spread to mammals, including horses and humans. Human infection results in symptomatic illness in approximately one-fifth of cases and neuroinvasive disease in less than 1% of infected persons. The most consistently recognized risk factor for neuroinvasive disease is older age, although diabetes mellitus, alcohol excess, and a history of cancer may also increase risk. Despite the increasing public health concern, the current WNV treatments are inadequate. Current evidence supporting the use of ribavirin, interferon α, and WNV-specific immunoglobulin are reviewed. Nucleic acid detection has been an important diagnostic development, which is particularly important for the protection of the donated blood supply. While effective WNV vaccines are widely available for horses, no human vaccine has been registered. Uncertainty surrounds the magnitude of future risk posed by WNV, and predictive models are limited by the heterogeneity of environmental, vector, and host factors, even in neighboring regions. However, recent history has demonstrated that for regions where suitable mosquito vectors and reservoir hosts are present, there will be a risk of major epidemics. Given the potential for these outbreaks to

  14. Identifying protective host gene expression signatures within the spleen during West Nile virus infection in the collaborative cross model

    Directory of Open Access Journals (Sweden)

    Richard Green

    2016-12-01

    Full Text Available Flaviviruses are hematophagous arthropod-viruses that pose global challenges to human health. Like Zika virus, West Nile Virus (WNV is a flavivirus for which no approved vaccine exists [1]. The role host genetics play in early detection and response to WNV still remains largely unexplained. In order to capture the impact of genetic variation on innate immune responses, we studied gene expression following WNV infection using the collaborative cross (CC. The CC is a mouse genetics resource composed of hundreds of independently bred, octo-parental recombinant inbred mouse lines [2]. To accurately capture the host immune gene expression signatures of West Nile infection, we used the nanostring platform to evaluate expression in spleen tissue isolated from CC mice infected with WNV over a time course of 4, 7, and 12 days' post-infection [3]. Nanostring is a non-amplification based digital method to quantitate gene expression that uses color-coded molecular barcodes to detect hundreds of transcripts in a sample. Using this approach, we identified unique gene signatures in spleen tissue at days 4, 7, and 12 following WNV infection, which delineated distinct differences between asymptomatic and symptomatic CC lines. We also identified novel immune genes. Data was deposited into the Gene Expression Omnibus under accession GSE86000.

  15. Identifying protective host gene expression signatures within the spleen during West Nile virus infection in the collaborative cross model.

    Science.gov (United States)

    Green, Richard; Wilkins, Courtney; Thomas, Sunil; Sekine, Aimee; Ireton, Renee C; Ferris, Martin T; Hendrick, Duncan M; Voss, Kathleen; de Villena, Fernando Pardo-Manuel; Baric, Ralph; Heise, Mark; Gale, Michael

    2016-12-01

    Flaviviruses are hematophagous arthropod-viruses that pose global challenges to human health. Like Zika virus, West Nile Virus (WNV) is a flavivirus for which no approved vaccine exists [1]. The role host genetics play in early detection and response to WNV still remains largely unexplained. In order to capture the impact of genetic variation on innate immune responses, we studied gene expression following WNV infection using the collaborative cross (CC). The CC is a mouse genetics resource composed of hundreds of independently bred, octo-parental recombinant inbred mouse lines [2]. To accurately capture the host immune gene expression signatures of West Nile infection, we used the nanostring platform to evaluate expression in spleen tissue isolated from CC mice infected with WNV over a time course of 4, 7, and 12 days' post-infection [3]. Nanostring is a non-amplification based digital method to quantitate gene expression that uses color-coded molecular barcodes to detect hundreds of transcripts in a sample. Using this approach, we identified unique gene signatures in spleen tissue at days 4, 7, and 12 following WNV infection, which delineated distinct differences between asymptomatic and symptomatic CC lines. We also identified novel immune genes. Data was deposited into the Gene Expression Omnibus under accession GSE86000.

  16. An examination of the effect of aerosolized permanone insecticide on zebra finch susceptibility to West Nile virus

    Science.gov (United States)

    Jankowski, Mark D.; Murray, E. Moore; Hofmeister, Erik K.

    2017-01-01

    West Nile virus is primarily maintained cryptically primarily in avian (Passerine) populations where it is transmitted by Culex spp. mosquitoes. Mosquito control measures currently include physical activities to reduce mosquito breeding sites, the application of mosquito larvicides, or aerosolized insecticides to kill adults (adulticides) when arboviral diseases such as West Nile virus (WNV) or Zika virus are detected in mosquito populations. Organochlorine, organohosphorus, carbamate and pyrethroid insecticides are often used. Previous work suggests an effect of pyrethroids on the immune system in a variety of vertebrates. We examined the effects of exposure to aerosolized Permanone® 30:30 insecticide (permethrin and piperonyl butoxide in soy oil vehicle) at ∼103−106x potential environmental concentrations on the response of captive zebra finches (Taeniopygia guttata) to experimental challenge with WNV. Compared to vehicle control birds, WNV outcome was unchanged (65% of birds produced a viremia) in the ‘low’ exposure (9.52 mg/m3±3.13 SD permethrin) group, but reduced in the ‘high’ exposure (mean 376.5 mg/m3±27.9 SD permethrin) group (30% were viremic) (p < 0.05). After clearing WNV infection, birds treated with Permanone regained less body mass than vehicle treated birds (p < 0.001). Our study suggests that exposure to aerosolized Permanone insecticide at levels exceeding typical application rates has the potential to not change or mildly enhance a bird's resistance to WNV.

  17. Short report: Changes in West Nile virus seroprevalence and antibody titers among Wisconsin mesopredators 2003-2006

    Science.gov (United States)

    Docherty, D.E.; Samuel, M.D.; Egstad, K.F.; Griffin, K.M.; Nolden, C.A.; Karwal, L.; Ip, Hon S.

    2009-01-01

    After the 2001 occurrence of West Nile virus (WNV) in Wisconsin (WI), we collected sera, during 2003-2006, from south-central WI mesopredators. We tested these sera to determine WNV antibody prevalence and geometric mean antibody titer (GMAT). Four-fold higher antibody prevalence and 2-fold higher GMAT in 2003-2004 indicated greater exposure of mesopredators to WNV during the apparent epizootic phase. The period 2005-2006 was likely the enzootic phase because WNV antibody prevalence fell to a level similar to other flaviviruses. Our results suggest that, in mesopredators, vector-borne transmission is the primary route of infection and WNV antibodies persist for West Nile virus spill-over into humans and horses. Mesopredator sero-surveys may complement dead crow surveillance by providing additional data for the timing of public health interventions. Research is needed to clarify the dynamics of WNV infection in these mammals and their role as potential WNV amplifiers. Copyright ?? 2009 by The American Society of Tropical Medicine and Hygiene.

  18. The West Nile virus assembly process evades the conserved antiviral mechanism of the interferon-induced MxA protein

    Energy Technology Data Exchange (ETDEWEB)

    Hoenen, Antje [School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane (Australia); Gillespie, Leah [Department of Microbiology, La Trobe University, Melbourne (Australia); Department of Microbiology and Immunology, University of Melbourne, Melbourne (Australia); Morgan, Garry; Heide, Peter van der [Institute for Molecular Bioscience, University of Queensland, Brisbane (Australia); Khromykh, Alexander [School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane (Australia); Australian Infectious Diseases Research Centre, University of Queensland, Brisbane (Australia); Mackenzie, Jason, E-mail: jason.mackenzie@unimelb.edu.au [Department of Microbiology, La Trobe University, Melbourne (Australia); Department of Microbiology and Immunology, University of Melbourne, Melbourne (Australia)

    2014-01-05

    Flaviviruses have evolved means to evade host innate immune responses. Recent evidence suggests this is due to prevention of interferon production and signaling in flavivirus-infected cells. Here we show that the interferon-induced MxA protein can sequester the West Nile virus strain Kunjin virus (WNV{sub KUN}) capsid protein in cytoplasmic tubular structures in an expression-replication system. This sequestering resulted in reduced titers of secreted WNV{sub KUN} particles. We show by electron microscopy, tomography and 3D modeling that these cytoplasmic tubular structures form organized bundles. Additionally we show that recombinant ER-targeted MxA can restrict production of infectious WNV{sub KUN} under conditions of virus infection. Our results indicate a co-ordinated and compartmentalized WNV{sub KUN} assembly process may prevent recognition of viral components by MxA, particularly the capsid protein. This recognition can be exploited if MxA is targeted to intracellular sites of WNV{sub KUN} assembly. This results in further understanding of the mechanisms of flavivirus evasion from the immune system. - Highlights: • We show that the ISG MxA can recognize the West Nile virus capsid protein. • Interaction between WNV C protein and MxA induces cytoplasmic fibrils. • MxA can be retargeted to the ER to restrict WNV particle release. • WNV assembly process is a strategy to avoid MxA recognition.

  19. West Nile virus epizootics in the Camargue (France) in 2015 and reinforcement of surveillance and control networks.

    Science.gov (United States)

    Bahuon, C; Marcillaud-Pitel, C; Bournez, L; Leblond, A; Beck, C; Hars, J; Leparc-Goffart, I; L'Ambert, G; Paty, M-C; Cavalerie, L; Daix, C; Tritz, P; Durand, B; Zientara, S; Lecollinet, S

    2016-12-01

    West Nile virus (WNV) infection is a non-contagious disease mainly transmitted by the bites of infected mosquitoes from the genus Culex. The virus is maintained in a mosquito-bird-mosquito cycle, and can accidentally be transmitted to mammalian hosts. Among mammalian hosts, equines and humans are the most sensitive to WNV infection and can develop severe meningoencephalitis. As WNV infections are zoonotic and can be severe in humans and equines, West Nile fever is considered to be a public and animal health concern. After a silent period of almost ten years, WNV re-emerged in France at the periphery of the Camargue area during the summer of 2015, underlining the fact that the Camargue area creates favourable conditions for WNV emergence and amplification in France. The French Network for Epidemiological Surveillance of Equine Diseases (Réseau d'Épidémio-Surveillance en Pathologie Équine [RESPE]) facilitated the early detection of WNV cases in horses. In total, 49 horses were found to be infected; among them, 44 presented clinical signs, 41 with meningoencephalitis and three with hyperthermia only. Six horses among the 41 with nervous symptoms died from the disease or were euthanised (a case fatality rate of 14.6%). The authors describe the characteristics of the 2015 WNV epizootics, the early detection of the first WNV equine cases via the RESPE network and the coordination of WNV surveillance in France. © OIE (World Organisation for Animal Health), 2016.

  20. Spatial distribution of West Nile virus in humans and mosquitoes in Israel, 2000–2014

    Directory of Open Access Journals (Sweden)

    Yaniv Lustig

    2017-11-01

    Full Text Available Objectives: Israel has a long history of West Nile virus (WNV morbidity, and the rate of detection of WNV in mosquitoes has been high since 2000. The aim of this study was to integrate several WNV datasets in order to gain an insight into the geographical distribution of WNV in Israel. Methods: Three choropleth maps were generated showing WNV human morbidity, WNV prevalence in mosquitoes, and the results of a nationwide serological survey, based on the division of Israel into 15 sub-districts. Results: The maps show a high endemicity of WNV in Israel. In respect to the morbidity map, the population residing in the central part of the country and in Arava Region is at higher risk of developing the disease than the population of the rest of Israel. Interestingly, high prevalence rates of both WNV serology and WNV-infected mosquitoes were detected in Arava Region, but lower prevalence rates were detected in most areas of the coastal region, suggesting that other factors might also be important in the development of symptomatic WNV infections. Conclusions: These results underline the high prevalence of WNV in Israel and point to specific risk areas for WNV infections across the country. Keywords: West Nile virus, Prevalence, Mosquitoes, WNV infection, Spatial distribution, Israel

  1. Ophthalmologic and oculopathologic findings in red-tailed hawks and Cooper's hawks with naturally acquired West Nile virus infection.

    Science.gov (United States)

    Pauli, Amy M; Cruz-Martinez, Luis A; Ponder, Julia B; Redig, Patrick T; Glaser, Amy L; Klauss, Gia; Schoster, James V; Wünschmann, Arno

    2007-10-15

    To assess ophthalmologic features and ocular lesions in red-tailed hawks and Cooper's hawks naturally infected with West Nile virus (WNV). Original study. 13 hawks. All hawks underwent complete ophthalmic examinations including slit lamp biomicroscopy and binocular indirect ophthalmoscopy. Eleven hawks were euthanized because of a grave prognosis; complete necropsies were performed. Eyes, brain, heart, and kidneys were processed for histologic and immunohistochemical examinations. Pooled tissue homogenates and aqueous humor samples were assessed for WNV nucleic acid via PCR assay, and anti-WNV antibody titers in aqueous humor and plasma were determined. All birds had similar funduscopic abnormalities including exudative chorioretinal lesions and chorioretinal scarring in a geographic or linear pattern. Eleven birds were euthanized, and 2 birds were released. Plasma from both released hawks and plasma and aqueous humor of all euthanized hawks that were evaluated contained anti-WNV antibodies. Except for 1 hawk, all euthanized hawks had WNV-associated disease (determined via detection of WNV antigen or nucleic acid in at least 1 organ). Histopathologic ocular abnormalities, most commonly pectenitis, were detected in all euthanized birds; several birds had segmental choroiditis, often with corresponding segmental retinal atrophy. West Nile virus antigen was detected in the retinas of 9 of the euthanized birds. In 2 hawks, WNV antigen was detected in the retina only. Results indicated that funduscopically detectable chorioretinal lesions appear to be associated with WNV disease in hawks. Detection of ocular lesions may aid in antemortem or postmortem diagnosis of this condition.

  2. Co-circulation of West Nile virus and distinct insect-specific flaviviruses in Turkey.

    Science.gov (United States)

    Ergünay, Koray; Litzba, Nadine; Brinkmann, Annika; Günay, Filiz; Sarıkaya, Yasemen; Kar, Sırrı; Örsten, Serra; Öter, Kerem; Domingo, Cristina; Erisoz Kasap, Özge; Özkul, Aykut; Mitchell, Luke; Nitsche, Andreas; Alten, Bülent; Linton, Yvonne-Marie

    2017-03-20

    Active vector surveillance provides an efficient tool for monitoring the presence or spread of emerging or re-emerging vector-borne viruses. This study was undertaken to investigate the circulation of flaviviruses. Mosquitoes were collected from 58 locations in 10 provinces across the Aegean, Thrace and Mediterranean Anatolian regions of Turkey in 2014 and 2015. Following morphological identification, mosquitoes were pooled and screened by nested and real-time PCR assays. Detected viruses were further characterised by sequencing. Positive pools were inoculated onto cell lines for virus isolation. Next generation sequencing was employed for genomic characterisation of the isolates. A total of 12,711 mosquito specimens representing 15 species were screened in 594 pools. Eleven pools (2%) were reactive in the virus screening assays. Sequencing revealed West Nile virus (WNV) in one Culex pipiens (s.l.) pool from Thrace. WNV sequence corresponded to lineage one clade 1a but clustered distinctly from the Turkish prototype isolate. In 10 pools, insect-specific flaviviruses were characterised as Culex theileri flavivirus in 5 pools of Culex theileri and one pool of Cx. pipiens (s.l.), Ochlerotatus caspius flavivirus in two pools of Aedes (Ochlerotatus) caspius, Flavivirus AV-2011 in one pool of Culiseta annulata, and an undetermined flavivirus in one pool of Uranotaenia unguiculata from the Aegean and Thrace regions. DNA forms or integration of the detected insect-specific flaviviruses were not observed. A virus strain, tentatively named as "Ochlerotatus caspius flavivirus Turkey", was isolated from an Ae. caspius pool in C6/36 cells. The viral genome comprised 10,370 nucleotides with a putative polyprotein of 3,385 amino acids that follows the canonical flavivirus polyprotein organisation. Sequence comparisons and phylogenetic analyses revealed the close relationship of this strain with Ochlerotatus caspius flavivirus from Portugal and Hanko virus from Finland. Several

  3. Synergized resmethrin and corticosterone alter the chicken's response to west nile virus

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Mark David [Los Alamos National Laboratory; Franson, J Christian [US GEOLOGICAL SURVEY; Mostl, Erich [UNIV OF VIENNA; Porter, Warren P [UNIV OF WISCONSIN; Hofmeister, Erik K [US GEOLOGICAL SURVEY

    2009-01-01

    Debate concerning arbovirus control strategies remains contentious because concern regarding the relative risk of viral infection and environmental toxicant exposure is high but inadequately characterized. Taking this into account, mosquito control agencies employ aerial insecticides only after arbovirus surveillance data indicate high local mosquito-infection-rates. Successfully mitigating the risk of adult-mosquito-control insecticides ('adulticides') to non-target species such as humans, domestic animals, fish, beneficial insects and wildlife, while increasing their efficacy to reduce arbovirus outbreak intensity requires targeted scientific data from animal toxicity studies and environmental monitoring activities. Wild birds are an important reservoir host for WNv and are potentially exposed to insecticides used for mosquito control. However, no risk assessments have evaluated whether insecticides augment or extend the potential transmissibility of West Nile virus (WNv) in birds. In order to augment existing resmethrin risk assessments, we aimed to determine whether synergized resmethrin (SR) may cause chickens to develop an elevated or extended WN viremia and if subacute stress may affect its immunotoxicity. We distributed 40 chickens into four groups then exposed them prior to and during WNv infection with SR (50 {mu}g/l resmethrin + 150 {mu}g/l piperonyl butoxide) and/or 20 mg/I corticosterone (CORT) in their drinking-water. Corticosterone was given for 10 continuous days and SR was given for 3 alternate days starting the 3rd day of CORT exposure, then chickens were subcutaneously inoculated with WNv on the 5th day of CORT treatment. Compared to controls, CORT treatment extended and elevated viremia, enhanced WNv-specific antibody and increased the percentage of birds that shed oral virus, whereas SR treatment extended viremia, depressed WNv-specific IgG, and increased the percentage of CORT-treated birds that shed oral virus. Corticosterone and SR

  4. [Meningoencephalitis caused by West Nile virus in a renal transplant recipient].

    Science.gov (United States)

    Ertilav, Muhittin; Ozkul, Aykut; Zeytinoğlu, Ayşın; Sen, Sait; Sipahi, Savaş; Töz, Hüseyin; Kitiş, Omer; Eraslan, Cenk

    2014-10-01

    West Nile virus (WNV) infection which is asymptomatic or mild in normal population, it may cause serious clinical conditions leading to death in eldery and immunosupressed patients. The virus is mainly transmitted by mosquito bites, however transfusion, transplantation, transplasental and nosocomial ways have also been reported to be responsible for viral transmission. It is known that WNV may cause life-threatining conditions such as central nervous system (CNS) infections especially in bone marrow and solid organ transplant recipients. In this report, the first case of WNV encephalitis in an immunosuppressed patient with renal transplant in Turkey was presented. A 25-year-old male patient admitted to our hospital with the complaints of generalized myalgia, nausea and vomiting, after the 24. day of renal transplantation from a live donor. Since he developed diffuse tonic clonic seizures during his follow up, he was diagnosed as meningoencephalitis with the results of cranial magnetic resonance imaging (MR) and cerebrospinal fluid (CSF) biochemistry. Bacterial and fungal cultures of blood and CSF yielded negative results. CMV antigenemia test and CMV IgM in blood, and nucleic acid tests for CMV, EBV, HSV-1/2, VZV, HHV-6, enterovirus and parvovirus in CSF were also negative. However, WNV RNA was detected in CSF by an in-house reverse transcriptase (RT) nested PCR method. The sequence analysis (GenBank BLAST) of the virus showed that it had 99% similarity with Lineage-1 WNV strains. To define the transmission way of the virus to the recipient, WNV-RNA was searched in the renal biopsy sample and found negative by RT nested PCR. The clinical condition of the patient was improved with supportive therapy and by the de-escalation of immunosuppressive drugs [Mycophenolate mofetil (MMF; 1 g/day), cyclosporin (1 mg/kg/day)]. However WNV meningoencephalitis recurred one month later. The patient presented with fever, myalgia, confusions, leukocytosis, anemia, and repeating WNV

  5. Global research trends in West Nile virus from 1943 to 2016: a bibliometric analysis.

    Science.gov (United States)

    Al-Jabi, Samah W

    2017-08-03

    West Nile virus (WNV) is an emerging infectious disease which is most commonly transmitted to humans through mosquito, and is considered a major public-health problem worldwide. The aim of the current study is to bibliometrically analyze the quantity and quality of publications indexed in Scopus from different countries to reveal the characteristics of global research output regarding WNV. This study is a bibliometric analysis based on the Scopus database. This study focused on identifying WNV publication trends with regard to publication year, publication type, prolific countries, language of publication, as well as, prolific journals, citations, and collaboration patterns. A total of 4729 publications were considered in this study, which were published between 1943 and 2016. The annual quantity of literature published before 2000 followed a low rate of research growth; while the quantity of publications after 2000 were published in a stage of rapid development. The country with the greatest number of publications in WNV research field was the USA with 2304 (48.7%) publications, followed by France with 224 (4.7%) publications, and Canada with 222 (4.7%) publications. Contributions from low- and middle-income countries (LMIC) were considerably small, that is, (n = 519 publications; 11%). All publications related to WNV achieved h-index of 140 and were cited 124,222 times. The median [interquartile range] number of citations per article thus amounts to 9 [2-28]. The USA had the highest h-index of 131. Emerging Infectious Diseases is the most productive journal with 227 articles, followed by Journal of Virology with 162 publications. The result designated that Centers for Disease Control and Prevention was ranked the first in terms of publication output, followed by National Center for Emerging and Zoonotic Infectious Diseases. There is an obvious trend of WNV research after 2000, and countries with high income have more contributions in WNV research field. The

  6. CCR5 limits cortical viral loads during West Nile virus infection of the central nervous system.

    Science.gov (United States)

    Durrant, Douglas M; Daniels, Brian P; Pasieka, TracyJo; Dorsey, Denise; Klein, Robyn S

    2015-12-15

    Cell-mediated immunity is critical for clearance of central nervous system (CNS) infection with the encephalitic flavivirus, West Nile virus (WNV). Prior studies from our laboratory have shown that WNV-infected neurons express chemoattractants that mediate recruitment of antiviral leukocytes into the CNS. Although the chemokine receptor, CCR5, has been shown to play an important role in CNS host defense during WNV infection, regional effects of its activity within the infected brain have not been defined. We used CCR5-deficient mice and an established murine model of WNV encephalitis to determine whether CCR5 activity impacts on WNV levels within the CNS in a region-specific fashion. Statistical comparisons between groups were made with one- or two-way analysis of variance; Bonferroni's post hoc test was subsequently used to compare individual means. Survival was analyzed by the log-rank test. Analyses were conducted using Prism software (GraphPad Prism). All data were expressed as means ± SEM. Differences were considered significant if P ≤ 0.05. As previously shown, lack of CCR5 activity led to increased symptomatic disease and mortality in mice after subcutaneous infection with WNV. Evaluation of viral burden in the footpad, draining lymph nodes, spleen, olfactory bulb, and cerebellum derived from WNV-infected wild-type, and CCR5(-/-) mice showed no differences between the genotypes. In contrast, WNV-infected, CCR5(-/-) mice exhibited significantly increased viral burden in cortical tissues, including the hippocampus, at day 8 post-infection. CNS regional studies of chemokine expression via luminex analysis revealed significantly increased expression of CCR5 ligands, CCL4 and CCL5, within the cortices of WNV-infected, CCR5(-/-) mice compared with those of similarly infected WT animals. Cortical elevations in viral loads and CCR5 ligands in WNV-infected, CCR5(-/-) mice, however, were associated with decreased numbers of infiltrating mononuclear cells

  7. Remote Sensing of Climatic Anomalies and West Nile Virus Risk in the United States

    Science.gov (United States)

    Wimberly, M. C.; Chuang, T.; Henebry, G. M.; Kimball, J. S.

    2012-12-01

    West Nile virus (WNV) is the most widespread and important mosquito-borne pathogen in North America, and the national resurgence of human WNV cases during the summer of 2012 has highlighted the persistent threat posed by this potentially fatal disease. Advance warning of the timing and locations of WNV outbreaks can help public health officials to more effectively target WNV prevention and control efforts. To this end, we used environmental monitoring data from earth observing satellites to develop environmental indices of WNV risk and applied these indices to model seasonal and interannual patterns of mosquito populations and human disease cases. Our overarching hypothesis is that anomalies of cumulative temperature and moisture throughout the mosquito season affect the risk of WNV transmission to humans through their influences on mosquito populations, bird communities, and the extrinsic incubation period of the virus itself. In a preliminary study, we developed a model of WNV in the northern Great Plains using satellite optical-IR remote sensing products from MODIS, including land surface temperature, vegetation indices, and actual evapotranspiration computed using the simplified surface energy balance method. This model was applied in 2011 and 2012 to forecast spatial patterns of WNV relative risk prior to the main transmission season in July-September. We expanded this modeling approach to a national level using a daily global land surface parameter database developed from the NASA Advanced Microwave Scanning Radiometer on the Earth Observing System (AMSR-E). This dataset provides several novel environmental variables that are potentially relevant to mosquito ecology, including near-surface air temperature, surface soil moisture, fractional open water cover, and estimates of vegetation canopy opacity to microwave emissions at three microwave frequencies. Preliminary analyses demonstrated that higher temperatures during the amplification season are consistently

  8. West Nile virus host-vector-pathogen interactions in a colonial raptor.

    Science.gov (United States)

    Soltész, Zoltán; Erdélyi, Károly; Bakonyi, Tamás; Barna, Mónika; Szentpáli-Gavallér, Katalin; Solt, Szabolcs; Horváth, Éva; Palatitz, Péter; Kotymán, László; Dán, Ádám; Papp, László; Harnos, Andrea; Fehérvári, Péter

    2017-09-29

    Avian host species have different roles in the amplification and maintenance of West Nile virus (WNV), therefore identifying key taxa is vital in understanding WNV epidemics. Here, we present a comprehensive case study conducted on red-footed falcons, where host-vector, vector-virus and host-virus interactions were simultaneously studied to evaluate host species contribution to WNV circulation qualitatively. Mosquitoes were trapped inside red-footed falcon nest-boxes by a method originally developed for the capture of blackflies and midges. We showed that this approach is also efficient for trapping mosquitoes and that the number of trapped vectors is a function of host attraction. Brood size and nestling age had a positive effect on the number of attracted Culex pipiens individuals while the blood-feeding success rate of both dominant Culex species (Culex pipiens and Culex modestus) markedly decreased after the nestlings reached 14 days of age. Using RT-PCR, we showed that WNV was present in these mosquitoes with 4.2% (CI: 0.9-7.5%) prevalence. We did not detect WNV in any of the nestling blood samples. However, a relatively high seroprevalence (25.4% CI: 18.8-33.2%) was detected with an enzyme-linked immunoabsorbent assay (ELISA). Using the ELISA OD ratios as a proxy to antibody titers, we showed that older seropositive nestlings have lower antibody levels than their younger conspecifics and that hatching order negatively influences antibody levels in broods with seropositive nestlings. Red-footed falcons in the studied system are exposed to a local sylvatic WNV circulation, and the risk of infection is higher for younger nestlings. However, the lack of individuals with viremia and the high WNV seroprevalence, indicate that either host has a very short viremic period or that a large percentage of nestlings in the population receive maternal antibodies. This latter assumption is supported by the age and hatching order dependence of antibody levels found for

  9. Seroprevalence screening for the West Nile virus in Malaysia's Orang Asli population.

    Science.gov (United States)

    Marlina, Suria; Radzi, Siti Fatimah Muhd; Lani, Rafidah; Sieng, Khor Chee; Rahim, Nurul Farhana Abdul; Hassan, Habibi; Li-Yen, Chang; AbuBakar, Sazaly; Zandi, Keivan

    2014-12-17

    West Nile virus (WNV) infection is an emerging zoonotic disease caused by an RNA virus of the genus Flavivirus. WNV is preserved in the environment through cyclic transmission, with mosquitoes, particularly Culex species, serving as a vector, birds as an amplifying host and humans and other mammals as dead-end hosts. To date, no studies have been carried out to determine the prevalence of the WNV antibody in Malaysia. The aim of this study was to screen for the seroprevalence of the WNV in Malaysia's Orang Asli population. Serum samples of 742 Orang Asli were collected in seven states in peninsular Malaysia. The samples were assessed to determine the seroprevalence of WNV immunoglobulin (Ig)G with the WNV IgG enzyme-linked immunosorbent assay (ELISA) method. For each individual, we documented the demographic factors. Anti-dengue and anti-tick-borne encephalitis virus IgG ELISA were also performed to rule out a cross reaction. All statistical analyses were performed using the GraphPad Prism 6 (GraphPad Software, Inc.); p values of less than 0.05 were considered significant. The serosurvey included 298 men (40.16%) and 444 women (59.84%) of Malaysia's Orang Asli. Anti-WNV IgG was found in 9 of the 742 samples (1.21%). The seroprevalence was 0.67% (2 of 298) in men and 1.58% (7 of 444) in women. The presence of anti-WNV IgG was found not to be associated with gender but, however, did correlate with age. The peak seroprevalence was found to be 2.06% (2 of 97) in individuals between 30 to 42 years of age. No previous studies have examined the seroprevalence of the WNV antibody in the human population in Malaysia, and no clinical reports of infections have been made. Screening for the WNV seroprevalence is very significant because of many risk factors contribute to the presence of WNV in Malaysia, such as the abundance of Culex mosquitoes as the main vector and a high degree of biodiversity, including migratory birds that serve as a reservoir to the virus.

  10. Outdoor Hazards & Preventive Measures: West Nile Virus: A Clinical Commentary for the Camp Health Care Community; Poison Ivy: A Primer for Prevention; Lyme Disease Prevention and Control.

    Science.gov (United States)

    Reynolds, Ellen; Bauer, Holly; Ratner-Connolly, Heidi

    2003-01-01

    Transmitted by mosquitos, West Nile virus may cause serious illness, but the actual likelihood of infection is low. Prevention, implications, and recommendations for camps are discussed. Poison ivy identification, treatment, and complications are presented; a prevention quiz is included. Signs and symptoms of Lyme disease are described, as are…

  11. Vaccine-induced protection of rhesus macaques against plasma viremia after intradermal infection with a European lineage 1 strain of west nile virus

    NARCIS (Netherlands)

    B.E. Verstrepen (Babs); Oostermeijer, H. (Herman); Z. Fagrouch (Zahra); Van Heteren, M. (Melanie); H. Niphuis (Henk); Haaksma, T. (Tom); I. Kondova (Ivanela); W. Bogers (Willy); De Filette, M. (Marina); N. Sanders; Stertman, L. (Linda); Magnusson, S. (Sofia); Lörincz, O. (Orsolya); Lisziewicz, J. (Julianna); Barzon, L. (Luisa); Palù, G. (Giorgio); Diamond, M.S. (Michael S.); Chabierski, S. (Stefan); S. Ulbert; E.J. Verschoor (Ernst)

    2014-01-01

    textabstractThe mosquito-borne West Nile virus (WNV) causes human and animal disease with outbreaks in several parts of the world including North America, the Mediterranean countries, Central and East Europe, the Middle East, and Africa. Particularly in elderly people and individuals with an

  12. Identification of CD8(+) T Cell Epitopes in the West Nile Virus Polyprotein by Reverse-Immunology Using NetCTL

    DEFF Research Database (Denmark)

    Larsen, Mette Voldby; Lelic, A.; Parsons, R.

    2010-01-01

    Background: West Nile virus (WNV) is a growing threat to public health and a greater understanding of the immune response raised against WNV is important for the development of prophylactic and therapeutic strategies. Methodology/Principal Findings: In a reverse-immunology approach, we used...

  13. Learning from Experience: The Public Health Response to West Nile Virus, SARS, Monkeypox, and Hepatitis A Outbreaks in the United States

    Science.gov (United States)

    2005-01-01

    mosquito densities and infection rates over time and space Human • Focus on encephalitis • Aseptic meningitis, Guillain - Barre syndrome , acute flaccid...local health departments to recent disease outbreaks—specifically, Severe Acute Respiratory Syndrome (SARS), monkeypox, and West Nile virus—to address...149 Appendix C: Severe Acute Respiratory Syndrome (SARS

  14. Serum Neutralization Assay Can Efficiently Replace Plaque Reduction Neutralization Test for Detection and Quantitation of West Nile Virus Antibodies in Human and Animal Serum Samples

    Science.gov (United States)

    Di Gennaro, Annapia; Casaccia, Claudia; Conte, Annamaria; Monaco, Federica; Savini, Giovanni

    2014-01-01

    A serum neutralization assay (SN) was compared with the official plaque reduction neutralization test for the quantitation of West Nile virus antibodies. A total of 1,348 samples from equid sera and 38 from human sera were tested by these two methods. Statistically significant differences were not observed, thus supporting the use of SN for routine purposes. PMID:25100824

  15. Creating a disease risk map for West Nile virus for surveillance in Central Texas using a Geographic Information System and Remote Sensing technologies

    Science.gov (United States)

    Following the discovery of the West Nile virus (WNv) in Brazos County, TX in 2002, mosquito research personnel at Texas A&M University established a routine WNv mosquito vector surveillance program in the county. In 2004, a map of Brazos County was created depicting areas that had a heightened leve...

  16. Surface-enhanced Raman scattering detection of DNA derived from the West Nile virus genome using magnetic capture of Raman-active gold nanoparticles

    Science.gov (United States)

    A model paramagnetic nanoparticle (MNP) assay is demonstrated for surface-enhanced Raman scattering (SERS) detection of DNA oligonucleotides derived from the West Nile virus (WNV) genome. Detection is based on the capture of WNV target sequences by hybridization with complementary oligonucleotide pr...

  17. Noncoding subgenomic flavivirus RNA is processed by the mosquito RNA interference machinery and determines West Nile virus transmission by Culex pipiens mosquitoes

    NARCIS (Netherlands)

    Göertz, G.P.; Fros, J.J.; Miesen, P.; Vogels, C.B.F.; Bent, van der M.L.; Geertsema, C.; Koenraadt, C.J.M.; Rij, van R.P.; Oers, van M.M.; Pijlman, G.P.

    2016-01-01

    Flaviviruses, such as Zika virus, yellow fever virus, dengue virus, and West Nile virus (WNV), are a serious concern for human health. Flaviviruses produce an abundant noncoding subgenomic flavivirus RNA (sfRNA) in infected cells. sfRNA results from stalling of the host 5=-3= exoribonuclease

  18. Noncoding Subgenomic Flavivirus RNA Is Processed by the Mosquito RNA Interference Machinery and Determines West Nile Virus Transmission by Culex pipiens Mosquitoes

    NARCIS (Netherlands)

    Goertz, G.P.; Fros, J.J.; Miesen, P.; Vogels, C.B.F.; Bent, M.L. van der; Geertsema, C.; Koenraadt, C.J.M.; Rij, R.P. van; Oers, M.M. van; Pijlman, G.P.

    2016-01-01

    Flaviviruses, such as Zika virus, yellow fever virus, dengue virus, and West Nile virus (WNV), are a serious concern for human health. Flaviviruses produce an abundant noncoding subgenomic flavivirus RNA (sfRNA) in infected cells. sfRNA results from stalling of the host 5'-3' exoribonuclease

  19. Chain Lakes massif, west central Maine: northern Appalachian basement or suspect terrane

    Energy Technology Data Exchange (ETDEWEB)

    Cheatham, M.M.; Olszewski, W.J. Jr.; Gaudette, H.E.

    1985-01-01

    The Chain Lakes massif of west-central Main is a 3 km thick sequence of diamictite and aquagene metavolcanics and metasediments, which contrasts strikingly with its surrounding Paleozoic rocks in lithology, structural style and metamorphic grade. The rocks of the massif are characterized by mineral assemblages developed during two separate metamorphic events. The first, of second sillimanite grade, is reflected by qtz-oligoclase-Kspar-sillimanite-biotite and muscovite. The second metamorphism is a retrograde event of greenschist facies, and chlorite grade. Isotopic Rb-Sr and Sm-Nd whole rock, and Rb-Sr mineral analyses of samples of the diamictite members, now gneiss and granofels, indicate that the first prograde metamorphism occurred at 770 Ma. with the retrograde event at approximately 405 Ma. Due to the restricted range of /sup 147/Sm//sup 144/Nd, no Sm-Nd isochron age could be determined. However, model ages for both Sr and Nd are approximately 1500 Ma for derivation of the Chain Lakes protolith material from depleted mantle. Lithology, bounding formations, complexes and plutons, and the isotopic data support previous contentions that the Chain Lakes massif is a suspect terrane. However, similarities with Proterozoic rocks along the Eastern Margin, as well as recent suggestions of similar rocks underlying the Kearsarge-Central Main synclinorium may suggest the possible widespread occurrence of dismembered masses of a perhaps once coherent, Precambrian terrane underlying the Northern Appalachians.

  20. Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA

    Directory of Open Access Journals (Sweden)

    Haramis Linn

    2010-03-01

    Full Text Available Abstract Background Models of the effects of environmental factors on West Nile virus disease risk have yielded conflicting outcomes. The role of precipitation has been especially difficult to discern from existing studies, due in part to habitat and behavior characteristics of specific vector species and because of differences in the temporal and spatial scales of the published studies. We used spatial and statistical modeling techniques to analyze and forecast fine scale spatial (2000 m grid and temporal (weekly patterns of West Nile virus mosquito infection relative to changing weather conditions in the urban landscape of the greater Chicago, Illinois, region for the years from 2004 to 2008. Results Increased air temperature was the strongest temporal predictor of increased infection in Culex pipiens and Culex restuans mosquitoes, with cumulative high temperature differences being a key factor distinguishing years with higher mosquito infection and higher human illness rates from those with lower rates. Drier conditions in the spring followed by wetter conditions just prior to an increase in infection were factors in some but not all years. Overall, 80% of the weekly variation in mosquito infection was explained by prior weather conditions. Spatially, lower precipitation was the most important variable predicting stronger mosquito infection; precipitation and temperature alone could explain the pattern of spatial variability better than could other environmental variables (79% explained in the best model. Variables related to impervious surfaces and elevation differences were of modest importance in the spatial model. Conclusion Finely grained temporal and spatial patterns of precipitation and air temperature have a consistent and significant impact on the timing and location of increased mosquito infection in the northeastern Illinois study area. The use of local weather data at multiple monitoring locations and the integration of mosquito

  1. Wetlands Management and risk for West Nile Virus Circulation in Camargue, Southern France

    Science.gov (United States)

    Leblond, Agnes; Pradier, Sophie; Paul, Mathilde; Lecollinet, Sylvie; Sandoz, Alain

    2016-04-01

    West Nile Virus (WNV) is a flavivirus transmitted between mosquitoes (mainly the genus Culex) and wild birds. Horses and humans are incidental hosts and can develop severe neurological disorders. During last decades, the number of WNV cases reported in Europe has increased dramatically. Large outbreaks of increased clinical severity have been reported in parts of Russia, Southern and Eastern Europe. In the Camargue area, WNV outbreaks have been reported in 2000, 2004 and more recently in 2015. We hypothesize that the management of Camargue wetlands could play a key role in the emergence of outbreaks in this area during recent years. WNV transmission requires competent vectors, receptive hosts, and environmental parameters which allow contact between the vectors and the different hosts. The Rhône Delta is known for its landscape of wetlands and its wealth of different bird species. It is also a region where mosquito populations are very abundant. Recent observations have shown that environmental changes, mainly resulting from anthropogenic practices, have had an impact on inter-annual variations in the wetlands and consequently on the abundance of mosquitoes. Water is provided either by rainfall or by a very tight canal network diverted from the river Rhone. Water management is under the control of individual field owners and dependent on its various uses (grazing, rice culture, hunting reserves). This specific management of water resources could play a role in the circulation of WNV in the area. Non-vaccinated horses (n = 1159 from 134 stables) were sampled in 2007 and 2008 in the Camargue area and a serological test was performed to identify a possible contact with the WNV. Environmental variables related to water resources and management were collected through fifteen Landsat images. Areas with open water and flooded vegetation and their variations within a year and between years (2007-08) were quantified for buffers of 2 km radius around the stables. Mean

  2. Ecological surveillance for West Nile in Catalonia (Spain), learning from a five-year period of follow-up.

    Science.gov (United States)

    Alba, A; Allepuz, A; Napp, S; Soler, M; Selga, I; Aranda, C; Casal, J; Pages, N; Hayes, E B; Busquets, N

    2014-05-01

    To enhance early detection of West Nile virus (WNV) transmission, an integrated ecological surveillance system was implemented in Catalonia (north-eastern Spain) from 2007 to 2011. This system incorporated passive and active equine surveillance, periodical testing of chicken sentinels in wetland areas, serosurveillance wild birds and testing of adult mosquitoes. Samples from 298 equines, 100 sentinel chickens, 1086 wild birds and 39 599 mosquitoes were analysed. During these 5 years, no acute WNV infection was detected in humans or domestic animal populations in Catalonia. WNV was not detected in mosquitoes either. Nevertheless, several seroconversions in resident and migrant wild birds indicate that local WNV or other closely related flaviviruses transmission was occurring among bird populations. These data indicate that bird and mosquito surveillance can detect otherwise silent transmission of flaviviruses and give some insights regarding possible avian hosts and vectors in a European setting. © 2013 Blackwell Verlag GmbH.

  3. Analysis of surveillance systems in place in European Mediterranean countries for West Nile virus (WNV) and Rift Valley fever (RVF).

    Science.gov (United States)

    Cito, F; Narcisi, V; Danzetta, M L; Iannetti, S; Sabatino, D D; Bruno, R; Carvelli, A; Atzeni, M; Sauro, F; Calistri, P

    2013-11-01

    West Nile virus (WNV) and Rift Valley fever virus (RVFV) represent an important group of viral agents responsible for vector-borne zoonotic diseases constituting an emerging sanitary threat for the Mediterranean Basin and the neighbouring countries. WNV infection is present in several Mediterranean countries, whereas RVF has never been introduced into Europe, but it is considered a major threat for North African countries. Being vector-borne diseases, they cannot be prevented only through an animal trade control policy. Several approaches are used for the surveillance of WNV and RVFV. With the aim of assessing the surveillance systems in place in Mediterranean countries, two disease-specific questionnaires (WNV, RVFV) have been prepared and submitted to Public Health and Veterinary Authorities of six EU countries. This study presents the information gathered through the questionnaires and describes some critical points in the prevention and surveillance of these diseases as emerged by the answers received. © 2013 Blackwell Verlag GmbH.

  4. Fine-scale genetic variation and evolution of West Nile Virus in a transmission "hot spot" in suburban Chicago, USA.

    Science.gov (United States)

    Bertolotti, Luigi; Kitron, Uriel D; Walker, Edward D; Ruiz, Marilyn O; Brawn, Jeffrey D; Loss, Scott R; Hamer, Gabriel L; Goldberg, Tony L

    2008-05-10

    Mosquitoes and birds were sampled for West Nile virus (WNV) in suburban Chicago, USA, in a "hot spot" of arboviral transmission. Viral genetic diversity within this area was similar to that within Illinois and the United States. Diversity was higher among viruses from mosquitoes than from birds, higher among viruses from birds in urban "green spaces" than from birds in residential areas, but lower among viruses from mosquitoes in green spaces than from mosquitoes in residential areas. Viral transmission was distance-limited, as evidenced by decreasing autocorrelation of WNV sequences with increasing geographic separation. The evolutionary rate of WNV within the study area between 21 July and 4 October 2005 was ten times higher than that for WNV across North America between 2002 and 2005. These results indicate that WNV transmission and evolutionary dynamics can vary seasonally and in response to fine-scale environmental conditions and landscape characteristics related to urbanization.

  5. Infodemiological data of West-Nile virus disease in Italy in the study period 2004–2015

    Directory of Open Access Journals (Sweden)

    Nicola Luigi Bragazzi

    2016-12-01

    Full Text Available Google Trends (GT was mined from 2004 to 2015, searching for West-Nile virus disease (WNVD in Italy. GT-generated data were modeled as a time series and were analyzed using classical time series analyses. In particular, correlation between GT-based Relative Search Volumes (RSVs related to WNVD and “real-world” epidemiological cases in the same study period resulted r=0.76 (p<0.0001 on a monthly basis and r=0.80 (p<0.0001 on a yearly basis. The partial autocorrelation analysis and the spectral analysis confirmed that a 1-year regular pattern could be detected. Correlation between GT-based RSVs related to WNVD yielded a r=0.54 (p<0.05 on a regional basis. Summarizing, GT-generated data concerning WNVD well correlated with epidemiology and could be exploited for complementing traditional surveillance.

  6. Vector Borne Infections in Italy: Results of the Integrated Surveillance System for West Nile Disease in 2013

    Directory of Open Access Journals (Sweden)

    Christian Napoli

    2015-01-01

    Full Text Available The epidemiology of West Nile disease (WND is influenced by multiple ecological factors and, therefore, integrated surveillance systems are needed for early detecting the infection and activating consequent control actions. As different animal species have different importance in the maintenance and in the spread of the infection, a multispecies surveillance approach is required. An integrated and comprehensive surveillance system is in place in Italy aiming at early detecting the virus introduction, monitoring the possible infection spread, and implementing preventive measures for human health. This paper describes the integrated surveillance system for WND in Italy, which incorporates data from veterinary and human side in order to evaluate the burden of infection in animals and humans and provide the public health authorities at regional and national levels with the information needed for a fine tune response.

  7. The Effect of West Nile Virus Infection on the Midgut Gene Expression of Culex pipiens quinquefasciatus Say (Diptera: Culicidae).

    Science.gov (United States)

    Smartt, Chelsea T; Shin, Dongyoung; Anderson, Sheri L

    2016-12-19

    The interaction of the mosquito and the invading virus is complex and can result in physiological and gene expression alterations in the insect. The association of West Nile virus (WNV) and Culex pipiens quinquefasciatus mosquitoes results in measurable changes in gene expression; 22 gene products were shown previously to have altered expression. Sequence analysis of one product, CQ G1A1, revealed 100% amino acid identity to gram negative bacteria binding proteins (CPQGBP) in Cx. p. quinquefasciatus, Aedes aegypti (70%) and Anopheles gambiae (63%) that function in pathogen recognition. CQ G1A1 also was differentially expressed following WNV infection in two populations of Cx. p. quinquefasciatus colonized from Florida with known differences in vector competence for WNV and showed spatial and temporal gene expression differences in midgut, thorax, and carcass tissues. These data suggest gene expression of CQ G1A1 is influenced by WNV infection and the WNV infection-controlled expression differs between populations and tissues.

  8. Vector Contact Rates on Eastern Bluebird Nestlings Do Not Indicate West Nile Virus Transmission in Henrico County, Virginia, USA

    Directory of Open Access Journals (Sweden)

    Kevin A. Caillouët

    2013-11-01

    Full Text Available Sensitive indicators of spatial and temporal variation in vector-host contact rates are critical to understanding the transmission and eventual prevention of arboviruses such as West Nile virus (WNV. Monitoring vector contact rates on particularly susceptible and perhaps more exposed avian nestlings may provide an advanced indication of local WNV amplification. To test this hypothesis we monitored WNV infection and vector contact rates among nestlings occupying nest boxes (primarily Eastern bluebirds; Sialia sialis, Turdidae across Henrico County, Virginia, USA, from May to August 2012. Observed host-seeking rates were temporally variable and associated with absolute vector and host abundances. Despite substantial effort to monitor WNV among nestlings and mosquitoes, we did not detect the presence of WNV in these populations. Generally low vector-nestling host contact rates combined with the negative WNV infection data suggest that monitoring transmission parameters among nestling Eastern bluebirds in Henrico County, Virginia, USA may not be a sensitive indicator of WNV activity.

  9. Seroprevalence of West Nile Virus in Wild Birds in Far Eastern Russia Using a Focus Reduction Neutralization Test

    Science.gov (United States)

    Murata, Ryo; Hashiguchi, Kazuaki; Yoshii, Kentaro; Kariwa, Hiroaki; Nakajima, Kensuke; Ivanov, Leonid I.; Leonova, Galina N.; Takashima, Ikuo

    2011-01-01

    West Nile (WN) virus has been spreading geographically to non-endemic areas in various parts of the world. However, little is known about the extent of WN virus infection in Russia. Japanese encephalitis (JE) virus, which is closely related to WN virus, is prevalent throughout East Asia. We evaluated the effectiveness of a focus reduction neutralization test in young chicks inoculated with JE and WN viruses, and conducted a survey of WN infection among wild birds in Far Eastern Russia. Following single virus infection, only neutralizing antibodies specific to the homologous virus were detected in chicks. The neutralization test was then applied to serum samples from 145 wild birds for WN and JE virus. Twenty-one samples were positive for neutralizing antibodies to WN. These results suggest that WN virus is prevalent among wild birds in the Far Eastern region of Russia. PMID:21363987

  10. Extensive nucleotide changes and deletions within the envelope glycoprotein gene of Euro-African West Nile viruses.

    Science.gov (United States)

    Berthet, F X; Zeller, H G; Drouet, M T; Rauzier, J; Digoutte, J P; Deubel, V

    1997-09-01

    We compared the sequence of an envelope protein gene fragment from 21 temporally distinct West Nile (WN) virus strains, isolated in nine African countries and in France. Alignment of nucleotide sequences defined two groups of viruses which diverged by up to 29%. The first group of subtypes is composed of nine WN strains from France and Africa. The Austral-Asian Kunjin virus was classified as a WN subtype in this first group. The second group includes 12 WN strains from Africa and Madagascar. Four strains harboured a 12 nucleotide in-frame deletion. The loss of the corresponding four amino acids resulted in the loss of the potential glycosylation site present in several WN strains. The distribution of virus subtypes into two lineages did not correlate with host preference or geographical origin. The isolation of closely related subtypes in distant countries is consistent with WN viruses being disseminated by migrating birds.

  11. The West Nile Virus outbreak in Israel (2000) from a new perspective: the regional impact of climate change.

    Science.gov (United States)

    Paz, Shlomit

    2006-02-01

    The West Nile Virus (WNV) outbreak in Israel in 2000 appeared after medical and climatic warning signs. Re-analysis of the epidemic from a new viewpoint, the regional impact of global warming, especially the worsening in the summers' heat conditions, is presented. The disease appeared averagely at a lag of 3-9 weeks (strongest correlation = lag of 7 weeks). The minimum temperature was found as the most important climatic factor that encourages the disease earlier appearance. Extreme heat is more significant than high air humidity for increasing WNV cases. An early extreme rise in the summer temperature could be a good indicator of increased vector populations. While 93.5% of cases were in the metropolitan areas, the disease was not reported in the sub-arid regions. The outbreak development was comparable to the cases from Romania (1996) and NYC (1999). Each of those epidemics appeared after a long heatwave.

  12. Short report: comparison of oral infectious dose of West Nile virus isolates representing three distinct genotypes in Culex quinquefasciatus.

    Science.gov (United States)

    Vanlandingham, Dana L; McGee, Charles E; Klingler, Kimberly A; Galbraith, Sareen E; Barrett, Alan D T; Higgs, Stephen

    2008-12-01

    Phylogenetic analysis of West Nile virus in North America has identified replacement of the originally introduced clade, Eastern United States (NY99), by the North American clade. In addition, the transient emergence of other clades and genetic variants has also been observed. In this study, we investigated the potential role of the mosquito in the selection of these clades and genetic variants. We determined the relative susceptibility of Culex quinquefasciatus to infection with isolates from the Eastern U.S. clade, the North American clade, and the Southeast coastal Texas clade. Although significant differences were observed in 50% oral infectious dose values between the Eastern U.S. and two attenuated North American genetic variants compared with the North American and Southeast coastal Texas clade viruses, these differences did not correlate with persistence of the genotype in nature. These results indicate that selection of these viral genotypes was independent of viral oral infectivity in the mosquito.

  13. West Nile and st. Louis encephalitis viruses antibodies surveillance in captive and free-ranging birds of prey from Argentina.

    Science.gov (United States)

    Quaglia, Agustin I; Diaz, Luis A; Argibay, Hernan; Contigiani, Marta S; Saggese, Miguel D

    2014-12-01

    We evaluated the prevalence of WNV and SLEV neutralizing antibodies in captive and free-ranging raptors from Argentina by plaque-reduction neutralization test. Eighty plasma samples from 12 species were analyzed. Only one captive adult Crowned Eagle (Harpyhaliaetus coronatus) was WNV seropositive (prevalence: 1.25%; antibody titer of 1:80). Two captive Crowned Eagles were SLEV seropositive (prevalence: 2.50%; antibody titers: 1:80 and 1:40).These findings expand the geographic distribution of WNV and SLEV and confirm their activity in central and northeastern Argentina. West Nile virus activity in Argentina may represent a potential threat to Crowned Eagles and other endangered raptors in this country.

  14. Delayed IFN response differentiates replication of West Nile virus and Japanese encephalitis virus in human neuroblastoma and glioblastoma cells.

    Science.gov (United States)

    Takamatsu, Yuki; Uchida, Leo; Morita, Kouichi

    2015-08-01

    West Nile virus (WNV) and Japanese encephalitis virus (JEV) are important causes of human encephalitis cases, which result in a high mortality ratio and neurological sequelae after recovery. Understanding the mechanism of neuropathogenicity in these viral infections is important for the development of specific antiviral therapy. Here, we focused on human-derived neuronal and glial cells to understand the cellular responses against WNV and JEV infection. It was demonstrated that early IFN-β induction regulated virus replication in glioblastoma tbl98G cells, whereas delayed IFN-β induction resulted in efficient virus replication in neuroblastoma SK-N-SH cells. Moreover, the concealing of viral dsRNA in the intracellular membrane resulted in the delayed IFN response in SK-N-SH cells. These results, which showed different IFN responses between human neuronal and glial cells after WNV or JEV infection, are expected to contribute to our understanding of the molecular mechanisms for neuropathology in these viral infections.

  15. Crow deaths as a sentinel surveillance system for West Nile virus in the northeastern United States, 1999

    Science.gov (United States)

    Eidson, M.; Komar, N.; Sorhage, F.; Nelson, R.; Talbot, T.; Mostashari, F.; McLean, R.; ,

    2001-01-01

    In addition to human encephalitis and meningitis cases, the West Nile (WN) virus outbreak in the summer and fall of 1999 in New York State resulted in bird deaths in New York, New Jersey, and Connecticut. From August to December 1999, 295 dead birds were laboratory-confirmed with WN virus infection; 262 (89%) were American Crows (Corvus brachyrhynchos). The New York State Department of Health received reports of 17,339 dead birds, including 5,697 (33%) crows; in Connecticut 1,040 dead crows were reported. Bird deaths were critical in identifying WN virus as the cause of the human outbreak and defining its geographic and temporal limits. If established before a WN virus outbreak, a surveillance system based on bird deaths may provide a sensitive method of detecting WN virus.

  16. Humoral Immunity to West Nile Virus Is Long-Lasting and Protective in the House Sparrow (Passer domesticus)

    Science.gov (United States)

    Nemeth, Nicole M.; Oesterle, Paul T.; Bowen, Richard A.

    2009-01-01

    The house sparrow (Passer domesticus) is a common and abundant amplifying host of West Nile virus (WNV) and many survive infection and develop humoral immunity. We experimentally inoculated house sparrows with WNV and monitored duration and protection of resulting antibodies. Neutralizing antibody titers remained relatively constant for ≥ 36 months (N = 42) and provided sterilizing immunity for up to 36 months post-inoculation in 98.6% of individuals (N = 72). These results imply that immune house sparrows are protected from WNV infection for multiple transmission seasons. Additionally, individuals experiencing WNV-associated mortality reached significantly higher peak viremia titers than survivors, and mortality during acute infection was significantly higher in caged versus free-flight sparrows. A better understanding of the long-term immunity and mortality rates in birds is valuable in interpreting serosurveillance and diagnostic data and modeling transmission and disease dynamics. PMID:19407139

  17. Fine-scale variation in vector host use and force of infection drive localized patterns of West Nile virus transmission.

    Science.gov (United States)

    Hamer, Gabriel L; Chaves, Luis F; Anderson, Tavis K; Kitron, Uriel D; Brawn, Jeffrey D; Ruiz, Marilyn O; Loss, Scott R; Walker, Edward D; Goldberg, Tony L

    2011-01-01

    The influence of host diversity on multi-host pathogen transmission and persistence can be confounded by the large number of species and biological interactions that can characterize many transmission systems. For vector-borne pathogens, the composition of host communities has been hypothesized to affect transmission; however, the specific characteristics of host communities that affect transmission remain largely unknown. We tested the hypothesis that vector host use and force of infection (i.e., the summed number of infectious mosquitoes resulting from feeding upon each vertebrate host within a community of hosts), and not simply host diversity or richness, determine local infection rates of West Nile virus (WNV) in mosquito vectors. In suburban Chicago, Illinois, USA, we estimated community force of infection for West Nile virus using data on Culex pipiens mosquito host selection and WNV vertebrate reservoir competence for each host species in multiple residential and semi-natural study sites. We found host community force of infection interacted with avian diversity to influence WNV infection in Culex mosquitoes across the study area. Two avian species, the American robin (Turdus migratorius) and the house sparrow (Passer domesticus), produced 95.8% of the infectious Cx. pipiens mosquitoes and showed a significant positive association with WNV infection in Culex spp. mosquitoes. Therefore, indices of community structure, such as species diversity or richness, may not be reliable indicators of transmission risk at fine spatial scales in vector-borne disease systems. Rather, robust assessment of local transmission risk should incorporate heterogeneity in vector host feeding and variation in vertebrate reservoir competence at the spatial scale of vector-host interaction.

  18. Culex pipiens, an experimental efficient vector of West Nile and Rift Valley fever viruses in the Maghreb region.

    Science.gov (United States)

    Amraoui, Fadila; Krida, Ghazi; Bouattour, Ali; Rhim, Adel; Daaboub, Jabeur; Harrat, Zoubir; Boubidi, Said-Chawki; Tijane, Mhamed; Sarih, Mhammed; Failloux, Anna-Bella

    2012-01-01

    West Nile fever (WNF) and Rift Valley fever (RVF) are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV) circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV) re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 10(7.8) and 10(8.5) plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14-21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology.

  19. Culex pipiens, an experimental efficient vector of West Nile and Rift Valley fever viruses in the Maghreb region.

    Directory of Open Access Journals (Sweden)

    Fadila Amraoui

    Full Text Available West Nile fever (WNF and Rift Valley fever (RVF are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 10(7.8 and 10(8.5 plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14-21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology.

  20. Fine-scale variation in vector host use and force of infection drive localized patterns of West Nile virus transmission.

    Directory of Open Access Journals (Sweden)

    Gabriel L Hamer

    Full Text Available The influence of host diversity on multi-host pathogen transmission and persistence can be confounded by the large number of species and biological interactions that can characterize many transmission systems. For vector-borne pathogens, the composition of host communities has been hypothesized to affect transmission; however, the specific characteristics of host communities that affect transmission remain largely unknown. We tested the hypothesis that vector host use and force of infection (i.e., the summed number of infectious mosquitoes resulting from feeding upon each vertebrate host within a community of hosts, and not simply host diversity or richness, determine local infection rates of West Nile virus (WNV in mosquito vectors. In suburban Chicago, Illinois, USA, we estimated community force of infection for West Nile virus using data on Culex pipiens mosquito host selection and WNV vertebrate reservoir competence for each host species in multiple residential and semi-natural study sites. We found host community force of infection interacted with avian diversity to influence WNV infection in Culex mosquitoes across the study area. Two avian species, the American robin (Turdus migratorius and the house sparrow (Passer domesticus, produced 95.8% of the infectious Cx. pipiens mosquitoes and showed a significant positive association with WNV infection in Culex spp. mosquitoes. Therefore, indices of community structure, such as species diversity or richness, may not be reliable indicators of transmission risk at fine spatial scales in vector-borne disease systems. Rather, robust assessment of local transmission risk should incorporate heterogeneity in vector host feeding and variation in vertebrate reservoir competence at the spatial scale of vector-host interaction.

  1. Safety and Pharmacokinetics of Single Intravenous Dose of MGAWN1, a Novel Monoclonal Antibody to West Nile Virus▿ †

    Science.gov (United States)

    Beigel, John H.; Nordstrom, Jeffrey L.; Pillemer, Stanley R.; Roncal, Cory; Goldwater, D. Ronald; Li, Hua; Holland, P. Chris; Johnson, Syd; Stein, Kathryn; Koenig, Scott

    2010-01-01

    West Nile Virus (WNV) is a neurotropic flavivirus that can cause debilitating diseases, such as encephalitis, meningitis, or flaccid paralysis. We report the safety, pharmacokinetics, and immunogenicity of a recombinant humanized monoclonal antibody (MGAWN1) targeting the E protein of WNV in a phase 1 study, the first to be performed on humans. A single intravenous infusion of saline or of MGAWN1 at escalating doses (0.3, 1, 3, 10, or 30 mg/kg of body weight) was administered to 40 healthy volunteers (30 receiving MGAWN1; 10 receiving placebo). Subjects were evaluated on days 0, 1, 3, 7, 14, 21, 28, 42, 56, 91, 120, and 180 by clinical assessments, clinical laboratory studies, electrocardiograms (ECGs), and pharmacokinetic and immunogenicity assays. All 40 subjects tolerated the infusion of the study drug, and 39 subjects completed the study. One serious adverse event of schizophrenia occurred in the 0.3-mg/kg cohort. One grade 3 neutropenia occurred in the 3-mg/kg cohort. Six MGAWN1-treated subjects experienced 11 drug-related adverse events, including diarrhea (1 subject), chest discomfort (1), oral herpes (1), rhinitis (1), neutropenia (2), leukopenia (1), dizziness (1), headache (2), and somnolence (1). In the 30-mg/kg cohort, MGAWN1 had a half-life of 26.7 days and a maximum concentration in serum (Cmax) of 953 μg/ml. This study suggests that single infusions of MGAWN1 up to 30 mg/kg appear to be safe and well tolerated in healthy subjects. The Cmax of 953 μg/ml exceeds the target level in serum estimated from hamster studies by 28-fold and should provide excess WNV neutralizing activity and penetration into the brain and cerebrospinal fluid (CSF). Further evaluation of MGAWN1 for the treatment of West Nile virus infections is warranted. PMID:20350945

  2. Safety and pharmacokinetics of single intravenous dose of MGAWN1, a novel monoclonal antibody to West Nile virus.

    Science.gov (United States)

    Beigel, John H; Nordstrom, Jeffrey L; Pillemer, Stanley R; Roncal, Cory; Goldwater, D Ronald; Li, Hua; Holland, P Chris; Johnson, Syd; Stein, Kathryn; Koenig, Scott

    2010-06-01

    West Nile Virus (WNV) is a neurotropic flavivirus that can cause debilitating diseases, such as encephalitis, meningitis, or flaccid paralysis. We report the safety, pharmacokinetics, and immunogenicity of a recombinant humanized monoclonal antibody (MGAWN1) targeting the E protein of WNV in a phase 1 study, the first to be performed on humans. A single intravenous infusion of saline or of MGAWN1 at escalating doses (0.3, 1, 3, 10, or 30 mg/kg of body weight) was administered to 40 healthy volunteers (30 receiving MGAWN1; 10 receiving placebo). Subjects were evaluated on days 0, 1, 3, 7, 14, 21, 28, 42, 56, 91, 120, and 180 by clinical assessments, clinical laboratory studies, electrocardiograms (ECGs), and pharmacokinetic and immunogenicity assays. All 40 subjects tolerated the infusion of the study drug, and 39 subjects completed the study. One serious adverse event of schizophrenia occurred in the 0.3-mg/kg cohort. One grade 3 neutropenia occurred in the 3-mg/kg cohort. Six MGAWN1-treated subjects experienced 11 drug-related adverse events, including diarrhea (1 subject), chest discomfort (1), oral herpes (1), rhinitis (1), neutropenia (2), leukopenia (1), dizziness (1), headache (2), and somnolence (1). In the 30-mg/kg cohort, MGAWN1 had a half-life of 26.7 days and a maximum concentration in serum (C(max)) of 953 microg/ml. This study suggests that single infusions of MGAWN1 up to 30 mg/kg appear to be safe and well tolerated in healthy subjects. The C(max) of 953 microg/ml exceeds the target level in serum estimated from hamster studies by 28-fold and should provide excess WNV neutralizing activity and penetration into the brain and cerebrospinal fluid (CSF). Further evaluation of MGAWN1 for the treatment of West Nile virus infections is warranted.

  3. High Prevalence of West Nile Virus in Domestic Birds and Detection in 2 New Mosquito Species in Madagascar.

    Science.gov (United States)

    Maquart, Marianne; Boyer, Sébastien; Rakotoharinome, Vincent Michel; Ravaomanana, Julie; Tantely, Michael Luciano; Heraud, Jean-Michel; Cardinale, Eric

    2016-01-01

    West Nile virus is an arthropod-borne zoonosis transmitted by a large number of mosquito species, and birds play a key role as reservoir of the virus. Its distribution is largely widespread over Africa, Asia, the Americas and Europe. Since 1978, it has frequently been reported in Madagascar. Studies described a high seroprevalence level of the virus in humans in different areas of the island and a human fatal case of WNV infection was reported in 2011. Despite these reports, the epidemiology of WNV in Madagascar, in particular, viral circulation remains unclear. To explore the transmission of WNV in two rural human populations of Madagascar, we investigated local mosquitoes and poultry for evidence of current infections, and determined seroprevalence of candidate sentinel species among the local poultry. These 2 areas are close to lakes where domestic birds, migratory wild birds and humans coexist. Serological analysis revealed WNV antibodies in domestic birds (duck, chicken, goose, turkey and guinea fowl) sampled in both districts (Antsalova 29.4% and Mitsinjo 16.7%). West Nile virus nucleic acid was detected in one chicken and in 8 pools of mosquitoes including 2 mosquito species (Aedeomyia madagascarica and Anopheles pauliani) that have not been previously described as candidate vectors for WNV. Molecular analysis of WNV isolates showed that all viruses detected were part of the lineage 2 that is mainly distributed in Africa, and were most closely matched by the previous Malagasy strains isolated in 1988. Our study showed that WNV circulates in Madagascar amongst domestic birds and mosquitoes, and highlights the utility of poultry as a surveillance tool to detect WNV transmission in a peri-domestic setting.

  4. High Prevalence of West Nile Virus in Domestic Birds and Detection in 2 New Mosquito Species in Madagascar.

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    Marianne Maquart

    Full Text Available West Nile virus is an arthropod-borne zoonosis transmitted by a large number of mosquito species, and birds play a key role as reservoir of the virus. Its distribution is largely widespread over Africa, Asia, the Americas and Europe. Since 1978, it has frequently been reported in Madagascar. Studies described a high seroprevalence level of the virus in humans in different areas of the island and a human fatal case of WNV infection was reported in 2011. Despite these reports, the epidemiology of WNV in Madagascar, in particular, viral circulation remains unclear. To explore the transmission of WNV in two rural human populations of Madagascar, we investigated local mosquitoes and poultry for evidence of current infections, and determined seroprevalence of candidate sentinel species among the local poultry. These 2 areas are close to lakes where domestic birds, migratory wild birds and humans coexist. Serological analysis revealed WNV antibodies in domestic birds (duck, chicken, goose, turkey and guinea fowl sampled in both districts (Antsalova 29.4% and Mitsinjo 16.7%. West Nile virus nucleic acid was detected in one chicken and in 8 pools of mosquitoes including 2 mosquito species (Aedeomyia madagascarica and Anopheles pauliani that have not been previously described as candidate vectors for WNV. Molecular analysis of WNV isolates showed that all viruses detected were part of the lineage 2 that is mainly distributed in Africa, and were most closely matched by the previous Malagasy strains isolated in 1988. Our study showed that WNV circulates in Madagascar amongst domestic birds and mosquitoes, and highlights the utility of poultry as a surveillance tool to detect WNV transmission in a peri-domestic setting.

  5. Investigation of Influenza A, West Nile and Newcastle Disease Viruses in Birds from the Pantanal Wetlands of Mato Grosso, Brazil

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    LB Pinto

    Full Text Available ABSTRACT The Pantanal is the world's largest wetland biome with a seasonal flood pulse that attracts a great diversity of birds, many of which are migratory. Birds can be natural reservoirs Influenza A, West Nile and Newcastle Disease viruses. However, the occurrence of carriers for these viruses in the Pantanal was not verified yet. The present study evaluated the occurrence of natural infection by Influenza A, WN and ND virus of birds in the municipality of Poconé, a subregion of the Pantanal in the state of Mato Grosso, Brazil. A total of 76 birds belonging to 11 orders and 20 families were captured using mist nets. The most representative order was Passeriformes, followed by the other nine orders, which included Columbiformes, Psittaciformes, Charadriiformes and Anseriformes. The most representative family was Thamnophilidae, with 16 individuals (21.0%, followed by the family Tyrannidae with 10 individuals (7.6% and the family Furnariidae, with eight individuals (10.5%. The bird species were identified, and cloacal and tracheal swab samples were collected. The samples were subjected to RNA extraction and tested for the presence of the three agents by real-time polymerase chain reaction (qRT-PCR. All the sampled birds were considered healthy, had no clinical sign of infection, and were tested negative for the three viruses. Based on our findings, we can conclude that Influenza, West Nile and Newcastle Disease viruses were absent from the samples in this region of the Pantanal wetlands during the period of this study.

  6. Spatio-Temporal Identification of Areas Suitable for West Nile Disease in the Mediterranean Basin and Central Europe.

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    Annamaria Conte

    Full Text Available West Nile virus (WNV is a mosquito-transmitted Flavivirus belonging to the Japanese encephalitis antigenic complex of the Flaviviridae family. Its spread in the Mediterranean basin and the Balkans poses a significant risk to human health and forces public health officials to constantly monitor the virus transmission to ensure prompt application of preventive measures. In this context, predictive tools indicating the areas and periods at major risk of WNV transmission are of paramount importance. Spatial analysis approaches, which use environmental and climatic variables to find suitable habitats for WNV spread, can enhance predictive techniques. Using the Mahalanobis Distance statistic, areas ecologically most suitable for sustaining WNV transmission were identified in the Mediterranean basin and Central Europe. About 270 human and equine clinical cases notified in Italy, Greece, Portugal, Morocco, and Tunisia, between 2008 and 2012, have been considered. The environmental variables included in the model were altitude, slope, night time Land Surface Temperature, Normalized Difference Vegetation Index, Enhanced Vegetation Index, and daily temperature range. Seasonality of mosquito population has been modelled and included in the analyses to produce monthly maps of suitable areas for West Nile Disease. Between May and July, the most suitable areas are located in Tunisia, Libya, Egypt, and North Cyprus. Summer/Autumn months, particularly between August and October, characterize the suitability in Italy, France, Spain, the Balkan countries, Morocco, North Tunisia, the Mediterranean coast of Africa, and the Middle East. The persistence of suitable conditions in December is confined to the coastal areas of Morocco, Tunisia, Libya, Egypt, and Israel.

  7. O vírus do Nilo Ocidental West Nile virus

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    Eduardo Furtado Flores

    2009-04-01

    árias brasileiras da área humana e animal temem que a infecção seja introduzida no país, onde provavelmente encontraria condições ecológicas para a sua disseminação e manutenção. Este artigo apresenta uma breve revisão dos principais aspectos epidemiológicos e clínico-patológicos da infecção pelo WNV, com ênfase na infecção de humanos, aves e eqüinos.West Nile virus (WNV is a Flavivirus maintained in nature through alternate cycles of infection in wild birds and haematophagus mosquitoes, mainly Culex sp. Natural infection by WNV has been demonstrated in more than 200 bird species, which present variable susceptibility to infection and disease. Corvids and passeriformes are particularly susceptible and develop high levels of viremia and mortality. Occasionally, the virus may be transmitted to mammals by mosquitoes feeding previously on viremic birds. Human and horses are highly susceptible to WNV infection and often develop fever, which may be followed by neurological infection and fatal meningoencephalitis. Originally identified in Uganda (1937, WNV infection remained for decades restricted to North Africa, East Asia, Middle East and Mediterranean Europe. In these areas, isolated cases of human and horse disease, or small outbreaks were occasionally reported. In 1999, the virus was introduced in New York, USA, where it caused mortality in thousands of wild and captive birds and infected hundreds of people, killing 21. Thereafter, the infection rapidly spread out over the US territory, causing thousands of human infections (more than 27.000 - around 1100 deaths and equine infections (more than 25.000 cases. WNV infection has also been detected in wild and domestic birds, horses and other mammals across Mexico, Central America and the Caribbean, and northern South America, indicating its dissemination southwards. In 2006, WNV was first identified as the agent of fatal neurological disease in three horses in Argentina, where it has been shown to be circulating in

  8. Climate Change Influences on the Global Potential Distribution of the Mosquito Culex quinquefasciatus, Vector of West Nile Virus and Lymphatic Filariasis

    OpenAIRE

    Samy,Abdallah M.; Elaagip, Arwa H.; Kenawy, Mohamed A.; Ayres, Const?ncia F. J.; Peterson, A Townsend; Soliman, Doaa E.

    2016-01-01

    Rapid emergence of most vector-borne diseases (VBDs) may be associated with range expansion of vector populations. Culex quinquefasciatus Say 1823 is a potential vector of West Nile virus, Saint Louis encephalitis virus, and lymphatic filariasis. We estimated the potential distribution of Cx. quinquefasciatus under both current and future climate conditions. The present potential distribution of Cx. quinquefasciatus showed high suitability across low-latitude parts of the world, reflecting th...

  9. Proximity of Residence to Bodies of Water and Risk for West Nile Virus Infection: A Case-Control Study in Houston, Texas

    OpenAIRE

    Nolan, Melissa S.; Zangeneh, Ana; Khuwaja, Salma A.; Martinez, Diana; Rossmann, Susan N.; Cardenas, Victor; Murray, Kristy O.

    2012-01-01

    West Nile virus (WNV), a mosquito-borne virus, has clinically affected hundreds of residents in the Houston metropolitan area since its introduction in 2002. This study aimed to determine if living within close proximity to a water source increases one’s odds of infection with WNV. We identified 356 eligible WNV-positive cases and 356 controls using a population proportionate to size model with US Census Bureau data. We found that living near slow moving water sources was statistically associ...

  10. Community diversity of mosquitoes and their microbes across different habitats endemic for West Nile Virus and other arthropod-borne diseases

    Science.gov (United States)

    Liu, R.; Bennett, S. N.; Thongsripong, P.; Chandler, J. S.

    2013-12-01

    Mosquitoes have long been vectors for disease, and humans, birds, and other vertebrates have served their role as hosts in the transmission cycle of arthropod-borne viruses. In California, there are several mosquito species that act as vectors, transmitting such disease agents as Western equine and St. Louis encephalitis viruses, filarial nematodes, Plasmodium (which causes malaria), and West Nile virus (WNV). Last year (2012-2013), California had over 450 reported cases of West Nile Virus in humans (http://westnile.ca.gov/). To begin to understand mosquitoes and their role in the bay area as vectors of diseases, including West Nile Virus, we trapped mosquitoes from various sites and examined their microbiomes, including bacteria, fungi, viruses, and eukaryotes. Study sites were in Marin, San Mateo, and San Francisco counties, in areas that represented, respectively, rural, suburban, and urban habitats. The mosquitoes were identified through morphological characteristics, and verified molecularly by sequencing of the cytochrome oxidase I (COI) gene extracted from a leg. Most mosquitoes were collected from San Mateo and Mill Valley and were identified as Culiseta incidens. Data from traditional culture-based and next-generation 454 sequencing methods applied to mosquito whole bodies, representing their microbiomes, will be discussed, to determine how mosquito and microbial diversity varies across sites sampled in the San Francisco Bay area.

  11. The Integrated System for Public Health Monitoring of West Nile Virus (ISPHM-WNV: a real-time GIS for surveillance and decision-making

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    Lebel Germain

    2005-09-01

    Full Text Available Abstract Background After its first detection in North America in New York in 1999, West Nile virus was detected for the first time in 2002 in the province of Quebec, Canada. This situation forced the Government of Quebec to adopt a public health protection plan against the virus. The plan comprises several fields of intervention including the monitoring of human cases, Corvidae and mosquitoes in order to ensure the early detection of the presence of the virus in a particular area. To help support the monitoring activities, the Integrated System for Public Health Monitoring of West Nile Virus (ISPHM-WNV has been developed. Results The ISPHM-WNV is a real-time geographic information system for public health surveillance of West Nile virus and includes information on Corvidae, mosquitoes, humans, horses, climate, and preventive larvicide interventions. It has been in operation in the province of Quebec, Canada, since May 2003. The ISPHM-WNV facilitates the collection, localization, management and analysis of monitoring data; it also allows for the display of the results of analyses on maps, tables and statistical diagrams. Conclusion The system is very helpful for field workers in all regions of the province, as well as for central authorities. It represents the common authoritative source of data for analysis, exchange and decision-making.

  12. Fluid Spatial Dynamics of West Nile Virus in the United States: Rapid Spread in a Permissive Host Environment.

    Science.gov (United States)

    Di Giallonardo, Francesca; Geoghegan, Jemma L; Docherty, Douglas E; McLean, Robert G; Zody, Michael C; Qu, James; Yang, Xiao; Birren, Bruce W; Malboeuf, Christine M; Newman, Ruchi M; Ip, Hon S; Holmes, Edward C

    2015-10-28

    The introduction of West Nile virus (WNV) into North America in 1999 is a classic example of viral emergence in a new environment, with its subsequent dispersion across the continent having a major impact on local bird populations. Despite the importance of this epizootic, the pattern, dynamics, and determinants of WNV spread in its natural hosts remain uncertain. In particular, it is unclear whether the virus encountered major barriers to transmission, or spread in an unconstrained manner, and if specific viral lineages were favored over others indicative of intrinsic differences in fitness. To address these key questions in WNV evolution and ecology, we sequenced the complete genomes of approximately 300 avian isolates sampled across the United States between 2001 and 2012. Phylogenetic analysis revealed a relatively star-like tree structure, indicative of explosive viral spread in the United States, although with some replacement of viral genotypes through time. These data are striking in that viral sequences exhibit relatively limited clustering according to geographic region, particularly for those viruses sampled from birds, and no strong phylogenetic association with well-sampled avian species. The genome sequence data analyzed here also contain relatively little evidence for adaptive evolution, particularly of structural proteins, suggesting that most viral lineages are of similar fitness and that WNV is well adapted to the ecology of mosquito vectors and diverse avian hosts in the United States. In sum, the molecular evolution of WNV in North America depicts a largely unfettered expansion within a permissive host and geographic population with little evidence of major adaptive barriers. How viruses spread in new host and geographic environments is central to understanding the emergence and evolution of novel infectious diseases and for predicting their likely impact. The emergence of the vector-borne West Nile virus (WNV) in North America in 1999

  13. Mapping of West Nile Virus Risk in the Northeast United States Using Multi-temporal Meteorological Satellite Data

    Science.gov (United States)

    Backenson, P.; White, D. J.; Eidson, M.; Smith, P. F.; Kramer, L. D.; Morse, D. L.; Tucker, C. J.; Myers, M. F.; Hay, S. I.; Rogers, D. J.

    2002-05-01

    West Nile Virus (WNV) was first discovered in the United States in September of 1999, after a cluster of cases of human neurological illness was identified in the borough of Queens in New York City. Eventually, that outbreak led to 62 human cases of WNV, including seven deaths. Multiple researchers identified and isolated the virus in several bird and mosquito species in New York. In 2000, an elaborate surveillance system was developed to detect the presence of WNV before human cases occur. This system was largely successful, as the number of WNV detections in birds and mosquitoes increased tremendously, while the number of human cases dropped to 14. In 2001, this surveillance system, and those like it in other states, detected the spread of WNV to over 25 states, with over 50 human cases. Detecting WNV in both birds and mosquitoes, however, is a time and labor intensive task, requiring dedicated staff and resources. In New York it has required hundreds of staff, and millions of dollars. It often takes at least 10 days from the time of specimen collection to the time when results are available. To improve efficiency and cost-effectiveness, proxies are sought to estimate the risk of WNV infection in a given area, preferably on a real-time basis. The project discussed here utilizes remotely sensed meteorological data to accomplish that goal. Data from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA series of meteorological satellites provided the Normalized Difference Vegetation Index (NDVI) and land surface temperature proxies, as well as elevation, and were temporal Fourier processed. Bird and mosquito data (both infected and uninfected) were added to these images to suggest conditions favoring disease transmission. AVHRR data were also used to analyze changes over time that might be associated with the arrival of WNV in the United States, and with its potential spread over time. Maximum likelihood methods applied to these satellite data allowed

  14. [2002 West Nile virus diagnostic services case report : Long Lake National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Diagnostic services case report for two Franklin's gull and two ring-billed gull carcasses collected from Long Lake National Wildlife Refuge to be tested for West...

  15. Contributions to integrative knowledge of West Nile virus reported in Romania - methods and tools for managing health-environment relationship at different spatial and temporal scales

    Science.gov (United States)

    Baltesiu, L.; Gomoiu, M. T.; Mudura, R.; Nicolescu, G.; Purcarea-Ciulacu, V.

    2012-04-01

    After 1990 there were environmental changes at national, European and global level which led to the emergence and re-emergence of infectious diseases. Among these diseases, those transmitted by vectors were installed on very large areas where pathogens entered the complex transmission cycles within the local ecosystems. Environmental changes were generated by climatic (temperature and precipitation), geomorphologic (altitude) and anthropogenic (land cover / land use) changes. Due to these environmental changes it became necessary to anticipate, prevent and control the epidemics in order to avoid major crises of natural and socio-economic systems. In these circumstances, the risk of re-emergence of West Nile virus infection increased, thus becoming a public health problem for Romania. Our research consisted in assessing this risk, depending on environmental changes that can influence the presence and space-time distribution as well as the dynamics of the elements of virus transmission cycle. Study areas were selected so that they should meet, on the one hand, very different natural ecosystems and on the other hand should include continuously changing anthropogenic ecosystems that provide optimal conditions for the vector-borne West Nile virus. These areas were: the Danube Delta including Razim-Sinoe complex (Tulcea County), Bucharest Metropolitan Area (BMA) (Bucharest and Ilfov & Giurgiu Counties). The Danube Delta lagoon area is the gateway to West Nile virus in Romania. During the neurological infection epidemic with West Nile virus in 1996, in BMA were recorded 60% of the total number of human cases. For the period 2009 - 2011 the authors developed risk maps to West Nile virus vectors to vertebrate hosts depending on climatic, geomorphologic and anthropogenic changes. Maps were made using ArcGis - ArcMap software, depending on the mean annual temperature and precipitation. We were used by the altitude risk map the hypsographic map of Romania and for the risk map

  16. The West Nile Virus-Like Flavivirus Koutango Is Highly Virulent in Mice due to Delayed Viral Clearance and the Induction of a Poor Neutralizing Antibody Response

    Science.gov (United States)

    Setoh, Yin X.; Biron, Rebecca M.; Sester, David P.; Kim, Kwang Sik; Hobson-Peters, Jody; Hall, Roy A.; Bielefeldt-Ohmann, Helle

    2014-01-01

    ABSTRACT The mosquito-borne West Nile virus (WNV) is responsible for outbreaks of viral encephalitis in humans, horses, and birds, with particularly virulent strains causing recent outbreaks of disease in eastern Europe, the Middle East, North America, and Australia. Previous studies have phylogenetically separated WNV strains into two main genetic lineages (I and II) containing virulent strains associated with neurological disease. Several WNV-like strains clustering outside these lineages have been identified and form an additional five proposed lineages. However, little is known about whether these strains have the potential to induce disease. In a comparative analysis with the highly virulent lineage I American strain (WNVNY99), the low-pathogenicity lineage II strain (B956), a benign Australian strain, Kunjin (WNVKUN), the African WNV-like Koutango virus (WNVKOU), and a WNV-like isolate from Sarawak, Malaysia (WNVSarawak), were assessed for neuroinvasive properties in a murine model and for their replication kinetics in vitro. While WNVNY99 replicated to the highest levels in vitro, in vivo mouse challenge revealed that WNVKOU was more virulent, with a shorter time to onset of neurological disease and higher morbidity. Histological analysis of WNVKOU- and WNVNY99-infected brain and spinal cords demonstrated more prominent meningoencephalitis and the presence of viral antigen in WNVKOU-infected mice. Enhanced virulence of WNVKOU also was associated with poor viral clearance in the periphery (sera and spleen), a skewed innate immune response, and poor neutralizing antibody development. These data demonstrate, for the first time, potent neuroinvasive and neurovirulent properties of a WNV-like virus outside lineages I and II. IMPORTANCE In this study, we characterized the in vitro and in vivo properties of previously uncharacterized West Nile virus strains and West Nile-like viruses. We identified a West Nile-like virus, Koutango virus (WNVKOU), that was more

  17. Landscape and Residential Variables Associated with Plague-Endemic Villages in the West Nile Region of Uganda

    Science.gov (United States)

    MacMillan, Katherine; Enscore, Russell E.; Ogen-Odoi, Asaph; Borchert, Jeff N.; Babi, Nackson; Amatre, Gerald; Atiku, Linda A.; Mead, Paul S.; Gage, Kenneth L.; Eisen, Rebecca J.

    2011-01-01

    Plague, caused by the bacteria Yersinia pestis, is a severe, often fatal disease. This study focuses on the plague-endemic West Nile region of Uganda, where limited information is available regarding environmental and behavioral risk factors associated with plague infection. We conducted observational surveys of 10 randomly selected huts within historically classified case and control villages (four each) two times during the dry season of 2006 (N = 78 case huts and N = 80 control huts), which immediately preceded a large plague outbreak. By coupling a previously published landscape-level statistical model of plague risk with this observational survey, we were able to identify potential residence-based risk factors for plague associated with huts within historic case or control villages (e.g., distance to neighboring homestead and presence of pigs near the home) and huts within areas previously predicted as elevated risk or low risk (e.g., corn and other annual crops grown near the home, water storage in the home, and processed commercial foods stored in the home). The identified variables are consistent with current ecologic theories on plague transmission dynamics. This preliminary study serves as a foundation for future case control studies in the area. PMID:21363983

  18. Use of Insecticide Delivery Tubes for Controlling Rodent-Associated Fleas in a Plague Endemic Region of West Nile, Uganda.

    Science.gov (United States)

    Boegler, Karen A; Atiku, Linda A; Mpanga, Joseph Tendo; Clark, Rebecca J; Delorey, Mark J; Gage, Kenneth L; Eisen, Rebecca J

    2014-11-01

    Plague is a primarily flea-borne rodent-associated zoonosis that is often fatal in humans. Our study focused on the plague-endemic West Nile region of Uganda where affordable means for the prevention of human plague are currently lacking. Traditional hut construction and food storage practices hinder rodent exclusion efforts, and emphasize the need for an inexpensive but effective host-targeted approach for controlling fleas within the domestic environment. Here we demonstrate the ability of an insecticide delivery tube that is made from inexpensive locally available materials to reduce fleas on domestic rodents. Unbaited tubes were treated with either an insecticide alone (fipronil) or in conjunction with an insect growth regulator [(S)-methoprene], and placed along natural rodent runways within participant huts. Performance was similar for both treatments throughout the course of the study, and showed significant reductions in the proportion of infested rodents relative to controls for at least 100 d posttreatment. © 2014 Entomological Society of America.

  19. Remote sensing of climatic anomalies and West Nile virus incidence in the northern Great Plains of the United States.

    Directory of Open Access Journals (Sweden)

    Ting-Wu Chuang

    Full Text Available The northern Great Plains (NGP of the United States has been a hotspot of West Nile virus (WNV incidence since 2002. Mosquito ecology and the transmission of vector-borne disease are influenced by multiple environmental factors, and climatic variability is an important driver of inter-annual variation in WNV transmission risk. This study applied multiple environmental predictors including land surface temperature (LST, the normalized difference vegetation index (NDVI and actual evapotranspiration (ETa derived from Moderate-Resolution Imaging Spectroradiometer (MODIS products to establish prediction models for WNV risk in the NGP. These environmental metrics are sensitive to seasonal and inter-annual fluctuations in temperature and precipitation, and are hypothesized to influence mosquito population dynamics and WNV transmission. Non-linear generalized additive models (GAMs were used to evaluate the influences of deviations of cumulative LST, NDVI, and ETa on inter-annual variations of WNV incidence from 2004-2010. The models were sensitive to the timing of spring green up (measured with NDVI, temperature variability in early spring and summer (measured with LST, and moisture availability from late spring through early summer (measured with ETa, highlighting seasonal changes in the influences of climatic fluctuations on WNV transmission. Predictions based on these variables indicated a low WNV risk across the NGP in 2011, which is concordant with the low case reports in this year. Environmental monitoring using remote-sensed data can contribute to surveillance of WNV risk and prediction of future WNV outbreaks in space and time.

  20. Mosquito distribution and West Nile virus infection in zoos and in important sites of migratory and resident birds, Thailand

    Directory of Open Access Journals (Sweden)

    Tanasak Changbunjong

    2012-08-01

    Full Text Available Objective: To investigate the distribution of mosquito species in the zoos and in important sites of migratory and resident birds and evaluate West Nile virus (WNV infection in mosquito species. Methods: Mosquitoes distribution investigation was carried out bimonthly from January 2009 to December 2010 in five areas of birds, Thailand by using Centers for Disease Control, light traps, and gravid traps. Mosquitoes were identified, pooled into groups of up to 50 mosquitoes by species, places and time of collection and tested for WNV infection by viral isolation and reverse transcriptase polymerase chain reaction. Results: A total of 66 597 mosquitoes comprising 26 species in 8 genera were collected. The five most abundant mosquito species collected were Culex tritaeniorhynchus (79.3%, Culex vishnui (8.2%, Culex sitiens (6%, Culex quinquefasciatus (3.3% and Anopheles peditaeniatus (1.1%. All 1 736 mosquito pools were negative for viral isolation and reverse transcriptase polymerase chain reaction. Conclusions: This study provides new information on number of mosquito species present and their relative abundance. Although our study found no evidence of WNV in the avifaunal sources of Thailand, mosquito active surveillance should be continuously conducted. The cooperation between related organizations is needed for early detection of WNV disease and development of effective veterinary and public health policies in this region.

  1. Incidence of West Nile virus infection in the Dallas-Fort Worth metropolitan area during the 2012 epidemic.

    Science.gov (United States)

    Williamson, P C; Custer, B; Biggerstaff, B J; Lanciotti, R S; Sayers, M H; Eason, S J; Dixon, M R; Winkelman, V; Lanteri, M C; Petersen, L R; Busch, M P

    2017-09-01

    The 2012 West Nile virus (WNV) epidemic was the largest since 2003 and the North Texas region was the most heavily impacted. We conducted a serosurvey of blood donors from four counties in the Dallas-Fort Worth area to characterize the epidemic. Blood donor specimens collected in November 2012 were tested for WNV-specific antibodies. Donors positive for WNV-specific IgG, IgM, and neutralizing antibodies were considered to have been infected in 2012. This number was adjusted using a multi-step process that accounted for timing of IgM seroreversion determined from previous longitudinal studies of WNV-infected donors. Of 4971 donations screened, 139 (2·8%) were confirmed WNV IgG positive, and 69 (1·4%) had IgM indicating infection in 2012. After adjusting for timing of sampling and potential seroreversion, we estimated that 1·8% [95% confidence interval (CI) 1·5-2·2] of the adult population in the Dallas-Fort Worth area were infected during 2012. The resulting overall estimate for the ratio of infections to reported WNV neuroinvasive disease (WNND) cases was 238:1 (95% CI 192-290), with significantly increased risk of WNND in older age groups. These findings were very similar to previous estimates of infections per WNND case, indicating no change in virulence as WNV evolved into an endemic infection in the United States.

  2. Flaviviruses in Europe: Complex Circulation Patterns and Their Consequences for the Diagnosis and Control of West Nile Disease

    Science.gov (United States)

    Beck, Cécile; Jimenez-Clavero, Miguel Angel; Leblond, Agnès; Durand, Benoît; Nowotny, Norbert; Leparc-Goffart, Isabelle; Zientara, Stéphan; Jourdain, Elsa; Lecollinet, Sylvie

    2013-01-01

    In Europe, many flaviviruses are endemic (West Nile, Usutu, tick-borne encephalitis viruses) or occasionally imported (dengue, yellow fever viruses). Due to the temporal and geographical co-circulation of flaviviruses in Europe, flavivirus differentiation by diagnostic tests is crucial in the adaptation of surveillance and control efforts. Serological diagnosis of flavivirus infections is complicated by the antigenic similarities among the Flavivirus genus. Indeed, most flavivirus antibodies are directed against the highly immunogenic envelope protein, which contains both flavivirus cross-reactive and virus-specific epitopes. Serological assay results should thus be interpreted with care and confirmed by comparative neutralization tests using a panel of viruses known to circulate in Europe. However, antibody cross-reactivity could be advantageous in efforts to control emerging flaviviruses because it ensures partial cross-protection. In contrast, it might also facilitate subsequent diseases, through a phenomenon called antibody-dependent enhancement mainly described for dengue virus infections. Here, we review the serological methods commonly used in WNV diagnosis and surveillance in Europe. By examining past and current epidemiological situations in different European countries, we present the challenges involved in interpreting flavivirus serological tests and setting up appropriate surveillance programs; we also address the consequences of flavivirus circulation and vaccination for host immunity. PMID:24225644

  3. Economics of One Health: Costs and benefits of integrated West Nile virus surveillance in Emilia-Romagna.

    Directory of Open Access Journals (Sweden)

    Giulia Paternoster

    Full Text Available Since 2013 in Emilia-Romagna, Italy, surveillance information generated in the public health and in the animal health sectors has been shared and used to guide public health interventions to mitigate the risk of West Nile virus (WNV transmission via blood transfusion. The objective of the current study was to identify and estimate the costs and benefits associated with this One Health surveillance approach, and to compare it to an approach that does not integrate animal health information in blood donations safety policy (uni-sectoral scenario. Costs of human, animal, and entomological surveillance, sharing of information, and triggered interventions were estimated. Benefits were quantified as the averted costs of potential human cases of WNV neuroinvasive disease associated to infected blood transfusion. In the 2009-2015 period, the One Health approach was estimated to represent a cost saving of €160,921 compared to the uni-sectoral scenario. Blood donation screening was the main cost for both scenarios. The One Health approach further allowed savings of €1.21 million in terms of avoided tests on blood units. Benefits of the One Health approach due to short-term costs of hospitalization and compensation for transfusion-associated disease potentially avoided, were estimated to range from €0 to €2.98 million according to the probability of developing WNV neuroinvasive disease after receiving an infected blood transfusion.

  4. Resistance to alpha/beta interferon is a determinant of West Nile virus replication fitness and virulence.

    Science.gov (United States)

    Keller, Brian C; Fredericksen, Brenda L; Samuel, Melanie A; Mock, Richard E; Mason, Peter W; Diamond, Michael S; Gale, Michael

    2006-10-01

    The emergence of West Nile virus (WNV) in the Western Hemisphere is marked by the spread of pathogenic lineage I strains, which differ from typically avirulent lineage II strains. To begin to understand the virus-host interactions that may influence the phenotypic properties of divergent lineage I and II viruses, we compared the genetic, pathogenic, and alpha/beta interferon (IFN-alpha/beta)-regulatory properties of a lineage II isolate from Madagascar (MAD78) with those of a new lineage I isolate from Texas (TX02). Full genome sequence analysis revealed that MAD78 clustered, albeit distantly, with other lineage II strains, while TX02 clustered with emergent North American isolates, more specifically with other Texas strains. Compared to TX02, MAD78 replicated at low levels in cultured human cells, was highly sensitive to the antiviral actions of IFN in vitro, and demonstrated a completely avirulent phenotype in wild-type mice. In contrast to TX02 and other pathogenic forms of WNV, MAD78 was defective in its ability to disrupt IFN-induced JAK-STAT signaling, including the activation of Tyk2 and downstream phosphorylation and nuclear translocation of STAT1 and STAT2. However, replication of MAD78 was rescued in cells with a nonfunctional IFN-alpha/beta receptor (IFNAR). Consistent with this finding, the virulence of MAD78 was unmasked upon infection of mice lacking IFNAR. Thus, control of the innate host response and IFN actions is a key feature of WNV pathogenesis and replication fitness.

  5. West Nile virus surveillance: A simple method for verifying the integrity of RNA in mosquito (Diptera: Culicidae) pools.

    Science.gov (United States)

    Hoffmann, Peter R; Woodrow, Robert J; Calimlim, Precilia S; Sciulli, Rebecca; Effler, Paul V; Miyamoto, Vernon; Imrie, Allison; Yanagihara, Richard; Nerurkar, Vivek R

    2004-07-01

    In a West Nile virus (WNV) -free ecosystem, it is essential to verify the integrity of RNA before concluding that RNA extracted from mosquito specimens is negative for WNV gene sequences. The primary objective of our study was to develop a rapid molecular assay to rapidly screen mosquitoes for the presence of 18S RNA and WNV gene sequences. Mosquitoes, collected from multiple sites on the island of O'ahu, were pooled into groups of 1-50 mosquitoes according to capture site, date, and species. Using primer design software and the GenBank database, generic oligonucleotide primer pairs were designed to amplify mosquito18S rRNA gene sequences from different species. RNA was extracted from mosquito pools, and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed for the presence of mosquito18S rRNA and WNV gene sequences. Three of the seven primer pairs successfully detected 18S rRNA sequences for both Aedes and Culex by RT-PCR, and one primer pair successfully amplified 18S rRNA sequences for 15 different mosquito species. All 64 mosquito pools from 10 different sites on the island of Oahu, Hawaii, were negative for WNV nonstructural protein-5 gene sequences. This simple, one-step RT-PCR method for screening mosquito pools for arboviruses will become an increasingly valuable tool as WNV becomes endemic throughout the Americas.

  6. Potential for water borne and invertebrate transmission of West Nile virus in the Great Salt Lake, Utah

    Science.gov (United States)

    Lund, Melissa; Shearn-Bochsler, Valerie I.; Dusek, Robert; Shivers, Jan; Hofmeister, Erik K.

    2017-01-01

    In November and December of 2013, a large mortality event involving 15,000 - 20,000 eared grebes (Podiceps nigricollis) occurred at the Great Salt Lake (GSL), UT. The onset of the outbreak in grebes was followed by a mortality event in > 86 bald eagles (Haliaeetus leucocephalus). During the die-off, West Nile virus (WNV) was detected by RT-PCR or viral culture in carcasses of grebes and eagles submitted to the National Wildlife Health Center. However, no mosquito activity, the primary vector of WNV, was detected by the State of Utah's WNV monitoring program. Transmission of WNV has rarely been reported during the winter in North America in the absence of known mosquito activity; however, the size of this die-off, the habitat in which it occurred, and the species involved are unique. We experimentally investigated whether WNV could survive in water with a high saline content, as found at the GSL, and whether brine shrimp, the primary food of migrating eared grebes on the GSL, could have played a role in transmission of WNV to feeding birds. We found that WNV can survive up to 72 h at 4°C in water containing 30 — 150 ppt NaCl and brine shrimp, incubated with WNV in 30 ppt NaCl, may adsorb WNV to their cuticle and, through feeding, may infect epithelial cells of their gut. Both mechanisms may have potentiated the WNV die-off in migrating eared grebes on the GSL.

  7. Spectral and Hydrodynamic Analysis of West Nile Virus RNA-Protein Interactions by Multiwavelength Sedimentation Velocity in the Analytical Ultracentrifuge.

    Science.gov (United States)

    Zhang, Jin; Pearson, Joseph Z; Gorbet, Gary E; Cölfen, Helmut; Germann, Markus W; Brinton, Margo A; Demeler, Borries

    2017-01-03

    Interactions between nucleic acids and proteins are critical for many cellular processes, and their study is of utmost importance to many areas of biochemistry, cellular biology, and virology. Here, we introduce a new analytical method based on sedimentation velocity (SV) analytical ultracentrifugation, in combination with a novel multiwavelength detector to characterize such interactions. We identified the stoichiometry and molar mass of a complex formed during the interaction of a West Nile virus RNA stem loop structure with the human T cell-restricted intracellular antigen-1 related protein. SV has long been proven as a powerful technique for studying dynamic assembly processes under physiological conditions in solution. Here, we demonstrate, for the first time, how the new multiwavelength technology can be exploited to study protein-RNA interactions, and show how the spectral information derived from the new detector complements the traditional hydrodynamic information from analytical ultracentrifugation. Our method allows the protein and nucleic acid signals to be separated by spectral decomposition such that sedimentation information from each individual species, including any complexes, can be clearly identified based on their spectral signatures. The method presented here extends to any interacting system where the interaction partners are spectrally separable.

  8. Modelling West Nile virus transmission risk in Europe: effect of temperature and mosquito biotypes on the basic reproduction number.

    Science.gov (United States)

    Vogels, Chantal B F; Hartemink, Nienke; Koenraadt, Constantianus J M

    2017-07-10

    West Nile virus (WNV) is a mosquito-borne flavivirus which has caused repeated outbreaks in humans in southern and central Europe, but thus far not in northern Europe. The main mosquito vector for WNV, Culex pipiens, consists of two behaviourally distinct biotypes, pipiens and molestus, which can form hybrids. Differences between biotypes, such as vector competence and host preference, could be important in determining the risk of WNV outbreaks. Risks for WNV establishment can be modelled with basic reproduction number (R 0) models. However, existing R 0 models have not differentiated between biotypes. The aim of this study was, therefore, to explore the role of temperature-dependent and biotype-specific effects on the risk of WNV establishment in Europe. We developed an R 0 model with temperature-dependent and biotype-specific parameters, and calculated R 0 values using the next-generation matrix for several scenarios relevant for Europe. In addition, elasticity analysis was done to investigate the contribution of each biotype to R 0. Global warming and increased mosquito-to-host ratios can possibly result in more intense WNV circulation in birds and spill-over to humans in northern Europe. Different contributions of the Cx. pipiens biotypes to R 0 shows the importance of including biotype-specific parameters in models for reliable WNV risk assessments.

  9. NKp44 receptor mediates interaction of the envelope glycoproteins from the West Nile and dengue viruses with NK cells.

    Science.gov (United States)

    Hershkovitz, Oren; Rosental, Benyamin; Rosenberg, Lior Ann; Navarro-Sanchez, Martha Erika; Jivov, Sergey; Zilka, Alon; Gershoni-Yahalom, Orly; Brient-Litzler, Elodie; Bedouelle, Hugues; Ho, Joanna W; Campbell, Kerry S; Rager-Zisman, Bracha; Despres, Philippe; Porgador, Angel

    2009-08-15

    Dengue virus (DV) and West Nile virus (WNV) have become a global concern due to their widespread distribution and their ability to cause a variety of human diseases. Antiviral immune defenses involve NK cells. In the present study, we investigated the interaction between NK cells and these two flaviviruses. We show that the NK-activating receptor NKp44 is involved in virally mediated NK activation through direct interaction with the flavivirus envelope protein. Recombinant NKp44 directly binds to purified DV and WNV envelope proteins and specifically to domain III of WNV envelope protein; it also binds to WNV virus-like particles. These WNV-virus-like particles and WNV-domain III of WNV envelope protein directly bind NK cells expressing high levels of NKp44. Functionally, interaction of NK cells with infective and inactivated WNV results in NKp44-mediated NK degranulation. Finally, WNV infection of cells results in increased binding of rNKp44 that is specifically inhibited by anti-WNV serum. WNV-infected target cells induce IFN-gamma secretion and augmented lysis by NKp44-expressing primary NK cells that are blocked by anti-NKp44 Abs. Our findings show that triggering of NK cells by flavivirus is mediated by interaction of NKp44 with the flavivirus envelope protein.

  10. The Effect of West Nile Virus Infection on the Midgut Gene Expression of Culex pipiens quinquefasciatus Say (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Chelsea T. Smartt

    2016-12-01

    Full Text Available The interaction of the mosquito and the invading virus is complex and can result in physiological and gene expression alterations in the insect. The association of West Nile virus (WNV and Culex pipiens quinquefasciatus mosquitoes results in measurable changes in gene expression; 22 gene products were shown previously to have altered expression. Sequence analysis of one product, CQ G1A1, revealed 100% amino acid identity to gram negative bacteria binding proteins (CPQGBP in Cx. p. quinquefasciatus, Aedes aegypti (70% and Anopheles gambiae (63% that function in pathogen recognition. CQ G1A1 also was differentially expressed following WNV infection in two populations of Cx. p. quinquefasciatus colonized from Florida with known differences in vector competence for WNV and showed spatial and temporal gene expression differences in midgut, thorax, and carcass tissues. These data suggest gene expression of CQ G1A1 is influenced by WNV infection and the WNV infection-controlled expression differs between populations and tissues.

  11. Climatic, ecological, and socioeconomic factors associated with West Nile virus incidence in Atlanta, Georgia, U.S.A.

    Science.gov (United States)

    Lockaby, Graeme; Noori, Navideh; Morse, Wayde; Zipperer, Wayne; Kalin, Latif; Governo, Robin; Sawant, Rajesh; Ricker, Matthew

    2016-12-01

    The integrated effects of the many risk factors associated with West Nile virus (WNV) incidence are complex and not well understood. We studied an array of risk factors in and around Atlanta, GA, that have been shown to be linked with WNV in other locations. This array was comprehensive and included climate and meteorological metrics, vegetation characteristics, land use / land cover analyses, and socioeconomic factors. Data on mosquito abundance and WNV mosquito infection rates were obtained for 58 sites and covered 2009-2011, a period following the combined storm water - sewer overflow remediation in that city. Risk factors were compared to mosquito abundance and the WNV vector index (VI) using regression analyses individually and in combination. Lagged climate variables, including soil moisture and temperature, were significantly correlated (positively) with vector index as were forest patch size and percent pine composition of patches (both negatively). Socioeconomic factors that were most highly correlated (positively) with the VI included the proportion of low income households and homes built before 1960 and housing density. The model selected through stepwise regression that related risk factors to the VI included (in the order of decreasing influence) proportion of houses built before 1960, percent of pine in patches, and proportion of low income households. © 2016 The Society for Vector Ecology.

  12. Flaviviruses in Europe: Complex Circulation Patterns and Their Consequences for the Diagnosis and Control of West Nile Disease

    Directory of Open Access Journals (Sweden)

    Elsa Jourdain

    2013-11-01

    Full Text Available In Europe, many flaviviruses are endemic (West Nile, Usutu, tick-borne encephalitis viruses or occasionally imported (dengue, yellow fever viruses. Due to the temporal and geographical co-circulation of flaviviruses in Europe, flavivirus differentiation by diagnostic tests is crucial in the adaptation of surveillance and control efforts. Serological diagnosis of flavivirus infections is complicated by the antigenic similarities among the Flavivirus genus. Indeed, most flavivirus antibodies are directed against the highly immunogenic envelope protein, which contains both flavivirus cross-reactive and virus-specific epitopes. Serological assay results should thus be interpreted with care and confirmed by comparative neutralization tests using a panel of viruses known to circulate in Europe. However, antibody cross-reactivity could be advantageous in efforts to control emerging flaviviruses because it ensures partial cross-protection. In contrast, it might also facilitate subsequent diseases, through a phenomenon called antibody-dependent enhancement mainly described for dengue virus infections. Here, we review the serological methods commonly used in WNV diagnosis and surveillance in Europe. By examining past and current epidemiological situations in different European countries, we present the challenges involved in interpreting flavivirus serological tests and setting up appropriate surveillance programs; we also address the consequences of flavivirus circulation and vaccination for host immunity.

  13. Evidence of exposure of laughing doves (Spilopelia senegalensis) to West Nile and Usutu viruses in southern Tunisian oases.

    Science.gov (United States)

    Ayadi, T; Hammouda, A; Poux, A; Boulinier, T; Lecollinet, S; Selmi, S

    2017-10-01

    It has previously been suggested that southern Tunisian oases may be suitable areas for the circulation of flaviviruses. In order to anticipate and prevent possible epidemiological spread of flaviviruses in humans and domestic animals, the ecology of their transmission in the oasis system needs to be better understood. Thus, the aim of this study was to assess the seroprevalence of anti-flavivirus antibodies in the laughing dove (Spilopelia senegalensis), an abundant resident bird in Tunisian oases. Anti-flavivirus antibodies were detected in 17% of sampled doves. Ten per cent of the total tested doves were West Nile virus (WNV) seropositive and 4% were Usutu virus (USUV) seropositive, which provides the first evidence of USUV circulation in Tunisian birds. We also found that the occurrence probability of anti-flavivirus antibodies in dove plasma increased with decreasing distance to coast, suggesting that doves inhabiting coastal oases were more exposed to flaviviruses compared with those inhabiting inland oases. We also found significantly higher antibody occurrence probability in adult doves compared with young doves, which underlines the effect of exposure time. Overall, our results suggest that the laughing dove may be used for WNV and USUV surveillance in southern Tunisia. They also stress the need for investigations combining data on birds and mosquitoes to better understand the ecological factors governing the circulation of flaviviruses in this area.

  14. A review of West Nile and Usutu virus co-circulation in Europe: how much do transmission cycles overlap?

    Science.gov (United States)

    Nikolay, Birgit

    2015-10-01

    Due to the increasing global spread of arboviruses, the geographic extent of virus co-circulation is expanding. This complicates the diagnosis of febrile conditions and can have direct effects on the epidemiology. As previously demonstrated, subsequent infections by two closely related viruses, such as those belonging to the Japanese encephalitis virus (JEV) serocomplex, can lead to partial or complete cross-immunity, altering the risk of infections or the outcome of disease. Two flaviviruses that may interact at population level are West Nile virus (WNV) and Usutu virus (USUV). These pathogens have antigenic cross-reactivity and affect human and animal populations throughout Europe. This systematic review investigates the overlap of WNV and USUV transmission cycles, not only geographically but also in terms of host and vector ranges. Co-circulation of WNV and USUV was reported in 10 countries and the viruses were found to infect 34 common bird species belonging to 11 orders. Moreover, four mosquito species are potential vectors for both viruses. Taken together, these data suggest that WNV and USUV transmission overlaps substantially in Europe and highlight the importance of further studies investigating the interactions between the two viruses within host and vector populations. © The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. West Nile Virus Temperature Sensitivity and Avian Virulence Are Modulated by NS1-2B Polymorphisms.

    Science.gov (United States)

    Dietrich, Elizabeth A; Langevin, Stanley A; Huang, Claire Y-H; Maharaj, Payal D; Delorey, Mark J; Bowen, Richard A; Kinney, Richard M; Brault, Aaron C

    2016-08-01

    West Nile virus (WNV) replicates in a wide variety of avian species, which serve as reservoir and amplification hosts. WNV strains isolated in North America, such as the prototype strain NY99, elicit a highly pathogenic response in certain avian species, notably American crows (AMCRs; Corvus brachyrhynchos). In contrast, a closely related strain, KN3829, isolated in Kenya, exhibits a low viremic response with limited mortality in AMCRs. Previous work has associated the difference in pathogenicity primarily with a single amino acid mutation at position 249 in the helicase domain of the NS3 protein. The NY99 strain encodes a proline residue at this position, while KN3829 encodes a threonine. Introduction of an NS3-T249P mutation in the KN3829 genetic background significantly increased virulence and mortality; however, peak viremia and mortality were lower than those of NY99. In order to elucidate the viral genetic basis for phenotype variations exclusive of the NS3-249 polymorphism, chimeric NY99/KN3829 viruses were created. We show herein that differences in the NS1-2B region contribute to avian pathogenicity in a manner that is independent of and additive with the NS3-249 mutation. Additionally, NS1-2B residues were found to alter temperature sensitivity when grown in avian cells.

  16. Landscape epidemiology and machine learning: A geospatial approach to modeling West Nile virus risk in the United States

    Science.gov (United States)

    Young, Sean Gregory

    The complex interactions between human health and the physical landscape and environment have been recognized, if not fully understood, since the ancient Greeks. Landscape epidemiology, sometimes called spatial epidemiology, is a sub-discipline of medical geography that uses environmental conditions as explanatory variables in the study of disease or other health phenomena. This theory suggests that pathogenic organisms (whether germs or larger vector and host species) are subject to environmental conditions that can be observed on the landscape, and by identifying where such organisms are likely to exist, areas at greatest risk of the disease can be derived. Machine learning is a sub-discipline of artificial intelligence that can be used to create predictive models from large and complex datasets. West Nile virus (WNV) is a relatively new infectious disease in the United States, and has a fairly well-understood transmission cycle that is believed to be highly dependent on environmental conditions. This study takes a geospatial approach to the study of WNV risk, using both landscape epidemiology and machine learning techniques. A combination of remotely sensed and in situ variables are used to predict WNV incidence with a correlation coefficient as high as 0.86. A novel method of mitigating the small numbers problem is also tested and ultimately discarded. Finally a consistent spatial pattern of model errors is identified, indicating the chosen variables are capable of predicting WNV disease risk across most of the United States, but are inadequate in the northern Great Plains region of the US.

  17. Virus genome dynamics under different propagation pressures: reconstruction of whole genome haplotypes of West Nile viruses from NGS data.

    Science.gov (United States)

    Kortenhoeven, Cornell; Joubert, Fourie; Bastos, Armanda D S; Abolnik, Celia

    2015-02-22

    Extensive focus is placed on the comparative analyses of consensus genotypes in the study of West Nile virus (WNV) emergence. Few studies account for genetic change in the underlying WNV quasispecies population variants. These variants are not discernable in the consensus genome at the time of emergence, and the maintenance of mutation-selection equilibria of population variants is greatly underestimated. The emergence of lineage 1 WNV strains has been studied extensively, but recent epidemics caused by lineage 2 WNV strains in Hungary, Austria, Greece and Italy emphasizes the increasing importance of this lineage to public health. In this study we explored the quasispecies dynamics of minority variants that contribute to cell-tropism and host determination, i.e. the ability to infect different cell types or cells from different species from Next Generation Sequencing (NGS) data of a historic lineage 2 WNV strain. Minority variants contributing to host cell membrane association persist in the viral population without contributing to the genetic change in the consensus genome. Minority variants are shown to maintain a stable mutation-selection equilibrium under positive selection, particularly in the capsid gene region. This study is the first to infer positive selection and the persistence of WNV haplotype variants that contribute to viral fitness without accompanying genetic change in the consensus genotype, documented solely from NGS sequence data. The approach used in this study streamlines the experimental design seeking viral minority variants accurately from NGS data whilst minimizing the influence of associated sequence error.

  18. Preclinical and clinical development of a YFV 17 D-based chimeric vaccine against West Nile virus.

    Science.gov (United States)

    Dayan, Gustavo H; Pugachev, Konstantin; Bevilacqua, Joan; Lang, Jean; Monath, Thomas P

    2013-12-09

    Substantial success has been achieved in the development and implementation of West Nile (WN) vaccines for horses; however, no human WN vaccines are approved. This review focuses on the construction, pre-clinical and clinical characterization of ChimeriVax-WN02 for humans, a live chimeric vaccine composed of a yellow fever (YF) 17D virus in which the prM-E envelope protein genes are replaced with the corresponding genes of the WN NY99 virus. Pre-clinical studies demonstrated that ChimeriVax-WN02 was significantly less neurovirulent than YF 17D in mice and rhesus and cynomolgus monkeys. The vaccine elicited neutralizing antibody titers after inoculation in hamsters and monkeys and protected immunized animals from lethal challenge including intracerebral inoculation of high dose of WN NY99 virus. Safety, viremia and immunogenicity of ChimeriVax-WN02 were assessed in one phase I study and in two phase II clinical trials. No safety signals were detected in the three clinical trials with no remarkable differences in incidence of adverse events (AEs) between vaccine and placebo recipients. Viremia was transient and the mean viremia levels were low. The vaccine elicited strong and durable neutralizing antibody and cytotoxic T cell responses. WN epidemiology impedes a classical licensure pathway; therefore, innovative licensure strategies should be explored.

  19. Ecology of West Nile virus across four European countries: review of weather profiles, vector population dynamics and vector control response.

    Science.gov (United States)

    Chaskopoulou, Alexandra; L'Ambert, Gregory; Petric, Dusan; Bellini, Romeo; Zgomba, Marija; Groen, Thomas A; Marrama, Laurence; Bicout, Dominique J

    2016-09-02

    West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause unforeseen and large epidemics. Until 2004, only lineage 1 and 3 WNV strains had been found in Europe. Lineage 2 strains were initially isolated in 2004 (Hungary) and in 2008 (Austria) and for the first time caused a major WNV epidemic in 2010 in Greece with 262 clinical human cases and 35 fatalities. Since then, WNV lineage 2 outbreaks have been reported in several European countries including Italy, Serbia and Greece. Understanding the interaction of ecological factors that affect WNV transmission is crucial for preventing or decreasing the impact of future epidemics. The synchronous co-occurrence of competent mosquito vectors, virus, bird reservoir hosts, and susceptible humans is necessary for the initiation and propagation of an epidemic. Weather is the key abiotic factor influencing the life-cycles of the mosquito vector, the virus, the reservoir hosts and the interactions between them. The purpose of this paper is to review and compare mosquito population dynamics, and weather conditions, in three ecologically different contexts (urban/semi-urban, rural/agricultural, natural) across four European countries (Italy, France, Serbia, Greece) with a history of WNV outbreaks. Local control strategies will be described as well. Improving our understanding of WNV ecology is a prerequisite step for appraising and optimizing vector control strategies in Europe with the ultimate goal to minimize the probability of WNV infection.

  20. Valosin-containing protein (VCP/p97) plays a role in the replication of West Nile virus.

    Science.gov (United States)

    Phongphaew, Wallaya; Kobayashi, Shintaro; Sasaki, Michihito; Carr, Michael; Hall, William W; Orba, Yasuko; Sawa, Hirofumi

    2017-01-15

    Valosin-containing protein (VCP) is classified as a member of the type II AAA + ATPase protein family. VCP functions in several cellular processes, including protein degradation, membrane fusion, vesicular trafficking and disassembly of stress granules. Moreover, VCP is considered to play a role in the replication of several viruses, albeit through different mechanisms. In the present study, we have investigated the role of VCP in West Nile virus (WNV) infection. Endogenous VCP expression was inhibited using either VCP inhibitors or by siRNA knockdown. It could be shown that the inhibition of endogenous VCP expression significantly inhibited WNV infection. The entry assay revealed that silencing of endogenous VCP caused a significant reduction in the expression levels of WNV-RNA compared to control siRNA-treated cells. This indicates that VCP may play a role in early steps either the binding or entry steps of the WNV life cycle. Using WNV virus like particles and WNV-DNA-based replicon, it could be demonstrated that perturbation of VCP expression decreased levels of newly synthesized WNV genomic RNA. These findings suggest that VCP is involved in early steps and during genome replication of the WNV life cycle. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Fluid spatial dynamics of West Nile virus in the USA: Rapid spread in a permissive host environment

    Science.gov (United States)

    Di Giallonardo , Francesca; Geoghegan, Jemma L.; Docherty, Douglas E.; McLean, Robert G.; Zody, Michael C.; Qu, James; Yang, Xiao; Birren, Bruce W.; Malboeuf, Christine M.; Newman, R.; Ip, Hon S.; Holmes, Edward C.

    2016-01-01

    The introduction of West Nile virus (WNV) into North America in 1999 is a classical example of viral emergence in a new environment, with its subsequent dispersion across the continent having a major impact on local bird populations. Despite the importance of this epizootic, the pattern, dynamics and determinants of WNV spread in its natural hosts remain uncertain. In particular, it is unclear whether the virus encountered major barriers to transmission, or spread in an unconstrained manner, and if specific viral lineages were favored over others indicative of intrinsic differences in fitness. To address these key questions in WNV evolution and ecology we sequenced the complete genomes of approximately 300 avian isolates sampled across the USA between 2001-2012. Phylogenetic analysis revealed a relatively ‘star-like' tree structure, indicative of explosive viral spread in US, although with some replacement of viral genotypes through time. These data are striking in that viral sequences exhibit relatively limited clustering according to geographic region, particularly for those viruses sampled from birds, and no strong phylogenetic association with well sampled avian species. The genome sequence data analysed here also contain relatively little evidence for adaptive evolution, particularly on structural proteins, suggesting that most viral lineages are of similar fitness, and that WNV is well adapted to the ecology of mosquito vectors and diverse avian hosts in the USA. In sum, the molecular evolution of WNV in North America depicts a largely unfettered expansion within a permissive host and geographic population with little evidence of major adaptive barriers.

  2. [Detection of West Nile virus in human samples: follow-up studies during the 2015 seasonal period].

    Science.gov (United States)

    Nagy, Anna; Nagy, Orsolya; Bán, Enikő; Molnár, Eszter; Müller, Zsófia; Orbán, Márton; Kecskés, Borbála; Harsányi, Emese Henriett; Kővágó, Levente; Jobbágy, Lajos; Németh, Zoltán; Várnai, Zsuzsanna; Takács, Mária

    2017-05-01

    West Nile virus, a mosquito-borne viral zoonosis is responsible for human infections in Hungary. Laboratory diagnosis is based on serological tests, however the application of molecular methods has been appreciated. The aim of the study was to investigate blood, cerebrospinal-fluid and urine samples of acutely ill patients and to follow-up PCR positive cases to ascertain the length of virus excretion. Clinical specimens were examined by indirect-immunofluorescent, haemagglutination-inhibition, two PCR tests and Sanger-sequencing. Virus isolation in case of two patients was successful. A follow-up study could be carried out in case of 5 patients. Viral nucleic acid was detectable in urine even for several weeks after symptom onset and viral RNA was present at higher concentration compared with other samples. PCR analysis of urine could provide useful epidemiological and diagnostic information. Therefore, it is recommended to collect urine samples in order to supplement the serological diagnosis. Orv Hetil. 2017; 158(20): 791-796.

  3. Intrinsic flexibility of West Nile virus protease in solution characterized using small-angle X-ray scattering.

    Science.gov (United States)

    Garces, Andrea P; Watowich, Stanley J

    2013-10-01

    West Nile virus (WNV) is a mosquito-borne flavivirus with a rapidly expanding global distribution. Infection can cause severe neurological disease and fatality in humans. Efforts are ongoing to develop antiviral drugs that inhibit the WNV protease, a viral enzyme required for polyprotein processing. Unfortunately, little is known about the solution structure of recombinant WNV protease (NS2B-NS3pro) used for antiviral drug discovery and development, although X-ray crystal structures and nuclear magnetic resonance (NMR) studies have provided valuable insights into the interactions between NS2B-NS3pro and peptide-based inhibitors. We completed small-angle X-ray scattering and Fourier transform infrared spectroscopy experiments to determine the solution structure and dynamics of WNV NS2B-NS3pro in the absence of a bound substrate or inhibitor. Importantly, these solution studies suggested that all or most of the NS2B cofactor was highly flexible and formed an ensemble of structures, in contrast to the NS2B tertiary structures observed in crystallographic and NMR studies. The secondary structure of NS2B-NS3pro in solution had high β-content, similar to the secondary structure observed in crystallographic studies. This work provided evidence of the intrinsic flexibility and conformational heterogeneity of the NS2B chain of the WNV protease in the absence of substratelike ligands, which should be considered during antiviral drug discovery and development efforts.

  4. Exploring vector-borne infection ecology in multi-host communities: A case study of West Nile virus.

    Science.gov (United States)

    Marini, Giovanni; Rosá, Roberto; Pugliese, Andrea; Heesterbeek, Hans

    2017-02-21

    In this study, we develop a model to investigate how ecological factors might affect the dynamics of a vector-borne pathogen in a population composed by different hosts which interact with each other. Specifically, we consider the case when different host species compete with each other, as they share the same habitat, and the vector might have different feeding preference, which can also be time dependent. As a prototypical example, we apply our model to study the invasion and spread, during a typical season, of West Nile virus in an ecosystem composed of two competent avian host species and possibly of dead-end host species. We found that competition and vector feeding preferences can profoundly influence pathogen invasion, influencing its probability to start an epidemic, and influencing transmission rates. Finally, when considering time-dependent feeding preferences, as observed in the field, we noted that the virus circulation could be amplified and that the timing of epidemic peaks could be changed. Our work highlights that ecological interactions between hosts can have a profound influence on the dynamics of the pathogen and that, when modeling vector-borne infections, vector feeding behavior should, for this reason, be carefully evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. [Immunochip for differentiation of IgG to tick-borne encephalitis and West Nile fever viruses].

    Science.gov (United States)

    Pomelova, V G; Bychenkova, T A; Bekman, N I; Osin, N S

    2010-01-01

    To demonstrate the possibility of development of test based on phosphorescent analysis (PHOSPHAN) for simultaneous identification and differentiation of specific IgG to tick-borne encephalitis (TBE) and West Nile fever (WNF) viruses. Twenty six serum samples from patients with TBE, twenty five from WNF, and sixty six fromclinically healthy donors were used for the study. Immunologic analysis was performed in plate wells with active microzones "printed" on the wells' bottom and corresponding the complex of virus-specific antigens with immobilized monoclonal antibodies; internal control of specificity was included in each well. Species specificity of antibodies was determined on the basis of not less than 2-fold elevation of value of positivity coefficient (P/N) of sample studied with homologous antigen compared to heterologous one. PHOSPHAN provides simultaneous detection of IgG in human serum to two related flaviviruses: TBE and WNF viruses. Usage of P/N criterion assessed with homologous and heterologous antigen allowed correct determination of species specificity of antibodies in 90% of serum samples from patients with TBE and WNF CONCLUSION: PHOSPHAN allows to detect and differentiate IgG to TBE and WNF viruses during testing of one serum sample in one plate well without decrease of sensitivity compared to enzyme immunoassay with separated testing of samples on two viruses. This provides savings of biomaterial, which is an advantage compared to enzyme immunoassay.

  6. Experimental West Nile Virus Infection in Rabbits: An Alternative Model for Studying Induction of Disease and Virus Control

    Directory of Open Access Journals (Sweden)

    Willy W. Suen

    2015-07-01

    Full Text Available The economic impact of non-lethal human and equine West Nile virus (WNV disease is substantial, since it is the most common presentation of the infection. Experimental infection with virulent WNV strains in the mouse and hamster models frequently results in severe neural infection and moderate to high mortality, both of which are not representative features of most human and equine infections. We have established a rabbit model for investigating pathogenesis and immune response of non-lethal WNV infection. Two species of rabbits, New Zealand White (Oryctolagus cuniculus and North American cottontail (Sylvilagus sp., were experimentally infected with virulent WNV and Murray Valley encephalitis virus strains. Infected rabbits exhibited a consistently resistant phenotype, with evidence of low viremia, minimal-absent neural infection, mild-moderate neuropathology, and the lack of mortality, even though productive virus replication occurred in the draining lymph node. The kinetics of anti-WNV neutralizing antibody response was comparable to that commonly seen in infected horses and humans. This may be explained by the early IFNα/β and/or γ response evident in the draining popliteal lymph node. Given this similarity to the human and equine disease, immunocompetent rabbits are, therefore, a valuable animal model for investigating various aspects of non-lethal WNV infections.

  7. Experimental West Nile Virus Infection in Rabbits: An Alternative Model for Studying Induction of Disease and Virus Control

    Science.gov (United States)

    Suen, Willy W.; Uddin, Muhammad J.; Wang, Wenqi; Brown, Vienna; Adney, Danielle R.; Broad, Nicole; Prow, Natalie A.; Bowen, Richard A.; Hall, Roy A.; Bielefeldt-Ohmann, Helle

    2015-01-01

    The economic impact of non-lethal human and equine West Nile virus (WNV) disease is substantial, since it is the most common presentation of the infection. Experimental infection with virulent WNV strains in the mouse and hamster models frequently results in severe neural infection and moderate to high mortality, both of which are not representative features of most human and equine infections. We have established a rabbit model for investigating pathogenesis and immune response of non-lethal WNV infection. Two species of rabbits, New Zealand White (Oryctolagus cuniculus) and North American cottontail (Sylvilagus sp.), were experimentally infected with virulent WNV and Murray Valley encephalitis virus strains. Infected rabbits exhibited a consistently resistant phenotype, with evidence of low viremia, minimal-absent neural infection, mild-moderate neuropathology, and the lack of mortality, even though productive virus replication occurred in the draining lymph node. The kinetics of anti-WNV neutralizing antibody response was comparable to that commonly seen in infected horses and humans. This may be explained by the early IFNα/β and/or γ response evident in the draining popliteal lymph node. Given this similarity to the human and equine disease, immunocompetent rabbits are, therefore, a valuable animal model for investigating various aspects of non-lethal WNV infections. PMID:26184326

  8. Age-Dependent Cell Trafficking Defects in Draining Lymph Nodes Impair Adaptive Immunity and Control of West Nile Virus Infection.

    Directory of Open Access Journals (Sweden)

    Justin M Richner

    2015-07-01

    Full Text Available Impaired immune responses in the elderly lead to reduced vaccine efficacy and increased susceptibility to viral infections. Although several groups have documented age-dependent defects in adaptive immune priming, the deficits that occur prior to antigen encounter remain largely unexplored. Herein, we identify novel mechanisms for compromised adaptive immunity that occurs with aging in the context of infection with West Nile virus (WNV, an encephalitic flavivirus that preferentially causes disease in the elderly. An impaired IgM and IgG response and enhanced vulnerability to WNV infection during aging was linked to delayed germinal center formation in the draining lymph node (DLN. Adoptive transfer studies and two-photon intravital microscopy revealed a decreased trafficking capacity of donor naïve CD4+ T cells from old mice, which manifested as impaired T cell diapedesis at high endothelial venules and reduced cell motility within DLN prior to antigen encounter. Furthermore, leukocyte accumulation in the DLN within the first few days of WNV infection or antigen-adjuvant administration was diminished more generally in old mice and associated with a second aging-related defect in local cytokine and chemokine production. Thus, age-dependent cell-intrinsic and environmental defects in the DLN result in delayed immune cell recruitment and antigen recognition. These deficits compromise priming of early adaptive immune responses and likely contribute to the susceptibility of old animals to acute WNV infection.

  9. Serological evidence of widespread circulation of West Nile virus and other flaviviruses in equines of the Pantanal, Brazil.

    Directory of Open Access Journals (Sweden)

    Alex Pauvolid-Corrêa

    2014-02-01

    Full Text Available A recent study reported neutralizing antibodies to West Nile virus (WNV in horses from four ranches of southern Pantanal. To extend that study, a serosurvey for WNV and 11 Brazilian flaviviruses was conducted with 760 equines, 238 sheep and 61 caimans from 17 local cattle ranches. Among the tested equines, 32 were collected from a ranch where a neurologic disorder outbreak had been recently reported. The sera were initially screened by using a blocking ELISA and then titrated by 90% plaque-reduction neutralization test (PRNT90 for 12 flaviviruses. Employing the criterion of 4-fold greater titer, 78 (10.3% equines were seropositive for Ilheus virus, 59 (7.8% for Saint Louis encephalitis virus, 24 (3.2% for WNV, two (0.3% for Cacipacore virus and one (0.1% for Rocio virus. No serological evidence was found linking the neurological disease that affected local equines to WNV. All caimans and sheep were negative by blocking ELISA for flaviviruses. There were no seropositive equines for Bussuquara, Iguape, Yellow fever and all four Dengue virus serotypes. The detection of WNV-seropositive equines in ten ranches and ILHV and SLEV-seropositive equines in fourteen ranches of two different sub-regions of Pantanal is strong evidence of widespread circulation of these flaviviruses in the region.

  10. Emerging vector-borne diseases in dromedaries in Tunisia: West Nile, bluetongue, epizootic haemorrhagic disease and Rift Valley fever

    Directory of Open Access Journals (Sweden)

    Thameur B. Hassine

    2017-01-01

    Full Text Available A total of 118 sera were collected during 2016 from two groups of dromedaries from Kebili and Medenine governorates in the south of Tunisia. The aim of this study was to provide the first serological investigation of four emerging vector-borne diseases in two groups of dromedaries in Tunisia. Sera were tested by ELISA and serum neutralisation test to identify West Nile virus (WNV, bluetongue virus (BTV, epizootic haemorrhagic disease virus (EHDV and Rift Valley fever virus (RVFV. In the first group, the seroprevalence for BTV was 4.6%, while in the second group, it was 25.8% for WNV and 9.7% for BTV. Only serotype 1 was detected for BTV in the two groups. No evidence for circulation of RVF and EHD viruses was revealed. Results indicated that dromedaries can be infected with BTV and WNV, suggesting that this species might play a significant role in the epizootiology of these viral diseases in Tunisia and neighbouring countries.

  11. Multiplexed microsatellite loci in American crow (Corvus brachyrhynchos): a severely affected natural host of West Nile virus.

    Science.gov (United States)

    Verdugo, Claudio; Clark, Ann Marie; Prakoso, Dhani; Kramer, Laura D; Long, Maureen T

    2012-12-01

    Recent advances in high throughput molecular techniques have allowed the development of cost- and time-effective libraries of molecular markers, such as microsatellites, for population genetic studies in non-model species. The American crow, Corvus brachyrhynchos, is recognized to be one of the species that has been most negatively affected by the emergence of West Nile virus (WNV) in North America in 1999. Genetic monitoring of the process of a declining population after the introduction of an infectious disease can provide insights into the demographic and evolutionary impact of a pathogen in a natural host population over time. In this study, shotgun pyrosequencing and validation of previously published cross-species markers were the approaches used to identify and develop a set of 32 polymorphic loci for the C. brachyrhynchos. Since the American crow is morphologically similar to the sympatric species Fish crow (Corvus ossifragus), we also designed a real-time PCR protocol to rapidly differentiate these two species using a set of primers and probes that can discriminate a section of the COI gene at the mitochondrial DNA. These new markers together with a faster method for species verification will allow further detailed studies to characterize and compare genetic diversity of historic and contemporary C. brachyrhynchos populations. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Serological evidence of widespread circulation of West Nile virus and other flaviviruses in equines of the Pantanal, Brazil.

    Science.gov (United States)

    Pauvolid-Corrêa, Alex; Campos, Zilca; Juliano, Raquel; Velez, Jason; Nogueira, Rita Maria Ribeiro; Komar, Nicholas

    2014-02-01

    A recent study reported neutralizing antibodies to West Nile virus (WNV) in horses from four ranches of southern Pantanal. To extend that study, a serosurvey for WNV and 11 Brazilian flaviviruses was conducted with 760 equines, 238 sheep and 61 caimans from 17 local cattle ranches. Among the tested equines, 32 were collected from a ranch where a neurologic disorder outbreak had been recently reported. The sera were initially screened by using a blocking ELISA and then titrated by 90% plaque-reduction neutralization test (PRNT90) for 12 flaviviruses. Employing the criterion of 4-fold greater titer, 78 (10.3%) equines were seropositive for Ilheus virus, 59 (7.8%) for Saint Louis encephalitis virus, 24 (3.2%) for WNV, two (0.3%) for Cacipacore virus and one (0.1%) for Rocio virus. No serological evidence was found linking the neurological disease that affected local equines to WNV. All caimans and sheep were negative by blocking ELISA for flaviviruses. There were no seropositive equines for Bussuquara, Iguape, Yellow fever and all four Dengue virus serotypes. The detection of WNV-seropositive equines in ten ranches and ILHV and SLEV-seropositive equines in fourteen ranches of two different sub-regions of Pantanal is strong evidence of widespread circulation of these flaviviruses in the region.

  13. A perspective on targeting non-structural proteins to combat neglected tropical diseases: Dengue, West Nile and Chikungunya viruses.

    Science.gov (United States)

    Bhakat, Soumendranath; Karubiu, Wilson; Jayaprakash, Venkatesan; Soliman, Mahmoud E S

    2014-11-24

    Neglected tropical diseases are major causes of fatality in poverty stricken regions across Africa, Asia and some part of America. The combined potential health risk associated with arthropod-borne viruses (arboviruses); Dengue virus (DENV), West Nile Virus (WNV) and Chikungunya Virus (CHIKV) is immense. These arboviruses are either emerging or re-emerging in many regions with recent documented outbreaks in the United States. Despite several recent evidences of emergence, currently there are no approved drugs or vaccines available to counter these diseases. Non-structural proteins encoded by these RNA viruses are essential for their replication and maturation and thus may offer ideal targets for developing antiviral drugs. In recent years, several protease inhibitors have been sourced from plant extract, synthesis, computer aided drug design and high throughput screening as well as through drug reposition based approaches to target the non-structural proteins. The protease inhibitors have shown different levels of inhibition and may thus provide template to develop selective and potent drugs against these devastating arboviruses. This review seeks to shed light on the design and development of antiviral drugs against DENV, WNV and CHIKV to date. To the best of our knowledge, this review provides the first comprehensive update on the development of protease inhibitors targeting non-structural proteins of three most devastating arboviruses, DENV, WNV and CHIKV. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  14. Host competence and helicase activity differences exhibited by West Nile viral variants expressing NS3-249 amino acid polymorphisms.

    Directory of Open Access Journals (Sweden)

    Stanley A Langevin

    Full Text Available A single helicase amino acid substitution, NS3-T249P, has been shown to increase viremia magnitude/mortality in American crows (AMCRs following West Nile virus (WNV infection. Lineage/intra-lineage geographic variants exhibit consistent amino acid polymorphisms at this locus; however, the majority of WNV isolates associated with recent outbreaks reported worldwide have a proline at the NS3-249 residue. In order to evaluate the impact of NS3-249 variants on avian and mammalian virulence, multiple amino acid substitutions were engineered into a WNV infectious cDNA (NY99; NS3-249P and the resulting viruses inoculated into AMCRs, house sparrows (HOSPs and mice. Differential viremia profiles were observed between mutant viruses in the two bird species; however, the NS3-249P virus produced the highest mean peak viral loads in both avian models. In contrast, this avian modulating virulence determinant had no effect on LD50 or the neurovirulence phenotype in the murine model. Recombinant helicase proteins demonstrated variable helicase and ATPase activities; however, differences did not correlate with avian or murine viremia phenotypes. These in vitro and in vivo data indicate that avian-specific phenotypes are modulated by critical viral-host protein interactions involving the NS3-249 residue that directly influence transmission efficiency and therefore the magnitude of WNV epizootics in nature.

  15. Integrated seismic tools to delineate Pliocene gas-charged geobody, offshore west Nile delta, Egypt

    Science.gov (United States)

    Othman, Adel A. A.; Bakr, Ali; Maher, Ali

    2017-06-01

    Nile delta province is rapidly emerging as a major gas province; commercial gas accumulations have been proved in shallow Pliocene channels of El-Wastani Formation. Solar gas discovery is one of the Turbidities Slope channels within the shallow Pliocene level that was proved by Solar-1 well. The main challenge of seismic reservoir characterization is to discriminate between Gas sand, Water sand and Shale, and extracting the gas-charged geobody from the seismic data. A detailed study for channel connectivity and lithological discrimination was established to delineate the gas charged geobody. Seismic data, being non-stationary in nature, have varying frequency content in time. Spectral decomposition of a seismic signal aims to characterize the time-dependent frequency response of subsurface rocks and reservoirs for imaging and mapping of bed thickness and geologic discontinuities. Spectral decomposition unravels the seismic signal into its constituent frequencies. A crossplot between P-wave Impedance (Ip) and S-wave Impedance (Is) derived from well logs (P-wave velocity, S-wave velocity and density) can be used to discriminate between gas-bearing sand, water-bearing sand, and shale. From Ip vs. Is crossplot, clear separation occurs in the P-impedance so post stack inversion is enough to be applied. Integration between Inversion results and Ip vs. Is crossplot cutoffs help to generate 3D lithofacies cubes, which is used to extract facies geobodies.

  16. A Therapeutic Antibody against West Nile Virus Neutralizes Infection by Blocking Fusion within Endosomes

    NARCIS (Netherlands)

    Thompson, Bruce S.; Moesker, Bastiaan; Smit, Jolanda M.; Wilschut, Jan; Diamond, Michael S.; Fremont, Daved H.

    Defining the precise cellular mechanisms of neutralization by potently inhibitory antibodies is important for understanding how the immune system successfully limits viral infections. We recently described a potently inhibitory monoclonal antibody (MAb E16) against the envelope (E) protein of West

  17. West nile virus-induced activation of mammalian target of rapamycin complex 1 supports viral growth and viral protein expression.

    Science.gov (United States)

    Shives, Katherine D; Beatman, Erica L; Chamanian, Mastooreh; O'Brien, Caitlin; Hobson-Peters, Jody; Beckham, J David

    2014-08-01

    Since its introduction in New York City, NY, in 1999, West Nile virus (WNV) has spread to all 48 contiguous states of the United States and is now the leading cause of epidemic encephalitis in North America. As a member of the family Flaviviridae, WNV is part of a group of clinically important human pathogens, including dengue virus and Japanese encephalitis virus. The members of this family of positive-sense, single-stranded RNA viruses have limited coding capacity and are therefore obligated to co-opt a significant amount of cellular factors to translate their genomes effectively. Our previous work has shown that WNV growth was independent of macroautophagy activation, but the role of the evolutionarily conserved mammalian target of rapamycin (mTOR) pathway during WNV infection was not well understood. mTOR is a serine/threonine kinase that acts as a central cellular censor of nutrient status and exercises control of vital anabolic and catabolic cellular responses such as protein synthesis and autophagy, respectively. We now show that WNV activates mTOR and cognate downstream activators of cap-dependent protein synthesis at early time points postinfection and that pharmacologic inhibition of mTOR (KU0063794) significantly reduced WNV growth. We used an inducible Raptor and Rictor knockout mouse embryonic fibroblast (MEF) system to further define the role of mTOR complexes 1 and 2 in WNV growth and viral protein synthesis. Following inducible genetic knockout of the major mTOR cofactors raptor (TOR complex 1 [TORC1]) and rictor (TORC2), we now show that TORC1 supports flavivirus protein synthesis via cap-dependent protein synthesis pathways and supports subsequent WNV growth. Since its introduction in New York City, NY, in 1999, West Nile virus (WNV) has spread to all 48 contiguous states in the United States and is now the leading cause of epidemic encephalitis in North America. Currently, the mechanism by which flaviviruses such as WNV translate their genomes in

  18. The native Wolbachia endosymbionts of Drosophila melanogaster and Culex quinquefasciatus increase host resistance to West Nile virus infection.

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    Robert L Glaser

    2010-08-01

    Full Text Available The bacterial endosymbiont Wolbachia pipientis has been shown to increase host resistance to viral infection in native Drosophila hosts and in the normally Wolbachia-free heterologous host Aedes aegypti when infected by Wolbachia from Drosophila melanogaster or Aedes albopictus. Wolbachia infection has not yet been demonstrated to increase viral resistance in a native Wolbachia-mosquito host system.In this study, we investigated Wolbachia-induced resistance to West Nile virus (WNV; Flaviviridae by measuring infection susceptibility in Wolbachia-infected and Wolbachia-free D. melanogaster and Culex quinquefasciatus, a natural mosquito vector of WNV. Wolbachia infection of D. melanogaster induces strong resistance to WNV infection. Wolbachia-infected flies had a 500-fold higher ID50 for WNV and produced 100,000-fold lower virus titers compared to flies lacking Wolbachia. The resistance phenotype was transmitted as a maternal, cytoplasmic factor and was fully reverted in flies cured of Wolbachia. Wolbachia infection had much less effect on the susceptibility of D. melanogaster to Chikungunya (Togaviridae and La Crosse (Bunyaviridae viruses. Wolbachia also induces resistance to WNV infection in Cx. quinquefasciatus. While Wolbachia had no effect on the overall rate of peroral infection by WNV, Wolbachia-infected mosquitoes produced lower virus titers and had 2 to 3-fold lower rates of virus transmission compared to mosquitoes lacking Wolbachia.This is the first demonstration that Wolbachia can increase resistance to arbovirus infection resulting in decreased virus transmission in a native Wolbachia-mosquito system. The results suggest that Wolbachia reduces vector competence in Cx. quinquefasciatus, and potentially in other Wolbachia-infected mosquito vectors.

  19. West Nile Virus transmission in winter: the 2013 Great Salt Lake Bald Eagle and Eared Grebes Mortality event

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    Ip, Hon S.; Van Wettere, Arnaud J.; McFarlan, Leslie; Shearn-Bochsler, Valerie I.; Dickson, Sammie L.; Baker, JoDee; Hatch, Gary; Cavender, Kimberly; Long, Renee Romaine; Bodenstein, Barbara L.

    2014-01-01

    West Nile Virus (WNV) infection has been reported in over 300 species of birds and mammals. Raptors such as eagles, hawks and falcons are remarkably susceptible, but reports of WNV infection in Bald Eagles (Haliaeetus leucocephalus) are rare and reports of WNV infection in grebes (Podicipediformes) even rarer. We report an unusually large wild bird mortality event involving between 15,000-20,000 Eared Grebes (Podiceps nigricollis) and over 40 Bald Eagles around the Great Salt Lake, Utah, in November-December 2013. Mortality in grebes was first reported in early November during a period when the area was unseasonably warm and the grebes were beginning to gather and stage prior to migration. Ten out of ten Eared Grebes collected during this period were WNV RT-PCR and/or isolation positive. This is the first report of WNV infection in Eared Grebes and the associated mortality event is matched in scale only by the combined outbreaks in American White Pelican (Pelecanus erythrorhynchos) colonies in the north central states in 2002-2003. We cannot be sure that all of the grebes were infected by mosquito transmission; some may have become infected through contact with WNV shed orally or cloacally from other infected grebes. Beginning in early December, Bald Eagles in the Great Salt Lake area were observed to display neurological signs such as body tremors, limb paralysis and lethargy. At least 43 Bald Eagles had died by the end of the month. Nine of nine Bald Eagles examined were infected with WNV. To the best of our knowledge, this is the largest single raptor mortality event since WNV became endemic in the USA. Because the majority of the eagles affected were found after onset of below-freezing temperatures, we suggest at least some of the Bald Eagles were infected with WNV via consumption of infected Eared Grebes or horizontal transmission at roost sites.

  20. Efficacy of wildlife rehabilitation centers in surveillance and monitoring of pathogen activity: a case study with West Nile virus.

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    Randall, Natalie J; Blitvich, Bradley J; Blanchong, Julie A

    2012-07-01

    Surveillance is critical for identifying and monitoring pathogen activity in wildlife populations, but often is cost- and time-prohibitive and logistically challenging. We tested the hypothesis that wildlife rehabilitation centers are useful for monitoring pathogen activity using West Nile virus (WNV) as a case study. We hypothesized that birds submitted to wildlife rehabilitation centers would have a similar prevalence of antibody to WNV as free-ranging birds. From 2008 to 2010, we collected sera from peridomestic birds submitted to the Wildlife Care Clinic (WCC), a wildlife rehabilitation center in central Iowa, and tested them for antibodies to WNV. We also collected and tested sera from free-ranging peridomestic birds in the area from which approximately 50% of WCC submissions historically originated. Prevalences of WNV antibodies in free-ranging birds and in peridomestic WCC birds were 2.3% (44/1,936) and 2.8% (2/72), respectively. However, none of the birds submitted to the WCC from the area where we captured free-ranging birds had antibodies (0/29). Our results indicate that rehabilitation facilities are not likely to be useful for monitoring WNV activity at small spatial scales or over short-time periods due to the low endemic prevalence of WNV, and low and variable submission rates. However, at larger spatial scales (ca. nine Iowa counties) WNV antibody prevalence in peridomestic birds submitted to the WCC was similar to that of free-ranging birds. Although limitations to using rehabilitation birds to monitor WNV must be considered, testing these birds could be useful for monitoring WNV activity regionally, especially with many states limiting surveillance due to budgetary constraints.

  1. Systematic analysis of viral genes responsible for differential virulence between American and Australian West Nile virus strains.

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    Setoh, Yin Xiang; Prow, Natalie A; Rawle, Daniel J; Tan, Cindy Si En; Edmonds, Judith H; Hall, Roy A; Khromykh, Alexander A

    2015-06-01

    A variant Australian West Nile virus (WNV) strain, WNVNSW2011, emerged in 2011 causing an unprecedented outbreak of encephalitis in horses in south-eastern Australia. However, no human cases associated with this strain have yet been reported. Studies using mouse models for WNV pathogenesis showed that WNVNSW2011 was less virulent than the human-pathogenic American strain of WNV, New York 99 (WNVNY99). To identify viral genes and mutations responsible for the difference in virulence between WNVNSW2011 and WNVNY99 strains, we constructed chimeric viruses with substitution of large genomic regions coding for the structural genes, non-structural genes and untranslated regions, as well as seven individual non-structural gene chimeras, using a modified circular polymerase extension cloning method. Our results showed that the complete non-structural region of WNVNSW2011, when substituted with that of WNVNY99, significantly enhanced viral replication and the ability to suppress type I IFN response in cells, resulting in higher virulence in mice. Analysis of the individual non-structural gene chimeras showed a predominant contribution of WNVNY99 NS3 to increased virus replication and evasion of IFN response in cells, and to virulence in mice. Other WNVNY99 non-structural proteins (NS2A, NS4B and NS5) were shown to contribute to the modulation of IFN response. Thus a combination of non-structural proteins, likely NS2A, NS3, NS4B and NS5, is primarily responsible for the difference in virulence between WNVNSW2011 and WNVNY99 strains, and accumulative mutations within these proteins would likely be required for the Australian WNVNSW2011 strain to become significantly more virulent. © 2015 The Authors.

  2. A temporal role of type I interferon signaling in CD8+ T cell maturation during acute West Nile virus infection.

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    Amelia K Pinto

    2011-12-01

    Full Text Available A genetic absence of the common IFN-α/β signaling receptor (IFNAR in mice is associated with enhanced viral replication and altered adaptive immune responses. However, analysis of IFNAR(-/- mice is limited for studying the functions of type I IFN at discrete stages of viral infection. To define the temporal functions of type I IFN signaling in the context of infection by West Nile virus (WNV, we treated mice with MAR1-5A3, a neutralizing, non cell-depleting anti-IFNAR antibody. Inhibition of type I IFN signaling at or before day 2 after infection was associated with markedly enhanced viral burden, whereas treatment at day 4 had substantially less effect on WNV dissemination. While antibody treatment prior to infection resulted in massive expansion of virus-specific CD8(+ T cells, blockade of type I IFN signaling starting at day 4 induced dysfunctional CD8(+ T cells with depressed cytokine responses and expression of phenotypic markers suggesting exhaustion. Thus, only the later maturation phase of anti-WNV CD8(+ T cell development requires type I IFN signaling. WNV infection experiments in BATF3(-/- mice, which lack CD8-α dendritic cells and have impaired priming due to inefficient antigen cross-presentation, revealed a similar effect of blocking IFN signaling on CD8(+ T cell maturation. Collectively, our results suggest that cell non-autonomous type I IFN signaling shapes maturation of antiviral CD8(+ T cell response at a stage distinct from the initial priming event.

  3. A Snapshot Avian Surveillance Reveals West Nile Virus and Evidence of Wild Birds Participating in Toscana Virus Circulation.

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    Hacioglu, Sabri; Dincer, Ender; Isler, Cafer Tayer; Karapinar, Zeynep; Ataseven, Veysel Soydal; Ozkul, Aykut; Ergunay, Koray

    2017-10-01

    Birds are involved in the epidemiology of several vector-borne viruses, as amplification hosts for viruses, dissemination vehicles for the vectors, and sources of emerging strains in cross-species transmission. Turkey provides diverse habitats for a variety of wild birds and is located along major bird migration routes. This study was undertaken to provide a cross-sectional screening of avian specimens for a spectrum of vector-borne viruses. The specimens were collected in Hatay province, in the Mediterranean coast of the Anatolian peninsula, located in the convergence zone of the known migration routes. Generic PCR assays were used for the detection of members of Nairovirus, Flavivirus, and Phlebovirus genera of Flaviviridae and Bunyaviridae families. The circulating viruses were characterized via sequencing and selected specimens were inoculated onto Vero cell lines for virus isolation. Specimens from 72 wild birds belonging in 8 orders and 14 species were collected. A total of 158 specimens that comprise 32 sera (20.3%) from 7 species and 126 tissues (79.7%) from 14 species were screened. Eight specimens (8/158, 5%), obtained from 4 individuals (4/72, 5.5%), were positive. West Nile virus (WNV) lineage 1 sequences were characterized in the spleen, heart, and kidney tissues from a lesser spotted eagle (Clanga pomarina), which distinctly clustered from sequences previously identified in Turkey. Toscana virus (TOSV) genotype A and B sequences were identified in brain and kidney tissues from a greater flamingo (Phoenicopterus roseus), a great white pelican (Pelecanus onocrotalus), and a black stork (Ciconia nigra), without successful virus isolation. Partial amino acid sequences of the viral nucleocapsid protein revealed previously unreported substitutions. This study documents the involvement of avians in WNV dispersion in Anatolia as well in TOSV life cycle.

  4. Ecology of potential West Nile virus vectors in southeastern Louisiana: enzootic transmission in the relative absence of Culex quinquefasciatus

    Science.gov (United States)

    Godsey, Marvin S.; King, Raymond J.; Burkhalter, Kristen; Delorey, Mark; Colton, Leah; Charnetzky, Dawn; Sutherland, Genevieve; Ezenwa, Vanessa O.; Wilson, Lawrence A.; Coffey, Michelle; Milheim, Lesley E.; Taylor, Viki G.; Palmisano, Charles; Wesson, Dawn M.; Guptill, Stephen C.

    2013-01-01

    A study of West Nile virus (WNV) ecology was conducted in St. Tammany Parish, Louisiana, from 2002 to 2004. Mosquitoes were collected weekly throughout the year using Centers for Disease Control and Prevention (CDC) light traps placed at 1.5 and 6 m above the ground and gravid traps. A total of 379,466 mosquitoes was collected. WNV was identified in 32 pools of mosquitoes comprising four species; 23 positive pools were from Culex nigripalpus collected during 2003. Significantly more positive pools were obtained from Cx. nigripalpus collected in traps placed at 6 m than 1.5 m that year, but abundance did not differ by trap height. In contrast, Cx. nigripalpus abundance was significantly greater in traps placed at 6 m in 2002 and 2004. Annual temporal variation in Cx. nigripalpus peak seasonal abundance has important implications for WNV transmission in Louisiana. One WNV-positive pool, from Cx. erraticus, was collected during the winter of 2004, showing year-round transmission. The potential roles of additional mosquito species in WNV transmission in southeastern Louisiana are discussed. Disclaimer: The opinions expressed in this article are the opinions of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. This article has been peer reviewed and approved for publication consistent with U.S. Geological Survey Fundamental Science Practices (http//pubs.usgs.gov/circ/1367/). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  5. A Single Amino Acid Substitution in the Core Protein of West Nile Virus Increases Resistance to Acidotropic Compounds

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    Martín-Acebes, Miguel A.; Blázquez, Ana-Belén; de Oya, Nereida Jiménez; Escribano-Romero, Estela; Shi, Pei-Yong; Saiz, Juan-Carlos

    2013-01-01

    West Nile virus (WNV) is a worldwide distributed mosquito-borne flavivirus that naturally cycles between birds and mosquitoes, although it can infect multiple vertebrate hosts including horses and humans. This virus is responsible for recurrent epidemics of febrile illness and encephalitis, and has recently become a global concern. WNV requires to transit through intracellular acidic compartments at two different steps to complete its infectious cycle. These include fusion between the viral envelope and the membrane of endosomes during viral entry, and virus maturation in the trans-Golgi network. In this study, we followed a genetic approach to study the connections between viral components and acidic pH. A WNV mutant with increased resistance to the acidotropic compound NH4Cl, which blocks organelle acidification and inhibits WNV infection, was selected. Nucleotide sequencing revealed that this mutant displayed a single amino acid substitution (Lys 3 to Glu) on the highly basic internal capsid or core (C) protein. The functional role of this replacement was confirmed by its introduction into a WNV infectious clone. This single amino acid substitution also increased resistance to other acidification inhibitor (concanamycin A) and induced a reduction of the neurovirulence in mice. Interestingly, a naturally occurring accompanying mutation found on prM protein abolished the resistant phenotype, supporting the idea of a genetic crosstalk between the internal C protein and the external glycoproteins of the virion. The findings here reported unveil a non-previously assessed connection between the C viral protein and the acidic pH necessary for entry and proper exit of flaviviruses. PMID:23874963

  6. An examination of the effect of aerosolized Permanone insecticide on zebra finch susceptibility to West Nile virus.

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    Jankowski, Mark D; Moore, Murray E; Hofmeister, Erik K

    2017-12-01

    West Nile virus (WNV) is maintained cryptically primarily in avian (passerine) populations, where it is transmitted by Culex spp. mosquitoes. Mosquito-control measures currently include physical activities to reduce mosquito-breeding sites and the application of mosquito larvicides or aerosolized insecticides to kill adults (adulticides) when arboviral diseases such as WNV or Zika virus are detected in mosquito populations. Organochlorine, organophosphorus, carbamate, and pyrethroid insecticides are often used. Previous work suggests an effect of pyrethroids on the immune system in a variety of vertebrates. We examined the effects of exposure to aerosolized Permanone® 30:30 insecticide (permethrin and piperonyl butoxide in soy oil vehicle) at approximately 10 3 to 10 6 times potential environmental concentrations on the response of captive zebra finches (Taeniopygia guttata) to experimental challenge with WNV. Compared to vehicle control birds, WNV outcome was unchanged (65% of birds produced a viremia) in the "low" exposure (9.52 ± 3.13 mg/m 3 standard deviation [SD] permethrin) group but reduced in the "high" exposure (mean 376.5 ± 27.9 mg/m 3 SD permethrin) group (30% were viremic; p < 0.05). After clearing WNV infection, birds treated with Permanone regained less body mass than vehicle-treated birds (p < 0.001). The present study suggests that exposure to aerosolized Permanone insecticide at levels exceeding typical application rates has the potential to not change or to mildly enhance a bird's resistance to WNV. Environ Toxicol Chem 2017;36:3376-3386. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  7. Phrenic nerve deficits and neurological immunopathology associated with acute West Nile virus infection in mice and hamsters.

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    Zukor, Katherine; Wang, Hong; Hurst, Brett L; Siddharthan, Venkatraman; Van Wettere, Arnaud; Pilowsky, Paul M; Morrey, John D

    2017-04-01

    Neurological respiratory deficits are serious outcomes of West Nile virus (WNV) disease. WNV patients requiring intubation have a poor prognosis. We previously reported that WNV-infected rodents also appear to have respiratory deficits when assessed by whole-body plethysmography and diaphragmatic electromyography. The purpose of this study was to determine if the nature of the respiratory deficits in WNV-infected rodents is neurological and if deficits are due to a disorder of brainstem respiratory centers, cervical spinal cord (CSC) phrenic motor neuron (PMN) circuitry, or both. We recorded phrenic nerve (PN) activity and found that in WNV-infected mice, PN amplitude is reduced, corroborating a neurological basis for respiratory deficits. These results were associated with a reduction in CSC motor neuron number. We found no dramatic deficits, however, in brainstem-mediated breathing rhythm generation or responses to hypercapnia. PN frequency and pattern parameters were normal, and all PN parameters changed appropriately upon a CO 2 challenge. Histological analysis revealed generalized microglia activation, astrocyte reactivity, T cell and neutrophil infiltration, and mild histopathologic lesions in both the brainstem and CSC, but none of these were tightly correlated with PN function. Similar results in PN activity, brainstem function, motor neuron number, and histopathology were seen in WNV-infected hamsters, except that histopathologic lesions were more severe. Taken together, the results suggest that respiratory deficits in acute WNV infection are primarily due to a lower motor neuron disorder affecting PMNs and the PN rather than a brainstem disorder. Future efforts should focus on markers of neuronal dysfunction, axonal degeneration, and myelination.

  8. Ecological Forecasting of West Nile Virus Outbreaks in a High-Risk Area of the North-Central United States

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    Wimberly, M. C.; Merkord, C. L.; Kightlinger, L.; Vincent, G.; Hildreth, M. B.

    2015-12-01

    West Nile virus (WNV) is the most widespread and important mosquito-borne pathogen in North America. Since its emergence in the western hemisphere in 1999, human WNV disease has continued to exhibit recurrent outbreaks. Perplexingly, the incidence of this tropical disease has been highest in the cold-temperate climates of the Northern Great Plains (NGP). The spatial and temporal distributions of the vector mosquitoes and bird hosts, and consequently the risk of disease in humans, are strongly influenced by temperature, precipitation, vegetation, soils, and land use. We have utilized satellite remote sensing to map these environmental factors through time and develop models of disease risk. Outbreak years in South Dakota were preceded by warm winters, and WNV cases were most likely to occur during the hottest weeks of summer. Hot spots of persistent WNV transmission within the state were associated with rural land cover as well as patterns of physiography and climate. These models are currently being integrated into the South Dakota Mosquito Early Warning system (SDMIS), an automated WNV outbreak detection system that integrates remotely-sensed environmental indicators with vector abundance and infection data from a statewide mosquito surveillance network. The major goal of this effort is to leverage global environmental monitoring datasets to provide up-to-date, locally relevant information that can improve the effectiveness of mosquito control and disease prevention activities. This system was implemented for the first time during the summer of 2015. We will review the outcomes of this implementation, including the underlying influences of temperature on WNV risk, a preliminary statewide WNV risk map, and dynamic risk predictions made during the 2015 WNV season. Lessons learned as well as plans for future years will be discussed.

  9. Modeled response of the West Nile virus vector Culex quinquefasciatus to changing climate using the dynamic mosquito simulation model

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    Morin, Cory W.; Comrie, Andrew C.

    2010-09-01

    Climate can strongly influence the population dynamics of disease vectors and is consequently a key component of disease ecology. Future climate change and variability may alter the location and seasonality of many disease vectors, possibly increasing the risk of disease transmission to humans. The mosquito species Culex quinquefasciatus is a concern across the southern United States because of its role as a West Nile virus vector and its affinity for urban environments. Using established relationships between atmospheric variables (temperature and precipitation) and mosquito development, we have created the Dynamic Mosquito Simulation Model (DyMSiM) to simulate Cx. quinquefasciatus population dynamics. The model is driven with climate data and validated against mosquito count data from Pasco County, Florida and Coachella Valley, California. Using 1-week and 2-week filters, mosquito trap data are reproduced well by the model ( P < 0.0001). Dry environments in southern California produce different mosquito population trends than moist locations in Florida. Florida and California mosquito populations are generally temperature-limited in winter. In California, locations are water-limited through much of the year. Using future climate projection data generated by the National Center for Atmospheric Research CCSM3 general circulation model, we applied temperature and precipitation offsets to the climate data at each location to evaluate mosquito population sensitivity to possible future climate conditions. We found that temperature and precipitation shifts act interdependently to cause remarkable changes in modeled mosquito population dynamics. Impacts include a summer population decline from drying in California due to loss of immature mosquito habitats, and in Florida a decrease in late-season mosquito populations due to drier late summer conditions.

  10. Ecological niche of the 2003 west nile virus epidemic in the northern great plains of the United States.

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    Michael C Wimberly

    Full Text Available BACKGROUND: The incidence of West Nile virus (WNv has remained high in the northern Great Plains compared to the rest of the United States. However, the reasons for the sustained high risk of WNv transmission in this region have not been determined. To assess the environmental drivers of WNv in the northern Great Plains, we analyzed the county-level spatial pattern of human cases during the 2003 epidemic across a seven-state region. METHODOLOGY/PRINCIPAL FINDINGS: County-level data on WNv cases were examined using spatial cluster analysis, and were used to fit statistical models with weather, climate, and land use variables as predictors. In 2003 there was a single large cluster of elevated WNv risk encompassing North Dakota, South Dakota, and Nebraska along with portions of eastern Montana and Wyoming. The relative risk of WNv remained high within the boundaries of this cluster from 2004-2007. WNv incidence during the 2003 epidemic was found to have a stronger relationship with long-term climate patterns than with annual weather in either 2002 or 2003. WNv incidence increased with mean May-July temperature and had a unimodal relationship with total May-July precipitation. WNv incidence also increased with the percentage of irrigated cropland and with the percentage of the human population living in rural areas. CONCLUSIONS/SIGNIFICANCE: The spatial pattern of WNv cases during the 2003 epidemic in the northern Great Plains was associated with both climatic gradients and land use patterns. These results were interpreted as evidence that environmental conditions across much of the northern Great Plains create a favorable ecological niche for Culex tarsalis, a particularly efficient vector of WNv. Further research is needed to determine the proximal causes of sustained WNv transmission and to enhance strategies for disease prevention.

  11. West Nile virus in Ontario, Canada: A twelve-year analysis of human case prevalence, mosquito surveillance, and climate data.

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    Bryan V Giordano

    Full Text Available West Nile Virus (WNV first arrived in Ontario, Canada in 2001 and has since spread throughout most of the province, causing disease in humans. The provincial government established a province-wide surveillance program to monitor WNV transmission throughout the 36 regional health units. Here we have acquired records of WNV human and mosquito surveillance from 2002 to 2013 to describe seasonal and geographic trends in WNV activity in southern Ontario. Additionally, we obtained climate data from seven municipalities to investigate how temperature and precipitation affect WNV transmission dynamics. We identified a strong quadratic relationship between the number of confirmed human cases and positive Culex mosquito pools recorded at the end of each year (R2 = 0.9783, p < 0.001. Using Spearman rank correlation tests, we identified that the minimum infection rate of Culex pipiens/restuans pools are the strongest predictor of human cases at a 1 week lag period. We also identified positive correlations between minimum infection rates, temperature, vector abundance, and cumulative precipitation. Global Moran's I index indicates strong positive autocorrelation and clustering of positive Culex pool counts in southern Ontario. Local indicators of spatial association tests revealed a total of 44 high-high and 1 high-low trap locations (n = 680. In the current work we have identified when and where hot spots of WNV activity have occurred in southern Ontario. The municipalities surrounding the western shore of the Lake Ontario and Windsor-Essex County have the largest records of positive mosquitoes and human cases. We identified that positive mosquitoes are a strong indicator of human cases to follow in the coming weeks. An epidemic action threshold of cumulative positive Culex pools was established, allowing Ontario public health officials to predict an epidemic at epidemiological week 34 (rho = 0.90, p < 0.001. These data have the potential to contribute to

  12. Immunogenicity of a West Nile Virus DIII-Cholera Toxin A2/B Chimera after Intranasal Delivery

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    Juliette K. Tinker

    2014-04-01

    Full Text Available West Nile virus (WNV causes potentially fatal neuroinvasive disease and persists at endemic levels in many parts of the world. Despite advances in our understanding of WNV pathogenesis, there remains a significant need for a human vaccine. The domain III (DIII region of the WNV envelope protein contains epitopes that are the target of neutralizing antibodies. We have constructed a chimeric fusion of the non-toxic cholera toxin (CT CTA2/B domains to DIII for investigation as a novel mucosally-delivered WNV vaccine. Purification and assembly of the chimera, as well as receptor-binding and antigen delivery, were verified by western blot, GM1 ELISA and confocal microscopy. Groups of BALB/c mice were immunized intranasally with DIII-CTA2/B, DIII, DIII mixed with CTA2/B, or CTA2/B control, and boosted at 10 days. Analysis of serum IgG after 14 and 45 days revealed that mucosal immunization with DIII-CTA2/B induced significant DIII-specific humoral immunity and drove isotype switching to IgG2a. The DIII-CTA2/B chimera also induced antigen-specific IgM and IgA responses. Bactericidal assays indicate that the DIII-CTA2/B immunized mice produced DIII-specific antibodies that can trigger complement-mediated killing. A dose escalation resulted in increased DIII-specific serum IgG titers on day 45. DIII antigen alone, in the absence of adjuvant, also induced significant systemic responses after intranasal delivery. Our results indicate that the DIII-CTA2/B chimera is immunogenic after intranasal delivery and merits further investigation as a novel WNV vaccine candidate.

  13. Pathologic findings in red-tailed hawks (Buteo jamaicensis) and Cooper's hawks (Accipiter cooper) naturally infected with West Nile virus.

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    Wünschmann, Arno; Shivers, Jan; Bender, Jeff; Carroll, Larry; Fuller, Susan; Saggese, Miguel; van Wettere, Arnaud; Redig, Pat

    2004-09-01

    Carcasses of 13 red-tailed hawks (RTHAs) and 11 Cooper's hawks (COHAs) were tested for West Nile virus (WNV) using WNV-specific reverse transcriptase-polymerase chain reaction (RT-PCR) on fresh brain tissue and WNV-specific immunohistochemistry (IHC) on various organs. Ten COHAs (91%) and 11 RTHAs (85%) were positive for WNV RNA by RT-PCR. All 11 COHAs (100%) and 10 RTHAs (77%) were positive for WNV antigen by IHC. A triad of inflammatory lesions, including chronic lymphoplasmacytic and histiocytic encephalitis, endophthalmitis, and myocarditis, was common in both species. In COHAs, the heart (54%), cerebrum (50%), and eye (45%) were the organs that most commonly contained WNV antigen. The amount of WNV antigen was usually small. In RTHAs, the kidney (38%), cerebrum (38%), cerebellum (38%), and eye (36%) were the organs most commonly containing WNV antigen. Unlike COHAs, larger amounts of WNV antigen were present in the cerebrum of RTHAs. WNV antigen was detected in similar cell populations in both species, including neurons of brain, spinal cord, and retina, pigmented epithelial cells of the retina, epithelial cells of renal medullary tubules, cardiomyocytes, endothelial cells and smooth muscle cells of arteries, dendritic cells of splenic lymph follicles, exocrine pancreatic cells, adrenal cells, and keratinocytes of the skin. The study presents strong evidence that WNV can cause a chronic fatal disease in RTHAs and COHAs. The lesion distribution of WNV infection in both species is variable, but inflammatory lesions are common, and a triad of lesions including encephalitis, myocarditis, and endophthalmitis is indicative of WNV infection in both species.

  14. A Retrospective Summary of Raptor Mortality in Ontario, Canada (1991-2014), Including the Effects of West Nile Virus.

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    Smith, Kathryn A; Campbell, G Douglas; Pearl, David L; Jardine, Claire M; Salgado-Bierman, Fernando; Nemeth, Nicole M

    2017-11-20

    The causes of mortality of free-ranging raptors range from anthropogenic (e.g., trauma) to dynamic environmental conditions that may affect habitat suitability and prey availability. The province of Ontario, Canada, is vulnerable to anthropogenic and environmental changes because of its northern latitudes and expanding human populations, both of which may impact wildlife. We retrospectively evaluated diagnostic data from raptors submitted to the Ontario-Nunavut node of the Canadian Wildlife Health Cooperative (CWHC) from 1991 to 2014 (n=1,448). Submissions encompassed 29 species, most commonly the Red-tailed Hawk (Buteo jamaicensis; n=308) and Great Horned Owl (Bubo virginianus; n=237). Trauma (n=716) accounted for the majority of deaths among all species, followed by emaciation (n=241). Traumatic deaths were most commonly attributed to collisions with stationary objects, and the odds of a diagnosis of trauma were significantly higher in adult versus immature raptors. The odds of being diagnosed with emaciation were significantly higher in males than in females but not in any age class or season. Mortality was less commonly attributed to infectious diseases (n=214), for which West Nile virus (WNV) was the most common etiology, making up 53.1% of infectious diagnoses after its 2001 arrival in Ontario. The odds of a raptor being diagnosed with an infectious disease were significantly greater in summer and fall versus spring. Immature Red-tailed Hawks had significantly greater odds of being diagnosed with WNV compared to adults. These results reveal that human- and potentially environmentally associated deaths (e.g., trauma and emaciation, respectively) are commonly diagnosed among Ontario raptors submitted to the CWHC. Infectious diseases are less commonly diagnosed, but WNV may have underlying, ongoing impacts on the health of some raptor species.

  15. When to Spray: a Time-Scale Calculus Approach to Controlling the Impact of West Nile Virus

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    Diana Thomas

    2009-12-01

    Full Text Available West Nile Virus (WNV made its initial appearance in the New York City (NYC metropolitan area in 1999 and was implicated in cases of human encephalitis and the extensive mortality in crows (Corvus sp. and other avian species. Mosquitoes were found to be the primary vectors and NYC's current policy on control strategies involved an eradication program that depends on the synchronicity of the summer mosquito population's increases with the occurrence of cases in humans. The purpose of this paper is to investigate whether this is the most effective control strategy because past mathematical models assumed discrete behavior that is modeled by difference equations for a single summer season was most important to the virus's life cycle. However, both surviving mosquito eggs and surviving migratory birds incubate the virus during the winter, leading to a continuation of infections in the following warmer spring and summer when the birds return and the eggs hatch. Additionally, the virulence of WNV has been observed to fluctuate with changes in temperature toward warmer conditions. Models are required that account for these multi-seasonal dynamics and time-scale calculus is a newly developed method for resolving the behavior of systems that exhibit both discrete and continuous behavior. We found that, although the static states of the new temperature delay model are no different from older models, simulations indicate that the rate of the infection is affected by avian recovery at a lower temperature threshold. Consequently, eradication strategies should consider that controlling mosquitoes during the fall when colder temperatures occur would cause a fast and efficient drop to a disease-free state. This could prove rather more effective than mosquito control in the warmer months.

  16. Comprehensive mapping of common immunodominant epitopes in the West Nile virus nonstructural protein 1 recognized by avian antibody responses.

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    Encheng Sun

    Full Text Available West Nile virus (WNV is a mosquito-borne flavivirus that primarily infects birds but occasionally infects humans and horses. Certain species of birds, including crows, house sparrows, geese, blue jays and ravens, are considered highly susceptible hosts to WNV. The nonstructural protein 1 (NS1 of WNV can elicit protective immune responses, including NS1-reactive antibodies, during infection of animals. The antigenicity of NS1 suggests that NS1-reactive antibodies could provide a basis for serological diagnostic reagents. To further define serological reagents for diagnostic use, the antigenic sites in NS1 that are targeted by host immune responses need to be identified and the potential diagnostic value of individual antigenic sites also needs to be defined. The present study describes comprehensive mapping of common immunodominant linear B-cell epitopes in the WNV NS1 using avian WNV NS1 antisera. We screened antisera from chickens, ducks and geese immunized with purified NS1 for reactivity against 35 partially overlapping peptides covering the entire WNV NS1. This study identified twelve, nine and six peptide epitopes recognized by chicken, duck and goose antibody responses, respectively. Three epitopes (NS1-3, 14 and 24 were recognized by antibodies elicited by immunization in all three avian species tested. We also found that NS1-3 and 24 were WNV-specific epitopes, whereas the NS1-14 epitope was conserved among the Japanese encephalitis virus (JEV serocomplex viruses based on the reactivity of avian WNV NS1 antisera against polypeptides derived from the NS1 sequences of viruses of the JEV serocomplex. Further analysis showed that the three common polypeptide epitopes were not recognized by antibodies in Avian Influenza Virus (AIV, Newcastle Disease Virus (NDV, Duck Plague Virus (DPV and Goose Parvovirus (GPV antisera. The knowledge and reagents generated in this study have potential applications in differential diagnostic approaches and

  17. Increased avian diversity is associated with lower incidence of human West Nile infection: observation of the dilution effect.

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    John P Swaddle

    Full Text Available Recent infectious disease models illustrate a suite of mechanisms that can result in lower incidence of disease in areas of higher disease host diversity--the 'dilution effect'. These models are particularly applicable to human zoonoses, which are infectious diseases of wildlife that spill over into human populations. As many recent emerging infectious diseases are zoonoses, the mechanisms that underlie the 'dilution effect' are potentially widely applicable and could contribute greatly to our understanding of a suite of diseases. The dilution effect has largely been observed in the context of Lyme disease and the predictions of the underlying models have rarely been examined for other infectious diseases on a broad geographic scale. Here, we explored whether the dilution effect can be observed in the relationship between the incidence of human West Nile virus (WNV infection and bird (host diversity in the eastern US. We constructed a novel geospatial contrasts analysis that compares the small differences in avian diversity of neighboring US counties (where one county reported human cases of WNV and the other reported no cases with associated between-county differences in human disease. We also controlled for confounding factors of climate, regional variation in mosquito vector type, urbanization, and human socioeconomic factors that are all likely to affect human disease incidence. We found there is lower incidence of human WNV in eastern US counties that have greater avian (viral host diversity. This pattern exists when examining diversity-disease relationships both before WNV reached the US (in 1998 and once the epidemic was underway (in 2002. The robust disease-diversity relationships confirm that the dilution effect can be observed in another emerging infectious disease and illustrate an important ecosystem service provided by biodiversity, further supporting the growing view that protecting biodiversity should be considered in public

  18. Clinical and pathologic responses of American crows (Corvus brachyrhynchos) and fish crows (C ossifragus) to experimental West Nile virus infection.

    Science.gov (United States)

    Nemeth, N M; Thomsen, B V; Spraker, T R; Benson, J M; Bosco-Lauth, A M; Oesterle, P T; Bright, J M; Muth, J P; Campbell, T W; Gidlewski, T L; Bowen, R A

    2011-11-01

    West Nile virus (WNV)-associated disease has a range of clinical manifestations among avian taxa, the reasons for which are not known. Species susceptibility varies within the avian family Corvidae, with estimated mortality rates ranging from 50 to 100%. We examined and compared virologic, immunologic, pathologic, and clinical responses in 2 corvid species, the American crow (Corvus brachyrhynchos) and the fish crow (C ossifragus), following experimental WNV inoculation. Unlike fish crows, which remained clinically normal throughout the study, American crows succumbed to WNV infection subsequent to dehydration, electrolyte and pH imbalances, and delayed or depressed humoral immune responses concurrent with marked, widespread virus replication. Viral titers were approximately 3,000 times greater in blood and 30,000 to 50,000 times greater in other tissues (eg, pancreas and small intestine) in American crows versus fish crows. Histologic lesion patterns and antigen deposition supported the differing clinical outcomes, with greater severity and distribution of lesions and WNV antigen in American crows. Both crow species had multiorgan necrosis and inflammation, although lesions were more frequent, severe, and widespread in American crows, in which the most commonly affected tissues were small intestine, spleen, and liver. American crows also had inflammation of vessels and nerves in multiple tissues, including heart, kidney, and the gastrointestinal tract. WNV antigen was most commonly observed within monocytes, macrophages, and other cells of the reticuloendothelial system of affected tissues. Collectively, the data support that WNV-infected American crows experience uncontrolled systemic infection leading to multiorgan failure and rapid death.

  19. The Degree of One Health Implementation in the West Nile Virus Integrated Surveillance in Northern Italy, 2016.

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    Paternoster, Giulia; Tomassone, Laura; Tamba, Marco; Chiari, Mario; Lavazza, Antonio; Piazzi, Mauro; Favretto, Anna R; Balduzzi, Giacomo; Pautasso, Alessandra; Vogler, Barbara R

    2017-01-01

    West Nile virus (WNV) is endemic in the Po valley area, Northern Italy, and within the legal framework of the national plan for the surveillance of human vector-borne diseases, WNV surveillance has over time been implemented. The surveillance plans are based on the transdisciplinary and trans-sectorial collaboration between regional institutions involved in public, animal, and environmental health. This integrated surveillance targets mosquitoes, wild birds, humans, and horses and aims at early detecting the viral circulation and reducing the risk of infection in the human populations. The objective of our study was to assess the degree of One Health (OH) implementation (OH-ness) of the WNV surveillance system in three North Italian regions (Emilia-Romagna, Lombardy, Piedmont) in 2016, following the evaluation protocol developed by the Network for Evaluation of One Health (NEOH). In detail, we (i) described the OH initiative (drivers, outcomes) and its system (boundaries, aim, dimensions, actors, stakeholders) and (ii) scored different aspects of this initiative (i.e., OH-thinking, -planning, -sharing, -learning, transdisciplinarity and leadership), with values from 0 (=no OH approach) to 1 (=perfect OH approach). We obtained a mean score for each aspect evaluated. We reached high scores for OH thinking (0.90) and OH planning (0.89). Lower scores were attributed to OH sharing (0.83), transdisciplinarity and leadership (0.77), and OH learning (0.67), highlighting some critical issues related to communication and learning gaps. The strengths and weaknesses detected by the described quantitative evaluation will be investigated in detail by a qualitative evaluation (process evaluation), aiming to provide a basis for the development of shared recommendations to refine the initiative and conduct it in a more OH-oriented perspective.

  20. Experimental infection of house sparrows (Passer domesticus) with West Nile virus strains of lineages 1 and 2.

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    Del Amo, Javier; Llorente, Francisco; Pérez-Ramirez, Elisa; Soriguer, Ramón C; Figuerola, Jordi; Nowotny, Norbert; Jiménez-Clavero, Miguel Angel

    2014-08-27

    West Nile virus (WNV) is a zoonotic pathogen which is maintained in an enzootic cycle between mosquitoes and birds; humans, equines, other mammals and some bird species are dead-end hosts. Lineage 1 WNV strains have predominated in Europe since the 1960s. However, in 2004 lineage 2 strains emerged in Hungary and Russia, respectively, spreading since then to a number of neighbouring countries (e.g., Austria, Greece, Italy, Serbia and Romania). Wild bird mortality is a hallmark of North American WNV outbreaks, a feature uncommon in Europe. This study aimed to compare the course of infection of lineage 1 (NY99) and lineage 2 (Austria/2008) WNV strains in the house sparrow, a bird species common in Europe and North America. House sparrows were inoculated with either NY99 or Austria/2008 WNV strains, or sham-inoculated, and clinical and analytic parameters (viraemia, viral load, antibodies) were examined until 14 days after inoculation. Although all inoculated sparrows became infected, no mortality or clinical signs were observed due to the infection. However, the magnitude and duration of viraemia were higher for NY99 - than for Austria/2008 - infected birds. The house sparrow proved to be a competent host for both strains, although the competence index calculated for NY99 was higher than for Austria/2008. Viral load in tissues and swabs was also higher in NY99-inoculated sparrows. In conclusion, the house sparrow is a convenient avian model for studying host competence of WNV strains. The observed differences between NY99 and Austria/2008 strains might have important epidemiological consequences for disease incidence and dispersal capacity. Copyright © 2014 Elsevier B.V. All rights reserved.