Predicting the potential distribution of the amphibian pathogen Batrachochytrium dendrobatidis in East and Southeast Asia.

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Moriguchi, Sachiko; Tominaga, Atsushi; Irwin, Kelly J; Freake, Michael J; Suzuki, Kazutaka; Goka, Koichi

2015-04-08

Batrachochytrium dendrobatidis (Bd) is the pathogen responsible for chytridiomycosis, a disease that is associated with a worldwide amphibian population decline. In this study, we predicted the potential distribution of Bd in East and Southeast Asia based on limited occurrence data. Our goal was to design an effective survey area where efforts to detect the pathogen can be focused. We generated ecological niche models using the maximum-entropy approach, with alleviation of multicollinearity and spatial autocorrelation. We applied eigenvector-based spatial filters as independent variables, in addition to environmental variables, to resolve spatial autocorrelation, and compared the model's accuracy and the degree of spatial autocorrelation with those of a model estimated using only environmental variables. We were able to identify areas of high suitability for Bd with accuracy. Among the environmental variables, factors related to temperature and precipitation were more effective in predicting the potential distribution of Bd than factors related to land use and cover type. Our study successfully predicted the potential distribution of Bd in East and Southeast Asia. This information should now be used to prioritize survey areas and generate a surveillance program to detect the pathogen.

Parallels in amphibian and bat declines from pathogenic fungi.

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Eskew, Evan A; Todd, Brian D

2013-03-01

Pathogenic fungi have substantial effects on global biodiversity, and 2 emerging pathogenic species-the chytridiomycete Batrachochytrium dendrobatidis, which causes chytridiomycosis in amphibians, and the ascomycete Geomyces destructans, which causes white-nose syndrome in hibernating bats-are implicated in the widespread decline of their vertebrate hosts. We synthesized current knowledge for chytridiomycosis and white-nose syndrome regarding disease emergence, environmental reservoirs, life history characteristics of the host, and host-pathogen interactions. We found striking similarities between these aspects of chytridiomycosis and white-nose syndrome, and the research that we review and propose should help guide management of future emerging fungal diseases.

Inhibition of Fungal Pathogens across Genotypes and Temperatures by Amphibian Skin Bacteria

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Carly R. Muletz-Wolz

2017-08-01

Full Text Available Symbiotic bacteria may dampen the impacts of infectious diseases on hosts by inhibiting pathogen growth. However, our understanding of the generality of pathogen inhibition by different bacterial taxa across pathogen genotypes and environmental conditions is limited. Bacterial inhibitory properties are of particular interest for the amphibian-killing fungal pathogens (Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, for which probiotic applications as conservation strategies have been proposed. We quantified the inhibition strength of five putatively B. dendrobatidis-inhibitory bacteria isolated from woodland salamander skin against six Batrachochytrium genotypes at two temperatures (12 and 18°C. We selected six genotypes from across the Batrachochytrium phylogeny: B. salamandrivorans, B. dendrobatidis-Brazil and four genotypes of the B. dendrobatidis Global Panzootic Lineage (GPL1: JEL647, JEL404; GPL2: SRS810, JEL423. We performed 96-well plate challenge assays in a full factorial design. We detected a Batrachochytrium genotype by temperature interaction on bacterial inhibition score for all bacteria, indicating that bacteria vary in ability to inhibit Batrachochytrium depending on pathogen genotype and temperature. Acinetobacter rhizosphaerae moderately inhibited B. salamandrivorans at both temperatures (μ = 46–53%, but not any B. dendrobatidis genotypes. Chryseobacterium sp. inhibited three Batrachochytrium genotypes at both temperatures (μ = 5–71%. Pseudomonas sp. strain 1 inhibited all Batrachochytrium genotypes at 12°C and four Batrachochytrium genotypes at 18°C (μ = 5–100%. Pseudomonas sp. strain 2 and Stenotrophomonas sp. moderately to strongly inhibited all six Batrachochytrium genotypes at both temperatures (μ = 57–100%. All bacteria consistently inhibited B. salamandrivorans. Using cluster analysis of inhibition scores, we found that more closely related Batrachochytrium genotypes grouped together

Characterization of the Carbohydrate Binding Module 18 gene family in the amphibian pathogen Batrachochytrium dendrobatidis.

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Liu, Peng; Stajich, Jason E

2015-04-01

Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis responsible for worldwide decline in amphibian populations. Previous analysis of the Bd genome revealed a unique expansion of the carbohydrate-binding module family 18 (CBM18) predicted to be a sub-class of chitin recognition domains. CBM expansions have been linked to the evolution of pathogenicity in a variety of fungal species by protecting the fungus from the host. Based on phylogenetic analysis and presence of additional protein domains, the gene family can be classified into 3 classes: Tyrosinase-, Deacetylase-, and Lectin-like. Examination of the mRNA expression levels from sporangia and zoospores of nine of the cbm18 genes found that the Lectin-like genes had the highest expression while the Tyrosinase-like genes showed little expression, especially in zoospores. Heterologous expression of GFP-tagged copies of four CBM18 genes in Saccharomyces cerevisiae demonstrated that two copies containing secretion signal peptides are trafficked to the cell boundary. The Lectin-like genes cbm18-ll1 and cbm18-ll2 co-localized with the chitinous cell boundaries visualized by staining with calcofluor white. In vitro assays of the full length and single domain copies from CBM18-LL1 demonstrated chitin binding and no binding to cellulose or xylan. Expressed CBM18 domain proteins were demonstrated to protect the fungus, Trichoderma reeseii, in vitro against hydrolysis from exogenously added chitinase, likely by binding and limiting exposure of fungal chitin. These results demonstrate that cbm18 genes can play a role in fungal defense and expansion of their copy number may be an important pathogenicity factor of this emerging infectious disease of amphibians. Copyright © 2015 Elsevier Inc. All rights reserved.

Linking ecology and epidemiology to understand predictors of multi-host responses to an emerging pathogen, the amphibian chytrid fungus

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Stephanie S. Gervasi; Patrick R. Stephens; Jessica Hua; Catherine L. Searle; Gisselle Yang Xie; Jenny Urbina; Deanna H. Olson; Betsy A. Bancroft; Virginia Weis; John I. Hammond; Rick A. Relyea; Andrew R. Blaustein; Stefan Lötters

2017-01-01

Variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. The fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been detected in almost 700 different...

Carotenoids and amphibians: effects on life history and susceptibility to the infectious pathogen, Batrachochytrium dendrobatidis.

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Cothran, Rickey D; Gervasi, Stephanie S; Murray, Cindy; French, Beverly J; Bradley, Paul W; Urbina, Jenny; Blaustein, Andrew R; Relyea, Rick A

2015-01-01

Carotenoids are considered beneficial nutrients because they provide increased immune capacity. Although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. We raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (Batrachochytrium dendrobatidis; Bd). Increased carotenoids had no effect on survival to metamorphosis in gray treefrogs (Hyla versicolor) but caused lower survival to metamorphosis in wood frogs [Lithobates sylvaticus (Rana sylvatica)]. Increased carotenoids caused both species to experience slower development and growth. When exposed to Bd after metamorphosis, wood frogs experienced high mortality, and the carotenoid diets had no mitigating effects. Gray treefrogs were less susceptible to Bd, which prevented an assessment of whether carotenoids could mitigate the effects of Bd. Moreover, carotenoids had no effect on pathogen load. As one of only a few studies examining the effects of carotenoids on amphibians and the first to examine potential interactions with Bd, our results suggest that carotenoids do not always serve amphibians in the many positive ways that have become the paradigm in other vertebrates.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone.

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Thekkiniath, Jose; Zabet-Moghaddam, Masoud; Kottapalli, Kameswara Rao; Pasham, Mithun R; San Francisco, Susan; San Francisco, Michael

2015-01-01

Batrachochytrium dendrobatidis (Bd), a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3). Tadpoles may be infected with Bd and the fungus may be exposed to T3 during metamorphosis. We hypothesize that exposure of Bd to T3 may induce the expression of factors associated with host colonization and pathogenicity. We utilized a proteomics approach to better understand the dynamics of the Bd-T3 interaction. Using liquid chromatography-mass spectrometry (LC-MS), we generated a data set of a large number of cytoplasmic and membrane proteins following exposure of Bd to T3. From these data, we identified a total of 263 proteins whose expression was significantly changed following T3 exposure. We provide evidence for expression of an array of proteins that may play key roles in both genomic and non-genomic actions of T3 in Bd. Additionally, our proteomics study shows an increase in several proteins including proteases and a class of uncommon crinkler and crinkler-like effector proteins suggesting their importance in Bd pathogenicity as well as those involved in metabolism and energy transfer, protein fate, transport and stress responses. This approach provides insights into the mechanistic basis of the Bd-amphibian interaction following T3 exposure.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone.

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Jose Thekkiniath

Full Text Available Batrachochytrium dendrobatidis (Bd, a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3. Tadpoles may be infected with Bd and the fungus may be exposed to T3 during metamorphosis. We hypothesize that exposure of Bd to T3 may induce the expression of factors associated with host colonization and pathogenicity. We utilized a proteomics approach to better understand the dynamics of the Bd-T3 interaction. Using liquid chromatography-mass spectrometry (LC-MS, we generated a data set of a large number of cytoplasmic and membrane proteins following exposure of Bd to T3. From these data, we identified a total of 263 proteins whose expression was significantly changed following T3 exposure. We provide evidence for expression of an array of proteins that may play key roles in both genomic and non-genomic actions of T3 in Bd. Additionally, our proteomics study shows an increase in several proteins including proteases and a class of uncommon crinkler and crinkler-like effector proteins suggesting their importance in Bd pathogenicity as well as those involved in metabolism and energy transfer, protein fate, transport and stress responses. This approach provides insights into the mechanistic basis of the Bd-amphibian interaction following T3 exposure.

Early action to address an emerging wildlife disease

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Adams, Michael J.; Harris, M. Camille; Grear, Daniel A.

2017-02-23

A deadly fungal pathogen, Batrachochytrium salamandrivorans (Bsal) that affects amphibian skin was discovered during a die-off of European fire salamanders (Salamandra salamandra) in 2014. This pathogen has the potential to worsen already severe worldwide amphibian declines. Bsal is a close relative to another fungal disease known as Batrachochytrium dendrobatidis (Bd). Many scientists consider Bd to be the greatest threat to amphibian biodiversity of any disease because it affects a large number of species and has the unusual ability to drive species and populations to extinction.Although not yet detected in the United States, the emergence of Bsal could threaten the salamander population, which is the most diverse in the world. The spread of Bsal likely will lead to more State and federally listed threatened or endangered amphibian species, and associated economic effects.Because of the concern expressed by resource management agencies, the U.S. Geological Survey (USGS) has made Bsal and similar pathogens a priority for research.

Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America.

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Tara Chestnut

Full Text Available Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd, is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L(-1. The highest density observed was ∼3 million zoospores L(-1. We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure to free

Distribution and pathogenicity of Batrachochytrium dendrobatidis in boreal toads from the grand teton area of western wyoming

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Murphy, P.J.; St-Hilaire, S.; Bruer, S.; Corn, P.S.; Peterson, C.R.

2009-01-01

The pathogen Batrachochytrium dendrobatidis (Bd), which causes the skin disease chytridiomycosis, has been linked to amphibian population declines and extinctions worldwide. Bd has been implicated in recent declines of boreal toads, Bufo boreas boreas, in Colorado but populations of boreal toads in western Wyoming have high prevalence of Bd without suffering catastrophic mortality. In a field and laboratory study, we investigated the prevalence of Bd in boreal toads from the Grand Teton ecosystem (GRTE) in Wyoming and tested the pathogenicity of Bd to these toads in several environments. The pathogen was present in breeding adults at all 10 sites sampled, with a mean prevalence of 67%. In an experiment with juvenile toadlets housed individually in wet environments, 106 zoospores of Bd isolated from GRTE caused lethal disease in all Wyoming and Colorado animals within 35 days. Survival time was longer in toadlets from Wyoming than Colorado and in toadlets spending more time in dry sites. In a second trial involving Colorado toadlets exposed to 35% fewer Bd zoospores, infection peaked and subsided over 68 days with no lethal chytridiomycosis in any treatment. However, compared with drier aquaria with dry refuges, Bd infection intensity was 41% higher in more humid aquaria and 81% higher without dry refuges available. Our findings suggest that although widely infected in nature, Wyoming toads may escape chytridiomycosis due to a slight advantage in innate resistance or because their native habitat hinders Bd growth or provides more opportunities to reduce pathogen loads behaviorally than in Colorado. ?? 2009 International Association for Ecology and Health.

Batrachochytrium salamandrivorans sp. nov. causes lethal chytridiomycosis in amphibians.

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Martel, An; Spitzen-van der Sluijs, Annemarieke; Blooi, Mark; Bert, Wim; Ducatelle, Richard; Fisher, Matthew C; Woeltjes, Antonius; Bosman, Wilbert; Chiers, Koen; Bossuyt, Franky; Pasmans, Frank

2013-09-17

The current biodiversity crisis encompasses a sixth mass extinction event affecting the entire class of amphibians. The infectious disease chytridiomycosis is considered one of the major drivers of global amphibian population decline and extinction and is thought to be caused by a single species of aquatic fungus, Batrachochytrium dendrobatidis. However, several amphibian population declines remain unexplained, among them a steep decrease in fire salamander populations (Salamandra salamandra) that has brought this species to the edge of local extinction. Here we isolated and characterized a unique chytrid fungus, Batrachochytrium salamandrivorans sp. nov., from this salamander population. This chytrid causes erosive skin disease and rapid mortality in experimentally infected fire salamanders and was present in skin lesions of salamanders found dead during the decline event. Together with the closely related B. dendrobatidis, this taxon forms a well-supported chytridiomycete clade, adapted to vertebrate hosts and highly pathogenic to amphibians. However, the lower thermal growth preference of B. salamandrivorans, compared with B. dendrobatidis, and resistance of midwife toads (Alytes obstetricans) to experimental infection with B. salamandrivorans suggest differential niche occupation of the two chytrid fungi.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone

OpenAIRE

Thekkiniath, Jose; Zabet-Moghaddam, Masoud; Kottapalli, Kameswara Rao; Pasham, Mithun R.; San Francisco, Susan; San Francisco, Michael

2015-01-01

Batrachochytrium dendrobatidis (Bd), a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3). Tadpoles may be...

Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar

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Bletz, Molly C.; Rosa, Gonçalo M.; Andreone, Franco; Courtois, Elodie A.; Schmeller, Dirk S.; Rabibisoa, Nirhy H. C.; Rabemananjara, Falitiana C. E.; Raharivololoniaina, Liliane; Vences, Miguel; Weldon, Ché; Edmonds, Devin; Raxworthy, Christopher J.; Harris, Reid N.; Fisher, Matthew C.; Crottini, Angelica

2015-01-01

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians. PMID:25719857

Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America

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Chestnut, Tara E.; Anderson, Chauncey; Popa, Radu; Blaustein, Andrew R.; Voytek, Mary; Olson, Deanna H.; Kirshtein, Julie

2014-01-01

Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L−1. The highest density observed was ∼3 million zoospores L−1. We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure

Emerging Pathogens Initiative (EPI)

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Department of Veterans Affairs — The Emerging Pathogens Initiative (EPI) database contains emerging pathogens information from the local Veterans Affairs Medical Centers (VAMCs). The EPI software...

Occurrence of Batrachochytrium dendrobatidis in an anuran community in the southeastern Talamanca Region of Costa Rica

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Daniel Saenz; Cory K. Adams; Josh B. Pierce; David Laurencio

2009-01-01

Soon after the discovery of the amphibian disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd, Longcore et al. 1999), it became apparent that Bd was a major threat to amphibians resulting in mass die-offs and population declines throughout the world (Berger et aI. 1998; Blaustein and Keisecker 2002; Daszak et aI. 2003; McCallum...

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in native amphibians exported from Madagascar.

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Jonathan E Kolby

Full Text Available The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd, a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented.

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in native amphibians exported from Madagascar.

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Kolby, Jonathan E

2014-01-01

The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented.

Spatial variation in risk and consequence of Batrachochytrium salamandrivorans introduction in the USA

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Richgels, Katherine L. D.; Russell, Robin E.; Adams, Michael J.; White, C. LeAnn; Campbell Grant, Evan H.

2016-01-01

A newly identified fungal pathogen, Batrachochytrium salamandrivorans (Bsal), is responsible for mass mortality events and severe population declines in European salamanders. The eastern USA has the highest diversity of salamanders in the world and the introduction of this pathogen is likely to be devastating. Although data are inevitably limited for new pathogens, disease-risk assessments use best available data to inform management decisions. Using characteristics of Bsal ecology, spatial data on imports and pet trade establishments, and salamander species diversity, we identify high-risk areas with both a high likelihood of introduction and severe consequences for local salamanders. We predict that the Pacific coast, southern Appalachian Mountains and mid-Atlantic regions will have the highest relative risk from Bsal. Management of invasive pathogens becomes difficult once they are established in wildlife populations; therefore, import restrictions to limit pathogen introduction and early detection through surveillance of high-risk areas are priorities for preventing the next crisis for North American salamanders.

Transient virulence of emerging pathogens.

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Bolker, Benjamin M; Nanda, Arjun; Shah, Dharmini

2010-05-06

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

Reptiles as potential vectors and hosts of the amphibian pathogen Batrachochytrium dendrobatidis in Panama.

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Kilburn, Vanessa L; Ibáñez, Roberto; Green, David M

2011-12-06

Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.

Effects of an infectious fungus, Batrachochytrium dendrobatidis, on amphibian predator-prey interactions.

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Barbara A Han

2011-02-01

Full Text Available The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e., non-selective predation could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.

New trends in emerging pathogens.

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Skovgaard, Niels

2007-12-15

The emergence of pathogens is the result of a number of impact in all parts of the food chain. The emerging technologies in food production explain how new pathogens can establish themselves in the food chain and compromise food safety. The impact of the food technology is analysed for several bacteria, such as Yersinia, Campylobacter, Arcobacter, Helicobacter pullorum, Enterobacter sakazakii, Mycobacterium avium spp. paratuberculosis, prions related to vCJD and others. The importance of the ability of many microbes to form VBNC forms is elaborated on. Research on culture independent methods may address this outstanding issue to the better understanding of emerging pathogens. The "demerging" of pathogens also occur, and examples of this are explained. The reaction of bacteria to stresses and sublethal treatments, and how exposure to one stress factor can confer resistance to other stresses, literally speaking causing contagious resistance, are explained. The implication of this e.g. in modern approaches of food preservation, such as Minimally processed Foods, is considerable. Intestinal colonization of EHEC may be regulated by Quorum sensing, and this ability of microbes plays an important role in the colonization of microbes in food and on food processing equipment, an important factor in the emergence of pathogens. The emergence of Saccharomyces cerevisiae, as an opportunistic human pathogen, used for centuries for food and production of alcoholic beverages, calls for research in molecular tools to distinguish between probiotic and clinical strains. Cyclospora cayetanensis and Norovirus outbreaks can no longer be designated as emerging pathogens, they share however one characteristic in the epidemiology of emerging nature, the importance of the hygiene in the primary production stage, including supply of potable water, and the application of GMP and the HACCP principles in the beginning of the food chain. Hepatitis E virus is a potential emerging food borne

Widespread occurrence of Batrachochytrium dendrobatidis in contemporary and historical samples of the endangered Bombina pachypus along the Italian peninsula.

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Daniele Canestrelli

Full Text Available Batrachochytrium dendrobatidis is considered a main driver of the worldwide declines and extinctions of amphibian populations. Nonetheless, fundamental questions about its epidemiology, including whether it acts mainly as a "lone killer" or in conjunction with other factors, remain largely open. In this paper we analysed contemporary and historical samples of the endangered Apennine yellow-bellied toad (Bombina pachypus along the Italian peninsula, in order to assess the presence of the pathogen and its spreading dynamics. Once common throughout its range, B. pachypus started to decline after the mid-1990s in the northern and central regions, whereas no declines have been observed so far in the southern region. We show that Batrachochytrium dendrobatidis is currently widespread along the entire peninsula, and that this was already so at least as early as the late 1970s, that is, well before the beginning of the observed declines. This temporal mismatch between pathogen occurrence and host decline, as well as the spatial pattern of the declines, suggests that the pathogen has not acted as a "lone killer", but in conjunction with other factors. Among the potentially interacting factors, we identified two as the most probable, genetic diversity of host populations and recent climate changes. We discuss the plausibility of this scenario and its implications on the conservation of B. pachypus populations.

Amphibians Testing Negative for Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans on the Qinghai-Tibetan Plateau, China

Institute of Scientific and Technical Information of China (English)

Supen WANG; Wei ZHU; Liqing FAN; Jiaqi LI; Yiming LI

2017-01-01

A disease caused by the fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) is responsible for recent worldwide declines and extinctions of amphibian populations.The Qinghai-Tibetan Plateau (QTP) is aglobal biodiversity hotspot,yet little is known about the prevalence of Bd and Bsal in this region.In this study,we collected 336 non-invasive skin swabs from wild amphibians (including an exotic amphibian species) on the QTP.In addition,to assess the historical prevalence of Bd and Bsal on the QTP,we collected 117 non-invasive skin swabs from museum-archived amphibian samples (from 1964-1982) originating from the QTP.Our results showed all samples to be negative for Bd and Bsal.The government should ban the potentially harmful introduction of non-native amphibian species to the QTP and educate the public about the impacts of releasing exotic amphibians from chytrid-infected areas into native environments of the QTP.

Efficacy of chemical disinfectants for the containment of the salamander chytrid fungus Batrachochytrium salamandrivorans

OpenAIRE

Van Rooij, Pascale; Pasmans, Frank; Coen, Yanaïka; Martel, An

2017-01-01

The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal) causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal (R), Chloramine-T (R), Dettol medical (R), Disolol (R), ethanol, F10 (R), Hibiscrub (R), potassium permanganate, Safe4 (R), sodium hypochlorite, and Virkon S (R), were ...

Potential influence of plant chemicals on infectivity of Batrachochytrium dendrobatidis.

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Davidson, Elizabeth W; Larsen, Andrew; Meins Palmer, Crystal

2012-11-08

We explored whether extracts of trees frequently found associated with amphibian habitats in Australia and Arizona, USA, may be inhibitory to the fungal pathogen Batrachochytrium dendrobatidis (Bd), which has been associated with global amphibian declines. We used salamanders Ambystoma tigrinum as the model system. Salamanders acquired significantly lower loads of Bd when exposed on leaves and extracts from the river red gum Eucalyptus camaldulensis, and loads were also low in some animals exposed on extracts of 2 oak species, Quercus emoryi and Q. turbinella. Some previously infected salamanders had their pathogen loads reduced, and some were fully cured, by placing them in leaf extracts, although some animals also self cured when housed in water alone. A significant number of animals cured of Bd infections 6 mo earlier were found to be resistant to reinfection. These results suggest that plants associated with amphibian habitats should be taken into consideration when explaining the prevalence of Bd in these habitats and that some amphibians may acquire resistance to the fungus if previously cured.

Climate forcing of an emerging pathogenic fungus across a montane multi-host community.

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Clare, Frances C; Halder, Julia B; Daniel, Olivia; Bielby, Jon; Semenov, Mikhail A; Jombart, Thibaut; Loyau, Adeline; Schmeller, Dirk S; Cunningham, Andrew A; Rowcliffe, Marcus; Garner, Trenton W J; Bosch, Jaime; Fisher, Matthew C

2016-12-05

Changes in the timings of seasonality as a result of anthropogenic climate change are predicted to occur over the coming decades. While this is expected to have widespread impacts on the dynamics of infectious disease through environmental forcing, empirical data are lacking. Here, we investigated whether seasonality, specifically the timing of spring ice-thaw, affected susceptibility to infection by the emerging pathogenic fungus Batrachochytrium dendrobatidis (Bd) across a montane community of amphibians that are suffering declines and extirpations as a consequence of this infection. We found a robust temporal association between the timing of the spring thaw and Bd infection in two host species, where we show that an early onset of spring forced high prevalences of infection. A third highly susceptible species (the midwife toad, Alytes obstetricans) maintained a high prevalence of infection independent of time of spring thaw. Our data show that perennially overwintering midwife toad larvae may act as a year-round reservoir of infection with variation in time of spring thaw determining the extent to which infection spills over into sympatric species. We used future temperature projections based on global climate models to demonstrate that the timing of spring thaw in this region will advance markedly by the 2050s, indicating that climate change will further force the severity of infection. Our findings on the effect of annual variability on multi-host infection dynamics show that the community-level impact of fungal infectious disease on biodiversity will need to be re-evaluated in the face of climate change.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Authors.

Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline

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Jonah Piovia-Scott; Karen Pope; S. Joy Worth; Erica Bree Rosenblum; Dean Simon; Gordon Warburton; Louise A. Rollins-Smith; Laura K. Reinert; Heather L. Wells; Dan Rejmanek; Sharon Lawler; Janet Foley

2015-01-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We...

Batrachochytrium salamandrivorans is the predominant chytrid fungus in Vietnamese salamanders

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Laking, Alexandra E.; Ngo, Hai Ngoc; Pasmans, Frank; Martel, An; Nguyen, Tao Thien

2017-01-01

The amphibian chytrid fungi, Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), pose a major threat to amphibian biodiversity. Recent evidence suggests Southeast Asia as a potential cradle for both fungi, which likely resulted in widespread host-pathogen co-existence. We sampled 583 salamanders from 8 species across Vietnam in 55 locations for Bsal and Bd, determined scaled mass index as a proxy for fitness and collected environmental data. Bsal was found within 14 of the 55 habitats (2 of which it was detected in 2013), in 5 salamandrid species, with a prevalence of 2.92%. The globalized pandemic lineage of Bd was found within one pond on one species with a prevalence of 0.69%. Combined with a complete lack of correlation between infection and individual body condition and absence of indication of associated disease, this suggests low level pathogen endemism and Bsal and Bd co-existence with Vietnamese salamandrid populations. Bsal was more widespread than Bd, and occurs at temperatures higher than tolerated by the type strain, suggesting a wider thermal niche than currently known. Therefore, this study provides support for the hypothesis that these chytrid fungi may be endemic to Asia and that species within this region may act as a disease reservoir. PMID:28287614

Using decision analysis to support proactive management of emerging infectious wildlife diseases

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Grant, Evan H. Campbell; Muths, Erin L.; Katz, Rachel A.; Canessa, Stefano; Adams, Michael J.; Ballard, Jennifer R.; Berger, Lee; Briggs, Cheryl J.; Coleman, Jeremy; Gray, Matthew J.; Harris, M. Camille; Harris, Reid N.; Hossack, Blake R.; Huyvaert, Kathryn P.; Kolby, Jonathan E.; Lips, Karen R.; Lovich, Robert E.; McCallum, Hamish I.; Mendelson, Joseph R.; Nanjappa, Priya; Olson, Deanna H.; Powers, Jenny G.; Richgels, Katherine L. D.; Russell, Robin E.; Schmidt, Benedikt R.; Spitzen-van der Sluijs, Annemarieke; Watry, Mary Kay; Woodhams, Douglas C.; White, C. LeAnn

2017-01-01

Despite calls for improved responses to emerging infectious diseases in wildlife, management is seldom considered until a disease has been detected in affected populations. Reactive approaches may limit the potential for control and increase total response costs. An alternative, proactive management framework can identify immediate actions that reduce future impacts even before a disease is detected, and plan subsequent actions that are conditional on disease emergence. We identify four main obstacles to developing proactive management strategies for the newly discovered salamander pathogen Batrachochytrium salamandrivorans (Bsal). Given that uncertainty is a hallmark of wildlife disease management and that associated decisions are often complicated by multiple competing objectives, we advocate using decision analysis to create and evaluate trade-offs between proactive (pre-emergence) and reactive (post-emergence) management options. Policy makers and natural resource agency personnel can apply principles from decision analysis to improve strategies for countering emerging infectious diseases.

Efficacy of chemical disinfectants for the containment of the salamander chytrid fungus Batrachochytrium salamandrivorans.

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Van Rooij, Pascale; Pasmans, Frank; Coen, Yanaika; Martel, An

2017-01-01

The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal) causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal®, Chloramine-T®, Dettol medical®, Disolol®, ethanol, F10®, Hibiscrub®, potassium permanganate, Safe4®, sodium hypochlorite, and Virkon S®, were effective at killing Bsal. Concentrations of 5% sodium chloride or lower, 0.01% peracetic acid and 0.001-1% copper sulphate were inactive against Bsal. None of the conditions tested for hydrogen peroxide affected Bsal viability, while it did kill Batrachochytrium dendrobatidis (Bd). For Bsal, enzymatic breakdown of hydrogen peroxide by catalases and specific morphological features (clustering of sporangia, development of new sporangia within the original sporangium), were identified as fungal factors altering susceptibility to several of the disinfectants tested. Based on the in vitro results we recommend 1% Virkon S®, 4% sodium hypochlorite and 70% ethanol for disinfecting equipment in the field, lab or captive setting, with a minimal contact time of 5 minutes for 1% Virkon S® and 1 minute for the latter disinfectants. These conditions not only efficiently target Bsal, but also Bd and Ranavirus.

Efficacy of chemical disinfectants for the containment of the salamander chytrid fungus Batrachochytrium salamandrivorans.

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Pascale Van Rooij

Full Text Available The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal®, Chloramine-T®, Dettol medical®, Disolol®, ethanol, F10®, Hibiscrub®, potassium permanganate, Safe4®, sodium hypochlorite, and Virkon S®, were effective at killing Bsal. Concentrations of 5% sodium chloride or lower, 0.01% peracetic acid and 0.001-1% copper sulphate were inactive against Bsal. None of the conditions tested for hydrogen peroxide affected Bsal viability, while it did kill Batrachochytrium dendrobatidis (Bd. For Bsal, enzymatic breakdown of hydrogen peroxide by catalases and specific morphological features (clustering of sporangia, development of new sporangia within the original sporangium, were identified as fungal factors altering susceptibility to several of the disinfectants tested. Based on the in vitro results we recommend 1% Virkon S®, 4% sodium hypochlorite and 70% ethanol for disinfecting equipment in the field, lab or captive setting, with a minimal contact time of 5 minutes for 1% Virkon S® and 1 minute for the latter disinfectants. These conditions not only efficiently target Bsal, but also Bd and Ranavirus.

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar

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Kolby, Jonathan E.; Smith, Kristine M.; Ramirez, Sara D.; Rabemananjara, Falitiana; Pessier, Allan P.; Brunner, Jesse L.; Goldberg, Caren S.; Berger, Lee; Skerratt, Lee F.

2015-01-01

We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by disease

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis and Ranavirus in Wild Amphibian Populations in Madagascar.

Directory of Open Access Journals (Sweden)

Jonathan E Kolby

Full Text Available We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar.

Science.gov (United States)

Kolby, Jonathan E; Smith, Kristine M; Ramirez, Sara D; Rabemananjara, Falitiana; Pessier, Allan P; Brunner, Jesse L; Goldberg, Caren S; Berger, Lee; Skerratt, Lee F

2015-01-01

We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by disease

Future potential distribution of the emerging amphibian chytrid fungus under anthropogenic climate change.

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Rödder, Dennis; Kielgast, Jos; Lötters, Stefan

2010-11-01

Anthropogenic climate change poses a major threat to global biodiversity with a potential to alter biological interactions at all spatial scales. Amphibians are the most threatened vertebrates and have been subject to increasing conservation attention over the past decade. A particular concern is the pandemic emergence of the parasitic chytrid fungus Batrachochytrium dendrobatidis, which has been identified as the cause of extremely rapid large-scale declines and species extinctions. Experimental and observational studies have demonstrated that the host-pathogen system is strongly influenced by climatic parameters and thereby potentially affected by climate change. Herein we project a species distribution model of the pathogen onto future climatic scenarios generated by the IPCC to examine their potential implications on the pandemic. Results suggest that predicted anthropogenic climate change may reduce the geographic range of B. dendrobatidis and its potential influence on amphibian biodiversity.

Efficacy of SYBR 14/propidium iodide viability stain for the amphibian chytrid fungus Batrachochytrium dendrobatidis.

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Stockwell, M P; Clulow, J; Mahony, M J

2010-01-25

The amphibian chytrid fungus Batrachochytrium dendrobatidis is a recently described pathogen that has been implicated as a causal agent in the global decline in amphibians. Research into its biology and epidemiology has frequently involved in vitro experimentation. However, this research is currently limited by the inability to differentiate between viable and inviable zoospores. Stains are frequently used to determine cell viability, and this study tested a 2-colour fluorescence assay for the detection and quantification of viable B. dendrobatidis zoospores. The results show that the nucleic acid stains SYBR 14 and propidium iodide are effective in distinguishing live from dead zoospores, and a protocol has been optimized for their use. This viability assay provides an efficient and reliable tool that will have applications in B. dendrobatidis challenge and amphibian exposure experiments.

Bd on the beach: high prevalence of Batrachochytrium dendrobatidis in the lowland forests of Gorgona Island (Colombia, South America).

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Flechas, Sandra Victoria; Sarmiento, Carolina; Amézquita, Adolfo

2012-09-01

The amphibian chytrid fungus, Batrachochytrium dendrobatidis, Bd, has been implicated in the decimation and extinction of many amphibian populations worldwide, especially at mid and high elevations. Recent studies have demonstrated the presence of the pathogen in the lowlands from Australia and Central America. We extend here its elevational range by demonstrating its presence at the sea level, in the lowland forests of Gorgona Island, off the Pacific coast of Colombia. We conducted two field surveys, separated by four years, and diagnosed Bd by performing polymerase chain reactions on swab samples from the skin of five amphibian species. All species, including the Critically Endangered Atelopus elegans, tested positive for the pathogen, with prevalences between 3.9 % in A. elegans (in 2010) and 52 % in Pristimantis achatinus. Clinical signs of chytridiomycosis were not detected in any species. To our knowledge, this is the first report of B. dendrobatidis in tropical lowlands at sea level, where temperatures may exceed optimal growth temperatures of this pathogen. This finding highlights the need to understand the mechanisms allowing the interaction between frogs and pathogen in lowland ecosystems.

Presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) in rainwater suggests aerial dispersal is possible

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Kolby, Jonathan E.; Sara D. Ramirez,; Lee Berger,; Griffin, Dale W.; Merlijn Jocque,; Lee F. Skerratt,

2015-01-01

Abstract Global spread of the pathogenic amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) may involve dispersal mechanisms not previously explored. Weather systems accompanied by strong wind and rainfall have been known to assist the dispersal of microbes pathogenic to plants and animals, and we considered a similar phenomenon might occur with Bd. We investigated this concept by sampling rainwater from 20 precipitation events for the presence of Bd in Cusuco National Park, Honduras: a site where high Bd prevalence was previously detected in stream-associated amphibians. Quantitative PCR analysis confirmed the presence of Bd in rainwater in one (5 %) of the weather events sampled, although viability cannot be ascertained from molecular presence alone. The source of the Bd and distance that the contaminated rainwater traveled could not be determined; however, this collection site was located approximately 600 m from the nearest observed perennial river by straight-line aerial distance. Although our results suggest atmospheric Bd dispersal is uncommon and unpredictable, even occasional short-distance aerial transport could considerably expand the taxonomic diversity of amphibians vulnerable to exposure and at risk of decline, including terrestrial and arboreal species that are not associated with permanent water bodies.

Molecular mechanisms underlying the emergence of bacterial pathogens: an ecological perspective.

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Bartoli, Claudia; Roux, Fabrice; Lamichhane, Jay Ram

2016-02-01

The rapid emergence of new bacterial diseases negatively affects both human health and agricultural productivity. Although the molecular mechanisms underlying these disease emergences are shared between human- and plant-pathogenic bacteria, not much effort has been made to date to understand disease emergences caused by plant-pathogenic bacteria. In particular, there is a paucity of information in the literature on the role of environmental habitats in which plant-pathogenic bacteria evolve and on the stress factors to which these microbes are unceasingly exposed. In this microreview, we focus on three molecular mechanisms underlying pathogenicity in bacteria, namely mutations, genomic rearrangements and the acquisition of new DNA sequences through horizontal gene transfer (HGT). We briefly discuss the role of these mechanisms in bacterial disease emergence and elucidate how the environment can influence the occurrence and regulation of these molecular mechanisms by directly impacting disease emergence. The understanding of such molecular evolutionary mechanisms and their environmental drivers will represent an important step towards predicting bacterial disease emergence and developing sustainable management strategies for crops. © 2015 BSPP AND JOHN WILEY & SONS LTD.

Differential patterns of Batrachochytrium dendrobatidis infection in relict amphibian populations following severe disease-associated declines.

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Whitfield, Steven M; Alvarado, Gilbert; Abarca, Juan; Zumbado, Hector; Zuñiga, Ibrahim; Wainwright, Mark; Kerby, Jacob

2017-09-20

Global amphibian biodiversity has declined dramatically in the past 4 decades, and many amphibian species have declined to near extinction as a result of emergence of the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). However, persistent or recovering populations of several amphibian species have recently been rediscovered, and such populations may illustrate how amphibian species that are highly susceptible to chytridiomycosis may survive in the presence of Bd. We conducted field surveys for Bd infection in 7 species of Costa Rican amphibians (all species that have declined to near extinction but for which isolated populations persist) to characterize infection profiles in highly Bd-susceptible amphibians post-decline. We found highly variable patterns in infection, with some species showing low prevalence (~10%) and low infection intensity and others showing high infection prevalence (>80%) and either low or high infection intensity. Across sites, infection rates were negatively associated with mean annual precipitation, and infection intensity across sites was negatively associated with mean average temperatures. Our results illustrate that even the most Bd-susceptible amphibians can persist in Bd-enzootic ecosystems, and that multiple ecological or evolutionary mechanisms likely exist for host-pathogen co-existence between Bd and the most Bd-susceptible amphibian species. Continued monitoring of these populations is necessary to evaluate population trends (continuing decline, stability, or population growth). These results should inform efforts to mitigate impacts of Bd on amphibians in the field.

Distribution and risk factors for spread of amphibian chytrid fungus Batrachochytrium dendrobatidis in the Tasmanian Wilderness World Heritage Area, Australia.

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Pauza, Matthew D; Driessen, Michael M; Skerratt, Lee F

2010-11-01

Chytridiomycosis is an emerging infectious disease caused by the pathogen Batrachochytrium dendrobatidis (Bd) and is the cause of the decline and extinction of amphibian species throughout the world. We surveyed the distribution of Bd within and around the Tasmanian Wilderness World Heritage Area (TWWHA), a 1.38 million ha area of significant fauna conservation value, which provides the majority of habitat for Tasmania's 3 endemic frog species (Litoria burrowsae, Bryobatrachus nimbus and Crinia tasmaniensis). Bd was detected at only 1 (3%) of the 33 sites surveyed within the TWWHA and at 15 (52%) of the 29 sites surveyed surrounding the TWWHA. The relatively low incidence of the disease within the TWWHA suggests that the majority of the TWWHA is currently free of the pathogen despite the fact that the region provides what appears to be optimal conditions for the persistence of Bd. For all survey sites within and around the TWWHA, the presence of Bd was strongly associated with the presence of gravel roads, forest and < 1000 m altitude--factors that in this study were associated with human-disturbed landscapes around the TWWHA. Conversely, the presence of walking tracks was strongly associated with the absence of Bd, suggesting an association of absence with relatively remote locations. The wide distribution of Bd in areas of Tasmania with high levels of human disturbance and its very limited occurrence in remote wilderness areas suggests that anthropogenic activities may facilitate the dissemination of the pathogen on a landscape scale in Tasmania. Because the majority of the TWWHA is not readily accessible and appears to be largely free of Bd, and because Tasmanian frogs reproduce in ponds rather than streams, it may be feasible to control the spread of the disease in the TWWHA.

Task 1.5 Genomic Shift and Drift Trends of Emerging Pathogens

Energy Technology Data Exchange (ETDEWEB)

Borucki, M

2010-01-05

The Lawrence Livermore National Laboratory (LLNL) Bioinformatics group has recently taken on a role in DTRA's Transformation Medical Technologies Initiative (TMTI). The high-level goal of TMTI is to accelerate the development of broad-spectrum countermeasures. To achieve those goals, TMTI has a near term need to conduct analyses of genomic shift and drift trends of emerging pathogens, with a focused eye on select agent pathogens, as well as antibiotic and virulence markers. Most emerging human pathogens are zoonotic viruses with a genome composed of RNA. The high mutation rate of the replication enzymes of RNA viruses contributes to sequence drift and provides one mechanism for these viruses to adapt to diverse hosts (interspecies transmission events) and cause new human and zoonotic diseases. Additionally, new viral pathogens frequently emerge due to genetic shift (recombination and segment reassortment) which allows for dramatic genotypic and phenotypic changes to occur rapidly. Bacterial pathogens also evolve via genetic drift and shift, although sequence drift generally occurs at a much slower rate for bacteria as compared to RNA viruses. However, genetic shift such as lateral gene transfer and inter- and intragenomic recombination enables bacteria to rapidly acquire new mechanisms of survival and antibiotic resistance. New technologies such as rapid whole genome sequencing of bacterial genomes, ultra-deep sequencing of RNA virus populations, metagenomic studies of environments rich in antibiotic resistance genes, and the use of microarrays for the detection and characterization of emerging pathogens provide mechanisms to address the challenges posed by the rapid emergence of pathogens. Bioinformatic algorithms that enable efficient analysis of the massive amounts of data generated by these technologies as well computational modeling of protein structures and evolutionary processes need to be developed to allow the technology to fulfill its potential.

Reduced itraconazole concentration and durations are successful in treating Batrachochytrium dendrobatidis infection in amphibians.

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Brannelly, Laura A

2014-03-14

Amphibians are experiencing the greatest decline of any vertebrate class and a leading cause of these declines is a fungal pathogen, Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis. Captive assurance colonies are important worldwide for threatened amphibian species and may be the only lifeline for those in critical threat of extinction. Maintaining disease free colonies is a priority of captive managers, yet safe and effective treatments for all species and across life stages have not been identified. The most widely used chemotherapeutic treatment is itraconazole, although the dosage commonly used can be harmful to some individuals and species. We performed a clinical treatment trial to assess whether a lower and safer but effective dose of itraconazole could be found to cure Bd infections. We found that by reducing the treatment concentration from 0.01-0.0025% and reducing the treatment duration from 11-6 days of 5 min baths, frogs could be cured of Bd infection with fewer side effects and less treatment-associated mortality.

Mycoplasmas and their host: emerging and re-emerging minimal pathogens.

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Citti, Christine; Blanchard, Alain

2013-04-01

Commonly known as mycoplasmas, bacteria of the class Mollicutes include the smallest and simplest life forms capable of self replication outside of a host. Yet, this minimalism hides major human and animal pathogens whose prevalence and occurrence have long been underestimated. Owing to advances in sequencing methods, large data sets have become available for a number of mycoplasma species and strains, providing new diagnostic approaches, typing strategies, and means for comprehensive studies. A broader picture is thus emerging in which mycoplasmas are successful pathogens having evolved a number of mechanisms and strategies for surviving hostile environments and adapting to new niches or hosts. Copyright © 2013 Elsevier Ltd. All rights reserved.

Patterns of Batrachochytrium dendrobatidis transmission between tadpoles in a high-elevation rainforest stream in tropical Australia.

Science.gov (United States)

Hagman, Mattias; Alford, Ross A

2015-08-20

The highly virulent fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a global threat to amphibian biodiversity. Streams and other water bodies are central habitats in the ecology of the disease, particularly in rainforests where they may transport and transmit the pathogen and harbor infected tadpoles that serve as reservoir hosts. We conducted an experiment using larval green-eyed tree frogs Litoria serrata in semi-natural streamside channels to test the hypotheses that (1) the fungus can be transmitted downstream in stream habitats and (2) infection affects tadpole growth and mouthpart loss. Our results showed that transmission can occur downstream in flowing water with no contact between individuals, that newly infected tadpoles suffered increased mouthpart loss in comparison with controls that were never infected and that infected tadpoles grew at reduced rates. Although recently infected tadpoles showed substantial loss of mouthparts, individuals with longstanding infections did not, suggesting that mouthparts may re-grow following initial loss. Our study suggests that any management efforts that can reduce the prevalence of infections in tadpoles may be particularly effective if applied in headwater areas, as their effects are likely to be felt downstream.

Bactericidal assessment of nano-silver on emerging and re-emerging human pathogens.

Science.gov (United States)

Anuj, Samir A; Gajera, Harsukh P; Hirpara, Darshna G; Golakiya, Baljibhai A

2018-04-24

With the threat of the growing number of bacteria resistant to antibiotics, the re-emergence of previously deadly infections and the emergence of new infections, there is an urgent need for novel therapeutic agent. Silver in the nano form, which is being used increasingly as antibacterial agents, may extend its antibacterial application to emerging and re-emerging multidrug-resistant pathogens, the main cause of nosocomial diseases worldwide. In the present study, a completely bottom up method to prepare green nano-silver was used. To explore the action of nano-silver on emerging Bacillus megaterium MTCC 7192 and re-emerging Pseudomonas aeruginosa MTCC 741 pathogenic bacteria, the study includes an analysis of the bacterial membrane damage through Scanning Electron Microscope (SEM) as well as alternation of zeta potential and intracellular leakages. In this work, we observed genuine bactericidal property of nano-silver as compare to broad spectrum antibiotics against emerging and re-emerging mode. After being exposed to nano-silver, the membrane becomes scattered from their original ordered arrangement based on SEM observation. Moreover, our results also suggested that alternation of zeta potential enhanced membrane permeability, and beyond a critical point, it leads to cell death. The leakages of intracellular constituents were confirmed by Gas Chromatography-Mass Spectrometry (GC-MS). In conclusion, the combine results suggested that at a specific dose, nano-silver may destroy the structure of bacterial membrane and depress its activity, which causes bacteria to die eventually. Copyright © 2018 Elsevier GmbH. All rights reserved.

Concurrent ranavirus and Batrachochytrium dendrobatidis infection in captive frogs (Phyllobates and Dendrobates species), The Netherlands, 2012: a first report.

Science.gov (United States)

Kik, Marja; Stege, Marisca; Boonyarittichaikij, Roschong; van Asten, Alphons

2012-11-01

A ranavirus infection with concurrent Batrachochytrium dendrobatidis infection and mortality in captive Phyllobates and Dendrobates species is reported. Greyish skin with hepato- and reno-megaly were evident. Microscopically, Batrachochytrium dendrobatidis was present in the stratum corneum of the hyperkeratotic skin. Intracytoplasmic inclusion bodies were present in erythrocytes and multiple organs. All samples examined tested positive using PCR for the major capsid protein (MCP) gene of ranavirus and the ITS-1-5.8S region of B. dendrobatidis. The sequence obtained showed a 99% identity with the deposited sequence of the MCP gene of the common midwife toad virus (CMTV). This is the first report of mortality in captivity in poison dart frogs caused by a ranavirus, CMTV or like virus, and Batrachochytrium dendrobatidis infection. Copyright © 2012 Elsevier Ltd. All rights reserved.

Occurrence of Batrachochytrium dendrobatidis in anurans of the Mediterranean region of Baja California, México

Science.gov (United States)

Peralta-Garcia, Anny; Adams, Andrea J.; Briggs, Cheryl J.; Galina-Tessaro, Patricia; Valdez-Villavicencio, Jorge H.; Hollingsworth, Bradford; Shaffer, H. Bradley; Fisher, Robert N.

2018-01-01

 Chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and is regarded as one of the most significant threats to global amphibian populations. In México, Bd was first reported in 2003 and has now been documented in 13 states. We visited 33 localities and swabbed 199 wild-caught anurans from 7 species (5 native, 2 exotic) across the Mediterranean region of the state of Baja California. Using quantitative PCR, Bd was detected in 94 individuals (47.2% of samples) at 25 of the 33 survey localities for 5 native and 1 exotic frog species. The exotic Xenopus laevis was the only species that tested completely negative for Bd. We found that remoteness, distance to agricultural land, and elevation were the best predictors of Bd presence. These are the first Bd-positive results for the state of Baja California and its presence should be regarded as an additional conservation threat to the region’s native frog species. 

Actinobaculum schaalii: A truly emerging pathogen?

Science.gov (United States)

Prigent, G.; Perillaud, C.; Amara, M.; Coutard, A.; Blanc, C.; Pangon, B.

2016-01-01

Actinobaculum schaalii is a Gram-positive facultative anaerobe bacillus. It is a commensal organism of the genitourinary tract. Its morphology is nonspecific. Aerobic culture is tedious, and identification techniques have long been inadequate. Thus, A. schaalii has often been considered as a nonpathogen bacterium or a contaminant. Its pathogenicity is now well described in urinary tract infections, and infections in other sites have been reported. This pathogen is considered as an emerging one following the growing use of mass spectrometry identification. In this context, the aim of our study was to evaluate the number of isolations of A. schaalii before and after the introduction of mass spectrometry in our hospital and to study the clinical circumstances in which isolates were found. PMID:27014462

Extremely low prevalence of Batrachochytrium dendrobatidis in frog populations from neotropical dry forest of Costa Rica supports the existence of a climatic refuge from disease.

Science.gov (United States)

Zumbado-Ulate, Héctor; Bolaños, Federico; Gutiérrez-Espeleta, Gustavo; Puschendorf, Robert

2014-12-01

Population declines and extinctions of numerous species of amphibians, especially stream-breeding frogs, have been linked to the emerging infectious disease chytridiomycosis, caused by the chytrid fungus, Batrachochytrium dendrobatidis. In Central America, most of the 34 species of the Craugastor punctariolus species group have disappeared in recent years in high- and low-elevation rainforests. Distribution models for B. dendrobatidis and the continuous presence of the extirpated stream-dwelling species, Craugastor ranoides, in the driest site of Costa Rica (Santa Elena Peninsula), suggest that environmental conditions might restrict the growth and development of B. dendrobatidis, existing as a refuge from chytridiomycosis-driven extinction. We conducted field surveys to detect and quantify the pathogen using Real-time PCR in samples from 15 species of frogs in two locations of tropical dry forest. In Santa Elena Peninsula, we swabbed 310 frogs, and only one sample of the species, C. ranoides, tested positive for B. dendrobatidis (prevalence dry and hot environments of tropical dry forest. This study supports the existence of climatic refuges from chytridiomycosis and highlights the importance of tropical dry forest conservation for amphibians in the face of epidemic disease.

Prevalence of Batrachochytrium dendrobatidis in a Nicaraguan, micro-endemic Neotropical salamander, Bolitoglossa mombachoensis

NARCIS (Netherlands)

Stark, Tariq; Laurijssens, Carlijn; Weterings, Martijn; Martel, An; Köhler, Gunther; Pasmans, Frank

2017-01-01

Amphibians are the most threatened terrestrial vertebrates on the planet and are iconic in the global biodiversity crisis. Their global decline caused by the fungal agent Batrachochytrium dendrobatidis (Bd) is well known. Declines of Mesoamerican salamanders of the family Plethodontidae, mainly

Low prevalence of chytrid fungus (Batrachochytrium dendrobatidis) in amphibians of U.S

Science.gov (United States)

Blake R. Hossack; Michael J. Adams; Evan H. Campbell Grant; Christopher A. Pearl; James B. Bettaso; William J. Barichivich; Winsor H. Lowe; Kimberly True; Joy L. Ware; Paul Stephen Corn

2010-01-01

Many declines of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd). Despite the relatively high prevalence of chytridiomycosis in stream amphibians globally, most surveys in North America have focused primarily on wetland-associated species, which are frequently infected. To...

Rapid emergence of pathogens in agro-ecosystems: global threats to agricultural sustainability and food security.

Science.gov (United States)

McDonald, Bruce A; Stukenbrock, Eva H

2016-12-05

Agricultural ecosystems are composed of genetically depauperate populations of crop plants grown at a high density and over large spatial scales, with the regional composition of crop species changing little from year to year. These environments are highly conducive for the emergence and dissemination of pathogens. The uniform host populations facilitate the specialization of pathogens to particular crop cultivars and allow the build-up of large population sizes. Population genetic and genomic studies have shed light on the evolutionary mechanisms underlying speciation processes, adaptive evolution and long-distance dispersal of highly damaging pathogens in agro-ecosystems. These studies document the speed with which pathogens evolve to overcome crop resistance genes and pesticides. They also show that crop pathogens can be disseminated very quickly across and among continents through human activities. In this review, we discuss how the peculiar architecture of agro-ecosystems facilitates pathogen emergence, evolution and dispersal. We present four example pathosystems that illustrate both pathogen specialization and pathogen speciation, including different time frames for emergence and different mechanisms underlying the emergence process. Lastly, we argue for a re-design of agro-ecosystems that embraces the concept of dynamic diversity to improve their resilience to pathogens. This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Author(s).

Host-pathogen metapopulation dynamics suggest high elevation refugia for boreal toads

Science.gov (United States)

Mosher, Brittany A.; Bailey, Larissa L.; Muths, Erin L.; Huyvaert, Kathryn P

2018-01-01

Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situdisease management. Declines of boreal toads (Anaxyrus boreas boreas) in the Southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic dataset, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be sub-optimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bdsystems. Our data suggest that in the southern Rocky Mountains high elevation sites should be prioritized for conservation initiatives like reintroductions.

Batrachochytrium dendrobatidis not found in rainforest frogs along an altitudinal gradient of Papua New Guinea

Czech Academy of Sciences Publication Activity Database

Dahl, C.; Kiatik, I.; Baisen, I.; Bronikowski, E.; Fleischer, R. C.; Rotzel, N. C.; Lock, J.; Novotný, Vojtěch; Narayan, E.; Hero, J.-M.

2012-01-01

Roč. 22, č. 3 (2012), s. 183-186 ISSN 0268-0130 Institutional support: RVO:60077344 Keywords : altitude * amphibians * Batrachochytrium dendrobatidis Subject RIV: EH - Ecology, Behaviour Impact factor: 1.081, year: 2012

Fluorescent probes as a tool for labelling and tracking the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Science.gov (United States)

Herbert, Sarah M; Leung, Tommy L F; Bishop, Phillip J

2011-09-09

The dissemination of the virulent pathogen Batrachochytrium dendrobatidis (Bd) has contributed to the decline and extinction of many amphibian species worldwide. Several different strains have been identified, some of which are sympatric. Interactions between co-infecting strains of a pathogen can have significant influences on disease epidemiology and evolution; therefore the dynamics of multi-strain infections is an important area of research. We stained Bd cells with 2 fluorescent BODIPY fatty acid probes to determine whether these can potentially be used to distinguish and track Bd cell lines in multi-strain experiments. Bd cells in broth culture were stained with 5 concentrations of green-fluorescent BODIPY FL and red-fluorescent BODIPY 558/568 and visualised under an epifluorescent microscope for up to 16 d post-dye. Dyed strains were also assessed for growth inhibition. The most effective concentration for both dyes was 10 pM. This concentration of dye produced strong fluorescence for 12 to 16 d in Bd cultures held at 23 degrees C (3 to 4 generations), and did not inhibit Bd growth. Cells dyed with BODIPY FL and BODIPY 558/568 can be distinguished from each other on the basis of their fluorescence characteristics. Therefore, it is likely that this technique will be useful for research into multi-strain dynamics of Bd infections.

Role of India's wildlife in the emergence and re-emergence of zoonotic pathogens, risk factors and public health implications.

Science.gov (United States)

Singh, B B; Gajadhar, A A

2014-10-01

Evolving land use practices have led to an increase in interactions at the human/wildlife interface. The presence and poor knowledge of zoonotic pathogens in India's wildlife and the occurrence of enormous human populations interfacing with, and critically linked to, forest ecosystems warrant attention. Factors such as diverse migratory bird populations, climate change, expanding human population and shrinking wildlife habitats play a significant role in the emergence and re-emergence of zoonotic pathogens from India's wildlife. The introduction of a novel Kyasanur forest disease virus (family flaviviridae) into human populations in 1957 and subsequent occurrence of seasonal outbreaks illustrate the key role that India's wild animals play in the emergence and reemergence of zoonotic pathogens. Other high priority zoonotic diseases of wildlife origin which could affect both livestock and humans include influenza, Nipah, Japanese encephalitis, rabies, plague, leptospirosis, anthrax and leishmaniasis. Continuous monitoring of India's extensively diverse and dispersed wildlife is challenging, but their use as indicators should facilitate efficient and rapid disease-outbreak response across the region and occasionally the globe. Defining and prioritizing research on zoonotic pathogens in wildlife are essential, particularly in a multidisciplinary one-world one-health approach which includes human and veterinary medical studies at the wildlife-livestock-human interfaces. This review indicates that wild animals play an important role in the emergence and re-emergence of zoonotic pathogens and provides brief summaries of the zoonotic diseases that have occurred in wild animals in India. Copyright © 2014 Elsevier B.V. All rights reserved.

Batrachochytrium dendrobatidis prevalence and haplotypes in domestic and imported pet amphibians in Japan.

Science.gov (United States)

Tamukai, Kenichi; Une, Yumi; Tominaga, Atsushi; Suzuki, Kazutaka; Goka, Koichi

2014-05-13

The international trade in amphibians is believed to have increased the spread of Batrachochytrium dendrobatidis (Bd), the fungal pathogen responsible for chytridiomycosis, which has caused a rapid decline in amphibian populations worldwide. We surveyed amphibians imported into Japan and those held in captivity for a long period or bred in Japan to clarify the Bd infection status. Samples were taken from 820 individuals of 109 amphibian species between 2008 and 2011 and were analyzed by a nested-PCR assay. Bd prevalence in imported amphibians was 10.3% (58/561), while it was 6.9% (18/259) in those in private collections and commercially bred amphibians in Japan. We identified the genotypes of this fungus using partial DNA sequences of the internal transcribed spacer (ITS) region. Sequencing of PCR products of all 76 Bd-positive samples revealed 11 haplotypes of the Bd ITS region. Haplotype A (DNA Data Bank of Japan accession number AB435211) was found in 90% (52/58) of imported amphibians. The results show that Bd is currently entering Japan via the international trade in exotic amphibians as pets, suggesting that the trade has indeed played a major role in the spread of Bd.

Distribution limits of Batrachochytrium dendrobatidis: a case study in the Rocky Mountains, USA

Science.gov (United States)

Hossack, Blake R.; Muths, Erin L.; Anderson, Chauncey W.; Kirshtein, Julie D.; Corn, P. Stephen

2009-01-01

Knowledge of the environmental constraints on a pathogen is critical to predicting its dynamics and effects on populations. Batrachochytrium dendrobatidis (Bd), an aquatic fungus that has been linked with widespread amphibian declines, is ubiquitous in the Rocky Mountains. As part of assessing the distribution limits of Bd in our study area, we sampled the water column and sediments for Bd zoospores in 30 high-elevation water bodies that lacked amphibians. All water bodies were in areas where Bd has been documented from neighboring, lower-elevation areas. We targeted areas lacking amphibians because existence of Bd independent of amphibians would have both ecologic and management implications. We did not detect Bd, which supports the hypothesis that it does not live independently of amphibians. However, assuming a detection sensitivity of 59.5% (based on sampling of water where amphibians tested positive for Bd), we only had 95% confidence of detecting Bd if it was in > or =16% of our sites. Further investigation into potential abiotic reservoirs is needed, but our results provide a strategic step in determining the distributional and environmental limitations of Bd in our study region.

Novel organisms: comparing invasive species, GMOs, and emerging pathogens.

Science.gov (United States)

Jeschke, Jonathan M; Keesing, Felicia; Ostfeld, Richard S

2013-09-01

Invasive species, range-expanding species, genetically modified organisms (GMOs), synthetic organisms, and emerging pathogens increasingly affect the human environment. We propose a framework that allows comparison of consecutive stages that such novel organisms go through. The framework provides a common terminology for novel organisms, facilitating knowledge exchange among researchers, managers, and policy makers that work on, or have to make effective decisions about, novel organisms. The framework also indicates that knowledge about the causes and consequences of stage transitions for the better studied novel organisms, such as invasive species, can be transferred to more poorly studied ones, such as GMOs and emerging pathogens. Finally, the framework advances understanding of how climate change can affect the establishment, spread, and impacts of novel organisms, and how biodiversity affects, and is affected by, novel organisms.

Meningitis secondary to Cryptococcus gattii,an emerging pathogen affecting immunocompetent hosts

Institute of Scientific and Technical Information of China (English)

Laura Cookman; Maria Hugi

2013-01-01

BACKGROUND:Meningitis continues to be one of the most important infections diagnosed and treated by emergency physicians.Despite the advent of anti-infective therapy,meningitis carries a mortality rate of 20%-40%.In this study,we describe the first reported emergency medicine case of meningitis associated with Cryptococcus gattii to alert providers of this insidious,emerging global pathogen infecting immunocompetent individuals.METHODS:We provided a case report and accompanying review of the literature.A MEDLINE search for the term Cryptoccocus gattii was performed to obtain background information on Cryptococcus gattii.RESULTS:After two months of hospitalization,the patient was eventually discharged neurologically intact except for a continued mild bilateral hearing deficit.CONCLUSION:Cryptococcus gattii is an emerging world pathogen,which affects otherwise healthy,immunocompetent patients and requires timely identification and treatment in order to prevent severe neurological sequelae.

Unlocking the story in the swab: A new genotyping assay for the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Science.gov (United States)

Byrne, Allison Q; Rothstein, Andrew P; Poorten, Thomas J; Erens, Jesse; Settles, Matthew L; Rosenblum, Erica Bree

2017-11-01

One of the most devastating emerging pathogens of wildlife is the chytrid fungus, Batrachochytrium dendrobatidis (Bd), which affects hundreds of amphibian species around the world. Genomic data from pure Bd cultures have advanced our understanding of Bd phylogenetics, genomic architecture and mechanisms of virulence. However, pure cultures are laborious to obtain and whole-genome sequencing is comparatively expensive, so relatively few isolates have been genetically characterized. Thus, we still know little about the genetic diversity of Bd in natural systems. The most common noninvasive method of sampling Bd from natural populations is to swab amphibian skin. Hundreds of thousands of swabs have been collected from amphibians around the world, but Bd DNA collected via swabs is often low in quality and/or quantity. In this study, we developed a custom Bd genotyping assay using the Fluidigm Access Array platform to amplify 192 carefully selected regions of the Bd genome. We obtained robust sequence data for pure Bd cultures and field-collected skin swabs. This new assay has the power to accurately discriminate among the major Bd clades, recovering the basic tree topology previously revealed using whole-genome data. Additionally, we established a critical value for initial Bd load for swab samples (150 Bd genomic equivalents) above which our assay performs well. By leveraging advances in microfluidic multiplex PCR technology and the globally distributed resource of amphibian swab samples, noninvasive skin swabs can now be used to address critical spatial and temporal questions about Bd and its effects on declining amphibian populations. © 2017 John Wiley & Sons Ltd.

Bacterial genomics reveal the complex epidemiology of an emerging pathogen in arctic and boreal ungulates

Science.gov (United States)

Forde, Taya L.; Orsel, Karin; Zadoks, Ruth N.; Biek, Roman; Adams, Layne G.; Checkley, Sylvia L.; Davison, Tracy; De Buck, Jeroen; Dumond, Mathieu; Elkin, Brett T.; Finnegan, Laura; Macbeth, Bryan J.; Nelson, Cait; Niptanatiak, Amanda; Sather, Shane; Schwantje, Helen M.; van der Meer, Frank; Kutz, Susan J.

2016-01-01

Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors.

Candida glabrata: an emerging oral opportunistic pathogen.

Science.gov (United States)

Li, L; Redding, S; Dongari-Bagtzoglou, A

2007-03-01

Following the widespread use of immunosuppressive therapy and broad-spectrum antimycotic prophylaxis, C. glabrata has emerged as an important opportunistic pathogen in the oral mucosa. In the past, studies on the virulence factors and host-pathogen interactions of this organism were scarce, but continued to rise in recent years. Denture-wearing, immunosuppression, antibiotic therapy, and aging are risk factors for oral colonization or infection with C. glabrata. Compared with C. albicans, C. glabrata exhibits lower oral keratinocyte-adherence capacity, but higher denture-surface-adherence ability. The role of extracellular hydrolase production in the virulence of this organism does not appear to be as important as it is in C. albicans pathogenesis. Although traditionally thought of as a non-transforming yeast organism, both phenotypic switching and pseudohyphal formation have recently been identified in C. glabrata, but their role in pathogenesis is not known. With the exception of granulocyte monocyte colony-stimulating factor, C. glabrata triggers a lower proinflammatory cytokine response in oral epithelial cells than does C. albicans, in a strain-dependent manner. C. glabrata is less susceptible to killing by human beta-defensins than is C. albicans and exhibits various degrees of resistance to the antifungal activity of salivary histatins and mucins. In addition, C. glabrata possesses both innate and acquired resistance against antifungal drugs, due to its ability to modify ergosterol biosynthesis, mitochondrial function, or antifungal efflux. This resistance allows for its relative overgrowth over other susceptible species and may contribute to the recent emergence of C. glabrata infections in chronically immunocompromised populations. Further investigations on the virulence and host-pathogen interactions of C. glabrata are needed to better define the pathogenesis of oral C. glabrata infection in susceptible hosts.

Campylobacter ureolyticus: an emerging gastrointestinal pathogen?

LENUS (Irish Health Repository)

Bullman, Susan

2011-03-01

A total of 7194 faecal samples collected over a 1-year period from patients presenting with diarrhoea were screened for Campylobacter spp. using EntericBio(®) , a multiplex-PCR system. Of 349 Campylobacter-positive samples, 23.8% were shown to be Campylobacter ureolyticus, using a combination of 16S rRNA gene analysis and highly specific primers targeting the HSP60 gene of this organism. This is, to the best of our knowledge, the first report of C. ureolyticus in the faeces of patients presenting with gastroenteritis and may suggest a role for this organism as an emerging enteric pathogen.

Hantaviruses in the Americas and Their Role as Emerging Pathogens

Directory of Open Access Journals (Sweden)

Fernando Torres-Pérez

2010-11-01

Full Text Available The continued emergence and re-emergence of pathogens represent an ongoing, sometimes major, threat to populations. Hantaviruses (family Bunyaviridae and their associated human diseases were considered to be confined to Eurasia, but the occurrence of an outbreak in 1993–94 in the southwestern United States led to a great increase in their study among virologists worldwide. Well over 40 hantaviral genotypes have been described, the large majority since 1993, and nearly half of them pathogenic for humans. Hantaviruses cause persistent infections in their reservoir hosts, and in the Americas, human disease is manifest as a cardiopulmonary compromise, hantavirus cardiopulmonary syndrome (HCPS, with case-fatality ratios, for the most common viral serotypes, between 30% and 40%. Habitat disturbance and larger-scale ecological disturbances, perhaps including climate change, are among the factors that may have increased the human caseload of HCPS between 1993 and the present. We consider here the features that influence the structure of host population dynamics that may lead to viral outbreaks, as well as the macromolecular determinants of hantaviruses that have been regarded as having potential contribution to pathogenicity.

Candida auris: An emerging multidrug-resistant pathogen

Directory of Open Access Journals (Sweden)

David Sears

2017-10-01

Full Text Available Candida aurisis an emerging multidrug-resistant pathogen that can be difficult to identify using traditional biochemical methods. C. auris is capable of causing invasive fungal infections, particularly among hospitalized patients with significant medical comorbidities. Echinocandins are the empiric drugs of choice for C. auris, although not all isolates are susceptible and resistance may develop on therapy. Nosocomial C. auris outbreaks have been reported in a number of countries and aggressive infection control measures are paramount to stopping transmission.

Salamander chytrid fungus (Batrachochytrium salamandrivorans) in the United States—Developing research, monitoring, and management strategies

Science.gov (United States)

Grant, Evan H. Campbell; Muths, Erin L.; Katz, Rachel A.; Canessa, Stefano; Adams, Michael J.; Ballard, Jennifer R.; Berger, Lee; Briggs, Cheryl J.; Coleman, Jeremy; Gray, Matthew J.; Harris, M. Camille; Harris, Reid N.; Hossack, Blake R.; Huyvaert, Kathryn P.; Kolby, Jonathan E.; Lips, Karen R.; Lovich, Robert E.; McCallum, Hamish I.; Mendelson, Joseph R.; Nanjappa, Priya; Olson, Deanna H.; Powers, Jenny G.; Richgels, Katherine L. D.; Russell, Robin E.; Schmidt, Benedikt R.; Spitzen-van der Sluijs, Annemarieke; Watry, Mary Kay; Woodhams, Douglas C.; White, C. LeAnn

2016-01-20

The recently (2013) identified pathogenic chytrid fungus, Batrachochytrium salamandrivorans (Bsal), poses a severe threat to the distribution and abundance of salamanders within the United States and Europe. Development of a response strategy for the potential, and likely, invasion of Bsal into the United States is crucial to protect global salamander biodiversity. A formal working group, led by Amphibian Research and Monitoring Initiative (ARMI) scientists from the U.S. Geological Survey (USGS) Patuxent Wildlife Research Center, Fort Collins Science Center, and Forest and Rangeland Ecosystem Science Center, was held at the USGS Powell Center for Analysis and Synthesis in Fort Collins, Colorado, United States from June 23 to June 25, 2015, to identify crucial Bsal research and monitoring needs that could inform conservation and management strategies for salamanders in the United States. Key findings of the workshop included the following: (1) the introduction of Bsal into the United States is highly probable, if not inevitable, thus requiring development of immediate short-term and long-term intervention strategies to prevent Bsal establishment and biodiversity decline; (2) management actions targeted towards pathogen containment may be ineffective in reducing the long-term spread of Bsal throughout the United States; and (3) early detection of Bsal through surveillance at key amphibian import locations, among high-risk wild populations, and through analysis of archived samples is necessary for developing management responses. Top research priorities during the preinvasion stage included the following: (1) deployment of qualified diagnostic methods for Bsal and establishment of standardized laboratory practices, (2) assessment of susceptibility for amphibian hosts (including anurans), and (3) development and evaluation of short- and long-term pathogen intervention and management strategies. Several outcomes were achieved during the workshop, including development

Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians.

Science.gov (United States)

Bataille, Arnaud; Fong, Jonathan J; Cha, Moonsuk; Wogan, Guinevere O U; Baek, Hae Jun; Lee, Hang; Min, Mi-Sook; Waldman, Bruce

2013-08-01

Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage ('Bd-GPL'). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus. Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations. © 2013 John Wiley & Sons Ltd.

Methods for Discovery and Surveillance of Pathogens in Hotspots of Emerging Infectious Diseases

DEFF Research Database (Denmark)

Jensen, Randi Holm

Viruses are everywhere, and can infect all living things. They are constantly evolving, and new diseases are emerging as a result. Consequently, they have always been of interest to scientists and people in general. Several outbreaks of emerging infectious diseases transmitting from animals...... to virion enrichment compared to samples with no enrichment. We have used these methods to perform pathogen discovery in faecal samples collected from small mammals in Sierra Leone, to describe the presence of pathogenic viruses and bacteria in this area. From these data we were furthermore able to acquire...

Vibrio parahaemolyticus- An emerging foodborne pathogen

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S Nelapati

2012-02-01

Full Text Available Vibrio parahaemolyticus is a halophilic gram negative, motile, oxidase positive, straight or curved rod-shaped, facultative anaerobic bacteria that occur naturally in the marine environment. They form part of the indigenous microflora of aquatic habitats of various salinity and are the major causative agents for some of the most serious diseases in fish, shellfish and penacid shrimp. This human pathogen causes acute gastroenteritis characterized by diarrhea, vomiting and abdominal cramps through consumption of contaminated raw fish or shellfish. V. parahaemolyticus is the leading cause of gastroenteritis due to the consumption of seafood worldwide. The incidence of V. parahaemolyticus infection has been increasing in many parts of the world, due to the emergence of O3:K6 serotype carrying the tdh gene which is responsible for most outbreaks worldwide. The pathogenicity of this organism is closely correlated with the Kanagawa phenomenon (KP + due to production of Kanagawa hemolysin or the thermostable direct hemolysin (TDH. The TDH and TRH (TDH-related hemolysin encoded by tdh and trh genes are considered to be important virulence factors. [Vet. World 2012; 5(1.000: 48-63

Case Study of Airborne Pathogen Dispersion Patterns in Emergency Departments with Different Ventilation and Partition Conditions.

Science.gov (United States)

Cheong, Chang Heon; Lee, Seonhye

2018-03-13

The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate. Installing partitions between the beds and changing the ventilation system's inlet and outlet diffuser positions contributed only minimally to reducing the concentration of airborne pathogens.

The plant pathogen Phytophthora andina emerged via hybridization of an unknown Phytophthora species and the Irish potato famine pathogen, P. infestans.

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Erica M Goss

Full Text Available Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c.

Epidemiology of Rhodotorula: An Emerging Pathogen

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Wirth, Fernanda; Goldani, Luciano Z.

2012-01-01

This is an updated paper focusing on the general epidemiological aspects of Rhodotorula in humans, animals, and the environment. Previously considered nonpathogenic, Rhodotorula species have emerged as opportunistic pathogens that have the ability to colonise and infect susceptible patients. Rhodotorula species are ubiquitous saprophytic yeasts that can be recovered from many environmental sources. Several authors describe the isolation of this fungus from different ecosystems, including sites with unfavourable conditions. Compared to R. mucilaginosa, R. glutinis and R. minuta are less frequently isolated from natural environments. Among the few references to the pathogenicity of Rhodotorula spp. in animals, there are several reports of an outbreak of skin infections in chickens and sea animals and lung infections and otitis in sheep and cattle. Most of the cases of infection due to Rhodotorula in humans were fungemia associated with central venous catheter (CVC) use. The most common underlying diseases included solid and haematologic malignancies in patients who were receiving corticosteroids and cytotoxic drugs, the presence of CVC, and the use of broad-spectrum antibiotics. Unlike fungemia, some of the other localised infections caused by Rhodotorula, including meningeal, skin, ocular, peritoneal, and prosthetic joint infections, are not necessarily linked to the use of CVCs or immunosuppression. PMID:23091485

Chytrid Fungus, Batrachochytrium dendrobatidis , in Wild Populations of the Lake Titicaca Frog, Telmatobius culeus, in Peru.

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Berenguel, Raul A; Elias, Roberto K; Weaver, Thomas J; Reading, Richard P

2016-10-01

The Lake Titicaca frog (Telmatobius culeus) is critically endangered, primarily from overexploitation. However, additional threats, such as chytrid fungus ( Batrachochytrium dendrobatidis ), are poorly studied. We found moderate levels of chytrid infection using quantitative PCR. Our results enhance our understanding of chytrid tolerance to high pH and low water temperature.

Detection of Emerging and Re-Emerging Pathogens in Surface Waters Close to an Urban Area

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Stefania Marcheggiani

2015-05-01

upstream of Rome and the downstream location was contaminated by emerging and re-emerging pathogens.

Evidence for acquisition of virulence effectors in pathogenic chytrids

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Summers Kyle

2011-07-01

Full Text Available Abstract Background The decline in amphibian populations across the world is frequently linked to the infection of the chytrid fungus Batrachochytrium dendrobatidis (Bd. This is particularly perplexing because Bd was only recently discovered in 1999 and no chytrid fungus had previously been identified as a vertebrate pathogen. Results In this study, we show that two large families of known virulence effector genes, crinkler (CRN proteins and serine peptidases, were acquired by Bd from oomycete pathogens and bacteria, respectively. These two families have been duplicated after their acquisition by Bd. Additional selection analyses indicate that both families evolved under strong positive selection, suggesting that they are involved in the adaptation of Bd to its hosts. Conclusions We propose that the acquisition of virulence effectors, in combination with habitat disruption and climate change, may have driven the Bd epidemics and the decline in amphibian populations. This finding provides a starting point for biochemical investigations of chytridiomycosis.

Emerging horizons for tick-borne pathogens: from the "one pathogen-one disease" vision to the pathobiome paradigm

Czech Academy of Sciences Publication Activity Database

Vayssier-Taussat, M.; Kazimírová, M.; Hubálek, Zdeněk; Hornok, S.; Farkas, R.; Cosson, J.-F.; Bonnet, S.; Vourch, G.; Gasqui, P.; Mihalca, A. D.; Plantard, O.; Silaghi, C.; Cutler, S.; Rizzoli, A.

2015-01-01

Roč. 10, č. 12 (2015), s. 2033-2043 ISSN 1746-0913 Institutional support: RVO:68081766 Keywords : co-infections * emerging diseases * Ixodes ricinus * new paradigm * next-generation sequencing * pathobiome * unknown pathogens * vector competence * zoonoses Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.637, year: 2015

Amphibian commerce as a likely source of pathogen pollution.

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Picco, Angela M; Collins, James P

2008-12-01

The commercial trade of wildlife occurs on a global scale. In addition to removing animals from their native populations, this trade may lead to the release and subsequent introduction of nonindigenous species and the pathogens they carry. Emerging infectious diseases, such as chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), and ranaviral disease have spread with global trade in amphibians and are linked to amphibian declines and die-offs worldwide, which suggests that the commercial trade in amphibians may be a source of pathogen pollution. We screened tiger salamanders involved in the bait trade in the western United States for both ranaviruses and Bd with polymerase chain reaction and used oral reports from bait shops and ranavirus DNA sequences from infected bait salamanders to determine how these animals and their pathogens are moved geographically by commerce. In addition, we conducted 2 surveys of anglers to determine how often tiger salamanders are used as bait and how often they are released into fishing waters by anglers, and organized bait-shop surveys to determine whether tiger salamanders are released back into the wild after being housed in bait shops. Ranaviruses were detected in the tiger salamander bait trade in Arizona, Colorado, and New Mexico, and Bd was detected in Arizona bait shops. Ranaviruses were spread geographically through the bait trade. All tiger salamanders in the bait trade were collected from the wild, and in general they moved east to west and north to south, bringing with them their multiple ranavirus strains. Finally, 26-73% of anglers used tiger salamanders as fishing bait, 26-67% of anglers released tiger salamanders bought as bait into fishing waters, and 4% of bait shops released tiger salamanders back into the wild after they were housed in shops with infected animals. The tiger salamander bait trade in the western United States is a useful model for understanding the consequences of the

Phylogenetic Analysis and Antimicrobial Profiles of Cultured Emerging Opportunistic Pathogens (Phyla Actinobacteria and Proteobacteria) Identified in Hot Springs.

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Jardine, Jocelyn Leonie; Abia, Akebe Luther King; Mavumengwana, Vuyo; Ubomba-Jaswa, Eunice

2017-09-15

Hot spring water may harbour emerging waterborne opportunistic pathogens that can cause infections in humans. We have investigated the diversity and antimicrobial resistance of culturable emerging and opportunistic bacterial pathogens, in water and sediment of hot springs located in Limpopo, South Africa. Aerobic bacteria were cultured and identified using 16S ribosomal DNA (rDNA) gene sequencing. The presence of Legionella spp. was investigated using real-time polymerase chain reaction. Isolates were tested for resistance to ten antibiotics representing six different classes: β-lactam (carbenicillin), aminoglycosides (gentamycin, kanamycin, streptomycin), tetracycline, amphenicols (chloramphenicol, ceftriaxone), sulphonamides (co-trimoxazole) and quinolones (nalidixic acid, norfloxacin). Gram-positive Kocuria sp. and Arthrobacter sp. and gram-negative Cupriavidus sp., Ralstonia sp., Cronobacter sp., Tepidimonas sp., Hafnia sp. and Sphingomonas sp. were isolated, all recognised as emerging food-borne pathogens. Legionella spp. was not detected throughout the study. Isolates of Kocuria , Arthrobacter and Hafnia and an unknown species of the class Gammaproteobacteria were resistant to two antibiotics in different combinations of carbenicillin, ceftriaxone, nalidixic acid and chloramphenicol. Cronobacter sp. was sensitive to all ten antibiotics. This study suggests that hot springs are potential reservoirs for emerging opportunistic pathogens, including multiple antibiotic resistant strains, and highlights the presence of unknown populations of emerging and potential waterborne opportunistic pathogens in the environment.

The Emerging Amphibian Fungal Disease, Chytridiomycosis: A Key Example of the Global Phenomenon of Wildlife Emerging Infectious Diseases.

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Kolby, Jonathan E; Daszak, Peter

2016-06-01

The spread of amphibian chytrid fungus, Batrachochytrium dendrobatidis, is associated with the emerging infectious wildlife disease chytridiomycosis. This fungus poses an overwhelming threat to global amphibian biodiversity and is contributing toward population declines and extinctions worldwide. Extremely low host-species specificity potentially threatens thousands of the 7,000+ amphibian species with infection, and hosts in additional classes of organisms have now also been identified, including crayfish and nematode worms.Soon after the discovery of B. dendrobatidis in 1999, it became apparent that this pathogen was already pandemic; dozens of countries and hundreds of amphibian species had already been exposed. The timeline of B. dendrobatidis's global emergence still remains a mystery, as does its point of origin. The reason why B. dendrobatidis seems to have only recently increased in virulence to catalyze this global disease event remains unknown, and despite 15 years of investigation, this wildlife pandemic continues primarily uncontrolled. Some disease treatments are effective on animals held in captivity, but there is currently no proven method to eradicate B. dendrobatidis from an affected habitat, nor have we been able to protect new regions from exposure despite knowledge of an approaching "wave" of B. dendrobatidis and ensuing disease.International spread of B. dendrobatidis is largely facilitated by the commercial trade in live amphibians. Chytridiomycosis was recently listed as a globally notifiable disease by the World Organization for Animal Health, but few countries, if any, have formally adopted recommended measures to control its spread. Wildlife diseases continue to emerge as a consequence of globalization, and greater effort is urgently needed to protect global health.

Population genomic insights into the emergence, crop-adaptation and dissemination of Pseudomonas syringae pathogens

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Although pathogen strains that cause disease outbreaks are often well characterized, relatively little is known about the reservoir populations from which they emerge. Genomic comparison of outbreak strains with isolates of reservoir populations can give new insight into mechanisms of disease emerge...

The Emerging British Verticillium longisporum Population Consists of Aggressive Brassica Pathogens.

Science.gov (United States)

Depotter, Jasper R L; Rodriguez-Moreno, Luis; Thomma, Bart P H J; Wood, Thomas A

2017-11-01

Verticillium longisporum is an economically important fungal pathogen of brassicaceous crops that originated from at least three hybridization events between different Verticillium spp., leading to the hybrid lineages A1/D1, A1/D2, and A1/D3. Isolates of lineage A1/D1 generally cause stem striping on oilseed rape (Brassica napus), which has recently been reported for the first time to occur in the United Kingdom. Intriguingly, the emerging U.K. population is distinct from the north-central European stem striping population. Little is known about the pathogenicity of the newly emerged U.K. population; hence, pathogenicity tests were executed to compare British isolates to previously characterized reference strains. In addition to the model plant Arabidopsis thaliana, the pathogenicity of four British isolates was assessed on four cultivars of three Brassica crop species: oilseed rape (Quartz and Incentive), cauliflower (Clapton), and Chinese cabbage (Hilton). To this end, vascular discoloration of the roots, plant biomass accumulations, and fungal stem colonization upon isolate infection were evaluated. The British isolates appeared to be remarkably aggressive, because plant biomass was significantly affected and severe vascular discoloration was observed. The British isolates were successful stem colonizers and the extent of fungal colonization negatively correlated with plant biomass of cauliflower and Quartz oilseed rape. However, in Quartz, the fungal colonization of A1/D1 isolates was significantly lower than that of the virulent reference isolate from lineage A1/D3, PD589. Moreover, despite levels of stem colonization similar to those of A1/D1 strains, PD589 did not cause significant disease on Incentive. Thus, A1/D1 isolates, including British isolates, are aggressive oilseed rape pathogens despite limited colonization levels in comparison with a virulent A1/D3 isolate.

Emerging tuberculosis pathogen hijacks social communication behavior in the group-living banded mongoose (Mungos mungo)

Science.gov (United States)

Mycobacterium mungi, a novel M. tuberculosis complex pathogen (MtbC), has emerged in wild banded mongoose (Mungos mungo) in Northern Botswana, causing significant mortality. Unlike other members of the MtbC, M. mungi is not transmitted through a primary aerosol route. Rather, pathogen invasion occur...

Short-term exposure to warm microhabitats could explain amphibian persistence with Batrachochytrium dendrobatidis.

Science.gov (United States)

Daskin, Joshua H; Alford, Ross A; Puschendorf, Robert

2011-01-01

Environmental conditions can alter the outcomes of symbiotic interactions. Many amphibian species have declined due to chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), but many others persist despite high Bd infection prevalence. This indicates that Bd's virulence is lower, or it may even be a commensal, in some hosts. In the Australian Wet Tropics, chytridiomycosis extirpated Litoria nannotis from high-elevation rain forests in the early 1990 s. Although the species is recolonizing many sites, no population has fully recovered. Litoria lorica disappeared from all known sites in the early 1990 s and was thought globally extinct, but a new population was discovered in 2008, in an upland dry forest habitat it shares with L. nannotis. All frogs of both species observed during three population censuses were apparently healthy, but most carried Bd. Frogs perch on sun-warmed rocks in dry forest streams, possibly keeping Bd infections below the lethal threshold attained in cooler rain forests. We tested whether short-term elevated temperatures can hamper Bd growth in vitro over one generation (four days). Simulating the temperatures available to frogs on strongly and moderately warmed rocks in dry forests, by incubating cultures at 33°C for one hour daily, reduced Bd growth below that of Bd held at 15°C constantly (representing rain forest habitats). Even small decreases in the exponential growth rate of Bd on hosts may contribute to the survival of frogs in dry forests.

Short-term exposure to warm microhabitats could explain amphibian persistence with Batrachochytrium dendrobatidis.

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Joshua H Daskin

Full Text Available Environmental conditions can alter the outcomes of symbiotic interactions. Many amphibian species have declined due to chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd, but many others persist despite high Bd infection prevalence. This indicates that Bd's virulence is lower, or it may even be a commensal, in some hosts. In the Australian Wet Tropics, chytridiomycosis extirpated Litoria nannotis from high-elevation rain forests in the early 1990 s. Although the species is recolonizing many sites, no population has fully recovered. Litoria lorica disappeared from all known sites in the early 1990 s and was thought globally extinct, but a new population was discovered in 2008, in an upland dry forest habitat it shares with L. nannotis. All frogs of both species observed during three population censuses were apparently healthy, but most carried Bd. Frogs perch on sun-warmed rocks in dry forest streams, possibly keeping Bd infections below the lethal threshold attained in cooler rain forests. We tested whether short-term elevated temperatures can hamper Bd growth in vitro over one generation (four days. Simulating the temperatures available to frogs on strongly and moderately warmed rocks in dry forests, by incubating cultures at 33°C for one hour daily, reduced Bd growth below that of Bd held at 15°C constantly (representing rain forest habitats. Even small decreases in the exponential growth rate of Bd on hosts may contribute to the survival of frogs in dry forests.

Species-level correlates of susceptibility to the pathogenic amphibian fungus Batrachochytrium dendrobatidis in the United States

Science.gov (United States)

Betsy A. Bancroft; Barbara A. Han; Catherine L. Searle; Lindsay M. Biga; Deanna H. Olson; Lee B. Kats; Joshua J. Lawler; Andrew R. Blaustein

2011-01-01

Disease is often implicated as a factor in population declines of wildlife and plants. Understanding the characteristics that may predispose a species to infection by a particular pathogen can help direct conservation efforts. Recent declines in amphibian populations world-wide are a major conservation issue and may be caused in part by a fungal pathogen, ...

Imperfect pathogen detection from non-invasive skin swabs biases disease inference

Science.gov (United States)

DiRenzo, Graziella V.; Grant, Evan H. Campbell; Longo, Ana; Che-Castaldo, Christian; Zamudio, Kelly R.; Lips, Karen

2018-01-01

1. Conservation managers rely on accurate estimates of disease parameters, such as pathogen prevalence and infection intensity, to assess disease status of a host population. However, these disease metrics may be biased if low-level infection intensities are missed by sampling methods or laboratory diagnostic tests. These false negatives underestimate pathogen prevalence and overestimate mean infection intensity of infected individuals. 2. Our objectives were two-fold. First, we quantified false negative error rates of Batrachochytrium dendrobatidis on non-invasive skin swabs collected from an amphibian community in El Copé, Panama. We swabbed amphibians twice in sequence, and we used a recently developed hierarchical Bayesian estimator to assess disease status of the population. Second, we developed a novel hierarchical Bayesian model to simultaneously account for imperfect pathogen detection from field sampling and laboratory diagnostic testing. We evaluated the performance of the model using simulations and varying sampling design to quantify the magnitude of bias in estimates of pathogen prevalence and infection intensity. 3. We show that Bd detection probability from skin swabs was related to host infection intensity, where Bd infections information in advance, we advocate that the most cautious approach is to assume all errors are possible and to accommodate them by adjusting sampling designs. The modeling framework presented here improves the accuracy in estimating pathogen prevalence and infection intensity.

Impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.

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Jes Johannesen

Full Text Available Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a and its vector (Hyalesthes obsoletus: Cixiidae affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector.

Composition of Micro-eukaryotes on the Skin of the Cascades Frog (Rana cascadae and Patterns of Correlation between Skin Microbes and Batrachochytrium dendrobatidis

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Jordan G. Kueneman

2017-12-01

Full Text Available Global amphibian decline linked to fungal pathogens has galvanized research on applied amphibian conservation. Skin-associated bacterial communities of amphibians have been shown to mediate fungal skin infections and the development of probiotic treatments with antifungal bacteria has become an emergent area of research. While exploring the role of protective bacteria has been a primary focus for amphibian conservation, we aim to expand and study the other microbes present in amphibian skin communities including fungi and other micro-eukaryotes. Here, we characterize skin-associated bacteria and micro-eukaryotic diversity found across life stages of Cascades frog (Rana cascadae and their associated aquatic environments using culture independent 16S and 18S rRNA marker-gene sequencing. Individuals of various life stages of Cascades frogs were sampled from a population located in the Trinity Alps in Northern California during an epidemic of the chytrid fungus, Batrachochytrium dendrobatidis. We filtered the bacterial sequences against a published database of bacteria known to inhibit B. dendrobatidis in co-culture to estimate the proportion of the skin bacterial community that is likely to provide defense against B. dendrobatidis. Tadpoles had a significantly higher proportion of B. dendrobatidis-inhibitory bacterial sequence matches relative to subadult and adult Cascades frogs. We applied a network analysis to examine patterns of correlation between bacterial taxa and B. dendrobatidis, as well as micro-eukaryotic taxa and B. dendrobatidis. Combined with the published database of bacteria known to inhibit B. dendrobatidis, we used the network analysis to identify bacteria that negatively correlated with B. dendrobatidis and thus could be good probiotic candidates in the Cascades frog system.

Making vaccines "on demand": a potential solution for emerging pathogens and biodefense?

Science.gov (United States)

De Groot, Anne S; Einck, Leo; Moise, Leonard; Chambers, Michael; Ballantyne, John; Malone, Robert W; Ardito, Matthew; Martin, William

2013-09-01

The integrated US Public Health Emergency Medical Countermeasures Enterprise (PHEMCE) has made great strides in strategic preparedness and response capabilities. There have been numerous advances in planning, biothreat countermeasure development, licensure, manufacturing, stockpiling and deployment. Increased biodefense surveillance capability has dramatically improved, while new tools and increased awareness have fostered rapid identification of new potential public health pathogens. Unfortunately, structural delays in vaccine design, development, manufacture, clinical testing and licensure processes remain significant obstacles to an effective national biodefense rapid response capability. This is particularly true for the very real threat of "novel pathogens" such as the avian-origin influenzas H7N9 and H5N1, and new coronaviruses such as hCoV-EMC. Conventional approaches to vaccine development, production, clinical testing and licensure are incompatible with the prompt deployment needed for an effective public health response. An alternative approach, proposed here, is to apply computational vaccine design tools and rapid production technologies that now make it possible to engineer vaccines for novel emerging pathogen and WMD biowarfare agent countermeasures in record time. These new tools have the potential to significantly reduce the time needed to design string-of-epitope vaccines for previously unknown pathogens. The design process-from genome to gene sequence, ready to insert in a DNA plasmid-can now be accomplished in less than 24 h. While these vaccines are by no means "standard," the need for innovation in the vaccine design and production process is great. Should such vaccines be developed, their 60-d start-to-finish timeline would represent a 2-fold faster response than the current standard.

Using omics and integrated multi-omics approaches to guide probiotic selection to mitigate chytridiomycosis and other emerging infectious diseases

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Eria Alaide Rebollar

2016-02-01

Full Text Available Emerging infectious diseases in wildlife are responsible for massive population declines. In amphibians, chytridiomycosis caused by Batrachochytrium dendrobatidis, Bd, has severely affected many amphibian populations and species around the world. One promising management strategy is probiotic bioaugmentation of antifungal bacteria on amphibian skin. In vivo experimental trials using bioaugmentation strategies have had mixed results, and therefore a more informed strategy is needed to select successful probiotic candidates. Metagenomic, transcriptomic, and metabolomic methods, colloquially called omics, are approaches that can better inform probiotic selection and optimize selection protocols. The integration of multiple omic data using bioinformatic and statistical tools and in silico models that link bacterial community structure with bacterial defensive function can allow the identification of species involved in pathogen inhibition. We recommend using 16S rRNA gene amplicon sequencing and methods such as indicator species analysis, the K-S Measure, and co-occurrence networks to identify bacteria that are associated with pathogen resistance in field surveys and experimental trials. In addition to 16S amplicon sequencing, we recommend approaches that give insight into symbiont function such as shotgun metagenomics, metatranscriptomics or metabolomics to maximize the probability of finding effective probiotic candidates, which can then be isolated in culture and tested in persistence and clinical trials. An effective mitigation strategy to ameliorate chytridiomycosis and other emerging infectious diseases is necessary; the advancement of omic methods and the integration of multiple omic data provide a promising avenue toward conservation of imperiled species.

Experimental single-strain mobilomics reveals events that shape pathogen emergence.

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Schoeniger, Joseph S; Hudson, Corey M; Bent, Zachary W; Sinha, Anupama; Williams, Kelly P

2016-08-19

Virulence genes on mobile DNAs such as genomic islands (GIs) and plasmids promote bacterial pathogen emergence. Excision is an early step in GI mobilization, producing a circular GI and a deletion site in the chromosome; circular forms are also known for some bacterial insertion sequences (ISs). The recombinant sequence at the junctions of such circles and deletions can be detected sensitively in high-throughput sequencing data, using new computational methods that enable empirical discovery of mobile DNAs. For the rich mobilome of a hospital Klebsiella pneumoniae strain, circularization junctions (CJs) were detected for six GIs and seven IS types. Our methods revealed differential biology of multiple mobile DNAs, imprecision of integrases and transposases, and differential activity among identical IS copies for IS26, ISKpn18 and ISKpn21 Using the resistance of circular dsDNA molecules to exonuclease, internally calibrated with the native plasmids, showed that not all molecules bearing GI CJs were circular. Transpositions were also detected, revealing replicon preference (ISKpn18 prefers a conjugative IncA/C2 plasmid), local action (IS26), regional preferences, selection (against capsule synthesis) and IS polarity inversion. Efficient discovery and global characterization of numerous mobile elements per experiment improves accounting for the new gene combinations that arise in emerging pathogens. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline.

Science.gov (United States)

Piovia-Scott, Jonah; Pope, Karen; Worth, S Joy; Rosenblum, Erica Bree; Poorten, Thomas; Refsnider, Jeanine; Rollins-Smith, Louise A; Reinert, Laura K; Wells, Heather L; Rejmanek, Dan; Lawler, Sharon; Foley, Janet

2015-07-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We documented a dramatic decline in juvenile frogs in a Bd-infected population of Cascades frogs (Rana cascadae) in the mountains of northern California and used a laboratory experiment to show that Bd isolated in the midst of this decline induced higher mortality than Bd isolated from a more stable population of the same species of frog. This highly virulent Bd isolate was more toxic to immune cells and attained higher density in liquid culture than comparable isolates. Genomic analyses revealed that this isolate is nested within the global panzootic lineage and exhibited unusual genomic patterns, including increased copy numbers of many chromosomal segments. This study integrates data from multiple sources to suggest specific phenotypic and genomic characteristics of the pathogen that may be linked to disease-related declines.

Batrachochytrium dendrobatidis infection patterns among Panamanian amphibian species, habitats and elevations during epizootic and enzootic stages.

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Brem, Forrest M R; Lips, Karen R

2008-09-24

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has caused declines of many amphibian populations, yet the full course of the epizootic has rarely been observed in wild populations. We determined effects of elevation, habitat, and aquatic index (AI) on prevalence of infection among Panamanian amphibians sampled along 2 elevational transects. Amphibian populations on the Santa Fé transect (SFT) had declined in 2002, while those on the El Copé transect (ECT) were healthy until September 2004. In 2004 we sampled Bd along both transects, surveying the SFT 2 yr after decline, and surveying the ECT 4 mo prior to the arrival of Bd, during the epizootic, and 2 mo later. Overall prevalence of Bd along the ECT increased from 0.0 (95% CI 0.00-0.0003) to 0.51 (95% CI 0.48-0.55) over a 3 mo period, accompanied by significant decreases in amphibian abundance and species richness in all habitats. Prevalence of infection on the ECT was highest along riparian transects and at higher elevations, but not among levels of AI. Prevalence of infection on the SFT was highest in pool transects, and at higher elevations, but not among levels of AI. Riparian amphibian abundance and species richness also declined at SFT following detection of Bd in 2002. Variation among species, microenvironmental conditions, and the length of coexistence with Bd may contribute to observed differences in prevalence of Bd and in population response.

Biomimicry of volatile-based microbial control for managing emerging fungal pathogens.

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Gabriel, K T; Joseph Sexton, D; Cornelison, C T

2018-05-01

Volatile organic compounds (VOCs) are known to be produced by a wide range of micro-organisms and for a number of purposes. Volatile-based microbial inhibition in environments such as soil is well-founded, with numerous antimicrobial VOCs having been identified. Inhibitory VOCs are of interest as microbial control agents, as low concentrations of gaseous VOCs can elicit significant antimicrobial effects. Volatile organic compounds are organic chemicals typically characterized as having low molecular weight, low solubility in water, and high vapour pressure. Consequently, VOCs readily evaporate to the gaseous phase at standard temperature and pressure. This contact-independent antagonism presents unique advantages over traditional, contact-dependent microbial control methods, including increased surface exposure and reduced environmental persistence. This approach has been the focus of our recent research, with positive results suggesting it may be particularly promising for the management of emerging fungal pathogens, such as the causative agents of white-nose syndrome of bats and snake fungal disease, which are difficult or impossible to treat using traditional approaches. Here, we review the history of volatile-based microbial control, discuss recent progress in formulations that mimic naturally antagonistic VOCs, outline the development of a novel treatment device, and highlight areas where further work is needed to successfully deploy VOCs against existing and emerging fungal pathogens. © 2017 The Society for Applied Microbiology.

Molecular surveillance of traditional and emerging pathogens associated with canine infectious respiratory disease.

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Decaro, Nicola; Mari, Viviana; Larocca, Vittorio; Losurdo, Michele; Lanave, Gianvito; Lucente, Maria Stella; Corrente, Marialaura; Catella, Cristiana; Bo, Stefano; Elia, Gabriella; Torre, Giorgio; Grandolfo, Erika; Martella, Vito; Buonavoglia, Canio

2016-08-30

A molecular survey for traditional and emerging pathogens associated with canine infectious respiratory disease (CIRD) was conducted in Italy between 2011 and 2013 on a total of 138 dogs, including 78 early acute clinically ill CIRD animals, 22 non-clinical but exposed to clinically ill CIRD dogs and 38 CIRD convalescent dogs. The results showed that canine parainfluenza virus (CPIV) was the most commonly detected CIRD pathogen, followed by canine respiratory coronavirus (CRCoV), Bordetella bronchiseptica, Mycoplasma cynos, Mycoplasma canis and canine pneumovirus (CnPnV). Some classical CIRD agents, such as canine adenoviruses, canine distemper virus and canid herpesvirus 1, were not detected at all, as were not other emerging respiratory viruses (canine influenza virus, canine hepacivirus) and bacteria (Streptococcus equi subsp. zooepidemicus). Most severe forms of respiratory disease were observed in the presence of CPIV, CRCoV and M. cynos alone or in combination with other pathogens, whereas single CnPnV or M. canis infections were detected in dogs with no or very mild respiratory signs. Interestingly, only the association of M. cynos (alone or in combination with either CRCoV or M. canis) with severe clinical forms was statistically significant. The study, while confirming CPIV as the main responsible for CIRD occurrence, highlights the increasing role of recently discovered viruses, such as CRCoV and CnPnV, for which effective vaccines are not available in the market. Copyright © 2016 Elsevier B.V. All rights reserved.

Interactions between amphibians’ symbiotic bacteria cause the production of emergent anti-fungal metabolites

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Andrew Howard Loudon

2014-08-01

Full Text Available Amphibians possess beneficial skin bacteria that protect against the disease chytridiomycosis by producing secondary metabolites that inhibit the pathogen Batrachochytrium dendrobatidis (Bd. Metabolite production may be a mechanism of competition between bacterial species that results in host protection as a by-product. We expect that some co-cultures of bacterial species or strains will result in greater Bd inhibition than mono-cultures. To test this, we cultured four bacterial isolates (Bacillus sp., Janthinobacterium sp., Pseudomonas sp. and Chitinophaga arvensicola from red-backed salamanders (Plethodon cinereus and cultured isolates both alone and together to collect their cell-free supernatants (CFS. We challenged Bd with CFSs from four bacterial species in varying combinations. This resulted in three experimental treatments: 1 CFSs of single isolates; 2 combined CFSs of two isolates; and 3 CFSs from co-cultures. Pair-wise combinations of four bacterial isolates CFSs were assayed against Bd and revealed additive Bd inhibition in 42.2% of trials, synergistic inhibition in 42.2% and no effect in 16.6% of trials. When bacteria isolates were grown in co-cultures, complete Bd inhibition was generally observed, and synergistic inhibition occurred in four out of six trials. A metabolite profile of the most potent co-culture, Bacillus sp. and Chitinophaga arvensicola, was determined with LC-MS and compared with the profiles of each isolate in mono-culture. Emergent metabolites appearing in the co-culture were inhibitory to Bd, and the most potent inhibitor was identified as tryptophol. Thus mono-cultures of bacteria cultured from red-backed salamanders interacted synergistically and additively to inhibit Bd, and such bacteria produced emergent metabolites when cultured together, with even greater pathogen inhibition. Knowledge of how bacterial species interact to inhibit Bd can be used to select probiotics to provide amphibians with protection

Do pathogens become more virulent as they spread? Evidence from the amphibian declines in Central America.

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Phillips, Ben L; Puschendorf, Robert

2013-09-07

The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence is regularly observed, directional shifts in virulence are less commonly observed and are typically associated with decreasing virulence of biological control agents through coevolution. It is increasingly appreciated, however, that spatial effects can lead to evolutionary trajectories that differ from standard expectations. One such possibility is that, as a pathogen spreads through a naive host population, its virulence increases on the invasion front. In Central America, there is compelling evidence for the recent spread of pathogenic Batrachochytrium dendrobatidis (Bd) and for its strong impact on amphibian populations. Here, we re-examine data on Bd prevalence and amphibian population decline across 13 sites from southern Mexico through Central America, and show that, in the initial phases of the Bd invasion, amphibian population decline lagged approximately 9 years behind the arrival of the pathogen, but that this lag diminished markedly over time. In total, our analysis suggests an increase in Bd virulence as it spread southwards, a pattern consistent with rapid evolution of increased virulence on Bd's invading front. The impact of Bd on amphibians might therefore be driven by rapid evolution in addition to more proximate environmental drivers.

Use of Bioclimatic Factors to Determine Potential Niche of Vaccinia Virus, an Emerging and Zoonotic Pathogen

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Quiner, C. A.; Nakazawa, Y.

2017-12-01

Emerging and understudied pathogens often lack information that most commonly used analytical tools require, such as negative controls or baseline data making public health control of emerging pathogens challenging. In lieu of opportunities to collect more data from larger outbreaks or formal epidemiological studies, new analytical strategies, merging case data with publically available datasets, can be used to understand transmission patterns and drivers of disease emergence. Zoonotic infections with Vaccinia virus (VACV) were first reported in Brazil in 1999, VACV is an emerging zoonotic Orthopoxvirus, which primarily infects dairy cattle and farmers in close contact with infected cows. Prospective studies of emerging pathogens could provide critical data that would inform public health planning and response to outbreaks. By using the location of 87-recorded outbreaks and publicly available bioclimatic data we demonstrate one such approach. Using an Ecological Niche Model (ENM), we identify the environmental conditions under which VACV outbreaks have occurred, and determine additional locations in two affected South American countries that may be susceptible to transmission. Further, we show how suitability for the virus responds to different levels of various environmental factors and highlight the most important climatic factors in determining its transmission. The final ENM predicted all areas where Brazilian outbreaks occurred, two out of five Colombian outbreaks and identified new regions within Brazil that are suitable for transmission based on bioclimatic factors. Further, the most important factors in determining transmission suitability are precipitation of the wettest quarter, annual precipitation, mean temperature of the coldest quarter and mean diurnal range. The analyses here provide a means by which to study patterns of an emerging infectious disease, and regions that are potentially at risk for it, in spite of the paucity of critical data. Policy

An emerging cyberinfrastructure for biodefense pathogen and pathogen-host data.

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Zhang, C; Crasta, O; Cammer, S; Will, R; Kenyon, R; Sullivan, D; Yu, Q; Sun, W; Jha, R; Liu, D; Xue, T; Zhang, Y; Moore, M; McGarvey, P; Huang, H; Chen, Y; Zhang, J; Mazumder, R; Wu, C; Sobral, B

2008-01-01

The NIAID-funded Biodefense Proteomics Resource Center (RC) provides storage, dissemination, visualization and analysis capabilities for the experimental data deposited by seven Proteomics Research Centers (PRCs). The data and its publication is to support researchers working to discover candidates for the next generation of vaccines, therapeutics and diagnostics against NIAID's Category A, B and C priority pathogens. The data includes transcriptional profiles, protein profiles, protein structural data and host-pathogen protein interactions, in the context of the pathogen life cycle in vivo and in vitro. The database has stored and supported host or pathogen data derived from Bacillus, Brucella, Cryptosporidium, Salmonella, SARS, Toxoplasma, Vibrio and Yersinia, human tissue libraries, and mouse macrophages. These publicly available data cover diverse data types such as mass spectrometry, yeast two-hybrid (Y2H), gene expression profiles, X-ray and NMR determined protein structures and protein expression clones. The growing database covers over 23 000 unique genes/proteins from different experiments and organisms. All of the genes/proteins are annotated and integrated across experiments using UniProt Knowledgebase (UniProtKB) accession numbers. The web-interface for the database enables searching, querying and downloading at the level of experiment, group and individual gene(s)/protein(s) via UniProtKB accession numbers or protein function keywords. The system is accessible at http://www.proteomicsresource.org/.

Diversification of an emerging pathogen in a biodiversity hotspot: Leptospira in endemic small mammals of Madagascar.

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Dietrich, Muriel; Wilkinson, David A; Soarimalala, Voahangy; Goodman, Steven M; Dellagi, Koussay; Tortosa, Pablo

2014-06-01

Biodiversity hotspots and associated endemism are ideal systems for the study of parasite diversity within host communities. Here, we investigated the ecological and evolutionary forces acting on the diversification of an emerging bacterial pathogen, Leptospira spp., in communities of endemic Malagasy small mammals. We determined the infection rate with pathogenic Leptospira in 20 species of sympatric rodents (subfamily Nesomyinae) and tenrecids (family Tenrecidae) at two eastern humid forest localities. A multilocus genotyping analysis allowed the characterization of bacterial diversity within small mammals and gave insights into their genetic relationships with Leptospira infecting endemic Malagasy bats (family Miniopteridae and Vespertilionidae). We report for the first time the presence of pathogenic Leptospira in Malagasy endemic small mammals, with an overall prevalence of 13%. In addition, these hosts harbour species of Leptospira (L. kirschneri, L. borgpetersenii and L. borgpetersenii group B) which are different from those reported in introduced rats (L. interrogans) on Madagascar. The diversification of Leptospira on Madagascar can be traced millions of years into evolutionary history, resulting in the divergence of endemic lineages and strong host specificity. These observations are discussed in relation to the relative roles of endemic vs. introduced mammal species in the evolution and epidemiology of Leptospira on Madagascar, specifically how biodiversity and biogeographical processes can shape community ecology of an emerging pathogen and lead to its diversification within native animal communities. © 2014 John Wiley & Sons Ltd.

Rapid Detection and Characterization of Emerging Foreign Animal Disease Pathogens

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Jaing, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-11-18

To best safeguard human and animal health requires early detection and characterization of disease events. This must include effective surveillance for emerging infectious diseases. Both deliberate and natural outbreaks have enormous economic and public health impacts, and can present serious threats to national security. In this project, we developed novel next generation detection technologies to protect the agricultural economy and biosecurity. The first technology is a multiplexed assay to simultaneously detection 10 swine viral and bacterial pathogens. The second one is the Lawrence Livermore Microbial Detection Array (LLMDA) which can detect more than 10,000 microbial species including 4219 viruses, 5367 bacteria, 265 fungi, 117 protozoa and 293 archaea. We analyzed a series of swine clinical samples from past disease events to demonstrate the utility of the assays for faster and cheaper detection of emerging and foreign animal disease pathogens, and their utility as s routine diagnosis and surveillance tool. A second goal of the study is to better understand mechanisms of African swine fever virus (ASFV) infection in pigs to aid the development of countermeasures and diagnostics. There is no vaccine available for ASF. ASF outbreak is on the rise on several European countries. Though ASF is not currently in the U.S., a potential outbreak in the U.S. would be detrimental to the swine industry and the US agricultural economy. We pursued a genome-wide approach to characterize the pig immune responses after ASFV infection. We used RNA sequencing and bioinformatics methods to identify genes and pathways that are affected during ASF infection. We have identified a list of most differentially expressed genes that are in the immune response pathways.

Over-wintering tadpoles of Mixophyes fasciolatus act as reservoir host for Batrachochytrium dendrobatidis.

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Edward J Narayan

Full Text Available Batrachochytrium dendrobatidis (Bd, a cutaneous amphibian fungus that causes the lethal disease chytridiomycosis, has been implicated as a cause of many amphibian declines. Bd can tolerate low temperatures with an optimum thermal range from 17-24°C. It has been shown that Bd infection may result in species extinction, avoiding the transmission threshold presented by density dependent transmission theory. Prevalence of Bd during autumn and winter has been shown to be as low as 0% in some species. It is currently unclear how Bd persists in field conditions and what processes result in carry-over between seasons. It has been hypothesised that overwintering tadpoles may host Bd between breeding seasons. The Great Barred Frog (Mixophyes fasciolatus is a common, stable and widespread species in Queensland, Australia, and is known to carry Bd. Investigation into Bd infection of different life stages of M. fasciolatus during seasonally low prevalence may potentially reveal persistence and carry-over methods between seasons. Metamorphs, juveniles, and adults were swabbed for Bd infection over three months (between March and May, 2011 at 5 sites of varying altitude (66 m-790 m. A total of 93 swabs were analysed using Polymerase Chain Reaction (PCR real-time analysis. PCR analysis showed 6 positive (1 excluded, 4 equivocal and 83 negative results for infection with Bd. Equivocal results were assumed to be negative using the precautionary principle. The 5 positive results consisted of 4 emerging (Gosner stage 43-45 metamorphs and 1 adult M. fasciolatus. Fisher's exact test on prevalence showed that the prevalence was significantly different between life stages. All positive results were sampled at high altitudes (790 m; however prevalence was not significantly different between altitudes. Infection of emerging metamorphs suggests that individuals were infected as tadpoles. We hypothesise that M. fasciolatus tadpoles carry Bd through seasons. Thus

DEVELOPMENT OF A MOLECULAR METHOD TO IDENTIFY THE EMERGING PATHOGEN HEPATITIS E IN WATER SAMPLES

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Hepatitis E virus (HEV) is an emerging pathogen that causes significant illness in the developing world. Like the hepatitis A virus, it is transmitted via the fecal-oral route and can cause short-term, acute hepatitis. In addition, hepatitis E has been found to cause a signific...

Emerging fungal pathogen Ophidiomyces ophiodiicola in wild European snakes

Science.gov (United States)

Franklinos, Lydia H. V.; Lorch, Jeffrey M.; Bohuski, Elizabeth A.; Rodriguez-Ramos Fernandez, Julia; Wright, Owen; Fitzpatrick, Liam; Petrovan, Silviu; Durrant, Chris; Linton, Chris; Baláž, Vojtech; Cunningham, Andrew A; Lawson, Becki

2017-01-01

Snake fungal disease (SFD) is an emerging disease of conservation concern in eastern North America. Ophidiomyces ophiodiicola, the causative agent of SFD, has been isolated from over 30 species of wild snakes from six families in North America. Whilst O. ophiodiicola has been isolated from captive snakes outside North America, the pathogen has not been reported from wild snakes elsewhere. We screened 33 carcasses and 303 moulted skins from wild snakes collected from 2010–2016 in Great Britain and the Czech Republic for the presence of macroscopic skin lesions and O. ophiodiicola. The fungus was detected using real-time PCR in 26 (8.6%) specimens across the period of collection. Follow up culture and histopathologic analyses confirmed that both O. ophiodiicola and SFD occur in wild European snakes. Although skin lesions were mild in most cases, in some snakes they were severe and were considered likely to have contributed to mortality. Culture characterisations demonstrated that European isolates grew more slowly than those from the United States, and phylogenetic analyses indicated that isolates from European wild snakes reside in a clade distinct from the North American isolates examined. These genetic and phenotypic differences indicate that the European isolates represent novel strains of O. ophiodiicola. Further work is required to understand the individual and population level impact of this pathogen in Europe.

European surveillance of emerging pathogens associated with canine infectious respiratory disease.

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Mitchell, Judy A; Cardwell, Jacqueline M; Leach, Heather; Walker, Caray A; Le Poder, Sophie; Decaro, Nicola; Rusvai, Miklos; Egberink, Herman; Rottier, Peter; Fernandez, Mireia; Fragkiadaki, Eirini; Shields, Shelly; Brownlie, Joe

2017-12-01

Canine infectious respiratory disease (CIRD) is a major cause of morbidity in dogs worldwide, and is associated with a number of new and emerging pathogens. In a large multi-centre European study the prevalences of four key emerging CIRD pathogens; canine respiratory coronavirus (CRCoV), canine pneumovirus (CnPnV), influenza A, and Mycoplasma cynos (M. cynos); were estimated, and risk factors for exposure, infection and clinical disease were investigated. CIRD affected 66% (381/572) of the dogs studied, including both pet and kennelled dogs. Disease occurrence and severity were significantly reduced in dogs vaccinated against classic CIRD agents, canine distemper virus (CDV), canine adenovirus 2 (CAV-2) and canine parainfluenza virus (CPIV), but substantial proportions (65.7%; 201/306) of vaccinated dogs remained affected. CRCoV and CnPnV were highly prevalent across the different dog populations, with overall seropositivity and detection rates of 47% and 7.7% for CRCoV, and 41.7% and 23.4% for CnPnV, respectively, and their presence was associated with increased occurrence and severity of clinical disease. Antibodies to CRCoV had a protective effect against CRCoV infection and more severe clinical signs of CIRD but antibodies to CnPnV did not. Involvement of M. cynos and influenza A in CIRD was less apparent. Despite 45% of dogs being seropositive for M. cynos, only 0.9% were PCR positive for M. cynos. Only 2.7% of dogs were seropositive for Influenza A, and none were positive by PCR. Copyright © 2017 Elsevier B.V. All rights reserved.

Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1 in Viet Nam.

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Sumeet Saksena

Full Text Available Building on a series of ground breaking reviews that first defined and drew attention to emerging infectious diseases (EID, the 'convergence model' was proposed to explain the multifactorial causality of disease emergence. The model broadly hypothesizes disease emergence is driven by the co-incidence of genetic, physical environmental, ecological, and social factors. We developed and tested a model of the emergence of highly pathogenic avian influenza (HPAI H5N1 based on suspected convergence factors that are mainly associated with land-use change. Building on previous geospatial statistical studies that identified natural and human risk factors associated with urbanization, we added new factors to test whether causal mechanisms and pathogenic landscapes could be more specifically identified. Our findings suggest that urbanization spatially combines risk factors to produce particular types of peri-urban landscapes with significantly higher HPAI H5N1 emergence risk. The work highlights that peri-urban areas of Viet Nam have higher levels of chicken densities, duck and geese flock size diversities, and fraction of land under rice or aquaculture than rural and urban areas. We also found that land-use diversity, a surrogate measure for potential mixing of host populations and other factors that likely influence viral transmission, significantly improves the model's predictability. Similarly, landscapes where intensive and extensive forms of poultry production overlap were found at greater risk. These results support the convergence hypothesis in general and demonstrate the potential to improve EID prevention and control by combing geospatial monitoring of these factors along with pathogen surveillance programs.

Amphibian chytridiomycosis: a review with focus on fungus-host interactions.

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Van Rooij, Pascale; Martel, An; Haesebrouck, Freddy; Pasmans, Frank

2015-11-25

Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans (Chytridiomycota). The skin disease caused by these fungi is named chytridiomycosis and affects the vital function of amphibian skin. Not all amphibians respond equally to infection and host responses might range from resistant, over tolerant to susceptible. The clinical outcome of infection is highly dependent on the amphibian host, the fungal virulence and environmental determinants. B. dendrobatidis infects the skin of a large range of anurans, urodeles and caecilians, whereas to date the host range of B. salamandrivorans seems limited to urodeles. So far, the epidemic of B. dendrobatidis is mainly limited to Australian, neotropical, South European and West American amphibians, while for B. salamandrivorans it is limited to European salamanders. Other striking differences between both fungi include gross pathology and thermal preferences. With this review we aim to provide the reader with a state-of-the art of host-pathogen interactions for both fungi, in which new data pertaining to the interaction of B. dendrobatidis and B. salamandrivorans with the host's skin are integrated. Furthermore, we pinpoint areas in which more detailed studies are necessary or which have not received the attention they merit.

The Effect of Human Impact on Batrachochytrium dendrobatidis prevalence in Taricha torosa

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Deng, V.; Macario, E.; Tumey, C.

2014-12-01

Batrachochytrium dendrobatidis (Bd) is emerging as a major cause of the amphibian extinction. As amphibians serve an important role as indicator species in their ecosystem and play a vital role in the food chain, Bd will not only affect the amphibian population but also the health of the environment. Bd is an aquatic fungus that blocks the porous skin of amphibians which interrupts electrolyte, gas and water transfer. This imbalances the electrolyte system which causes cells and organs to malfunction, therefore killing the amphibian. While frogs are more common for Bd, it is not often found in newts. However, Dr. Vance Vredenburg recently found an outbreak of Bd in Taricha torosa in Marin Headlands, California. This location was used in the research as the sample site with most human impact and was expected to have the highest prevalence according to the proposed hypothesis that more human impact will correspond with a higher prevalence of Bd. Decreasing the level of human impact, Fairfield Osborn Preserve and Galbreath Preserve were picked as the other sample sites. After the samples went through qPCR, all of them came back negative for Bd. These results did not support the hypothesis, however, it contributed data to explaining the dynamics of Bd when combined with Dr. Vance Vredenburg's data from 2 months earlier. Within the two months, there was a huge difference in the prevalence of Bd as it dropped from 88% to 0%. This shows that Taricha torosa does in fact get Bd. However, it is rarely detected because Bd is fast-acting and has high mortality rates. Therefore, it is least likely for current nonspecific surveys to swab the newts during a short but lethal Bd outbreak.

Geographical and Historical Patterns in the Emergences of Novel Highly Pathogenic Avian Influenza (HPAI H5 and H7 Viruses in Poultry

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Madhur S. Dhingra

2018-06-01

Full Text Available Over the years, the emergence of novel H5 and H7 highly pathogenic avian influenza viruses (HPAI has been taking place through two main mechanisms: first, the conversion of a low pathogenic into a highly pathogenic virus, and second, the reassortment between different genetic segments of low and highly pathogenic viruses already in circulation. We investigated and summarized the literature on emerging HPAI H5 and H7 viruses with the aim of building a spatio-temporal database of all these recorded conversions and reassortments events. We subsequently mapped the spatio-temporal distribution of known emergence events, as well as the species and production systems that they were associated with, the aim being to establish their main characteristics. From 1959 onwards, we identified a total of 39 independent H7 and H5 LPAI to HPAI conversion events. All but two of these events were reported in commercial poultry production systems, and a majority of these events took place in high-income countries. In contrast, a total of 127 reassortments have been reported from 1983 to 2015, which predominantly took place in countries with poultry production systems transitioning from backyard to intensive production systems. Those systems are characterized by several co-circulating viruses, multiple host species, regular contact points in live bird markets, limited biosecurity within value chains, and frequent vaccination campaigns that impose selection pressures for emergence of novel reassortants. We conclude that novel HPAI emergences by these two mechanisms occur in different ecological niches, with different viral, environmental and host associated factors, which has implications in early detection and management and mitigation of the risk of emergence of novel HPAI viruses.

Xylella fastidiosa: an examination of a re-emerging plant pathogen.

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Rapicavoli, Jeannette; Ingel, Brian; Blanco-Ulate, Barbara; Cantu, Dario; Roper, Caroline

2018-04-01

Xylella fastidiosa is a Gram-negative bacterial plant pathogen with an extremely wide host range. This species has recently been resolved into subspecies that correlate with host specificity. This review focuses on the status of X. fastidiosa pathogenic associations in plant hosts in which the bacterium is either endemic or has been recently introduced. Plant diseases associated with X. fastidiosa have been documented for over a century, and much about what is known in the context of host-pathogen interactions is based on these hosts, such as grape and citrus, in which this pathogen has been well described. Recent attention has focused on newly emerging X. fastidiosa diseases, such as in olives. Bacteria; Gammaproteobacteria; family Xanthomonadaceae; genus Xylella; species fastidiosa. Gram-negative rod (0.25-0.35 × 0.9-3.5 μm), non-flagellate, motile via Type IV pili-mediated twitching, fastidious. Xylella fastidiosa has a broad host range that includes ornamental, ecological and agricultural plants belonging to over 300 different species in 63 different families. To date, X. fastidiosa has been found to be pathogenic in over 100 plant species. In addition, it can establish non-symptomatic associations with many plants as a commensal endophyte. Here, we list the four distinct subspecies of X. fastidiosa and some of the agriculturally relevant diseases caused by them: X. fastidiosa ssp. fastidiosa causes Pierce's disease (PD) of grapevine (Vitis vinifera); X. fastidiosa ssp. multiplex causes almond leaf scorch (ALS) and diseases on other nut and shade tree crops; X. fastidiosa ssp. pauca causes citrus variegated chlorosis (CVC) (Citrus spp.), coffee leaf scorch and olive quick decline syndrome (OQDS) (Olea europaea); X. fastidiosa ssp. sandyi causes oleander leaf scorch (OLS) (Nerium oleander). Significant host specificity seemingly exists for some of the subspecies, although this could be a result of technical biases based on the limited number of

Blood stream infection by an emerging pathogen Oligella ureolytica in a cancer patient: Case report and review of literature

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Frincy K Baruah

2014-01-01

Full Text Available Oligella ureolytica is an emerging bacteria rarely implicated as a human pathogen. It is infrequently recovered from clinical specimens probably because of inadequate processing of non-fermenting oxidase positive Gram negative bacilli. We present here a case of a 30 year old male suffering from right lung adenocarcinoma (moderately differentiated with multiple abdominal lymph node metastasis with Syringohydromyelia whose blood culture yielded Oligella ureolytica in pure culture. Oligella ureolytica isolation in pure culture and the patient′s response to targeted treatment supported that Oligella ureolytica was the true causative agent of the blood stream infection. Early suspicion, diagnosis and treatment with potent antibiotics are needed to prevent further complications resulting from infection with this emerging pathogen.

Pathology of Penicillium marneffei. An emerging acquired immunodeficiency syndrome-related pathogen.

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Cooper, C R; McGinnis, M R

1997-08-01

To summarize current knowledge regarding the opportunistic dimorphic fungal pathogen Penicillium marneffei. Clinical presentation, differential diagnosis, mycology, histopathology, diagnostic serology, in vitro antifungal agent susceptibility testing, and therapy are discussed for human immunodeficiency virus-infected individuals primarily living in Southeast Asia. Critical evaluation of peer-reviewed publications located through an electronic literature database search, supplemented by unpublished observations, were used to prepare this report. Studies were selected based on either the fungal name Penicillium marneffei, penicilliosis, penicilliosis marneffei, or a combination of these. Articles were reviewed with appropriate data being abstracted and then synthesized into the review. Differential diagnostic criteria for tissue diagnosis and laboratory identification of the fungus are detailed. The usefulness of mycoserology and antifungal therapy are evaluated. Penicillium marneffei is an emerging pathogen, primarily among patients with acquired immunodeficiency syndrome residing in Southeast Asia. Although infection caused by P marneffei is endemic to this portion of the world, cases are being diagnosed and treated involving individuals who have traveled to this region. Penicilliosis marneffei can clinically resemble tuberculosis, molluscum contagiosum, cryptococcosis, and histoplasmosis. The successful treatment of P marneffei infection is dependent on its rapid and accurate diagnosis.

CRN13 candidate effectors from plant and animal eukaryotic pathogens are DNA-binding proteins which trigger host DNA damage response.

Science.gov (United States)

Ramirez-Garcés, Diana; Camborde, Laurent; Pel, Michiel J C; Jauneau, Alain; Martinez, Yves; Néant, Isabelle; Leclerc, Catherine; Moreau, Marc; Dumas, Bernard; Gaulin, Elodie

2016-04-01

To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Actinobaculum schaalii an emerging pediatric pathogen?

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Zimmermann Petra

2012-08-01

Full Text Available Abstract Background Actinobaculum schaalii was first described as a causative agent for human infection in 1997. Since then it has mainly been reported causing urinary tract infections (UTI in elderly individuals with underlying urological diseases. Isolation and identification is challenging and often needs molecular techniques. A. schaalii is increasingly reported as a cause of infection in humans, however data in children is very limited. Case presentation We present the case of an 8-month-old Caucasian boy suffering from myelomeningocele and neurogenic bladder who presented with a UTI. An ultrasound of the urinary tract was unremarkable. Urinalysis and microscopy showed an elevated leukocyte esterase test, pyuria and a high number of bacteria. Empiric treatment with oral co-trimoxazole was started. Growth of small colonies of Gram-positive rods was observed after 48 h. Sequencing of the 16S rRNA gene confirmed an A. schaalii infection 9 days later. Treatment was changed to oral amoxicillin for 14 days. On follow-up urinalysis was normal and urine cultures were negative. Conclusions A.schaalii is an emerging pathogen in adults and children. Colonization and subsequent infection seem to be influenced by the age of the patient. In young children with high suspicion of UTI who use diapers or in children who have known abnormalities of their urogenital tract, infection with A. schaalii should be considered and empiric antimicrobial therapy chosen accordingly.

Copper Resistance of the Emerging Pathogen Acinetobacter baumannii

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Williams, Caitlin L.; Neu, Heather M.; Gilbreath, Jeremy J.; Michel, Sarah L. J.; Zurawski, Daniel V.

2016-01-01

ABSTRACT Acinetobacter baumannii is an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. Since A. baumannii can rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies against Acinetobacter infections, we characterized copper resistance in a panel of recent clinical A. baumannii isolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper on A. baumannii revealed that resistance to copper increased dramatically in stationary phase. Moreover, A. baumannii biofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins in Escherichia coli and Pseudomonas aeruginosa. Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics against Acinetobacter and other highly antibiotic-resistant pathogens. IMPORTANCE Acinetobacter baumannii causes many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic

Copper Resistance of the Emerging Pathogen Acinetobacter baumannii.

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Williams, Caitlin L; Neu, Heather M; Gilbreath, Jeremy J; Michel, Sarah L J; Zurawski, Daniel V; Merrell, D Scott

2016-10-15

Acinetobacter baumannii is an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. Since A. baumannii can rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies against Acinetobacter infections, we characterized copper resistance in a panel of recent clinical A. baumannii isolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper on A. baumannii revealed that resistance to copper increased dramatically in stationary phase. Moreover, A. baumannii biofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins in Escherichia coli and Pseudomonas aeruginosa Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics against Acinetobacter and other highly antibiotic-resistant pathogens. Acinetobacter baumannii causes many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic, and treatment options

A framework for the study of zoonotic disease emergence and its drivers: spillover of bat pathogens as a case study

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Wood, James L. N.; Leach, Melissa; Waldman, Linda; MacGregor, Hayley; Fooks, Anthony R.; Jones, Kate E.; Restif, Olivier; Dechmann, Dina; Hayman, David T. S.; Baker, Kate S.; Peel, Alison J.; Kamins, Alexandra O.; Fahr, Jakob; Ntiamoa-Baidu, Yaa; Suu-Ire, Richard; Breiman, Robert F.; Epstein, Jonathan H.; Field, Hume E.; Cunningham, Andrew A.

2012-01-01

Many serious emerging zoonotic infections have recently arisen from bats, including Ebola, Marburg, SARS-coronavirus, Hendra, Nipah, and a number of rabies and rabies-related viruses, consistent with the overall observation that wildlife are an important source of emerging zoonoses for the human population. Mechanisms underlying the recognized association between ecosystem health and human health remain poorly understood and responding appropriately to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial societal challenge. In the context of disease emergence from wildlife, wildlife and habitat should be conserved, which in turn will preserve vital ecosystem structure and function, which has broader implications for human wellbeing and environmental sustainability, while simultaneously minimizing the spillover of pathogens from wild animals into human beings. In this review, we propose a novel framework for the holistic and interdisciplinary investigation of zoonotic disease emergence and its drivers, using the spillover of bat pathogens as a case study. This study has been developed to gain a detailed interdisciplinary understanding, and it combines cutting-edge perspectives from both natural and social sciences, linked to policy impacts on public health, land use and conservation. PMID:22966143

A framework for the study of zoonotic disease emergence and its drivers: spillover of bat pathogens as a case study.

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Wood, James L N; Leach, Melissa; Waldman, Linda; Macgregor, Hayley; Fooks, Anthony R; Jones, Kate E; Restif, Olivier; Dechmann, Dina; Hayman, David T S; Baker, Kate S; Peel, Alison J; Kamins, Alexandra O; Fahr, Jakob; Ntiamoa-Baidu, Yaa; Suu-Ire, Richard; Breiman, Robert F; Epstein, Jonathan H; Field, Hume E; Cunningham, Andrew A

2012-10-19

Many serious emerging zoonotic infections have recently arisen from bats, including Ebola, Marburg, SARS-coronavirus, Hendra, Nipah, and a number of rabies and rabies-related viruses, consistent with the overall observation that wildlife are an important source of emerging zoonoses for the human population. Mechanisms underlying the recognized association between ecosystem health and human health remain poorly understood and responding appropriately to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial societal challenge. In the context of disease emergence from wildlife, wildlife and habitat should be conserved, which in turn will preserve vital ecosystem structure and function, which has broader implications for human wellbeing and environmental sustainability, while simultaneously minimizing the spillover of pathogens from wild animals into human beings. In this review, we propose a novel framework for the holistic and interdisciplinary investigation of zoonotic disease emergence and its drivers, using the spillover of bat pathogens as a case study. This study has been developed to gain a detailed interdisciplinary understanding, and it combines cutting-edge perspectives from both natural and social sciences, linked to policy impacts on public health, land use and conservation.

Searching for animal models and potential target species for emerging pathogens: Experience gained from Middle East respiratory syndrome (MERS coronavirus

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Júlia Vergara-Alert

2017-06-01

Full Text Available Emerging and re-emerging pathogens represent a substantial threat to public health, as demonstrated with numerous outbreaks over the past years, including the 2013–2016 outbreak of Ebola virus in western Africa. Coronaviruses are also a threat for humans, as evidenced in 2002/2003 with infection by the severe acute respiratory syndrome coronavirus (SARS-CoV, which caused more than 8000 human infections with 10% fatality rate in 37 countries. Ten years later, a novel human coronavirus (Middle East respiratory syndrome coronavirus, MERS-CoV, associated with severe pneumonia, arose in the Kingdom of Saudi Arabia. Until December 2016, MERS has accounted for more than 1800 cases and 35% fatality rate. Finding an animal model of disease is key to develop vaccines or antivirals against such emerging pathogens and to understand its pathogenesis. Knowledge of the potential role of domestic livestock and other animal species in the transmission of pathogens is of importance to understand the epidemiology of the disease. Little is known about MERS-CoV animal host range. In this paper, experimental data on potential hosts for MERS-CoV is reviewed. Advantages and limitations of different animal models are evaluated in relation to viral pathogenesis and transmission studies. Finally, the relevance of potential new target species is discussed.

Whether the weather drives patterns of endemic amphibian chytridiomycosis: a pathogen proliferation approach.

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Kris A Murray

Full Text Available The pandemic amphibian disease chytridiomycosis often exhibits strong seasonality in both prevalence and disease-associated mortality once it becomes endemic. One hypothesis that could explain this temporal pattern is that simple weather-driven pathogen proliferation (population growth is a major driver of chytridiomycosis disease dynamics. Despite various elaborations of this hypothesis in the literature for explaining amphibian declines (e.g., the chytrid thermal-optimum hypothesis it has not been formally tested on infection patterns in the wild. In this study we developed a simple process-based model to simulate the growth of the pathogen Batrachochytrium dendrobatidis (Bd under varying weather conditions to provide an a priori test of a weather-linked pathogen proliferation hypothesis for endemic chytridiomycosis. We found strong support for several predictions of the proliferation hypothesis when applied to our model species, Litoria pearsoniana, sampled across multiple sites and years: the weather-driven simulations of pathogen growth potential (represented as a growth index in the 30 days prior to sampling; GI30 were positively related to both the prevalence and intensity of Bd infections, which were themselves strongly and positively correlated. In addition, a machine-learning classifier achieved ~72% success in classifying positive qPCR results when utilising just three informative predictors 1 GI30, 2 frog body size and 3 rain on the day of sampling. Hence, while intrinsic traits of the individuals sampled (species, size, sex and nuisance sampling variables (rainfall when sampling influenced infection patterns obtained when sampling via qPCR, our results also strongly suggest that weather-linked pathogen proliferation plays a key role in the infection dynamics of endemic chytridiomycosis in our study system. Predictive applications of the model include surveillance design, outbreak preparedness and response, climate change scenario

Whether the weather drives patterns of endemic amphibian chytridiomycosis: a pathogen proliferation approach.

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Murray, Kris A; Skerratt, Lee F; Garland, Stephen; Kriticos, Darren; McCallum, Hamish

2013-01-01

The pandemic amphibian disease chytridiomycosis often exhibits strong seasonality in both prevalence and disease-associated mortality once it becomes endemic. One hypothesis that could explain this temporal pattern is that simple weather-driven pathogen proliferation (population growth) is a major driver of chytridiomycosis disease dynamics. Despite various elaborations of this hypothesis in the literature for explaining amphibian declines (e.g., the chytrid thermal-optimum hypothesis) it has not been formally tested on infection patterns in the wild. In this study we developed a simple process-based model to simulate the growth of the pathogen Batrachochytrium dendrobatidis (Bd) under varying weather conditions to provide an a priori test of a weather-linked pathogen proliferation hypothesis for endemic chytridiomycosis. We found strong support for several predictions of the proliferation hypothesis when applied to our model species, Litoria pearsoniana, sampled across multiple sites and years: the weather-driven simulations of pathogen growth potential (represented as a growth index in the 30 days prior to sampling; GI30) were positively related to both the prevalence and intensity of Bd infections, which were themselves strongly and positively correlated. In addition, a machine-learning classifier achieved ~72% success in classifying positive qPCR results when utilising just three informative predictors 1) GI30, 2) frog body size and 3) rain on the day of sampling. Hence, while intrinsic traits of the individuals sampled (species, size, sex) and nuisance sampling variables (rainfall when sampling) influenced infection patterns obtained when sampling via qPCR, our results also strongly suggest that weather-linked pathogen proliferation plays a key role in the infection dynamics of endemic chytridiomycosis in our study system. Predictive applications of the model include surveillance design, outbreak preparedness and response, climate change scenario modelling and

Surveillance programs for detection and characterization of emergent pathogens and antimicrobial resistance: results from the Division of Infectious Diseases, UNIFESP.

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Colombo, Arnaldo L; Janini, Mario; Salomão, Reinaldo; Medeiros, Eduardo A S; Wey, Sergio B; Pignatari, Antonio C C

2009-09-01

Several epidemiological changes have occurred in the pattern of nosocomial and community acquired infectious diseases during the past 25 years. Social and demographic changes possibly related to this phenomenon include a rapid population growth, the increase in urban migration and movement across international borders by tourists and immigrants, alterations in the habitats of animals and arthropods that transmit disease, as well as the raise of patients with impaired host defense abilities. Continuous surveillance programs of emergent pathogens and antimicrobial resistance are warranted for detecting in real time new pathogens, as well as to characterize molecular mechanisms of resistance. In order to become more effective, surveillance programs of emergent pathogens should be organized as a multicenter laboratory network connected to the main public and private infection control centers. Microbiological data should be integrated to guide therapy, adapting therapy to local ecology and resistance patterns. This paper presents an overview of data generated by the Division of Infectious Diseases, Federal University of São Paulo, along with its participation in different surveillance programs of nosocomial and community acquired infectious diseases.

Infections and Coinfections of Questing Ixodes ricinus Ticks by Emerging Zoonotic Pathogens in Western Switzerland

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Lommano, Elena; Bertaiola, Luce; Dupasquier, Christèle

2012-01-01

In Europe, Ixodes ricinus is the vector of many pathogens of medical and veterinary relevance, among them Borrelia burgdorferi sensu lato and tick-borne encephalitis virus, which have been the subject of numerous investigations. Less is known about the occurrence of emerging tick-borne pathogens like Rickettsia spp., Babesia spp., “Candidatus Neoehrlichia mikurensis,” and Anaplasma phagocytophilum in questing ticks. In this study, questing nymph and adult I. ricinus ticks were collected at 11 sites located in Western Switzerland. A total of 1,476 ticks were analyzed individually for the simultaneous presence of B. burgdorferi sensu lato, Rickettsia spp., Babesia spp., “Candidatus Neoehrlichia mikurensis,” and A. phagocytophilum. B. burgdorferi sensu lato, Rickettsia spp., and “Candidatus Neoehrlichia mikurensis” were detected in ticks at all sites with global prevalences of 22.5%, 10.2%, and 6.4%, respectively. Babesia- and A. phagocytophilum-infected ticks showed a more restricted geographic distribution, and their prevalences were lower (1.9% and 1.5%, respectively). Species rarely reported in Switzerland, like Borrelia spielmanii, Borrelia lusitaniae, and Rickettsia monacensis, were identified. Infections with more than one pathogenic species, involving mostly Borrelia spp. and Rickettsia helvetica, were detected in 19.6% of infected ticks. Globally, 34.2% of ticks were infected with at least one pathogen. The diversity of tick-borne pathogens detected in I. ricinus in this study and the frequency of coinfections underline the need to take them seriously into consideration when evaluating the risks of infection following a tick bite. PMID:22522688

Emerging and Re-Emerging Zoonoses of Dogs and Cats

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Bruno B. Chomel

2014-07-01

Full Text Available Since the middle of the 20th century, pets are more frequently considered as “family members” within households. However, cats and dogs still can be a source of human infection by various zoonotic pathogens. Among emerging or re-emerging zoonoses, viral diseases, such as rabies (mainly from dog pet trade or travel abroad, but also feline cowpox and newly recognized noroviruses or rotaviruses or influenza viruses can sicken our pets and be transmitted to humans. Bacterial zoonoses include bacteria transmitted by bites or scratches, such as pasteurellosis or cat scratch disease, leading to severe clinical manifestations in people because of their age or immune status and also because of our closeness, not to say intimacy, with our pets. Cutaneous contamination with methicillin-resistant Staphylococcus aureus, Leptospira spp., and/or aerosolization of bacteria causing tuberculosis or kennel cough are also emerging/re-emerging pathogens that can be transmitted by our pets, as well as gastro-intestinal pathogens such as Salmonella or Campylobacter. Parasitic and fungal pathogens, such as echinococcosis, leishmaniasis, onchocercosis, or sporotrichosis, are also re-emerging or emerging pet related zoonoses. Common sense and good personal and pet hygiene are the key elements to prevent such a risk of zoonotic infection.

Elizabethkingia meningoseptica : An emerging pathogen causing meningitis in a hospitalized adult trauma patient

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V Tak

2013-01-01

Full Text Available A 23-year-old male patient who was a follow-up case of neurosurgery presented to our emergency department with a history of high-grade fever and clinical features of meningitis for 1 week. The cerebrospinal fluid (CSF was sent to our laboratory for culture. The culture demonstrated growth of 1-2 mm in diameter light yellow coloured colonies of Gram-negative bacilli on chocolate and blood agar. There was no growth on MacConkey agar. The bacterium was multidrug resistant. Based upon the growth characteristics, bio-chemical reactions, drug susceptibility pattern and identification by Vitek 2 system the isolate was identified as Elizabethkingia meningoseptica. Patient was treated with injection piperacillin-tazobactam, injection vancomycin and cotrimoxazole tablets for 21 days along with intrathecal injection of tigecycline and finally, patient improved clinically and the CSF cultures became sterile. The presence in hospital environment along with multidrug resistance makes E. meningoseptica a successful emerging nosocomial pathogen.

Using a Bayesian network to clarify areas requiring research in a host-pathogen system.

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Bower, D S; Mengersen, K; Alford, R A; Schwarzkopf, L

2017-12-01

Bayesian network analyses can be used to interactively change the strength of effect of variables in a model to explore complex relationships in new ways. In doing so, they allow one to identify influential nodes that are not well studied empirically so that future research can be prioritized. We identified relationships in host and pathogen biology to examine disease-driven declines of amphibians associated with amphibian chytrid fungus (Batrachochytrium dendrobatidis). We constructed a Bayesian network consisting of behavioral, genetic, physiological, and environmental variables that influence disease and used them to predict host population trends. We varied the impacts of specific variables in the model to reveal factors with the most influence on host population trend. The behavior of the nodes (the way in which the variables probabilistically responded to changes in states of the parents, which are the nodes or variables that directly influenced them in the graphical model) was consistent with published results. The frog population had a 49% probability of decline when all states were set at their original values, and this probability increased when body temperatures were cold, the immune system was not suppressing infection, and the ambient environment was conducive to growth of B. dendrobatidis. These findings suggest the construction of our model reflected the complex relationships characteristic of host-pathogen interactions. Changes to climatic variables alone did not strongly influence the probability of population decline, which suggests that climate interacts with other factors such as the capacity of the frog immune system to suppress disease. Changes to the adaptive immune system and disease reservoirs had a large effect on the population trend, but there was little empirical information available for model construction. Our model inputs can be used as a base to examine other systems, and our results show that such analyses are useful tools for

Lipids in host-pathogen interactions: pathogens exploit the complexity of the host cell lipidome.

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van der Meer-Janssen, Ynske P M; van Galen, Josse; Batenburg, Joseph J; Helms, J Bernd

2010-01-01

Lipids were long believed to have a structural role in biomembranes and a role in energy storage utilizing cellular lipid droplets and plasma lipoproteins. Research over the last decades has identified an additional role of lipids in cellular signaling, membrane microdomain organization and dynamics, and membrane trafficking. These properties make lipids an attractive target for pathogens to modulate host cell processes in order to allow their survival and replication. In this review we will summarize the often ingenious strategies of pathogens to modify the lipid homeostasis of host cells, allowing them to divert cellular processes. To this end pathogens take full advantage of the complexity of the lipidome. The examples are categorized in generalized and emerging principles describing the involvement of lipids in host-pathogen interactions. Several pathogens are described that simultaneously induce multiple changes in the host cell signaling and trafficking mechanisms. Elucidation of these pathogen-induced changes may have important implications for drug development. The emergence of high-throughput lipidomic techniques will allow the description of changes of the host cell lipidome at the level of individual molecular lipid species and the identification of lipid biomarkers.

Unlikely remedy: fungicide clears infection from pathogenic fungus in larval southern leopard frogs (Lithobates sphenocephalus.

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Shane M Hanlon

Full Text Available Amphibians are often exposed to a wide variety of perturbations. Two of these, pesticides and pathogens, are linked to declines in both amphibian health and population viability. Many studies have examined the separate effects of such perturbations; however, few have examined the effects of simultaneous exposure of both to amphibians. In this study, we exposed larval southern leopard frog tadpoles (Lithobates sphenocephalus to the chytrid fungus Batrachochytrium dendrobatidis and the fungicide thiophanate-methyl (TM at 0.6 mg/L under laboratory conditions. The experiment was continued until all larvae completed metamorphosis or died. Overall, TM facilitated increases in tadpole mass and length. Additionally, individuals exposed to both TM and Bd were heavier and larger, compared to all other treatments. TM also cleared Bd in infected larvae. We conclude that TM affects larval anurans to facilitate growth and development while clearing Bd infection. Our findings highlight the need for more research into multiple perturbations, specifically pesticides and disease, to further promote amphibian heath.

Emergence of pathogenic coronaviruses in cats by homologous recombination between feline and canine coronaviruses.

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Yutaka Terada

Full Text Available Type II feline coronavirus (FCoV emerged via double recombination between type I FCoV and type II canine coronavirus (CCoV. In this study, two type I FCoVs, three type II FCoVs and ten type II CCoVs were genetically compared. The results showed that three Japanese type II FCoVs, M91-267, KUK-H/L and Tokyo/cat/130627, also emerged by homologous recombination between type I FCoV and type II CCoV and their parent viruses were genetically different from one another. In addition, the 3'-terminal recombination sites of M91-267, KUK-H/L and Tokyo/cat/130627 were different from one another within the genes encoding membrane and spike proteins, and the 5'-terminal recombination sites were also located at different regions of ORF1. These results indicate that at least three Japanese type II FCoVs emerged independently. Sera from a cat experimentally infected with type I FCoV was unable to neutralize type II CCoV infection, indicating that cats persistently infected with type I FCoV may be superinfected with type II CCoV. Our previous study reported that few Japanese cats have antibody against type II FCoV. All of these observations suggest that type II FCoV emerged inside the cat body and is unable to readily spread among cats, indicating that these recombination events for emergence of pathogenic coronaviruses occur frequently.

Actinobaculum schaalii: A truly emerging pathogen?: Actinobaculum schaalii: un pathogène réellement émergent?

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Prigent, G; Perillaud, C; Amara, M; Coutard, A; Blanc, C; Pangon, B

2016-05-01

Actinobaculum schaalii is a Gram-positive facultative anaerobe bacillus. It is a commensal organism of the genitourinary tract. Its morphology is nonspecific. Aerobic culture is tedious, and identification techniques have long been inadequate. Thus, A. schaalii has often been considered as a nonpathogen bacterium or a contaminant. Its pathogenicity is now well described in urinary tract infections, and infections in other sites have been reported. This pathogen is considered as an emerging one following the growing use of mass spectrometry identification. In this context, the aim of our study was to evaluate the number of isolations of A. schaalii before and after the introduction of mass spectrometry in our hospital and to study the clinical circumstances in which isolates were found.

Differentiation of the emerging human pathogens Trichosporon asahii and Trichosporon asteroides from other pathogenic yeasts and moulds by using species-specific monoclonal antibodies.

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Genna E Davies

Full Text Available The fungal genus Trichosporon contains emerging opportunistic pathogens of humans, and is the third most commonly isolated non-candidal yeast from humans. Trichosporon asahii and T. asteroides are the most important species causing disseminated disease in immunocompromised patients, while inhalation of T. asahii spores is the most important cause of summer-type hypersensitivity pneumonitis in healthy individuals. Trichosporonosis is misdiagnosed as candidiasis or cryptococcosis due to a lack of awareness and the ambiguity of diagnostic tests for these pathogens. In this study, hybridoma technology was used to produce two murine monoclonal antibodies (MAbs, CA7 and TH1, for detection and differentiation of Trichosporon from other human pathogenic yeasts and moulds. The MAbs react with extracellular antigens from T. asahii and T. asteroides, but do not recognise other related Trichosporon spp., or unrelated pathogenic yeasts and moulds including Candida, Cryptococcus, Aspergillus, Fusarium, and Scedosporium spp., or the etiologic agents of mucormycosis. Immunofluorescence and Western blotting studies show that MAb CA7, an immunoglobulin G1 (IgG1, binds to a major 60 kDa glycoprotein antigen produced on the surface of hyphae, while TH1, an immunoglobulin M (IgM, binds to an antigen produced on the surface of conidia. The MAbs were used in combination with a standard mycological growth medium (Sabouraud Dextrose Agar to develop an enzyme-linked immunosorbent assay (ELISA for differentiation of T. asahii from Candida albicans and Cryptococcus neoformans in single and mixed species cultures. The MAbs represent a major advance in the identification of T. asahii and T. asteroides using standard mycological identification methods.

There is no evidence for a temporal link between pathogen arrival and frog extinctions in north-eastern Australia.

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Ben L Phillips

Full Text Available Pathogen spread can cause population declines and even species extinctions. Nonetheless, in the absence of tailored monitoring schemes, documenting pathogen spread can be difficult. In the case of worldwide amphibian declines the best present understanding is that the chytrid fungus Batrachochytrium dendrobatidis (Bd has recently spread, causing amphibian declines and extinction in the process. However, good evidence demonstrating pathogen arrival followed by amphibian decline is rare, and analysis of putative evidence is often inadequate. Here we attempt to examine the relationship between Bd arrival and amphibian decline across north-eastern Australia, using sites where a wave-like pattern of amphibian decline was first noticed and at which intensive research has since been conducted. We develop an analytical framework that allows rigorous estimation of pathogen arrival date, which can then be used to test for a correlation between the time of pathogen arrival and amphibian decline across sites. Our results show that, with the current dataset, the earliest possible arrival date of Bd in north-eastern Australia is completely unresolved; Bd could have arrived immediately before sampling commenced or may have arrived thousands of years earlier, the present data simply cannot say. The currently available data are thus insufficient to assess the link between timing of pathogen arrival and population decline in this part of the world. This data insufficiency is surprising given that there have been decades of research on chytridiomycosis in Australia and that there is a general belief that the link between Bd arrival and population decline is well resolved in this region. The lack of data on Bd arrival currently acts as a major impediment to determining the role of environmental factors in driving the global amphibian declines, and should be a major focus of future research.

Ewingella Americana: An Emerging True Pathogen

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Syed Hassan

2012-01-01

Full Text Available Infections caused by Ewingella americana have been rarely reported in the literature. Most of the cases that have been reported were among the immunocompromised patients. We report a case of E. americana causing osteomyelitis and septic arthritis of the shoulder joint in a previous intravenous drug abuser. The causative pathogen was identified by synovial fluid analysis and culture.

Emerging Preservation Techniques for Controlling Spoilage and Pathogenic Microorganisms in Fruit Juices

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Aneja, Kamal Rai; Dhiman, Romika; Aggarwal, Neeraj Kumar; Aneja, Ashish

2014-01-01

Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed. PMID:25332721

Emerging Preservation Techniques for Controlling Spoilage and Pathogenic Microorganisms in Fruit Juices

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Kamal Rai Aneja

2014-01-01

Full Text Available Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed.

Emerging preservation techniques for controlling spoilage and pathogenic microorganisms in fruit juices.

Science.gov (United States)

Aneja, Kamal Rai; Dhiman, Romika; Aggarwal, Neeraj Kumar; Aneja, Ashish

2014-01-01

Fruit juices are important commodities in the global market providing vast possibilities for new value added products to meet consumer demand for convenience, nutrition, and health. Fruit juices are spoiled primarily due to proliferation of acid tolerant and osmophilic microflora. There is also risk of food borne microbial infections which is associated with the consumption of fruit juices. In order to reduce the incidence of outbreaks, fruit juices are preserved by various techniques. Thermal pasteurization is used commercially by fruit juice industries for the preservation of fruit juices but results in losses of essential nutrients and changes in physicochemical and organoleptic properties. Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, and ultrasound and irradiations have also been employed in fruit juices to overcome the negative effects of thermal pasteurization. Some of these techniques have already been commercialized. Some are still in research or pilot scale. Apart from these emerging techniques, preservatives from natural sources have also shown considerable promise for use in some food products. In this review article, spoilage, pathogenic microflora, and food borne outbreaks associated with fruit juices of last two decades are given in one section. In other sections various prevention methods to control the growth of spoilage and pathogenic microflora to increase the shelf life of fruit juices are discussed.

When outgroups fail; phylogenomics of rooting the emerging pathogen, Coxiella burnetii.

Science.gov (United States)

Pearson, Talima; Hornstra, Heidie M; Sahl, Jason W; Schaack, Sarah; Schupp, James M; Beckstrom-Sternberg, Stephen M; O'Neill, Matthew W; Priestley, Rachael A; Champion, Mia D; Beckstrom-Sternberg, James S; Kersh, Gilbert J; Samuel, James E; Massung, Robert F; Keim, Paul

2013-09-01

Rooting phylogenies is critical for understanding evolution, yet the importance, intricacies and difficulties of rooting are often overlooked. For rooting, polymorphic characters among the group of interest (ingroup) must be compared to those of a relative (outgroup) that diverged before the last common ancestor (LCA) of the ingroup. Problems arise if an outgroup does not exist, is unknown, or is so distant that few characters are shared, in which case duplicated genes originating before the LCA can be used as proxy outgroups to root diverse phylogenies. Here, we describe a genome-wide expansion of this technique that can be used to solve problems at the other end of the evolutionary scale: where ingroup individuals are all very closely related to each other, but the next closest relative is very distant. We used shared orthologous single nucleotide polymorphisms (SNPs) from 10 whole genome sequences of Coxiella burnetii, the causative agent of Q fever in humans, to create a robust, but unrooted phylogeny. To maximize the number of characters informative about the rooting, we searched entire genomes for polymorphic duplicated regions where orthologs of each paralog could be identified so that the paralogs could be used to root the tree. Recent radiations, such as those of emerging pathogens, often pose rooting challenges due to a lack of ingroup variation and large genomic differences with known outgroups. Using a phylogenomic approach, we created a robust, rooted phylogeny for C. burnetii. [Coxiella burnetii; paralog SNPs; pathogen evolution; phylogeny; recent radiation; root; rooting using duplicated genes.].

Antifungal susceptibility profiles of 1698 yeast reference strains revealing potential emerging human pathogens.

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Marie Desnos-Ollivier

Full Text Available New molecular identification techniques and the increased number of patients with various immune defects or underlying conditions lead to the emergence and/or the description of novel species of human and animal fungal opportunistic pathogens. Antifungal susceptibility provides important information for ecological, epidemiological and therapeutic issues. The aim of this study was to assess the potential risk of the various species based on their antifungal drug resistance, keeping in mind the methodological limitations. Antifungal susceptibility profiles to the five classes of antifungal drugs (polyens, azoles, echinocandins, allylamines and antimetabolites were determined for 1698 yeast reference strains belonging to 992 species (634 Ascomycetes and 358 Basidiomycetes. Interestingly, geometric mean minimum inhibitory concentrations (MICs of all antifungal drugs tested were significantly higher for Basidiomycetes compared to Ascomycetes (p<0.001. Twenty four strains belonging to 23 species of which 19 were Basidiomycetes seem to be intrinsically "resistant" to all drugs. Comparison of the antifungal susceptibility profiles of the 4240 clinical isolates and the 315 reference strains belonging to 53 shared species showed similar results. Even in the absence of demonstrated in vitro/in vivo correlation, knowing the in vitro susceptibility to systemic antifungal agents and the putative intrinsic resistance of yeast species present in the environment is important because they could become opportunistic pathogens.

Introduced bullfrogs are associated with increased Batrachochytrium dendrobatidis prevalence and reduced occurrence of Korean treefrogs.

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Amaël Borzée

Full Text Available Bullfrogs, Lithobates catesbeianus, have been described as major vectors of the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd. Bd is widespread throughout the range of amphibians yet varies considerably within and among populations in prevalence and host impact. In our study, the presence of L. catesbeianus is correlated with a 2.5 increase in Bd prevalence in treefrogs, and the endangered Dryophytes suweonensis displays a significantly higher Bd prevalence than the more abundant D. japonicus for the 37 sites surveyed. In addition, the occurrence of L. catesbeianus was significantly correlated with a decrease in presence of D. suweonensis at sites. We could not determine if it is the presence of bullfrogs as competitors or predators that is limiting the distribution of D. suweonensis or whether this is caused by bullfrogs acting as a reservoir for Bd. However, L. catesbeianus can now be added to the list of factors responsible for the decline of D. suweonensis populations.

Chytrid fungus acts as a generalist pathogen infecting species-rich amphibian families in Brazilian rainforests.

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Valencia-Aguilar, Anyelet; Ruano-Fajardo, Gustavo; Lambertini, Carolina; da Silva Leite, Domingos; Toledo, Luís Felipe; Mott, Tamí

2015-05-11

The fungus Batrachochytrium dendrobatidis (Bd) is among the main causes of declines in amphibian populations. This fungus is considered a generalist pathogen because it infects several species and spreads rapidly in the wild. To date, Bd has been detected in more than 100 anuran species in Brazil, mostly in the southern portion of the Atlantic forest. Here, we report survey data from some poorly explored regions; these data considerably extend current information on the distribution of Bd in the northern Atlantic forest region. In addition, we tested the hypothesis that Bd is a generalist pathogen in this biome. We also report the first positive record for Bd in an anuran caught in the wild in Amazonia. In total, we screened 90 individuals (from 27 species), of which 39 individuals (from 22 species) were Bd-positive. All samples collected in Bahia (2 individuals), Pernambuco (3 individuals), Pará (1 individual), and Minas Gerais (1 individual) showed positive results for Bd. We found a positive correlation between anuran richness per family and the number of infected species in the Atlantic forest, supporting previous observations that Bd lacks strong host specificity; of 38% of the anuran species in the Atlantic forest that were tested for Bd infection, 25% showed positive results. The results of our study exemplify the pandemic and widespread nature of Bd infection in amphibians.

Redefining disease emergence to improve prioritization and macro-ecological analyses.

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Rosenthal, Samantha R; Ostfeld, Richard S; McGarvey, Stephen T; Lurie, Mark N; Smith, Katherine F

2015-12-01

Microbial infections are as old as the hosts they sicken, but interest in the emergence of pathogens and the diseases they cause has been accelerating rapidly. The term 'emerging infectious disease' was coined in the mid-1900s to describe changes in disease dynamics in the modern era. Both the term and the phenomena it is meant to characterize have evolved and diversified over time, leading to inconsistencies and confusion. Here, we review the evolution of the term 'emerging infectious disease' (EID) in the literature as applied to human hosts. We examine the pathways (e.g., speciation or strain differentiation in the causative agent vs. rapid geographic expansion of an existing pathogen) by which diseases emerge. We propose a new framework for disease and pathogen emergence to improve prioritization. And we illustrate how the operational definition of an EID affects conclusions concerning the pathways by which diseases emerge and the ecological and socioeconomic drivers that elicit emergence. As EIDs appear to be increasing globally, and resources for science level off or decline, the research community is pushed to prioritize its focus on the most threatening diseases, riskiest potential pathogens, and the places they occur. The working definition of emerging infectious diseases and pathogens plays a crucial role in prioritization, but we argue that the current definitions may be impeding these efforts. We propose a new framework for classifying pathogens and diseases as "emerging" that distinguishes EIDs from emerging pathogens and novel potential pathogens. We suggest prioritization of: 1) EIDs for adaptation and mitigation, 2) emerging pathogens for preventive measures, and 3) novel potential pathogens for intensive surveillance.

Quantitative risk assessment: an emerging tool for emerging foodborne pathogens.

OpenAIRE

Lammerding, A. M.; Paoli, G. M.

1997-01-01

New challenges to the safety of the food supply require new strategies for evaluating and managing food safety risks. Changes in pathogens, food preparation, distribution, and consumption, and population immunity have the potential to adversely affect human health. Risk assessment offers a framework for predicting the impact of changes and trends on the provision of safe food. Risk assessment models facilitate the evaluation of active or passive changes in how foods are produced, processed, d...

Prevalence and pathogen load estimates for the fungus Batrachochytrium dendrobatidis are impacted by ITS DNA copy number variation

DEFF Research Database (Denmark)

Rebollar, Eria A.; Woodhams, Douglas C.; LaBumbard, Brandon

2017-01-01

The ribosomal gene complex is a multi-copy region that is widely used for phylogenetic analyses of organisms from all 3 domains of life. In fungi, the copy number of the internal transcribed spacer (ITS) is used to detect abundance of pathogens causing diseases such as chytridiomycosis in amphibi...

Emerging and potentially emerging viruses in water environments

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Giuseppina La Rosa

2012-12-01

Full Text Available Among microorganisms, viruses are best fit to become emerging pathogens since they are able to adapt not only by mutation but also through recombination and reassortment and can thus become able to infect new hosts and to adjust to new environments. Enteric viruses are among the commonest and most hazardous waterborne pathogens, causing both sporadic and outbreak-related illness. The main health effect associated with enteric viruses is gastrointestinal illness, but they can also cause respiratory symptoms, conjunctivitis, hepatitis, central nervous system infections, and chronic diseases. Non-enteric viruses, such as respiratory and epitheliotrophic viruses are not considered waterborne, as they are not readily transmitted to water sources from infected individuals. The present review will focus on viral pathogens shown to be transmitted through water. It will also provide an overview of viruses that had not been a concern for waterborne transmission in the past, but that may represent potentially emerging waterborne pathogens due to their occurrence and persistence in water environments.

Insights into the emergent bacterial pathogen Cronobacter spp., generated by multilocus sequence typing and analysis

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Susan eJoseph

2012-11-01

Full Text Available Cronobacter spp. (previously known as Enterobacter sakazakii is a bacterial pathogen affecting all age groups, with particularly severe clinical complications in neonates and infants. One recognised route of infection being the consumption of contaminated infant formula. As a recently recognised bacterial pathogen of considerable importance and regulatory control, appropriate detection and identification schemes are required. The application of multilocus sequence typing (MLST and analysis (MLSA of the seven alleles atpD, fusA, glnS, gltB, gyrB, infB and ppsA (concatenated length 3036 base pairs has led to considerable advances in our understanding of the genus. This approach is supported by both the reliability of DNA sequencing over subjective phenotyping and the establishment of a MLST database which has open access and is also curated; http://www.pubMLST.org/cronobacter. MLST has been used to describe the diversity of the newly recognised genus, instrumental in the formal recognition of new Cronobacter species (C. universalis and C. condimenti and revealed the high clonality of strains and the association of clonal complex 4 with neonatal meningitis cases. Clearly the MLST approach has considerable benefits over the use of non-DNA sequence based methods of analysis for newly emergent bacterial pathogens. The application of MLST and MLSA has dramatically enabled us to better understand this opportunistic bacterium which can cause irreparable damage to a newborn baby’s brain, and has contributed to improved control measures to protect neonatal health.

Understanding the Pathogenicity of Burkholderia contaminans, an Emerging Pathogen in Cystic Fibrosis.

Science.gov (United States)

Nunvar, Jaroslav; Kalferstova, Lucie; Bloodworth, Ruhi A M; Kolar, Michal; Degrossi, Jose; Lubovich, Silvina; Cardona, Silvia T; Drevinek, Pavel

2016-01-01

Several bacterial species from the Burkholderia cepacia complex (Bcc) are feared opportunistic pathogens that lead to debilitating lung infections with a high risk of developing fatal septicemia in cystic fibrosis (CF) patients. However, the pathogenic potential of other Bcc species is yet unknown. To elucidate clinical relevance of Burkholderia contaminans, a species frequently isolated from CF respiratory samples in Ibero-American countries, we aimed to identify its key virulence factors possibly linked with an unfavorable clinical outcome. We performed a genome-wide comparative analysis of two isolates of B. contaminans ST872 from sputum and blood culture of a female CF patient in Argentina. RNA-seq data showed significant changes in expression for quorum sensing-regulated virulence factors and motility and chemotaxis. Furthermore, we detected expression changes in a recently described low-oxygen-activated (lxa) locus which encodes stress-related proteins, and for two clusters responsible for the biosynthesis of antifungal and hemolytic compounds pyrrolnitrin and occidiofungin. Based on phenotypic assays that confirmed changes in motility and in proteolytic, hemolytic and antifungal activities, we were able to distinguish two phenotypes of B. contaminans that coexisted in the host and entered her bloodstream. Whole genome sequencing revealed that the sputum and bloodstream isolates (each representing a distinct phenotype) differed by over 1,400 mutations as a result of a mismatch repair-deficient hypermutable state of the sputum isolate. The inferred lack of purifying selection against nonsynonymous mutations and the high rate of pseudogenization in the derived isolate indicated limited evolutionary pressure during evolution in the nutrient-rich, stable CF sputum environment. The present study is the first to examine the genomic and transcriptomic differences between longitudinal isolates of B. contaminans. Detected activity of a number of putative virulence

Redefining disease emergence to improve prioritization and macro-ecological analyses

Directory of Open Access Journals (Sweden)

Samantha R. Rosenthal

2015-12-01

Full Text Available Microbial infections are as old as the hosts they sicken, but interest in the emergence of pathogens and the diseases they cause has been accelerating rapidly. The term ‘emerging infectious disease’ was coined in the mid-1900s to describe changes in disease dynamics in the modern era. Both the term and the phenomena it is meant to characterize have evolved and diversified over time, leading to inconsistencies and confusion. Here, we review the evolution of the term ‘emerging infectious disease’ (EID in the literature as applied to human hosts. We examine the pathways (e.g., speciation or strain differentiation in the causative agent vs. rapid geographic expansion of an existing pathogen by which diseases emerge. We propose a new framework for disease and pathogen emergence to improve prioritization. And we illustrate how the operational definition of an EID affects conclusions concerning the pathways by which diseases emerge and the ecological and socioeconomic drivers that elicit emergence. As EIDs appear to be increasing globally, and resources for science level off or decline, the research community is pushed to prioritize its focus on the most threatening diseases, riskiest potential pathogens, and the places they occur. The working definition of emerging infectious diseases and pathogens plays a crucial role in prioritization, but we argue that the current definitions may be impeding these efforts. We propose a new framework for classifying pathogens and diseases as “emerging” that distinguishes EIDs from emerging pathogens and novel potential pathogens. We suggest prioritization of: 1 EIDs for adaptation and mitigation, 2 emerging pathogens for preventive measures, and 3 novel potential pathogens for intensive surveillance.

Phylogenetic incongruence in E. coli O104: understanding the evolutionary relationships of emerging pathogens in the face of homologous recombination.

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Weilong Hao

Full Text Available Escherichia coli O104:H4 was identified as an emerging pathogen during the spring and summer of 2011 and was responsible for a widespread outbreak that resulted in the deaths of 50 people and sickened over 4075. Traditional phenotypic and genotypic assays, such as serotyping, pulsed field gel electrophoresis (PFGE, and multilocus sequence typing (MLST, permit identification and classification of bacterial pathogens, but cannot accurately resolve relationships among genotypically similar but pathotypically different isolates. To understand the evolutionary origins of E. coli O104:H4, we sequenced two strains isolated in Ontario, Canada. One was epidemiologically linked to the 2011 outbreak, and the second, unrelated isolate, was obtained in 2010. MLST analysis indicated that both isolates are of the same sequence type (ST678, but whole-genome sequencing revealed differences in chromosomal and plasmid content. Through comprehensive phylogenetic analysis of five O104:H4 ST678 genomes, we identified 167 genes in three gene clusters that have undergone homologous recombination with distantly related E. coli strains. These recombination events have resulted in unexpectedly high sequence diversity within the same sequence type. Failure to recognize or adjust for homologous recombination can result in phylogenetic incongruence. Understanding the extent of homologous recombination among different strains of the same sequence type may explain the pathotypic differences between the ON2010 and ON2011 strains and help shed new light on the emergence of this new pathogen.

Emergence and Adaptation of a Novel Highly Pathogenic H7N9 Influenza Virus in Birds and Humans from a 2013 Human-Infecting Low-Pathogenic Ancestor.

Science.gov (United States)

Qi, Wenbao; Jia, Weixin; Liu, Di; Li, Jing; Bi, Yuhai; Xie, Shumin; Li, Bo; Hu, Tao; Du, Yingying; Xing, Li; Zhang, Jiahao; Zhang, Fuchun; Wei, Xiaoman; Eden, John-Sebastian; Li, Huanan; Tian, Huaiyu; Li, Wei; Su, Guanming; Lao, Guangjie; Xu, Chenggang; Xu, Bing; Liu, Wenjun; Zhang, Guihong; Ren, Tao; Holmes, Edward C; Cui, Jie; Shi, Weifeng; Gao, George F; Liao, Ming

2018-01-15

Since its emergence in 2013, the H7N9 low-pathogenic avian influenza virus (LPAIV) has been circulating in domestic poultry in China, causing five waves of human infections. A novel H7N9 highly pathogenic avian influenza virus (HPAIV) variant possessing multiple basic amino acids at the cleavage site of the hemagglutinin (HA) protein was first reported in two cases of human infection in January 2017. More seriously, those novel H7N9 HPAIV variants have been transmitted and caused outbreaks on poultry farms in eight provinces in China. Herein, we demonstrate the presence of three different amino acid motifs at the cleavage sites of these HPAIV variants which were isolated from chickens and humans and likely evolved from the preexisting LPAIVs. Animal experiments showed that these novel H7N9 HPAIV variants are both highly pathogenic in chickens and lethal to mice. Notably, human-origin viruses were more pathogenic in mice than avian viruses, and the mutations in the PB2 gene associated with adaptation to mammals (E627K, A588V, and D701N) were identified by next-generation sequencing (NGS) and Sanger sequencing of the isolates from infected mice. No polymorphisms in the key amino acid substitutions of PB2 and HA in isolates from infected chicken lungs were detected by NGS. In sum, these results highlight the high degree of pathogenicity and the valid transmissibility of this new H7N9 variant in chickens and the quick adaptation of this new H7N9 variant to mammals, so the risk should be evaluated and more attention should be paid to this variant. IMPORTANCE Due to the recent increased numbers of zoonotic infections in poultry and persistent human infections in China, influenza A(H7N9) virus has remained a public health threat. Most of the influenza A(H7N9) viruses reported previously have been of low pathogenicity. Now, these novel H7N9 HPAIV variants have caused human infections in three provinces and outbreaks on poultry farms in eight provinces in China. We analyzed

Viral pathogen discovery

Science.gov (United States)

Chiu, Charles Y

2015-01-01

Viral pathogen discovery is of critical importance to clinical microbiology, infectious diseases, and public health. Genomic approaches for pathogen discovery, including consensus polymerase chain reaction (PCR), microarrays, and unbiased next-generation sequencing (NGS), have the capacity to comprehensively identify novel microbes present in clinical samples. Although numerous challenges remain to be addressed, including the bioinformatics analysis and interpretation of large datasets, these technologies have been successful in rapidly identifying emerging outbreak threats, screening vaccines and other biological products for microbial contamination, and discovering novel viruses associated with both acute and chronic illnesses. Downstream studies such as genome assembly, epidemiologic screening, and a culture system or animal model of infection are necessary to establish an association of a candidate pathogen with disease. PMID:23725672

New and emerging pathogens in canine infectious respiratory disease.

Science.gov (United States)

Priestnall, S L; Mitchell, J A; Walker, C A; Erles, K; Brownlie, J

2014-03-01

Canine infectious respiratory disease is a common, worldwide disease syndrome of multifactorial etiology. This review presents a summary of 6 viruses (canine respiratory coronavirus, canine pneumovirus, canine influenza virus, pantropic canine coronavirus, canine bocavirus, and canine hepacivirus) and 2 bacteria (Streptococcus zooepidemicus and Mycoplasma cynos) that have been associated with respiratory disease in dogs. For some pathogens a causal role is clear, whereas for others, ongoing research aims to uncover their pathogenesis and contribution to this complex syndrome. Etiology, clinical disease, pathogenesis, and epidemiology are described for each pathogen, with an emphasis on recent discoveries or novel findings.

The trans-kingdom identification of negative regulators of pathogen hypervirulence.

Science.gov (United States)

Brown, Neil A; Urban, Martin; Hammond-Kosack, Kim E

2016-01-01

Modern society and global ecosystems are increasingly under threat from pathogens, which cause a plethora of human, animal, invertebrate and plant diseases. Of increasing concern is the trans-kingdom tendency for increased pathogen virulence that is beginning to emerge in natural, clinical and agricultural settings. The study of pathogenicity has revealed multiple examples of convergently evolved virulence mechanisms. Originally described as rare, but increasingly common, are interactions where a single gene deletion in a pathogenic species causes hypervirulence. This review utilised the pathogen-host interaction database (www.PHI-base.org) to identify 112 hypervirulent mutations from 37 pathogen species, and subsequently interrogates the trans-kingdom, conserved, molecular, biochemical and cellular themes that cause hypervirulence. This study investigates 22 animal and 15 plant pathogens including 17 bacterial and 17 fungal species. Finally, the evolutionary significance and trans-kingdom requirement for negative regulators of hypervirulence and the implication of pathogen hypervirulence and emerging infectious diseases on society are discussed. © FEMS 2015.

Escherichia coli O157:H7 - An Emerging Pathogen in foods of Animal Origin

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Ch. Bindu Kiranmayi

Full Text Available Escherichia coli O157:H7 is an emerging public health concern in most countries of the world. E. coli O157:H7 was known to be a human pathogen for nearly 24 years. EHEC O157 infection is estimated to be the fourth most costly food borne disease in Canada and USA, not counting the cost of possible litigation. E. coli O157:H7 and Salmonella are the leading causes of produce related outbreaks, accounting for 20 and 30% respectively. The authority of the Federal Meat Inspection Act, FSIS (Food Safety and Inspection Service declared Escherichia coli O157:H7, an adulterant in raw ground beef and enforced “zero tolerance” (USDA-FSIS, 17 December 1998. Because of the severity of these illnesses and the apparent low infective dose (less than 10 cells, Escherichia coli O157:H7 is considered one of the most serious of known food borne pathogens. Escherichia coli O157:H7 is mainly pathogenic to human but in cattle and other animals, it did not induce any clinical disease except diarrhea. So, these animals act as carriers to Escherichia coli O157:H7. The majority transmission is through eating of undercooked contaminated ground meat and consumption of raw milk, raw vegetables, fruits contaminated by water, cheese, curd and also through consumption of sprouts, lettuce and juice. The conventional isolation procedure includes growth in enrichment broth like modified EC (E. coli broth or modified tryptic soy broth (mTSB Since the infection primarily occurs via faeco-oral route, the preventive measures include food hygiene measures like proper cooking of meat, consumption of pasteurized milk, washing fruits and vegetables especially those to be eaten raw and drinking chlorine treated water and personnel hygiene measures like washing hands after toilet visits. [Veterinary World 2010; 3(8.000: 382-389

The arable plant ecosystem as battleground for emergence of human pathogens

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Leo eVan Overbeek

2014-03-01

Full Text Available Disease incidences related to Escherichia coli and Salmonella enterica infections by consumption of (fresh vegetables, sprouts and occasionally fruits made clear that these pathogens are not only transmitted to humans via the ‘classical’ routes of meat, eggs and dairy products, but also can be transmitted to humans via plants or products derived from plants. Nowadays, it is of major concern that these human pathogens, especially the ones belonging to the taxonomical family of Enterobacteriaceae, become adapted to environmental habitats without losing their virulence to humans. Adaptation to the plant environment would lead to longer persistence in plants, increasing their chances on transmission to humans via consumption of plant-derived food. One of the mechanisms of adaptation to the plant environment in human pathogens, proposed in this paper, is horizontal transfer of genes from different microbial communities present in the arable ecosystem, like the ones originating from soil, animal digestive track systems (manure, water and plants themselves. Genes that would confer better adaptation to the phytosphere might be genes involved in plant colonization, stress resistance and nutrient acquisition and utilization. Because human pathogenic enterics often were prone to genetic exchanges via phages and conjugative plasmids, it was postulated that these genetic elements may be hold key responsible for horizontal gene transfers between human pathogens and indigenous microbes in agroproduction systems. In analogy to zoonosis, we coin the term phytonosis for a human pathogen that is transmitted via plants and not exclusively via animals.

76 FR 61956 - Endangered and Threatened Wildlife and Plants; Endangered Status for the Ozark Hellbender Salamander

Science.gov (United States)

2011-10-06

... stated that animals infected with Batrachochytrium dendrobatidis (the pathogen which causes amphibian... seq.) is a law that was passed to prevent extinction of species by providing measures to help alleviate the loss of species and their habitats. Before a plant or animal species can receive the...

Dr Jekyll and Mrs Hyde: Risky hybrid sex by amphibian-parasitizing chytrids in the Brazilian Atlantic Forests.

Science.gov (United States)

Ghosh, Pria; Fisher, Matthew C

2016-07-01

In their article in this issue of Molecular Ecology, Jenkinson et al. () and colleagues address a worrying question-how could arguably the most dangerous pathogen known to science, Batrachochytrium dendrobatidis (Bd), become even more virulent? The answer: start having sex. Jenkinson et al. present a case for how the introduction into Brazil of the globally invasive lineage of Bd, BdGPL, has disrupted the relationship between native amphibians and an endemic Bd lineage, BdBrazil. BdBrazil is hypothesized to be native to the Atlantic Forest and so have a long co-evolutionary history with biodiverse Atlantic Forest amphibian community. The authors suggest that this has resulted in a zone of hybrid Bd genotypes which are potentially more likely to cause fatal chytridiomycosis than either parent lineage. The endemic-nonendemic Bd hybrid genotypes described in this study, and the evidence for pathogen translocation via the global amphibian trade presented, highlights the danger of anthropogenic pathogen dispersal. This research emphasizes that biosecurity regulations may have to refocus on lineages within species if we are to mitigate against the danger of new, possibly hypervirulent genotypes of pathogens emerging as phylogeographic barriers are breached. © 2016 John Wiley & Sons Ltd.

Challenges in Fusarium, a Trans-Kingdom Pathogen

NARCIS (Netherlands)

van Diepeningen, Anne D; de Hoog, G Sybren

Fusarium species are emerging human pathogens, next to being plant pathogens. Problems with Fusarium are in their diagnostics and in their difficult treatment, but also in what are actual Fusarium species or rather Fusarium-like species. In this issue Guevara-Suarez et al. (Mycopathologia. doi:

Low-pathogenic influenza A viruses in North American diving ducks contribute to the emergence of a novel highly pathogenic influenza A(H7N8) virus

Science.gov (United States)

Xu, Yifei; Ramey, Andrew M.; Bowman, Andrew S; DeLiberto, Thomas J.; Killian, Mary Lea; Krauss, Scott; Nolting, Jacqueline M.; Torchetti, Mia Kim; Reeves, Andrew B.; Webby, Richard J.; Stallknecht, David E.; Wan, Xiu-Feng

2017-01-01

Introductions of low-pathogenic avian influenza (LPAI) viruses of subtypes H5 and H7 into poultry from wild birds have the potential to mutate to highly pathogenic avian influenza (HPAI) viruses, but such viruses' origins are often unclear. In January 2016, a novel H7N8 HPAI virus caused an outbreak in turkeys in Indiana, USA. To determine the virus's origin, we sequenced the genomes of 441 wild-bird origin influenza A viruses (IAVs) from North America and subjected them to evolutionary analyses. The results showed that the H7N8 LPAI virus most likely circulated among diving ducks in the Mississippi flyway during autumn 2015 and was subsequently introduced to Indiana turkeys, in which it evolved high pathogenicity. Preceding the outbreak, an isolate with six gene segments (PB2, PB1, PA, HA, NA, and NS) sharing >99% sequence identity with those of H7N8 turkey isolates was recovered from a diving duck sampled in Kentucky, USA. H4N8 IAVs from other diving ducks possessed five H7N8-like gene segments (PB2, PB1, NA, MP, and NS; >98% sequence identity). Our findings suggest that viral gene constellations circulating among diving ducks can contribute to the emergence of IAVs that affect poultry. Therefore, diving ducks may serve an important and understudied role in the maintenance, diversification, and transmission of IAVs in the wild-bird reservoir.

Identifying species conservation strategies to reduce disease-associated declines

Science.gov (United States)

Gerber, Brian D.; Converse, Sarah J.; Muths, Erin L.; Crockett, Harry J.; Mosher, Brittany A.; Bailey, Larissa L.

2018-01-01

Emerging infectious diseases (EIDs) are a salient threat to many animal taxa, causing local and global extinctions, altering communities and ecosystem function. The EID chytridiomycosis is a prominent driver of amphibian declines, which is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). To guide conservation policy, we developed a predictive decision-analytic model that combines empirical knowledge of host-pathogen metapopulation dynamics with expert judgment regarding effects of management actions, to select from potential conservation strategies. We apply our approach to a boreal toad (Anaxyrus boreas boreas) and Bd system, identifying optimal strategies that balance tradeoffs in maximizing toad population persistence and landscape-level distribution, while considering costs. The most robust strategy is expected to reduce the decline of toad breeding sites from 53% to 21% over 50 years. Our findings are incorporated into management policy to guide conservation planning. Our online modeling application provides a template for managers of other systems challenged by EIDs.

ISOLATION AND PATHOGENICITY OF A POSSIBLE Pythium aphanidermatum IN Jatropha Curcas L. NON TOXIC

Directory of Open Access Journals (Sweden)

Ofelia Andrea Valdes Rodriguez

2011-03-01

A chromista, possible Pythium aphanidermatum, was isolated from severely damage seeds and seedlings recently started from Jatropha curcas L. non toxic seeds sown in the tropical area of Veracruz, Mexico. In order to study pathogenic Pythium aphanidermatum effects over pre-emergent and post-emergent stages, seeds and young seedlings were inoculated with the isolated pathogen, and the chromista showed possible pathogenic activity against pre-emergency and recently started post-emergency; however, statistically significant damaged was not found in older seedlings.   Â

Effects of the Chytrid fungus on the Tarahumara frog (Rana tarahumarae) in Arizona and Sonora, Mexico

Science.gov (United States)

Stephen F. Hale; Philip C. Rosen; James L. Jarchow; Gregory A. Bradley

2005-01-01

We conducted histological analyses on museum specimens collected 1975-1999 from 10 sites in Arizona and Sonora to test for the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) in ranid frogs, focusing on the Tarahumara frog (Rana tarahumarae). During 1981-2000, frogs displaying disease signs were found in the field, and...

An emerging cyberinfrastructure for biodefense pathogen and pathogen–host data

Science.gov (United States)

Zhang, C.; Crasta, O.; Cammer, S.; Will, R.; Kenyon, R.; Sullivan, D.; Yu, Q.; Sun, W.; Jha, R.; Liu, D.; Xue, T.; Zhang, Y.; Moore, M.; McGarvey, P.; Huang, H.; Chen, Y.; Zhang, J.; Mazumder, R.; Wu, C.; Sobral, B.

2008-01-01

The NIAID-funded Biodefense Proteomics Resource Center (RC) provides storage, dissemination, visualization and analysis capabilities for the experimental data deposited by seven Proteomics Research Centers (PRCs). The data and its publication is to support researchers working to discover candidates for the next generation of vaccines, therapeutics and diagnostics against NIAID's Category A, B and C priority pathogens. The data includes transcriptional profiles, protein profiles, protein structural data and host–pathogen protein interactions, in the context of the pathogen life cycle in vivo and in vitro. The database has stored and supported host or pathogen data derived from Bacillus, Brucella, Cryptosporidium, Salmonella, SARS, Toxoplasma, Vibrio and Yersinia, human tissue libraries, and mouse macrophages. These publicly available data cover diverse data types such as mass spectrometry, yeast two-hybrid (Y2H), gene expression profiles, X-ray and NMR determined protein structures and protein expression clones. The growing database covers over 23 000 unique genes/proteins from different experiments and organisms. All of the genes/proteins are annotated and integrated across experiments using UniProt Knowledgebase (UniProtKB) accession numbers. The web-interface for the database enables searching, querying and downloading at the level of experiment, group and individual gene(s)/protein(s) via UniProtKB accession numbers or protein function keywords. The system is accessible at http://www.proteomicsresource.org/. PMID:17984082

Emerging microbial biocontrol strategies for plant pathogens.

Science.gov (United States)

Syed Ab Rahman, Sharifah Farhana; Singh, Eugenie; Pieterse, Corné M J; Schenk, Peer M

2018-02-01

To address food security, agricultural yields must increase to match the growing human population in the near future. There is now a strong push to develop low-input and more sustainable agricultural practices that include alternatives to chemicals for controlling pests and diseases, a major factor of heavy losses in agricultural production. Based on the adverse effects of some chemicals on human health, the environment and living organisms, researchers are focusing on potential biological control microbes as viable alternatives for the management of pests and plant pathogens. There is a growing body of evidence that demonstrates the potential of leaf and root-associated microbiomes to increase plant efficiency and yield in cropping systems. It is important to understand the role of these microbes in promoting growth and controlling diseases, and their application as biofertilizers and biopesticides whose success in the field is still inconsistent. This review focusses on how biocontrol microbes modulate plant defense mechanisms, deploy biocontrol actions in plants and offer new strategies to control plant pathogens. Apart from simply applying individual biocontrol microbes, there are now efforts to improve, facilitate and maintain long-term plant colonization. In particular, great hopes are associated with the new approaches of using "plant-optimized microbiomes" (microbiome engineering) and establishing the genetic basis of beneficial plant-microbe interactions to enable breeding of "microbe-optimized crops". Copyright © 2017 Elsevier B.V. All rights reserved.

Childhood urinary tract infection in Benin City: pathogens and ...

African Journals Online (AJOL)

Childhood urinary tract infection in Benin City: pathogens and antimicrobial ... of bacterial isolates implicated in urinary tract infection (UTI) amongst children was ... There is also an emerging resistance of common pathogens to azithromycin ...

Arcobacter: an emerging food-borne zoonotic pathogen, its public health concerns and advances in diagnosis and control - a comprehensive review.

Science.gov (United States)

Ramees, Thadiyam Puram; Dhama, Kuldeep; Karthik, Kumaragurubaran; Rathore, Ramswaroop Singh; Kumar, Ashok; Saminathan, Mani; Tiwari, Ruchi; Malik, Yashpal Singh; Singh, Raj Kumar

2017-12-01

Arcobacter has emerged as an important food-borne zoonotic pathogen, causing sometimes serious infections in humans and animals. Newer species of Arcobacter are being incessantly emerging (presently 25 species have been identified) with novel information on the evolutionary mechanisms and genetic diversity among different Arcobacter species. These have been reported from chickens, domestic animals (cattle, pigs, sheep, horses, dogs), reptiles (lizards, snakes and chelonians), meat (poultry, pork, goat, lamb, beef, rabbit), vegetables and from humans in different countries. Arcobacters are implicated as causative agents of diarrhea, mastitis and abortion in animals, while causing bacteremia, endocarditis, peritonitis, gastroenteritis and diarrhea in humans. Three species including A. butzleri, A. cryaerophilus and A. skirrowii are predominantly associated with clinical conditions. Arcobacters are primarily transmitted through contaminated food and water sources. Identification of Arcobacter by biochemical tests is difficult and isolation remains the gold standard method. Current diagnostic advances have provided various molecular methods for efficient detection and differentiation of the Arcobacters at genus and species level. To overcome the emerging antibiotic resistance problem there is an essential need to explore the potential of novel and alternative therapies. Strengthening of the diagnostic aspects is also suggested as in most cases Arcobacters goes unnoticed and hence the exact epidemiological status remains uncertain. This review updates the current knowledge and many aspects of this important food-borne pathogen, namely etiology, evolution and emergence, genetic diversity, epidemiology, the disease in animals and humans, public health concerns, and advances in its diagnosis, prevention and control.

Rapid and Accurate Molecular Identification of the Emerging Multidrug-Resistant Pathogen Candida auris.

Science.gov (United States)

Kordalewska, Milena; Zhao, Yanan; Lockhart, Shawn R; Chowdhary, Anuradha; Berrio, Indira; Perlin, David S

2017-08-01

Candida auris is an emerging multidrug-resistant fungal pathogen causing nosocomial and invasive infections associated with high mortality. C. auris is commonly misidentified as several different yeast species by commercially available phenotypic identification platforms. Thus, there is an urgent need for a reliable diagnostic method. In this paper, we present fast, robust, easy-to-perform and interpret PCR and real-time PCR assays to identify C. auris and related species: Candida duobushaemulonii , Candida haemulonii , and Candida lusitaniae Targeting rDNA region nucleotide sequences, primers specific for C. auris only or C. auris and related species were designed. A panel of 140 clinical fungal isolates was used in both PCR and real-time PCR assays followed by electrophoresis or melting temperature analysis, respectively. The identification results from the assays were 100% concordant with DNA sequencing results. These molecular assays overcome the deficiencies of existing phenotypic tests to identify C. auris and related species. Copyright © 2017 Kordalewska et al.

The Emergence of Vibrio pathogens in Europe: Ecology, Evolution and Pathogenesis (Paris, 11-12 March 2015

Directory of Open Access Journals (Sweden)

Frederique eLe Roux

2015-08-01

Full Text Available Global change has caused a worldwide increase in reports of Vibrio-associated diseases with ecosystem-wide impacts on humans and marine animals. In Europe, higher prevalence of human infections followed regional climatic trends with outbreaks occurring during episodes of unusually warm weather. Similar patterns were also observed in Vibrio-associated diseases affecting marine organisms such as fish, bivalves and corals. Basic knowledge is still lacking on the ecology and evolutionary biology of these bacteria as well as on their virulence mechanisms. Current limitations in experimental systems to study infection and the lack of diagnostic tools still prevent a better understanding of Vibrio emergence. A major challenge is to foster cooperation between fundamental and applied research in order to investigate the consequences of pathogen emergence in natural Vibrio populations and answer federative questions that meet societal needs. Here we report the proceedings of the first European workshop dedicated to these specific goals of the Vibrio research community by connecting current knowledge to societal issues related to ocean health and food security.

Role of domestic ducks in the emergence of a new genotype of highly pathogenic H5N1 avian influenza A viruses in Bangladesh.

Science.gov (United States)

Barman, Subrata; Marinova-Petkova, Atanaska; Hasan, M Kamrul; Akhtar, Sharmin; El-Shesheny, Rabeh; Turner, Jasmine Cm; Franks, John; Walker, David; Seiler, Jon; Friedman, Kimberly; Kercher, Lisa; Jeevan, Trushar; Darnell, Daniel; Kayali, Ghazi; Jones-Engel, Lisa; McKenzie, Pamela; Krauss, Scott; Webby, Richard J; Webster, Robert G; Feeroz, Mohammed M

2017-08-09

Highly pathogenic avian influenza H5N1 viruses were first isolated in Bangladesh in February 2007. Subsequently, clades 2.2.2, 2.3.4.2 and 2.3.2.1a were identified in Bangladesh, and our previous surveillance data revealed that by the end of 2014, the circulating viruses exclusively comprised clade 2.3.2.1a. We recently determined the status of circulating avian influenza viruses in Bangladesh by conducting surveillance of live poultry markets and waterfowl in wetland areas from February 2015 through February 2016. Until April 2015, clade 2.3.2.1a persisted without any change in genotype. However, in June 2015, we identified a new genotype of H5N1 viruses, clade 2.3.2.1a, which quickly became predominant. These newly emerged H5N1 viruses contained the hemagglutinin, neuraminidase and matrix genes of circulating 2.3.2.1a Bangladeshi H5N1 viruses and five other genes of low pathogenic Eurasian-lineage avian influenza A viruses. Some of these internal genes were closely related to those of low pathogenic viruses isolated from ducks in free-range farms and wild birds in a wetland region of northeastern Bangladesh, where commercially raised domestic ducks have frequent contact with migratory birds. These findings indicate that migratory birds of the Central Asian flyway and domestic ducks in the free-range farms in Tanguar haor-like wetlands played an important role in the emergence of this novel genotype of highly pathogenic H5N1 viruses.

Bacteraemia Due to ESKAPE Pathogens: An Emerging Problem in Cancer Patients

International Nuclear Information System (INIS)

El-Mahallawy, H.A.; Hassan, S.S.; El-Wakil, M.; Moneer, M.M.

2016-01-01

Background and aim: In recent years, a few of the antibiotic-resistant bacteria, known as ESKAPE pathogens, have been found responsible for serious infections. We investigated the risk factors, and impact of ESKAPE pathogens on course of blood stream infections (BSIs) in cancer patients in comparison to coagulase negative Staphylococci (CoNS). Patients and methods: The data of patients with ESKAPE positive blood cultures at National Cancer Institute, Cairo University were analyzed. Identification and antimicrobial susceptibility of isolates were done using Microscan Walk Away 96. Results: In a 6 month period, ESKAPE pathogens were isolated from non-duplicate blood cultures in 81 episodes of 72 cases of pediatric cancer patients, while CoNS were isolated from 135 blood cultures of 116 patients. The ESKAPE pathogens isolated were Enterobacter spp., methicillin- resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae , Acinetobacter baumannii , Pseudomonas aeruginosa , and Enterococci in 12%, 23%, 37%, 10%, 9%, and 9% of episodes, respectively. Health-care acquired infections constituted 75% of ESKAPE infections. Duration of episodes and overall mortality were significantly higher in ESKAPE BSIs when compared to CoNS (14.5 ± 7.6 versus 09.9 ± 6.9), and (26% versus 4%); respectively, p value <0.001. Conclusions: ESKAPE pathogens were significantly associated with higher rates of morbidity and mortality indicating the need for improving the means of prevention of these types of infections within health care premises. Microbiology laboratories have a role in defining more dangerous infections and rapid diagnostics are required in the era of resistance.

Emerging trends in molecular interactions between plants and the broad host range fungal pathogens Botrytis cinerea and Sclerotinia sclerotiorum

Directory of Open Access Journals (Sweden)

Malick eMbengue

2016-03-01

Full Text Available Fungal plant pathogens are major threats to food security worldwide. Sclerotinia sclerotiorum and Botrytis cinerea are closely related Ascomycete plant pathogens causing mold diseases on hundreds of plant species. There is no genetic source of complete plant resistance to these broad host range pathogens known to date. Instead, natural plant populations show a continuum of resistance levels controlled by multiple genes, a phenotype designated as quantitative disease resistance. Little is known about the molecular mechanisms controlling the interaction between plants and S. sclerotiorum and B. cinerea but significant advances were made on this topic in the last years. This minireview highlights a selection of nine themes that emerged in recent research reports on the molecular bases of plant-S. sclerotiorum and plant-B. cinerea interactions. On the fungal side, this includes progress on understanding the role of oxalic acid, on the study of fungal small secreted proteins. Next, we discuss the exchanges of small RNA between organisms and the control of cell death in plant and fungi during pathogenic interactions. Finally on the plant side, we highlight defense priming by mechanical signals, the characterization of plant Receptor-like proteins and the hormone abscisic acid in the response to B. cinerea and S. sclerotiorum , the role of plant general transcription machinery and plant small bioactive peptides. These represent nine trends we selected as remarkable in our understanding of fungal molecules causing disease and plant mechanisms associated with disease resistance to two devastating broad host range fungi.

Mechanisms of innate immune evasion in re-emerging RNA viruses.

Science.gov (United States)

Ma, Daphne Y; Suthar, Mehul S

2015-06-01

Recent outbreaks of Ebola, West Nile, Chikungunya, Middle Eastern Respiratory and other emerging/re-emerging RNA viruses continue to highlight the need to further understand the virus-host interactions that govern disease severity and infection outcome. As part of the early host antiviral defense, the innate immune system mediates pathogen recognition and initiation of potent antiviral programs that serve to limit virus replication, limit virus spread and activate adaptive immune responses. Concordantly, viral pathogens have evolved several strategies to counteract pathogen recognition and cell-intrinsic antiviral responses. In this review, we highlight the major mechanisms of innate immune evasion by emerging and re-emerging RNA viruses, focusing on pathogens that pose significant risk to public health. Copyright © 2015 Elsevier B.V. All rights reserved.

Pathogenic human viruses in coastal waters

Science.gov (United States)

Griffin, Dale W.; Donaldson, Kim A.; Paul, J.H.; Rose, Joan B.

2003-01-01

This review addresses both historical and recent investigations into viral contamination of marine waters. With the relatively recent emergence of molecular biology-based assays, a number of investigations have shown that pathogenic viruses are prevalent in marine waters being impacted by sewage. Research has shown that this group of fecal-oral viral pathogens (enteroviruses, hepatitis A viruses, Norwalk viruses, reoviruses, adenoviruses, rotaviruses, etc.) can cause a broad range of asymptomatic to severe gastrointestinal, respiratory, and eye, nose, ear, and skin infections in people exposed through recreational use of the water. The viruses and the nucleic acid signature survive for an extended period in the marine environment. One of the primary concerns of public health officials is the relationship between the presence of pathogens and the recreational risk to human health in polluted marine environments. While a number of studies have attempted to address this issue, the relationship is still poorly understood. A contributing factor to our lack of progress in the field has been the lack of sensitive methods to detect the broad range of both bacterial and viral pathogens. The application of new and advanced molecular methods will continue to contribute to our current state of knowledge in this emerging and

Future research needs involving pathogens in groundwater

Science.gov (United States)

Bradford, Scott A.; Harvey, Ronald W.

2017-01-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Future research needs involving pathogens in groundwater

Science.gov (United States)

Bradford, Scott A.; Harvey, Ronald W.

2017-06-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Corynebacterium striatum infecting a malignant cutaneous lesion: the emergence of an opportunistic pathogen Corynebacterium striatum infectando lesão cutânea maligna: a emergência de um patógeno oportunista

Directory of Open Access Journals (Sweden)

Silvana Vargas Superti

2009-04-01

Full Text Available We described a case of a 27-year old male patient with skin and soft tissue infection of a neoplastic lesion caused by Corynebacterium striatum, an organism which has been rarely described as a human pathogen. Identification was confirmed by DNA sequencing. Successful treatment with penicillin was achieved. The role of the C. striatum as an emerging opportunistic pathogen is discussed.Descrevemos infecção de lesão neoplásica em paciente masculino de 27 anos, envolvendo pele e partes moles, causada por Corynebacterium striatum, um microrganismo raramente descrito como patógeno humano. A identificação foi confirmada por seqüenciamento de DNA. O paciente foi tratado com penicilina, com sucesso. O papel do C. striatum como patógeno oportunista é discutido.

Emerging zoonotic viral diseases.

Science.gov (United States)

Wang, L-F; Crameri, G

2014-08-01

Zoonotic diseases are infectious diseases that are naturally transmitted from vertebrate animals to humans and vice versa. They are caused by all types of pathogenic agents, including bacteria, parasites, fungi, viruses and prions. Although they have been recognised for many centuries, their impact on public health has increased in the last few decades due to a combination of the success in reducing the spread of human infectious diseases through vaccination and effective therapies and the emergence of novel zoonotic diseases. It is being increasingly recognised that a One Health approach at the human-animal-ecosystem interface is needed for effective investigation, prevention and control of any emerging zoonotic disease. Here, the authors will review the drivers for emergence, highlight some of the high-impact emerging zoonotic diseases of the last two decades and provide examples of novel One Health approaches for disease investigation, prevention and control. Although this review focuses on emerging zoonotic viral diseases, the authors consider that the discussions presented in this paper will be equally applicable to emerging zoonotic diseases of other pathogen types.

Low-Incidence, High-Consequence Pathogens

Centers for Disease Control (CDC) Podcasts

2014-02-21

Dr. Stephan Monroe, a deputy director at CDC, discusses the impact of low-incidence, high-consequence pathogens globally.  Created: 2/21/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/26/2014.

Evolution and population genetics of exotic and reemerging pathogens: traditional and novel tools and approaches

Science.gov (United States)

N.J. Grünwald; E.M. Goss

2011-01-01

Given human population growth and accelerated global trade, the rate of emergence of exotic plant pathogens is bound to increase. Understanding the processes that lead to the emergence of new pathogens can help manage emerging epidemics. Novel tools for analyzing population genetic variation can be used to infer the evolutionary history of populations or species,...

Adaptive potential of maritime pine (Pinus pinaster populations to the emerging pitch canker pathogen, Fusarium circinatum.

Directory of Open Access Journals (Sweden)

Margarita Elvira-Recuenco

Full Text Available There is a concern on how emerging pests and diseases will affect the distribution range and adaptability of their host species, especially due to different conditions derived from climate change and growing globalization. Fusarium circinatum, which causes pitch canker disease in Pinus species, is an exotic pathogen of recent introduction in Spain that threatens its maritime pine (P. pinaster stands. To predict the impact this disease will have on the species, we examine host resistance traits and their genetic architecture. Resistance phenotyping was done in a clonal provenance/progeny trial, using three-year-old cuttings artificially inoculated with the pathogen and maintained under controlled environmental conditions. A total number of 670 ramets were assessed, distributed in 10 populations, with a total of 47 families, 2 to 5 half-sibs per family, and 3-7 ramets per clone. High genetic variation was found at the three hierarchical levels studied: population, family and clone, being both additive and non-additive effects important. Narrow-sense and broad-sense heritability estimates were relatively high, with respective values of 0.43-0.58 and 0.51-0.8, depending on the resistance traits measured (lesion length, lesion length rate, time to wilting, and survival. These values suggest the species' high capacity of evolutionary response to the F. circinatum pathogen. A population originated in Northern Spain was the most resistant, while another from Morocco was the most susceptible. The total number of plants that did not show lesion development or presented a small lesion (length<30 mm was 224 out of 670, indicating a high proportion of resistant trees in the offspring within the analyzed populations. We found large differences among populations and considerable genetic variation within populations, which should allow, through natural or artificial selection, the successful adaptation of maritime pine to pitch canker disease.

Adaptive potential of maritime pine (Pinus pinaster) populations to the emerging pitch canker pathogen, Fusarium circinatum.

Science.gov (United States)

Elvira-Recuenco, Margarita; Iturritxa, Eugenia; Majada, Juan; Alia, Ricardo; Raposo, Rosa

2014-01-01

There is a concern on how emerging pests and diseases will affect the distribution range and adaptability of their host species, especially due to different conditions derived from climate change and growing globalization. Fusarium circinatum, which causes pitch canker disease in Pinus species, is an exotic pathogen of recent introduction in Spain that threatens its maritime pine (P. pinaster) stands. To predict the impact this disease will have on the species, we examine host resistance traits and their genetic architecture. Resistance phenotyping was done in a clonal provenance/progeny trial, using three-year-old cuttings artificially inoculated with the pathogen and maintained under controlled environmental conditions. A total number of 670 ramets were assessed, distributed in 10 populations, with a total of 47 families, 2 to 5 half-sibs per family, and 3-7 ramets per clone. High genetic variation was found at the three hierarchical levels studied: population, family and clone, being both additive and non-additive effects important. Narrow-sense and broad-sense heritability estimates were relatively high, with respective values of 0.43-0.58 and 0.51-0.8, depending on the resistance traits measured (lesion length, lesion length rate, time to wilting, and survival). These values suggest the species' high capacity of evolutionary response to the F. circinatum pathogen. A population originated in Northern Spain was the most resistant, while another from Morocco was the most susceptible. The total number of plants that did not show lesion development or presented a small lesion (length<30 mm) was 224 out of 670, indicating a high proportion of resistant trees in the offspring within the analyzed populations. We found large differences among populations and considerable genetic variation within populations, which should allow, through natural or artificial selection, the successful adaptation of maritime pine to pitch canker disease.

Applied Genomics of Foodborne Pathogens

DEFF Research Database (Denmark)

and customized source of information designed for and accessible to microbiologists interested in applying cutting-edge genomics in food safety and public health research. This book fills this void with a well-selected collection of topics, case studies, and bioinformatics tools contributed by experts......This book provides a timely and thorough snapshot into the emerging and fast evolving area of applied genomics of foodborne pathogens. Driven by the drastic advance of whole genome shot gun sequencing (WGS) technologies, genomics applications are becoming increasingly valuable and even essential...... at the forefront of foodborne pathogen genomics research....

Sexual Reproduction of Human Fungal Pathogens

Science.gov (United States)

Heitman, Joseph; Carter, Dee A.; Dyer, Paul S.; Soll, David R.

2014-01-01

We review here recent advances in our understanding of sexual reproduction in fungal pathogens that commonly infect humans, including Candida albicans, Cryptococcus neoformans/gattii, and Aspergillus fumigatus. Where appropriate or relevant, we introduce findings on other species associated with human infections. In particular, we focus on rapid advances involving genetic, genomic, and population genetic approaches that have reshaped our view of how fungal pathogens evolve. Rather than being asexual, mitotic, and largely clonal, as was thought to be prevalent as recently as a decade ago, we now appreciate that the vast majority of pathogenic fungi have retained extant sexual, or parasexual, cycles. In some examples, sexual and parasexual unions of pathogenic fungi involve closely related individuals, generating diversity in the population but with more restricted recombination than expected from fertile, sexual, outcrossing and recombining populations. In other cases, species and isolates participate in global outcrossing populations with the capacity for considerable levels of gene flow. These findings illustrate general principles of eukaryotic pathogen emergence with relevance for other fungi, parasitic eukaryotic pathogens, and both unicellular and multicellular eukaryotic organisms. PMID:25085958

Pathogenicity island mobility and gene content.

Energy Technology Data Exchange (ETDEWEB)

Williams, Kelly Porter

2013-10-01

Key goals towards national biosecurity include methods for analyzing pathogens, predicting their emergence, and developing countermeasures. These goals are served by studying bacterial genes that promote pathogenicity and the pathogenicity islands that mobilize them. Cyberinfrastructure promoting an island database advances this field and enables deeper bioinformatic analysis that may identify novel pathogenicity genes. New automated methods and rich visualizations were developed for identifying pathogenicity islands, based on the principle that islands occur sporadically among closely related strains. The chromosomally-ordered pan-genome organizes all genes from a clade of strains; gaps in this visualization indicate islands, and decorations of the gene matrix facilitate exploration of island gene functions. A %E2%80%9Clearned phyloblocks%E2%80%9D method was developed for automated island identification, that trains on the phylogenetic patterns of islands identified by other methods. Learned phyloblocks better defined termini of previously identified islands in multidrug-resistant Klebsiella pneumoniae ATCC BAA-2146, and found its only antibiotic resistance island.

Are outbreaks of emerging pathogens correlated with construction of wetlands? Report 2 : amphibian breeding and disease outbreaks during 2014-2015 and possible correlates with environmental variables : research report.

Science.gov (United States)

2016-10-01

A study of wetlands near the Intercounty Connector construction site (now a toll facility MD 200) in Maryland, : found that an emerging pathogen known as Ranavirus was having a significant impact on at least two species of : amphibians as well as...

Methods to classify bacterial pathogens in cystic fibrosis

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Nielsen, Xiaohui Chen; Johansen, Ulla

2011-01-01

for identification of isolates from the Burkholderia complex to the species level. DNA typing by PFGE, which can be used for any bacterial pathogen, is described as it is employed for Pseudomonas aeruginosa. A commercially available ELISA method is described for measuring IgG antibodies against P. aeruginosa in CF......Many bacteria can be detected in CF sputum, pathogenic and commensal. Modified Koch's criteria for identification of established and emerging CF pathogens are therefore described. Methods are described to isolate bacteria and to detect bacterial biofilms in sputum or lung tissue from CF patients...

Phaeohyphomycoses, Emerging Opportunistic Diseases in Animals

NARCIS (Netherlands)

Seyedmousavi, S.; Guillot, J.; de Hoog, G.S.

2013-01-01

Emerging fungal diseases due to black yeasts and relatives in domestic or wild animals and in invertebrates or cold- and warm-blooded vertebrates are continually being reported, either as novel pathogens or as familiar pathogens affecting new species of hosts. Different epidemiological situations

Phaeohyphomycoses, emerging opportunistic diseases in animals

NARCIS (Netherlands)

Seyedmousavi, S.; Guillot, J.; de Hoog, G.S.

2013-01-01

Emerging fungal diseases due to black yeasts and relatives in domestic or wild animals and in invertebrates or cold- and warm-blooded vertebrates are continually being reported, either as novel pathogens or as familiar pathogens affecting new species of hosts. Different epidemiological situations

Emergence of resistant pathogens against colistin

OpenAIRE

Rakesh Kumar; Baljit Jassal; Bhupinder Kumar

2015-01-01

Emergence of resistant strain to antimicrobials is a growing problem worldwide. Here, we report a case of multidrug-resistant Klebsiella pneumoniae and Acinectobacter baumannii, Gram-negative bacilli, which was only intermediate sensitive to colistin; a polymyxin E. Colistin has attracted more interest recently because of its significant activity against multi-resistant Pseudomonas aeruginosa, A. baumannii and K. pneumoniae, and the low resistance rates to it. The decrease in sensitivity of c...

Laser inactivation of pathogenic viruses in water

Science.gov (United States)

Grishkanich, Alexander; Zhevlakov, Alexander; Kascheev, Sergey; Sidorov, Igor; Ruzankina, Julia; Yakovlev, Alexey; Mak, Andrey

2016-03-01

Currently there is a situation that makes it difficult to provide the population with quality drinking water for the sanitary-hygienic requirements. One of the urgent problems is the need for water disinfection. Since the emergence of microorganisms that are pathogens transmitted through water such as typhoid, cholera, etc. requires constant cleansing of waters against pathogenic bacteria. In the water treatment process is destroyed up to 98% of germs, but among the remaining can be pathogenic viruses, the destruction of which requires special handling. As a result, the conducted research the following methods have been proposed for combating harmful microorganisms: sterilization of water by laser radiation and using a UV lamp.

Low prevalence of chytrid fungus (Batrachochytrium dendrobatidis) in amphibians of U.S. headwater streams

Science.gov (United States)

Hossack, Blake R.; Adams, Michael J.; Campbell Grant, Evan H.; Pearl, Chistopher A.; Bettaso, James B.; Barichivich, William J.; Lowe, Winsor H.; True, Kimberly; Ware, Joy L.; Corn, Paul Stephen

2010-01-01

Many declines of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd). Despite the relatively high prevalence of chytridiomycosis in stream amphibians globally, most surveys in North America have focused primarily on wetland-associated species, which are frequently infected. To better understand the distribution and prevalence of Bd in headwater amphibian communities, we sampled 452 tailed frogs (Ascaphus truei and Ascaphus montanus) and 304 stream salamanders (seven species in the Dicamptodontidae and Plethodontidae) for Bd in 38, first- to third-order streams in five montane areas across the United States. We tested for presence of Bd by using PCR on skin swabs from salamanders and metamorphosed tailed frogs or the oral disc of frog larvae. We detected Bd on only seven individuals (0.93%) in four streams. Based on our study and results from five other studies that have sampled headwater- or seep-associated amphibians in the United States, Bd has been detected on only 3% of 1,322 individuals from 21 species. These results differ strongly from surveys in Central America and Australia, where Bd is more prevalent on stream-breeding species, as well as results from wetland-associated anurans in the same regions of the United States that we sampled. Differences in the prevalence of Bd between stream- and wetland-associated amphibians in the United States may be related to species-specific variation in susceptibility to chytridiomycosis or habitat differences.

Ecological niche of plant pathogens

Directory of Open Access Journals (Sweden)

Ecaterina Fodor

2011-06-01

Full Text Available Disease ecology is a new approach to the understanding of the spread and dynamics of pathogens in natural and man-made environments. Defining and describing the ecological niche of the pathogens is one of the major tasks for ecological theory, as well as for practitioners preoccupied with the control and forecasting of established and emerging diseases. Niche theory has been periodically revised, not including in an explicit way the pathogens. However, many progresses have been achieved in niche modeling of disease spread, but few attempts were made to construct a theoretical frame for the ecological niche of pathogens. The paper is a review of the knowledge accumulated during last decades in the niche theory of pathogens and proposes an ecological approach in research. It quest for new control methods in what concerns forest plant pathogens, with a special emphasis on fungi like organisms of the genus Phytophthora. Species of Phytophthora are the most successful plant pathogens of the moment, affecting forest and agricultural systems worldwide, many of them being invasive alien organisms in many ecosystems. The hyperspace of their ecological niche is defined by hosts, environment and human interference, as main axes. To select most important variables within the hyperspace, is important the understanding of the complex role of pathogens in the ecosystems as well as for control programs. Biotic relationships within ecosystem of host-pathogen couple are depicted by ecological network and specific metrics attached to this. The star shaped network is characterized by few high degree nodes, by short path lengths and relatively low connectivity, premises for a rapid disturbance spread. 

Ecological niche of plant pathogens

Directory of Open Access Journals (Sweden)

Ecaterina Fodor

2011-02-01

Full Text Available Disease ecology is a new approach to the understanding of the spread and dynamics of pathogens in natural and man-made environments. Defining and describing the ecological niche of the pathogens is one of the major tasks for ecological theory, as well as for practitioners preoccupied with the control and forecasting of established and emerging diseases. Niche theory has been periodically revised, not including in an explicit way the pathogens. However, many progresses have been achieved in niche modeling of disease spread, but few attempts were made to construct a theoretical frame for the ecological niche of pathogens. The paper is a review of the knowledge accumulated during last decades in the niche theory of pathogens and proposes an ecological approach in research. It quest for new control methods in what concerns forest plant pathogens, with a special emphasis on fungi like organisms of the genus Phytophthora. Species of Phytophthora are the most successful plant pathogens of the moment, affecting forest and agricultural systems worldwide, many of them being invasive alien organisms in many ecosystems. The hyperspace of their ecological niche is defined by hosts, environment and human interference, as main axes. To select most important variables within the hyperspace, is important for the understanding of the complex role of pathogens in the ecosystems as well as for control programs. Biotic relationships within ecosystem of host-pathogen couple are depicted by ecological network and specific metrics attached to this. The star shaped network is characterized by few high degree nodes, by short path lengths and relatively low connectivity, premises for a rapid disturbance spread.

Challenges in Fusarium, a Trans-Kingdom Pathogen.

Science.gov (United States)

van Diepeningen, Anne D; de Hoog, G Sybren

2016-04-01

Fusarium species are emerging human pathogens, next to being plant pathogens. Problems with Fusarium are in their diagnostics and in their difficult treatment, but also in what are actual Fusarium species or rather Fusarium-like species. In this issue Guevara-Suarez et al. (Mycopathologia. doi: 10.1007/s11046-016-9983-9 , 2016) characterized 89 isolates of Fusarium from Colombia showing especially lineages within the Fusarium solani and oxysporum species complexes to be responsible for onychomycosis.

Unravelling the microbiome of eggs of the endangered sea turtle Eretmochelys imbricata identifies bacteria with activity against the emerging pathogen Fusarium falciforme.

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Jullie M Sarmiento-Ramírez

Full Text Available Habitat bioaugmentation and introduction of protective microbiota have been proposed as potential conservation strategies to rescue endangered mammals and amphibians from emerging diseases. For both strategies, insight into the microbiomes of the endangered species and their habitats is essential. Here, we sampled nests of the endangered sea turtle species Eretmochelys imbricata that were infected with the fungal pathogen Fusarium falciforme. Metagenomic analysis of the bacterial communities associated with the shells of the sea turtle eggs revealed approximately 16,664 operational taxonomic units, with Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes as the most dominant phyla. Subsequent isolation of Actinobacteria from the eggshells led to the identification of several genera (Streptomyces, Amycolaptosis, Micromomospora Plantactinospora and Solwaraspora that inhibit hyphal growth of the pathogen F. falciforme. These bacterial genera constitute a first set of microbial indicators to evaluate the potential role of microbiota in conservation of endangered sea turtle species.

Unravelling the microbiome of eggs of the endangered sea turtle Eretmochelys imbricata identifies bacteria with activity against the emerging pathogen Fusarium falciforme.

Science.gov (United States)

Sarmiento-Ramírez, Jullie M; van der Voort, Menno; Raaijmakers, Jos M; Diéguez-Uribeondo, Javier

2014-01-01

Habitat bioaugmentation and introduction of protective microbiota have been proposed as potential conservation strategies to rescue endangered mammals and amphibians from emerging diseases. For both strategies, insight into the microbiomes of the endangered species and their habitats is essential. Here, we sampled nests of the endangered sea turtle species Eretmochelys imbricata that were infected with the fungal pathogen Fusarium falciforme. Metagenomic analysis of the bacterial communities associated with the shells of the sea turtle eggs revealed approximately 16,664 operational taxonomic units, with Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes as the most dominant phyla. Subsequent isolation of Actinobacteria from the eggshells led to the identification of several genera (Streptomyces, Amycolaptosis, Micromomospora Plantactinospora and Solwaraspora) that inhibit hyphal growth of the pathogen F. falciforme. These bacterial genera constitute a first set of microbial indicators to evaluate the potential role of microbiota in conservation of endangered sea turtle species.

Streptococcus suis, an emerging drug-resistant animal and human pathogen

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Claudio ePalmieri

2011-11-01

Full Text Available Streptococcus suis, a major porcine pathogen, has been receiving growing attention not only for its role in severe and increasingly reported infections in humans, but also for its involvement in drug resistance. Recent studies and the analysis of sequenced genomes have been providing important insights into the S. suis resistome, and have resulted in the identification of resistance determinants for tetracyclines, macrolides, aminoglycosides, chloramphenicol, antifolate drugs, streptothricin, and cadmium salts. Resistance gene-carrying genetic elements described so far include integrative and conjugative elements, transposons, genomic islands, phages, and chimeric elements. Some of these elements are similar to those reported in major streptococcal pathogens such as Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus agalactiae and share the same chromosomal insertion sites. The available information strongly suggests that S. suis is an important antibiotic resistance reservoir that can contribute to the spread of resistance genes to the above-mentioned streptococci. S. suis is thus a paradigmatic example of possible intersections between animal and human resistomes.

Immunity to plant pathogens and iron homeostasis.

Science.gov (United States)

Aznar, Aude; Chen, Nicolas W G; Thomine, Sebastien; Dellagi, Alia

2015-11-01

Iron is essential for metabolic processes in most living organisms. Pathogens and their hosts often compete for the acquisition of this nutrient. However, iron can catalyze the formation of deleterious reactive oxygen species. Hosts may use iron to increase local oxidative stress in defense responses against pathogens. Due to this duality, iron plays a complex role in plant-pathogen interactions. Plant defenses against pathogens and plant response to iron deficiency share several features, such as secretion of phenolic compounds, and use common hormone signaling pathways. Moreover, fine tuning of iron localization during infection involves genes coding iron transport and iron storage proteins, which have been shown to contribute to immunity. The influence of the plant iron status on the outcome of a given pathogen attack is strongly dependent on the nature of the pathogen infection strategy and on the host species. Microbial siderophores emerged as important factors as they have the ability to trigger plant defense responses. Depending on the plant species, siderophore perception can be mediated by their strong iron scavenging capacity or possibly via specific recognition as pathogen associated molecular patterns. This review highlights that iron has a key role in several plant-pathogen interactions by modulating immunity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The making of a new pathogen

DEFF Research Database (Denmark)

Stukenbrock, Eva; Bataillon, Thomas; Dutheil, Julien

2011-01-01

that gene-rich regions or regions with low recombination experience stronger effects of natural selection on neutral diversity. Emergence of a new agricultural host selected a highly specialized and fast-evolving pathogen with unique evolutionary patterns compared with its wild relatives. The strong impact...

Effect of sunlight on the survival of pathogenic E. coli in freshwater and sea water

DEFF Research Database (Denmark)

Surendraraj, Alagarsamy; Farvin, Sabeena; Thampuran, N.

2011-01-01

An enteropathogenic group of E. coli are the emerging category of pathogen of public health significance. Several recent pathogenic E. coli outbreaks are associated with drinking water. Aquaculture, the fast emerging food production sector also poses a pathogenic EHEC outbreak risk, as it regularly...... uses cow dung, a reservoir of this organism. Hence, a experiment was set up to study the duration of survival of pathogenic E. coli under sunlight and darkness. Eight pathogenic E. coli isolates from clinical (EPEC, ETEC, EHEC, EAEC), veterinary (CTE3, CTE4) and environmental sources (ASHE3, Rao II......) were studied for their survival under sunlight and darkness in fresh water and seawater. Effect of direct sunlight on the viable but nonculturable (VBNC) state of cultures was also studied. The results of the study indicated a distinct pattern between freshwater system and seawater system. Pathogenic E...

Pathogens Use and Abuse MicroRNAs to Deceive the Immune System

NARCIS (Netherlands)

Flór, Thomas B.; Blom, Bianca

2016-01-01

Emerging evidence has demonstrated that microRNAs (miRs) play a role in the survival and amplification of viruses, bacteria and other pathogens. There are various ways in which pathogens can benefit from miR-directed alterations in protein translation and signal transduction. Members of the

Suppression of Emergence of Resistance in Pathogenic Bacteria: Keeping Our Powder Dry, Part 1.

Science.gov (United States)

Drusano, G L; Louie, Arnold; MacGowan, Alasdair; Hope, William

2015-12-28

We are in a crisis of bacterial resistance. For economic reasons, most pharmaceutical companies are abandoning antimicrobial discovery efforts, while, in health care itself, infection control and antibiotic stewardship programs have generally failed to prevent the spread of drug-resistant bacteria. At this point, what can be done? The first step has been taken. Governments and international bodies have declared there is a worldwide crisis in antibiotic drug resistance. As discovery efforts begin anew, what more can be done to protect newly developing agents and improve the use of new drugs to suppress resistance emergence? A neglected path has been the use of recent knowledge regarding antibiotic dosing as single agents and in combination to minimize resistance emergence, while also providing sufficient early bacterial kill. In this review, we look at the data for resistance suppression. Approaches include increasing the intensity of therapy to suppress resistant subpopulations; developing concepts of clinical breakpoints to include issues surrounding suppression of resistance; and paying attention to the duration of therapy, which is another important issue for resistance suppression. New understanding of optimizing combination therapy is of interest for difficult-to-treat pathogens like Pseudomonas aeruginosa, Acinetobacter spp., and multidrug-resistant (MDR) Enterobacteriaceae. These lessons need to be applied to our old drugs to preserve them as well and need to be put into national and international antibiotic resistance strategies. As importantly, from a regulatory perspective, new chemical entities should have a corresponding resistance suppression plan at the time of regulatory review. In this way, we can make the best of our current situation and improve future prospects. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Suppression of Emergence of Resistance in Pathogenic Bacteria: Keeping Our Powder Dry, Part 2.

Science.gov (United States)

Drusano, G L; Hope, William; MacGowan, Alasdair; Louie, Arnold

2015-12-28

We are in a crisis of bacterial resistance. For economic reasons, most pharmaceutical companies are abandoning antimicrobial discovery efforts, while, in health care itself, infection control and antibiotic stewardship programs have generally failed to prevent the spread of drug-resistant bacteria. At this point, what can be done? The first step has been taken. Governments and international bodies have declared there is a worldwide crisis in antibiotic drug resistance. As discovery efforts begin anew, what more can be done to protect newly developing agents and improve the use of new drugs to suppress resistance emergence? A neglected path has been the use of recent knowledge regarding antibiotic dosing as single agents and in combination to minimize resistance emergence, while also providing sufficient early bacterial kill. In this review, we look at the data for resistance suppression. Approaches include increasing the intensity of therapy to suppress resistant subpopulations; developing concepts of clinical breakpoints to include issues surrounding suppression of resistance; and paying attention to the duration of therapy, which is another important issue for resistance suppression. New understanding of optimizing combination therapy is of interest for difficult-to-treat pathogens like Pseudomonas aeruginosa, Acinetobacter spp., and multidrug-resistant (MDR) Enterobacteriaceae. These lessons need to be applied to our old drugs as well to preserve them and to be put into national and international antibiotic resistance strategies. As importantly, from a regulatory perspective, new chemical entities should have a resistance suppression plan at the time of regulatory review. In this way, we can make the best of our current situation and improve future prospects. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria

OpenAIRE

Bletz, Molly C.; Myers, Jillian; Woodhams, Douglas C.; Rabemananjara, Falitiana C. E.; Rakotonirina, Angela; Weldon, Che; Edmonds, Devin; Vences, Miguel; Harris, Reid N.

2017-01-01

For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd) has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, inc...

New and emerging chlamydial infections of creatures great and small

Directory of Open Access Journals (Sweden)

A. Taylor-Brown

2017-07-01

Full Text Available Until recently, our knowledge of the host range and diversity of members of the Chlamydiaceae, obligate intracellular bacterial pathogens of humans and animals, was thought to be nearly complete. Aided by advances in molecular diagnostics, a new picture is emerging, however, that the host barriers may be looser than previously thought for many chlamydial species. While cross-host transmission of chlamydial species is a concern for animal health, new reports highlight an emerging zoonotic risk for several species associated with intensification of farming and the widespread popularity of companion animals. The description of an expanded cohort of new species within this family from avian and reptilian hosts has also highlighted how much we still have to learn about the biology and pathogenicity of the Chlamydiaceae as a whole. Reports emerging about these relatives of the traditional chlamydial pathogens are matched by the continued identification of novel Chlamydia-related bacteria in the phylum Chlamydiae, providing evidence that many may be pathogenic to humans or animals and pose a zoonotic or vector-borne risk. The review examines the new hosts described for well-characterized chlamydial veterinary pathogens, emerging novel chlamydial species and the potential for these to cause disease in their respective hosts.

Inflammasome/IL-1β Responses to Streptococcal Pathogens

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Christopher N. LaRock

2015-10-01

Full Text Available Inflammation mediated by the inflammasome and the cytokine IL-1β are some of the earliest and most important alarms to infection. These pathways are responsive to the virulence factors that pathogens use to subvert immune processes, and thus are typically activated only by microbes with potential to cause severe disease. Among the most serious human infections are those caused by the pathogenic streptococci, in part because these species numerous strategies for immune evasion. Since the virulence factor armament of each pathogen is unique, the role of IL-1β and the pathways leading to its activation varies for each infection. This review summarizes the role of IL-1β during infections caused by streptococcal pathogens, with emphasis on emergent mechanisms and concepts countering paradigms determined for other organisms.

Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part II – Pathogenesis

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Jacek Dutkiewicz

2018-03-01

Full Text Available Streptococcus suis is a re-emerging zoonotic pathogen that may cause severe disease, mostly meningitis, in pigs and in humans having occupational contact with pigs and pork, such as farmers, slaughterhose workers and butchers. The first stage of the pathogenic process, similar in pigs and humans, is adherence to and colonisation of mucosal and/or epithelial surface(s of the host. The second stage is invasion into deeper tissue and extracellular translocation of bacterium in the bloodstream, either free in circulation or attached to the surface of monocytes. If S. suis present in blood fails to cause fatal septicaemia, it is able to progress into the third stage comprising penetration into host’s organs, mostly by crossing the blood-brain barrier and/or blood–cerebrospinal fluid barrier to gain access to the central nervous system (CNS and cause meningitis. The fourth stage is inflammation that plays a key role in the pathogen esis of both systemic and CNS infections caused by S. suis . The pathogen may induce the overproduction of pro-inflammatory cytokines that cause septic shock and/or the recruitment and activation of different leukocyte populations, causing acute inflammation of the CNS. Streptococcus suis can also evoke – through activation of microglial cells, astrocytes and possibly other cell types – a fulminant inflammatory reaction of the brain which leads to intracranial complications, including brain oedema, increased intracranial pressure, cerebrovascular insults, and deafness, as a result of cochlear sepsis. In all stages of the pathogenic process, S. suis interacts with many types of immunocompetent host’s cells, such as polymorphonuclear leukocytes, mononuclear macrophages, lymphocytes, dendritic cells and microglia, using a range of versatile virulence factors for evasion of the innate and adaptive immune defence of the host, and for overcoming environmental stress. It is estimated that S. suis produces more than

Cold plasma inactivation of human pathogens on foods and regulatory status update

Science.gov (United States)

Contamination of foods with human pathogens such as Salmonella, Listeria monocytogenes, Escherichia coli O157:H7, norovirus, and other pathogens is an ongoing challenge for growers and processors. In recent years, cold plasma has emerged as a promising antimicrobial treatment for fresh and fresh-cut...

[Emerging infectious diseases: complex, unpredictable processes].

Science.gov (United States)

Guégan, Jean-François

2016-01-01

In the light of a double approach, at first empirical, later theoretical and comparative, illustrated by the example of the Buruli ulcer and its mycobacterial agent Mycobacterium ulcerans on which I focused my research activity these last ten years by studying determinants and factors of emerging infectious or parasitic diseases, the complexity of events explaining emerging diseases will be presented. The cascade of events occurring at various levels of spatiotemporal scales and organization of life, which lead to the numerous observed emergences, nowadays requires better taking into account the interactions between host(s), pathogen(s) and the environment by including the behavior of both individuals and the population. In numerous research studies on emerging infectious diseases, microbial hazard is described rather than infectious disease risk, the latter resulting from the confrontation between an association of threatening phenomena, or hazards, and a susceptible population. Beyond, the theme of emerging infectious diseases and its links with global environmental and societal changes leads to reconsider some well-established knowledge in infectiology and parasitology. © Société de Biologie, 2017.

Effect of Intermediate Hosts on Emerging Zoonoses.

Science.gov (United States)

Cui, Jing-An; Chen, Fangyuan; Fan, Shengjie

2017-08-01

Most emerging zoonotic pathogens originate from animals. They can directly infect humans through natural reservoirs or indirectly through intermediate hosts. As a bridge, an intermediate host plays different roles in the transmission of zoonotic pathogens. In this study, we present three types of pathogen transmission to evaluate the effect of intermediate hosts on emerging zoonotic diseases in human epidemics. These types are identified as follows: TYPE 1, pathogen transmission without an intermediate host for comparison; TYPE 2, pathogen transmission with an intermediate host as an amplifier; and TYPE 3, pathogen transmission with an intermediate host as a vessel for genetic variation. In addition, we established three mathematical models to elucidate the mechanisms underlying zoonotic disease transmission according to these three types. Stability analysis indicated that the existence of intermediate hosts increased the difficulty of controlling zoonotic diseases because of more difficult conditions to satisfy for the disease to die out. The human epidemic would die out under the following conditions: TYPE 1: [Formula: see text] and [Formula: see text]; TYPE 2: [Formula: see text], [Formula: see text], and [Formula: see text]; and TYPE 3: [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] Simulation with similar parameters demonstrated that intermediate hosts could change the peak time and number of infected humans during a human epidemic; intermediate hosts also exerted different effects on controlling the prevalence of a human epidemic with natural reservoirs in different periods, which is important in addressing problems in public health. Monitoring and controlling the number of natural reservoirs and intermediate hosts at the right time would successfully manage and prevent the prevalence of emerging zoonoses in humans.

Escherichia coli O157:H7- patógeno alimentar emergente / Escherichia coli O157:H7 - emerging food pathogen

Directory of Open Access Journals (Sweden)

Cheila Minéia Daniel de Paula

2014-11-01

Full Text Available Segundo a Organização Mundial da Saúde, cerca de 2,2 milhões de pessoas morrem anualmente em função de doenças hídricas ou alimentares, a maioria dos quais são crianças. Estas doenças são causadas por patógenos já conhecidos, emergentes ou reemergentes, principalmente bactérias. A globalização tem contribuído na disseminação de patógenos de origem alimentar, aumentando o desafio relacionado à identificação da origem desses agentes e à elaboração de regulamentação e fiscalização adequadas. O cenário das Doenças Transmitidas por Alimentos (DTA muda constantemente e a prevalência de determinada doença varia de época para época, assim como os agentes etiológicos destas. Dentre os principais patógenos emergentes em nível mundial, E. coli O157:H7 tem ganhado grande destaque nos últimos 20 anos, devido à severidade de seus surtos. Até pouco tempo, o Brasil era considerado livre desse patógeno, porém a bibliografia científica e registros epidemiológicos demonstram o contrário. Em vista disso, o presente artigo objetiva realizar uma revisão integrativa da literatura, enfocando as características, os métodos de isolamento e detecção e os dados epidemiológicos da E. coli O157:H7 no Brasil e no mundo. =============================================== According to the World Health Organization, about 2.2 million people, most of whom are children, die each year due to water and foodborne illnesses. These illnesses are caused by known, emerging, or reemerging pathogens, mainly bacteria. Globalization has contributed to the spread of foodborne pathogens, increasing the challenge of identifying the origin of these agents and of developing appropriate regulation and monitoring. The scenario of Foodborne Illnesses (FI constantly changes and the prevalence of a particular illnesses as well as its etiological agents, vary from season to season. Among the major emerging pathogens at a global level, E. coli O157:H7

Bats prove to be rich reservoirs for emerging viruses

Science.gov (United States)

Calisher, Charles H.; Holmes, Kathryn V.; Dominguez, Samuel R.; Schountz, Tony; Cryan, Paul M.

2008-01-01

Emerging pathogens, many of them viruses, continue to surprise us, providing many newly recognized diseases to study and to try to control. Many of these emergent viruses are zoonotic, transmitted from reservoirs in wild or domestic animals to humans, either by insect vectors or by exposure to the droppings or tissues of such animals. One rich- but, until recently, underappreciated-source of emergent viruses is bats (Chiroptera, meaning "hand wing"). Accounting for 1,116, or nearly one fourth, of the 4,600 recognized species of mammals, bats are grouped into two suborders Megachiroptera, which contains a single family, Pteropodidae, consisting of 42 genera and 186 species, and Microchiroptera, which contains 17 families, 160 genera, and 930 species. Although bats are among the most abundant, diverse, and geographically dispersed orders of terrestrial mammals, research on these flying mammals historically focused more on their habits and outward characteristics than on their role in carrying microorganisms and transmitting pathogens to other species. Even in those cases where bats were known to carry particular pathogens, the microbiologists who studied those pathogens typically knew little about the bat hosts. Hence, investigators now are seeking to explain how variations of anatomy, physiology, ecology, and behavior influence the roles of bats as hosts for viral pathogens.

Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama

OpenAIRE

Crawford, Andrew J.; Lips, Karen R.; Bermingham, Eldredge

2010-01-01

Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytrium dendrobatidis. Despite the severity of the crisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing...

Bats, emerging infectious diseases, and the rabies paradigm revisited

Science.gov (United States)

Kuzmin, Ivan V.; Bozick, Brooke; Guagliardo, Sarah A.; Kunkel, Rebekah; Shak, Joshua R.; Tong, Suxiang; Rupprecht, Charles E

2011-01-01

The significance of bats as sources of emerging infectious diseases has been increasingly appreciated, and new data have been accumulated rapidly during recent years. For some emerging pathogens the bat origin has been confirmed (such as lyssaviruses, henipaviruses, coronaviruses), for other it has been suggested (filoviruses). Several recently identified viruses remain to be ‘orphan’ but have a potential for further emergence (such as Tioman, Menangle, and Pulau viruses). In the present review we summarize information on major bat-associated emerging infections and discuss specific characteristics of bats as carriers of pathogens (from evolutionary, ecological, and immunological positions). We also discuss drivers and forces of an infectious disease emergence and describe various existing and potential approaches for control and prevention of such infections at individual, populational, and societal levels. PMID:24149032

Bats, emerging infectious diseases, and the rabies paradigm revisited.

Science.gov (United States)

Kuzmin, Ivan V; Bozick, Brooke; Guagliardo, Sarah A; Kunkel, Rebekah; Shak, Joshua R; Tong, Suxiang; Rupprecht, Charles E

2011-06-20

The significance of bats as sources of emerging infectious diseases has been increasingly appreciated, and new data have been accumulated rapidly during recent years. For some emerging pathogens the bat origin has been confirmed (such as lyssaviruses, henipaviruses, coronaviruses), for other it has been suggested (filoviruses). Several recently identified viruses remain to be 'orphan' but have a potential for further emergence (such as Tioman, Menangle, and Pulau viruses). In the present review we summarize information on major bat-associated emerging infections and discuss specific characteristics of bats as carriers of pathogens (from evolutionary, ecological, and immunological positions). We also discuss drivers and forces of an infectious disease emergence and describe various existing and potential approaches for control and prevention of such infections at individual, populational, and societal levels.

Pathogens in drinking water: Are there any new ones

Energy Technology Data Exchange (ETDEWEB)

Reasoner, D.J.

1993-01-01

Since 1976 three newly recognized human pathogens have become familiar to the drinking water industry as waterborne disease agents. These are: the legionnaires disease agent, Legionella pneumophila and related species; and two protozoan pathogens, Giardia lamblia and Cryptosporidium parvum, both of which form highly disinfectant resistant cysts that are shed in the feces of infected individuals. The question frequently arises - are there other emerging waterborne pathogens that may pose a human health problem that the drinking water industry will have to deal with. The paper will review the current state of knowledge of the occurrence and incidence of pathogens and opportunistic pathogens other than Legionella, Giardia and Cryptosporidium in treated and untreated drinking water. Bacterial agents that will be reviewed include Aeromonas, Pseudomonas, Campylobacter, Mycobacterium, Yersinia and Plesiomonas. Aspects of detection of these agents including detection methods and feasibility of monitoring will be addressed.

Vaccination of Non-Domestic Animals against Emerging Virus Infections

NARCIS (Netherlands)

J.D.W. Philippa (Joost)

2007-01-01

markdownabstract__Abstract__ Since the 1980's, emerging and re-emerging infectious diseases have made an enormous impact on public and animal health, food supply, economies, and the environment. An estimated 75% of emerging infectious diseases in humans are zoonotic (pathogens of non-human

Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium

Energy Technology Data Exchange (ETDEWEB)

Ma, Li Jun; van der Does, H. C.; Borkovich, Katherine A.; Coleman, Jeffrey J.; Daboussi, Marie-Jose; Di Pietro, Antonio; Dufresne, Marie; Freitag, Michael; Grabherr, Manfred; Henrissat, Bernard; Houterman, Petra M.; Kang, Seogchan; Shim, Won-Bo; Wolochuk, Charles; Xie, Xiaohui; Xu, Jin Rong; Antoniw, John; Baker, Scott E.; Bluhm, Burton H.; Breakspear, Andrew; Brown, Daren W.; Butchko, Robert A.; Chapman, Sinead; Coulson, Richard; Coutinho, Pedro M.; Danchin, Etienne G.; Diener, Andrew; Gale, Liane R.; Gardiner, Donald; Goff, Steven; Hammond-Kossack, Kim; Hilburn, Karen; Hua-Van, Aurelie; Jonkers, Wilfried; Kazan, Kemal; Kodira, Chinnappa D.; Koehrsen, Michael; Kumar, Lokesh; Lee, Yong Hwan; Li, Liande; Manners, John M.; Miranda-Saavedra, Diego; Mukherjee, Mala; Park, Gyungsoon; Park, Jongsun; Park, Sook Young; Proctor, Robert H.; Regev, Aviv; Ruiz-Roldan, M. C.; Sain, Divya; Sakthikumar, Sharadha; Sykes, Sean; Schwartz, David C.; Turgeon, Barbara G.; Wapinski, Ilan; Yoder, Olen; Young, Sarah; Zeng, Qiandong; Zhou, Shiguo; Galagan, James; Cuomo, Christina A.; Kistler, H. Corby; Rep, Martijn

2010-03-18

Fusarium species are among the most important phytopathogenic and toxigenic fungi, having significant impact on crop production and animal health. Distinctively, members of the F. oxysporum species complex exhibit wide host range but discontinuously distributed host specificity, reflecting remarkable genetic adaptability. To understand the molecular underpinnings of diverse phenotypic traits and their evolution in Fusarium, we compared the genomes of three economically important and phylogenetically related, yet phenotypically diverse plant-pathogenic species, F. graminearum, F. verticillioides and F. oxysporum f. sp. lycopersici. Our analysis revealed greatly expanded lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes, accounting for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity. Experimentally, we demonstrate for the first time the transfer of two LS chromosomes between strains of F. oxysporum, resulting in the conversion of a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in the F. oxysporum species complex, putting the evolution of fungal pathogenicity into a new perspective.

[Predictors of drug-resistant pathogens in community-onset pneumonia: Are factors considered in health-care-associated pneumonia useful in the emergency department?

Science.gov (United States)

Torres Bonafonte, Olga H; Gil Olivas, Eva; Pérez Macho, Estefanía; Pacho Pacho, Cristina; Mateo Roca, Miriam; Casademont Pou, Jordi; Ruiz Hidalgo, Domingo

2017-10-01

To analyze factors related to drug-resistant pathogens (DRPs) in community-onset pneumonia (COP) and whether previously suggested criteria are useful in our emergency-department. Prospective 1-year study of adults coming to the emergency department for COP. We assessed the usefulness of criteria used in health-care-associated pneumonia (HCAP), as well the Shorr index, the Barthel index, and clinical suspicion of resistant pathogens. Data were analyzed by multiple logistic regression and the area under the receiver operating characteristic curve (AUC). We included 139 patients with a mean (SD) age of 75.9 (15.3) years; 63.3% were men. Forty-nine COP patients (35.2%) were at risk for DRP-caused pneumonia according to HCAP criteria; 43 (30.9%) according to the Shorr index, and 56 (40.3%) according to the Aliberti index. A score of less than 60 derived from the Barthel index was recorded for 25 patients (18%). Clinical suspicion of a DRP was recorded for 11 (7.9%). A DRP was isolated in 5 patients (3.6%) (3, Pseudomonas aeruginosa; 2, methicillin-resistant Staphylococcus aureus). Multiple logistic regression analysis identified 2 predictors of DRP-caused COP: hospital admission within the last 90 days (odds ratio [OR], 8.92; 95% CI, 1.92-41.45) and initial arterial blood oxygen saturation (OR, 0.85; 95% CI, 0.74-0.98). The AUC was 0.91 (95% CI, 0.85-0.98). The model identified 22 patients (16.8%) at risk for DRP-caused pneumonia. The positive and negative predictive values were 20% and 99.1%, respectively, for the model 90-day period (vs 8.7% and 98.9%, respectively, for criteria used in HCAP). Hospitalization within the 90-day period before a COP emergency and arterial blood oxygen saturation were good predictors of DRP in our setting. Criteria of DRP in HCAP, on the other hand, had lower ability to identify patients at risk in COP.

The use of singleplex and nested PCR to detect Batrachochytrium dendrobatidis in free-living frogs.

Science.gov (United States)

Coutinho, Selene Dall'Acqua; Burke, Julieta Catarina; de Paula, Catia Dejuste; Rodrigues, Miguel Trefaut; Catão-Dias, José Luiz

2015-06-01

Many microorganisms are able to cause diseases in amphibians, and in the past few years one of the most reported has been Batrachochytrium dendrobatidis. This fungus was first reported in Brazil in 2005; following this, other reports were made in specimens deposited in museum collections, captive and free-living frogs. The aim of this study was to compare singleplex and nested-PCR techniques to detect B. dendrobatidis in free-living and apparently healthy adult frogs from the Brazilian Atlantic Forest. The sample collection area was a protected government park, with no general entrance permitted and no management of the animals there. Swabs were taken from the skin of 107 animals without macroscopic lesions and they were maintained in ethanol p.a. Fungal DNA was extracted and identification of B. dendrobatidis was performed using singleplex and nested-PCR techniques, employing specific primers sequences. B. dendrobatidis was detected in 61/107 (57%) and 18/107 (17%) animals, respectively by nested and singleplex-PCR. Nested-PCR was statistically more sensible than the conventional for the detection of B. dendrobatidis (Chi-square = 37.1; α = 1%) and the agreement between both techniques was considered just fair (Kappa = 0.27). The high prevalence obtained confirms that these fungi occur in free-living frogs from the Brazilian Atlantic Forest with no macroscopic lesions, characterizing the state of asymptomatic carrier. We concluded that the nested-PCR technique, due to its ease of execution and reproducibility, can be recommended as one of the alternatives in epidemiological surveys to detect B. dendrobatidis in healthy free-living frog populations.

Sexual reproduction and the evolution of microbial pathogens.

Science.gov (United States)

Heitman, Joseph

2006-09-05

Three common systemic human fungal pathogens--Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus--have retained all the machinery to engage in sexual reproduction, and yet their populations are often clonal with limited evidence for recombination. Striking parallels have emerged with four protozoan parasites that infect humans: Toxoplasma gondii, Trypanosoma brucei, Trypanosoma cruzi and Plasmodium falciparum. Limiting sexual reproduction appears to be a common virulence strategy, enabling generation of clonal populations well adapted to host and environmental niches, yet retaining the ability to engage in sexual or parasexual reproduction and respond to selective pressure. Continued investigation of the sexual nature of microbial pathogens should facilitate both laboratory investigation and an understanding of the complex interplay between pathogens, hosts, vectors, and their environments.

Bacteremia due to ESKAPE pathogens: An emerging problem in cancer patients

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Hadir A. El-Mahallawy

2016-09-01

Conclusions: ESKAPE pathogens were significantly associated with higher rates of morbidity and mortality indicating the need for improving the means of prevention of these types of infections within health care premises. Microbiology laboratories have a role in defining more dangerous infections and rapid diagnostics are required in the era of resistance.

Occurrence of human pathogenic Clostridium botulinum among healthy dairy animals: an emerging public health hazard.

Science.gov (United States)

Abdel-Moein, Khaled A; Hamza, Dalia A

2016-01-01

The current study was conducted to investigate the occurrence of human pathogenic Clostridium botulinum in the feces of dairy animals. Fecal samples were collected from 203 apparently healthy dairy animals (50 cattle, 50 buffaloes, 52 sheep, 51 goats). Samples were cultured to recover C. botulinum while human pathogenic C. botulinum strains were identified after screening of all C. botulinum isolates for the presence of genes that encode toxins type A, B, E, F. The overall prevalence of C. botulinum was 18.7% whereas human pathogenic C. botulinum strains (only type A) were isolated from six animals at the rates of 2, 2, 5.8, and 2% for cattle, buffaloes, sheep, and goats, respectively. High fecal carriage rates of C. botulinum among apparently healthy dairy animals especially type A alarm both veterinary and public health communities for a potential role which may be played by dairy animals in the epidemiology of such pathogen.

Multi-criteria decision analysis tools for prioritising emerging or re-emerging infectious diseases associated with climate change in Canada.

Science.gov (United States)

Cox, Ruth; Sanchez, Javier; Revie, Crawford W

2013-01-01

Global climate change is known to result in the emergence or re-emergence of some infectious diseases. Reliable methods to identify the infectious diseases of humans and animals and that are most likely to be influenced by climate are therefore required. Since different priorities will affect the decision to address a particular pathogen threat, decision makers need a standardised method of prioritisation. Ranking methods and Multi-Criteria Decision approaches provide such a standardised method and were employed here to design two different pathogen prioritisation tools. The opinion of 64 experts was elicited to assess the importance of 40 criteria that could be used to prioritise emerging infectious diseases of humans and animals in Canada. A weight was calculated for each criterion according to the expert opinion. Attributes were defined for each criterion as a transparent and repeatable method of measurement. Two different Multi-Criteria Decision Analysis tools were tested, both of which used an additive aggregation approach. These were an Excel spreadsheet tool and a tool developed in software 'M-MACBETH'. The tools were trialed on nine 'test' pathogens. Two different methods of criteria weighting were compared, one using fixed weighting values, the other using probability distributions to account for uncertainty and variation in expert opinion. The ranking of the nine pathogens varied according to the weighting method that was used. In both tools, using both weighting methods, the diseases that tended to rank the highest were West Nile virus, Giardiasis and Chagas, while Coccidioidomycosis tended to rank the lowest. Both tools are a simple and user friendly approach to prioritising pathogens according to climate change by including explicit scoring of 40 criteria and incorporating weighting methods based on expert opinion. They provide a dynamic interactive method that can help to identify pathogens for which a full risk assessment should be pursued.

Multi-criteria decision analysis tools for prioritising emerging or re-emerging infectious diseases associated with climate change in Canada.

Directory of Open Access Journals (Sweden)

Ruth Cox

Full Text Available Global climate change is known to result in the emergence or re-emergence of some infectious diseases. Reliable methods to identify the infectious diseases of humans and animals and that are most likely to be influenced by climate are therefore required. Since different priorities will affect the decision to address a particular pathogen threat, decision makers need a standardised method of prioritisation. Ranking methods and Multi-Criteria Decision approaches provide such a standardised method and were employed here to design two different pathogen prioritisation tools. The opinion of 64 experts was elicited to assess the importance of 40 criteria that could be used to prioritise emerging infectious diseases of humans and animals in Canada. A weight was calculated for each criterion according to the expert opinion. Attributes were defined for each criterion as a transparent and repeatable method of measurement. Two different Multi-Criteria Decision Analysis tools were tested, both of which used an additive aggregation approach. These were an Excel spreadsheet tool and a tool developed in software 'M-MACBETH'. The tools were trialed on nine 'test' pathogens. Two different methods of criteria weighting were compared, one using fixed weighting values, the other using probability distributions to account for uncertainty and variation in expert opinion. The ranking of the nine pathogens varied according to the weighting method that was used. In both tools, using both weighting methods, the diseases that tended to rank the highest were West Nile virus, Giardiasis and Chagas, while Coccidioidomycosis tended to rank the lowest. Both tools are a simple and user friendly approach to prioritising pathogens according to climate change by including explicit scoring of 40 criteria and incorporating weighting methods based on expert opinion. They provide a dynamic interactive method that can help to identify pathogens for which a full risk assessment should

Genome Analyses of an Aggressive and Invasive Lineage of the Irish Potato Famine Pathogen

NARCIS (Netherlands)

Cooke, D.E.L.; Cano, L.M.; Raffaele, S.; Bain, R.A.; Cooke, L.R.; Etherington, G.J.; Deahl, K.L.; Farrer, R.A.; Gilroy, E.M.; Goss, E.M.; Grünwald, N.J.; Hein, I.; Maclean, D.; McNicol, J.W.; Randall, E.; Oliva, R.F.; Pel, M.; Shaw, D.S.; Squires, J.N.; Taylor, M.C.; Vleeshouwers, V.G.A.A.; Birch, P.R.J.; Lees, A.K.; Kamoun, S.

2012-01-01

Pest and pathogen losses jeopardise global food security and ever since the 19th century Irish famine, potato late blight has exemplified this threat. The causal oomycete pathogen, Phytophthora infestans, undergoes major population shifts in agricultural systems via the successive emergence and

Emerging arboviral human diseases in Southern Europe.

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Papa, Anna

2017-08-01

Southern Europe is characterized by unique landscape and climate which attract tourists, but also arthropod vectors, some of them carrying pathogens. Among several arboviral diseases that emerged in the region during the last decade, West Nile fever accounted for high number of human cases and fatalities, while Crimean-Congo hemorrhagic fever expanded its geographic distribution, and is considered as a real threat for Europe. Viruses evolve rapidly and acquire mutations making themselves stronger and naive populations more vulnerable. In an effort to tackle efficiently the emerging arboviral diseases, preparedness and strategic surveillance are needed for the early detection of the pathogen and containment and mitigation of probable outbreaks. In this review, the main human arboviral diseases that emerged in Southern Europe are described. © 2017 Wiley Periodicals, Inc.

Prospects for a novel ultrashort pulsed laser technology for pathogen inactivation

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Tsen Shaw-Wei D

2012-07-01

Full Text Available Abstract The threat of emerging pathogens and microbial drug resistance has spurred tremendous efforts to develop new and more effective antimicrobial strategies. Recently, a novel ultrashort pulsed (USP laser technology has been developed that enables efficient and chemical-free inactivation of a wide spectrum of viral and bacterial pathogens. Such a technology circumvents the need to introduce potentially toxic chemicals and could permit safe and environmentally friendly pathogen reduction, with a multitude of possible applications including the sterilization of pharmaceuticals and blood products, and the generation of attenuated or inactivated vaccines.

Invasive Fungal Infections in Patients with Hematological Malignancies: Emergence of Resistant Pathogens and New Antifungal Therapies

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Maria N. Gamaletsou

2018-02-01

Full Text Available Invasive fungal infections caused by drug-resistant organisms are an emerging threat to heavily immunosuppressed patients with hematological malignancies. Modern early antifungal treatment strategies, such as prophylaxis and empirical and preemptive therapy, result in long-term exposure to antifungal agents, which is a major driving force for the development of resistance. The extended use of central venous catheters, the nonlinear pharmacokinetics of certain antifungal agents, neutropenia, other forms of intense immunosuppression, and drug toxicities are other contributing factors. The widespread use of agricultural and industrial fungicides with similar chemical structures and mechanisms of action has resulted in the development of environmental reservoirs for some drug-resistant fungi, especially azole-resistant Aspergillus species, which have been reported from four continents. The majority of resistant strains have the mutation TR34/L98H, a finding suggesting that the source of resistance is the environment. The global emergence of new fungal pathogens with inherent resistance, such as Candida auris, is a new public health threat. The most common mechanism of antifungal drug resistance is the induction of efflux pumps, which decrease intracellular drug concentrations. Overexpression, depletion, and alteration of the drug target are other mechanisms of resistance. Mutations in the ERG11 gene alter the protein structure of C-demethylase, reducing the efficacy of antifungal triazoles. Candida species become echinocandin-resistant by mutations in FKS genes. A shift in the epidemiology of Candida towards resistant non-albicans Candida spp. has emerged among patients with hematological malignancies. There is no definite association between antifungal resistance, as defined by elevated minimum inhibitory concentrations, and clinical outcomes in this population. Detection of genes or mutations conferring resistance with the use of molecular methods

RecA: a universal drug target in pathogenic bacteria.

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Pavlopoulou, Athanasia

2018-01-01

The spread of bacterial infectious diseases due to the development of resistance to antibiotic drugs in pathogenic bacteria is an emerging global concern. Therefore, the efficacious management and prevention of bacterial infections are major public health challenges. RecA is a pleiotropic recombinase protein that has been demonstrated to be implicated strongly in the bacterial drug resistance, survival and pathogenicity. In this minireview, RecA's role in the development of antibiotic resistance and its potential as an antimicrobial drug target are discussed.

Bacteremias in liver transplant recipients: shift toward gram-negative bacteria as predominant pathogens.

Science.gov (United States)

Singh, Nina; Wagener, Marilyn M; Obman, Asia; Cacciarelli, Thomas V; de Vera, Michael E; Gayowski, Timothy

2004-07-01

During the 1990s, gram-positive bacteria emerged as major pathogens after liver transplantation. We sought to determine whether the pathogens associated with bacteremias in liver transplant recipients have changed. Patients included 233 liver transplant recipients transplanted between 1989 and 2003. The proportion of all infections due to bacteremias increased significantly over time (P gram-negatives increased from 25% in the period of 1989-1993 to 51.8% in 1998-03, that of gram-positive bacteria decreased from 75% in the period of 1989-93 to 48.2% in the period of 1998-2003. Methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most frequent pathogens in bacteremic patients. The incidence of bacteremias due to MRSA and Pseudomonas aeruginosa has remained unchanged (P gram-negative bacteria, particularly Klebsiella pneumoniae has increased (P =.02). Klebsiella pneumoniae isolates in the current quartile were not clonally related. In conclusion, bacteremias as a proportion of all infections in liver transplant recipients have increased significantly over time, due in part to a decline in infections due to other major pathogens, e.g., fungi, primarily Candida species, and CMV. Gram-negative bacteria have emerged as predominant pathogens in bacteremic liver transplant recipients.

Rapid screening for entry inhibitors of highly pathogenic viruses under low-level biocontainment.

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Aparna Talekar

Full Text Available Emerging viruses including Nipah, Hendra, Lujo, and Junin viruses have enormous potential to spread rapidly. Nipah virus, after emerging as a zoonosis, has also evolved the capacity for human-to-human transmission. Most of the diseases caused by these pathogens are untreatable and require high biocontainment conditions. Universal methods for rapidly identifying and screening candidate antivirals are urgently needed. We have developed a modular antiviral platform strategy that relies on simple bioinformatic and genetic information about each pathogen. Central to this platform is the use of envelope glycoprotein cDNAs to establish multi-cycle replication systems under BSL2 conditions for viral pathogens that normally require BSL3 and BSL4 facilities. We generated monoclonal antibodies against Nipah G by cDNA immunization in rats, and we showed that these antibodies neutralize both Nipah and Hendra live viruses. We then used these effective Henipavirus inhibitors to validate our screening strategy. Our proposed strategy should contribute to the response capability for emerging infectious diseases, providing a way to initiate antiviral development immediately upon identifying novel viruses.

Individualizing Risk of Multidrug-Resistant Pathogens in Community-Onset Pneumonia

OpenAIRE

Falcone, Marco; Russo, Alessandro; Giannella, Maddalena; Cangemi, Roberto; Scarpellini, Maria Gabriella; Bertazzoni, Giuliano; Alarc?n, Jos? Mart?nez; Taliani, Gloria; Palange, Paolo; Farcomeni, Alessio; Vestri, Annarita; Bouza, Emilio; Violi, Francesco; Venditti, Mario

2015-01-01

Introduction The diffusion of multidrug-resistant (MDR) bacteria has created the need to identify risk factors for acquiring resistant pathogens in patients living in the community. Objective To analyze clinical features of patients with community-onset pneumonia due to MDR pathogens, to evaluate performance of existing scoring tools and to develop a bedside risk score for an early identification of these patients in the Emergency Department. Patients and Methods This was an open, observation...

Context-dependent conservation responses to emerging wildlife diseases

Science.gov (United States)

Kate E Langwig; Jamie Voyles; Mark Q Wilber; Winifred F Frick; Kris A Murray; Benjamin M Bolker; James P Collins; Tina L Cheng; Matthew C Fisher; Joseph R Hoyt; Daniel L Lindner; Hamish I McCallum; Robert Puschendorf; Erica Bree Rosenblum; Mary Toothman; Craig KR Willis; Cheryl J Briggs; A Marm Kilpatrick

2015-01-01

Emerging infectious diseases pose an important threat to wildlife. While established protocols exist for combating outbreaks of human and agricultural pathogens, appropriate management actions before, during, and after the invasion of wildlife pathogens have not been developed. We describe stage-specific goals and management actions that minimize disease impacts on...

Bacteriophages in the control of pathogenic vibrios

DEFF Research Database (Denmark)

Plaza, Nicolás; Castillo Bermúdez, Daniel Elías; Perez-Reytor, Diliana

2018-01-01

constitute a continuing threat for aquaculture. Moreover, the continuous use of antibiotics has been accompanied by an emergence of antibiotic resistance in Vibrio species, implying a necessity for efficient treatments. One promising alternative that emerges is the use of lytic bacteriophages; however......, there are some drawbacks that should be overcome to make phage therapy a widely accepted method. In this work, we discuss about the major pathogenic Vibrio species and the progress, benefits and disadvantages that have been detected during the experimental use of bacteriophages to their control....

Trends in udder health and emerging mastitogenic pathogens in South African dairy herds

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I.M. Petzer

2009-05-01

Full Text Available The aim of this study was to retrospectively analyse the results of milk samples obtained from South African dairy herds during the period 1996 to April 2007 in order to identify possible trends in isolates of microorganisms and their pathogenicity under field conditions. Milk samples were obtained from 7 of the 9 provinces in South Africa where there are low numbers of dairy cows. Although there is scientific limitation to a country wide survey, such as the variation in herd size, management skills, parity, milk yield, milking frequency and other parameters, the size of this database helps to give a fair indication of general udder health in South Africa. Cytology and routine bacteriology were performed on 379 000 milk samples of lactating cows and bacteriology on 11 946 samples from non-lactating cows. According to the results obtained, mastitis did not decrease in South Africa over the test period. The prevalence of mastitis and teat canal infection was lowest in 2002. Mastitis and teat canal infection increased from 2002 to 2006 from 8.1 % and 24.1 % to 15.4 and 30.0 % respectively. The percentage of mastitogenic pathogens isolated from cows over these years also varied. Previously unknown or almost eradicated mastitogenic pathogens such as αβ haemolytic Staphylococcus aureus which is thought to be of human origin, Streptococcus agalactiae and Enterococcus canis were responsible for numerous mastitis outbreaks seen in the test samples. Coagulase-negative staphylococci were the most frequently isolated bacteria in milk samples from both lactating and dry cows, followed by Staphylococcus aureus and Streptococcus agalactiae. Although Staphylococcus aureus remained the principal mastitogenic pathogen in South Africa, owing to its chronic nature and resultant economic losses, most cases of mastitis were caused by coagulase-negative staphylococci. This finding increases the importance of coagulase-negative staphylococci (formerly described as a

Incorporating indel information into phylogeny estimation for rapidly emerging pathogens

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Suchard Marc A

2007-03-01

Full Text Available Abstract Background Phylogenies of rapidly evolving pathogens can be difficult to resolve because of the small number of substitutions that accumulate in the short times since divergence. To improve resolution of such phylogenies we propose using insertion and deletion (indel information in addition to substitution information. We accomplish this through joint estimation of alignment and phylogeny in a Bayesian framework, drawing inference using Markov chain Monte Carlo. Joint estimation of alignment and phylogeny sidesteps biases that stem from conditioning on a single alignment by taking into account the ensemble of near-optimal alignments. Results We introduce a novel Markov chain transition kernel that improves computational efficiency by proposing non-local topology rearrangements and by block sampling alignment and topology parameters. In addition, we extend our previous indel model to increase biological realism by placing indels preferentially on longer branches. We demonstrate the ability of indel information to increase phylogenetic resolution in examples drawn from within-host viral sequence samples. We also demonstrate the importance of taking alignment uncertainty into account when using such information. Finally, we show that codon-based substitution models can significantly affect alignment quality and phylogenetic inference by unrealistically forcing indels to begin and end between codons. Conclusion These results indicate that indel information can improve phylogenetic resolution of recently diverged pathogens and that alignment uncertainty should be considered in such analyses.

Neutral genomic microevolution of a recently emerged pathogen, Salmonella enterica serovar Agona.

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Zhemin Zhou

2013-04-01

Full Text Available Salmonella enterica serovar Agona has caused multiple food-borne outbreaks of gastroenteritis since it was first isolated in 1952. We analyzed the genomes of 73 isolates from global sources, comparing five distinct outbreaks with sporadic infections as well as food contamination and the environment. Agona consists of three lineages with minimal mutational diversity: only 846 single nucleotide polymorphisms (SNPs have accumulated in the non-repetitive, core genome since Agona evolved in 1932 and subsequently underwent a major population expansion in the 1960s. Homologous recombination with other serovars of S. enterica imported 42 recombinational tracts (360 kb in 5/143 nodes within the genealogy, which resulted in 3,164 additional SNPs. In contrast to this paucity of genetic diversity, Agona is highly diverse according to pulsed-field gel electrophoresis (PFGE, which is used to assign isolates to outbreaks. PFGE diversity reflects a highly dynamic accessory genome associated with the gain or loss (indels of 51 bacteriophages, 10 plasmids, and 6 integrative conjugational elements (ICE/IMEs, but did not correlate uniquely with outbreaks. Unlike the core genome, indels occurred repeatedly in independent nodes (homoplasies, resulting in inaccurate PFGE genealogies. The accessory genome contained only few cargo genes relevant to infection, other than antibiotic resistance. Thus, most of the genetic diversity within this recently emerged pathogen reflects changes in the accessory genome, or is due to recombination, but these changes seemed to reflect neutral processes rather than Darwinian selection. Each outbreak was caused by an independent clade, without universal, outbreak-associated genomic features, and none of the variable genes in the pan-genome seemed to be associated with an ability to cause outbreaks.

Rapid identification of emerging human-pathogenic Sporothrix species with rolling circle amplification

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Anderson Messias Rodrigues

2015-12-01

Full Text Available Sporothrix infections are emerging as an important human and animal threat among otherwise healthy patients, especially in Brazil and China. Correct identification of sporotrichosis agents is beneficial for epidemiological surveillance, enabling implementation of adequate public-health policies and guiding antifungal therapy. In areas of limited resources where sporotrichosis is endemic, high-throughput detection methods that are specific and sensitive are preferred over phenotypic methods that usually result in misidentification of closely related Sporothrix species. We sought to establish rolling circle amplification (RCA as a low-cost screening tool for species-specific identification of human-pathogenic Sporothrix. We developed six species-specific padlock probes targeting polymorphisms in the gene encoding calmodulin. BLAST-searches revealed candidate probes that were conserved intraspecifically; no significant homology with sequences from humans, mice, plants or microorganisms outside members of Sporothrix were found. The accuracy of our RCA-based assay was demonstrated through the specificity of probe-template binding to 25 S. brasiliensis, 58 S. schenckii, 5 S. globosa, 1 S. luriei, 4 S. mexicana, and 3 S. pallida samples. No cross reactivity between closely related species was evident in vitro, and padlock probes yielded 100% specificity and sensitivity down to 3 x 10 6 copies of the target sequence. RCA-based speciation matched identifications via phylogenetic analysis of the gene encoding calmodulin and the rDNA operon (kappa 1.0; 95% confidence interval 1.0-1.0, supporting its use as a reliable alternative to DNA sequencing. This method is a powerful tool for rapid identification and specific detection of medically relevant Sporothrix, and due to its robustness has potential for ecological studies.

High throughput sequencing and proteomics to identify immunogenic proteins of a new pathogen: the dirty genome approach.

Science.gov (United States)

Greub, Gilbert; Kebbi-Beghdadi, Carole; Bertelli, Claire; Collyn, François; Riederer, Beat M; Yersin, Camille; Croxatto, Antony; Raoult, Didier

2009-12-23

With the availability of new generation sequencing technologies, bacterial genome projects have undergone a major boost. Still, chromosome completion needs a costly and time-consuming gap closure, especially when containing highly repetitive elements. However, incomplete genome data may be sufficiently informative to derive the pursued information. For emerging pathogens, i.e. newly identified pathogens, lack of release of genome data during gap closure stage is clearly medically counterproductive. We thus investigated the feasibility of a dirty genome approach, i.e. the release of unfinished genome sequences to develop serological diagnostic tools. We showed that almost the whole genome sequence of the emerging pathogen Parachlamydia acanthamoebae was retrieved even with relatively short reads from Genome Sequencer 20 and Solexa. The bacterial proteome was analyzed to select immunogenic proteins, which were then expressed and used to elaborate the first steps of an ELISA. This work constitutes the proof of principle for a dirty genome approach, i.e. the use of unfinished genome sequences of pathogenic bacteria, coupled with proteomics to rapidly identify new immunogenic proteins useful to develop in the future specific diagnostic tests such as ELISA, immunohistochemistry and direct antigen detection. Although applied here to an emerging pathogen, this combined dirty genome sequencing/proteomic approach may be used for any pathogen for which better diagnostics are needed. These genome sequences may also be very useful to develop DNA based diagnostic tests. All these diagnostic tools will allow further evaluations of the pathogenic potential of this obligate intracellular bacterium.

Comparative Genomics of Smut Pathogens: Insights From Orphans and Positively Selected Genes Into Host Specialization

NARCIS (Netherlands)

Benevenuto, J.; Texeira-Silva, N.S.; Kuramae, E.E.; Croll, D.; Vitorello, C.B.M.

2018-01-01

Host specialization is a key evolutionary process for the diversification and emergence of new pathogens. However, the molecular determinants of host range are poorly understood. Smut fungi are biotrophic pathogens that have distinct and narrow host ranges based on largely unknown genetic

Exploring virulence and immunogenicity in the emerging pathogen Sporothrix brasiliensis.

Science.gov (United States)

Della Terra, Paula Portella; Rodrigues, Anderson Messias; Fernandes, Geisa Ferreira; Nishikaku, Angela Satie; Burger, Eva; de Camargo, Zoilo Pires

2017-08-01

Sporotrichosis is a polymorphic chronic infection of humans and animals classically acquired after traumatic inoculation with soil and plant material contaminated with Sporothrix spp. propagules. An alternative and successful route of transmission is bites and scratches from diseased cats, through which Sporothrix yeasts are inoculated into mammalian tissue. The development of a murine model of subcutaneous sporotrichosis mimicking the alternative route of transmission is essential to understanding disease pathogenesis and the development of novel therapeutic strategies. To explore the impact of horizontal transmission in animals (e.g., cat-cat) and zoonotic transmission on Sporothrix fitness, the left hind footpads of BALB/c mice were inoculated with 5×106 yeasts (n = 11 S. brasiliensis, n = 2 S. schenckii, or n = 1 S. globosa). Twenty days post-infection, our model reproduced both the pathophysiology and symptomology of sporotrichosis with suppurating subcutaneous nodules that progressed proximally along lymphatic channels. Across the main pathogenic members of the S. schenckii clade, S. brasiliensis was usually more virulent than S. schenckii and S. globosa. However, the virulence in S. brasiliensis was strain-dependent, and we demonstrated that highly virulent isolates disseminate from the left hind footpad to the liver, spleen, kidneys, lungs, heart, and brain of infected animals, inducing significant and chronic weight loss (losing up to 15% of their body weight). The weight loss correlated with host death between 2 and 16 weeks post-infection. Histopathological features included necrosis, suppurative inflammation, and polymorphonuclear and mononuclear inflammatory infiltrates. Immunoblot using specific antisera and homologous exoantigen investigated the humoral response. Antigenic profiles were isolate-specific, supporting the hypothesis that different Sporothrix species can elicit a heterogeneous humoral response over time, but cross reaction was observed

Pathology of the emerging Mycobacterium tuberculosis complex pathogen, M. mungi in the banded mongoose (Mungos mungo)

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Wild banded mongooses (Mungos mungo) in northeastern Botswana and Northwest Zimbabwe are infected with a novel Mycobacterium tuberculosis complex pathogen (MTC), M. mungi. This pathogen is transmitted environmentally between mongoose hosts through exposure to infected scent marks used in olfactory c...

Lawrence Livermore National Laboratory Workshop Characterization of Pathogenicity, Virulence and Host-Pathogen Interactions

Energy Technology Data Exchange (ETDEWEB)

Krishnan, A

2006-08-30

The threats of bio-terrorism and newly emerging infectious diseases pose serious challenges to the national security infrastructure. Rapid detection and diagnosis of infectious disease in human populations, as well as characterizing pathogen biology, are critical for reducing the morbidity and mortality associated with such threats. One of the key challenges in managing an infectious disease outbreak, whether through natural causes or acts of overt terrorism, is detection early enough to initiate effective countermeasures. Much recent attention has been directed towards the utility of biomarkers or molecular signatures that result from the interaction of the pathogen with the host for improving our ability to diagnose and mitigate the impact of a developing infection during the time window when effective countermeasures can be instituted. Host responses may provide early signals in blood even from localized infections. Multiple innate and adaptive immune molecules, in combination with other biochemical markers, may provide disease-specific information and new targets for countermeasures. The presence of pathogen specific markers and an understanding of the molecular capabilities and adaptations of the pathogen when it interacts with its host may likewise assist in early detection and provide opportunities for targeting countermeasures. An important question that needs to be addressed is whether these molecular-based approaches will prove useful for early diagnosis, complement current methods of direct agent detection, and aid development and use of countermeasures. Lawrence Livermore National Laboratory (LLNL) will host a workshop to explore the utility of host- and pathogen-based molecular diagnostics, prioritize key research issues, and determine the critical steps needed to transition host-pathogen research to tools that can be applied towards a more effective national bio-defense strategy. The workshop will bring together leading researchers/scientists in the

Genomic analysis of the Kiwifruit pathogen Pseudomonas syringae pv. actinidiae provides insight into the origins of an emergent plant disease.

Directory of Open Access Journals (Sweden)

Honour C McCann

Full Text Available The origins of crop diseases are linked to domestication of plants. Most crops were domesticated centuries--even millennia--ago, thus limiting opportunity to understand the concomitant emergence of disease. Kiwifruit (Actinidia spp. is an exception: domestication began in the 1930s with outbreaks of canker disease caused by P. syringae pv. actinidiae (Psa first recorded in the 1980s. Based on SNP analyses of two circularized and 34 draft genomes, we show that Psa is comprised of distinct clades exhibiting negligible within-clade diversity, consistent with disease arising by independent samplings from a source population. Three clades correspond to their geographical source of isolation; a fourth, encompassing the Psa-V lineage responsible for the 2008 outbreak, is now globally distributed. Psa has an overall clonal population structure, however, genomes carry a marked signature of within-pathovar recombination. SNP analysis of Psa-V reveals hundreds of polymorphisms; however, most reside within PPHGI-1-like conjugative elements whose evolution is unlinked to the core genome. Removal of SNPs due to recombination yields an uninformative (star-like phylogeny consistent with diversification of Psa-V from a single clone within the last ten years. Growth assays provide evidence of cultivar specificity, with rapid systemic movement of Psa-V in Actinidia chinensis. Genomic comparisons show a dynamic genome with evidence of positive selection on type III effectors and other candidate virulence genes. Each clade has highly varied complements of accessory genes encoding effectors and toxins with evidence of gain and loss via multiple genetic routes. Genes with orthologs in vascular pathogens were found exclusively within Psa-V. Our analyses capture a pathogen in the early stages of emergence from a predicted source population associated with wild Actinidia species. In addition to candidate genes as targets for resistance breeding programs, our findings

Brain transcriptomes of honey bees (Apis mellifera experimentally infected by two pathogens: Black queen cell virus and Nosema ceranae

Directory of Open Access Journals (Sweden)

Vincent Doublet

2016-12-01

Full Text Available Regulation of gene expression in the brain plays an important role in behavioral plasticity and decision making in response to external stimuli. However, both can be severely affected by environmental factors, such as parasites and pathogens. In honey bees, the emergence and re-emergence of pathogens and potential for pathogen co-infection and interaction have been suggested as major components that significantly impaired social behavior and survival. To understand how the honey bee is affected and responds to interacting pathogens, we co-infected workers with two prevalent pathogens of different nature, the positive single strand RNA virus Black queen cell virus (BQCV, and the Microsporidia Nosema ceranae, and explored gene expression changes in brains upon single infections and co-infections. Our data provide an important resource for research on honey bee diseases, and more generally on insect host-pathogen and pathogen-pathogen interactions. Raw and processed data are publicly available in the NCBI/GEO database: (http://www.ncbi.nlm.nih.gov/geo/ under accession number GSE81664.

Molecular biology of Ganoderma pathogenicity and diagnosis in coconut seedlings.

Science.gov (United States)

Kandan, A; Radjacommare, R; Ramanathan, A; Raguchander, T; Balasubramanian, P; Samiyappan, R

2009-01-01

The pathogenicity of Ganoderma boninense was tested on coconut seedlings under greenhouse conditions and infection confirmed by using immunological and molecular diagnostic tools. Desiccation of older leaves and the emergence of sporophores were observed from pathogen-inoculated seedlings, whereas a control seedling does not show any pathogenic symptoms. Mature sporophores were formed within 10-13 weeks after inoculation. Polyclonal antibodies raised against mycelial proteins of Ganoderma were used for detection of Ganoderma in infected field palm and seedlings through indirect enzyme-linked immunosorbent assay technique. We adopted dot-immunobinding assay for the detection of Ganoderma from greenhouse and field samples. Under nucleic-acid-based diagnosis, G. boninense (167 bp) was detected from artificially inoculated seedlings and infected field palms by polymerase chain reaction. Apart from these, histopathological studies also support the Ganoderma pathogenicity in coconut seedlings. The pathogenicity test and combination of all the three diagnostic methods for Ganoderma could be highly reliable, rapid, sensitive and effective screening of resistance in planting material in the future.

Emerging Acinetobacter schindleri in red eye infection of Pangasius ...

African Journals Online (AJOL)

This communication provides an insight into the emerging of new infection “red eye” in Pangasius sutchi and aimed to screen the prime pathogens involved in disease. The pathogen was isolated from diseased P. sutchi and characterized by morphological, biochemical and molecular approach, which includes 16s r RNA ...

Extreme sensitivity to ultraviolet light in the fungal pathogen causing white-nose syndrome of bats

Science.gov (United States)

Jonathan M. Palmer; Kevin P. Drees; Jeffrey T. Foster; Daniel L. Lindner

2018-01-01

Bat white-nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans, has decimated North American hibernating bats since its emergence in 2006. Here, we utilize comparative genomics to examine the evolutionary history of this pathogen in comparison to six closely related nonpathogenic species....

Diversity of Andean amphibians of the Tamá National Natural Park in Colombia: a survey for the presence of Batrachochytrium dendrobatidis

Energy Technology Data Exchange (ETDEWEB)

Acevedo, A.A.; Franco, R.; Carrero, D.A.

2016-07-01

Changes in diversity and possible decreases in populations of amphibians have not yet been determined in many areas in the Andes. This study aimed to develop an inventory of the biodiversity of amphibians in the Andean areas of the Tamá National Natural Park (Tamá NNP) and to evaluate the patterns of infection by Batrachochytrium dendrobatidis (Bd) in preserved and degraded areas. We performed samplings focused on three habitats (forest, open areas and streams) in four localities from 2,000 to 3,200 m in altitude. Fourteen species were recorded, 12 of which were positive for Bd. A total of 541 individuals were diagnosed and 100 were positive. Our analyses showed that preserved areas play an important role in keeping many individuals Bd–free as compared to those in degraded areas. This was the first study to evaluate diversity and infection by Bd in the northeast region of Colombia. Our findings may help improve our knowledge of the diversity of amphibian species in the area and facilitate the implementation of action plans to mitigate the causes associated with the decrease in amphibian populations. (Author)

The Search for Violacein-Producing Microbes to Combat Batrachochytrium dendrobatidis: A Collaborative Research Project between Secondary School and College Research Students

Directory of Open Access Journals (Sweden)

Larra Agate

2015-10-01

Full Text Available In this citizen science–aided, college laboratory–based microbiology research project, secondary school students collaborate with college research students on an investigation centered around bacterial species in the local watershed. This study specifically investigated the prevalence of violacein-producing bacterial isolates, as violacein has been demonstrated as a potential bioremediation treatment for outbreaks of the worldwide invasive chytrid, Batrachochytrium dendrobatidis (Bd. The impact of this invasion has been linked to widespread amphibian decline, and tracking of the spread of Bd is currently ongoing. Secondary school students participated in this research project by sterilely collecting water samples from a local watershed, documenting the samples, and completing the initial sample plating in a BSL1 environment. In the second phase of this project, trained college students working in courses and as research assistants in the academic year and summer term in a BSL2 laboratory facility were able to use physiological, biochemical, and molecular techniques to further identify individual isolates as well as characterize their properties. Collaboration between these learning spaces provides an increased interest in the community for environmentally relevant research projects and allows for an expansion of the research team to increase study robustness.

Aerobic pathogenic bacteria in post-operative wounds at Moi ...

African Journals Online (AJOL)

Background: The emergence of bacterial antimicrobial resistance associated with acquired infections has made the choice of empirical therapy more difficult and expensive, hence the need for continuous research to determine their sensitivity patterns. Objectives: To identify the common aerobic pathogenic bacteria in ...

The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens.

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Sánchez-Vallet, Andrea; Fouché, Simone; Fudal, Isabelle; Hartmann, Fanny E; Soyer, Jessica L; Tellier, Aurélien; Croll, Daniel

2018-05-16

Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation. Expected final online publication date for the Annual Review of Phytopathology Volume 56 is August 25, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

High throughput sequencing and proteomics to identify immunogenic proteins of a new pathogen: the dirty genome approach.

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Gilbert Greub

Full Text Available BACKGROUND: With the availability of new generation sequencing technologies, bacterial genome projects have undergone a major boost. Still, chromosome completion needs a costly and time-consuming gap closure, especially when containing highly repetitive elements. However, incomplete genome data may be sufficiently informative to derive the pursued information. For emerging pathogens, i.e. newly identified pathogens, lack of release of genome data during gap closure stage is clearly medically counterproductive. METHODS/PRINCIPAL FINDINGS: We thus investigated the feasibility of a dirty genome approach, i.e. the release of unfinished genome sequences to develop serological diagnostic tools. We showed that almost the whole genome sequence of the emerging pathogen Parachlamydia acanthamoebae was retrieved even with relatively short reads from Genome Sequencer 20 and Solexa. The bacterial proteome was analyzed to select immunogenic proteins, which were then expressed and used to elaborate the first steps of an ELISA. CONCLUSIONS/SIGNIFICANCE: This work constitutes the proof of principle for a dirty genome approach, i.e. the use of unfinished genome sequences of pathogenic bacteria, coupled with proteomics to rapidly identify new immunogenic proteins useful to develop in the future specific diagnostic tests such as ELISA, immunohistochemistry and direct antigen detection. Although applied here to an emerging pathogen, this combined dirty genome sequencing/proteomic approach may be used for any pathogen for which better diagnostics are needed. These genome sequences may also be very useful to develop DNA based diagnostic tests. All these diagnostic tools will allow further evaluations of the pathogenic potential of this obligate intracellular bacterium.

[Anthropocene and Emerging viral diseases].

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Chastel, C

2016-08-01

We propose to bring together the new geologic concept of Anthropocene and its consequences on our environment with the observed increasing emergence of new viruses - a pathogen for both humans and animals, mainly since the mid of the twentieth century.

RNA ‘Information Warfare’ in Pathogenic and Mutualistic Interactions

NARCIS (Netherlands)

Chaloner, Thomas; Kan, van Jan A.L.; Grant-Downton, Robert T.

2016-01-01

Regulatory non-coding RNAs are emerging as key players in host–pathogen interactions. Small RNAs such as microRNAs are implicated in regulating plant transcripts involved in immunity and defence. Surprisingly, RNAs with silencing properties can be translocated from plant hosts to various invading

Prioritizing emerging zoonoses in the Netherlands.

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Arie H Havelaar

Full Text Available BACKGROUND: To support the development of early warning and surveillance systems of emerging zoonoses, we present a general method to prioritize pathogens using a quantitative, stochastic multi-criteria model, parameterized for the Netherlands. METHODOLOGY/PRINCIPAL FINDINGS: A risk score was based on seven criteria, reflecting assessments of the epidemiology and impact of these pathogens on society. Criteria were weighed, based on the preferences of a panel of judges with a background in infectious disease control. CONCLUSIONS/SIGNIFICANCE: Pathogens with the highest risk for the Netherlands included pathogens in the livestock reservoir with a high actual human disease burden (e.g. Campylobacter spp., Toxoplasma gondii, Coxiella burnetii or a low current but higher historic burden (e.g. Mycobacterium bovis, rare zoonotic pathogens in domestic animals with severe disease manifestations in humans (e.g. BSE prion, Capnocytophaga canimorsus as well as arthropod-borne and wildlife associated pathogens which may pose a severe risk in future (e.g. Japanese encephalitis virus and West-Nile virus. These agents are key targets for development of early warning and surveillance.

Meat products: main pathogens and non-thermal control strategies

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Norma Heredia

2014-12-01

Full Text Available Meat is a rich nutrient matrix that allows the proper environment for diverse microorganisms’ proliferation, deteriorative and pathogen. E. coli O157 and non-O157, Salmonella spp. and Listeria monocytogenes are among the pathogen ones. On other hand, the growing demand for “fresh-like” products with high sanitary, organoleptic and nutritional quality had drive the development of alternative technologies to traditional or thermal, to satisfy consumers’ demand. In the last decades new food preservation techniques with no effect on nutritional or organoleptic characteristics had been developed, maintaining or improving microbiological stability and quality. This work is review of the most common pathogen microorganisms in meat and meat products, and the emerging technologies like high hydrostatic pressure, radiation, intelligent and active packages, and the use of natutal compounds for their control.

Common and emerging infectious diseases in the animal shelter.

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Pesavento, P A; Murphy, B G

2014-03-01

The beneficial role that animal shelters play is unquestionable. An estimated 3 to 4 million animals are cared for or placed in homes each year, and most shelters promote public health and support responsible pet ownership. It is, nonetheless, inevitable that shelters are prime examples of anthropogenic biological instability: even well-run shelters often house transient, displaced, and mixed populations of animals. Many of these animals have received minimal to no prior health care, and some have a history of scavenging or predation to survive. Overcrowding and poor shelter conditions further magnify these inherent risks to create individual, intraspecies, and interspecies stress and provide an environment conducive to exposure to numerous potentially collaborative pathogens. All of these factors can contribute to the evolution and emergence of new pathogens or to alterations in virulence of endemic pathogens. While it is not possible to effectively anticipate the timing or the pathogen type in emergence events, their sites of origin are less enigmatic, and pathologists and diagnosticians who work with sheltered animal populations have recognized several such events in the past decade. This article first considers the contribution of the shelter environment to canine and feline disease. This is followed by summaries of recent research on the pathogenesis of common shelter pathogens, as well as research that has led to the discovery of novel or emerging diseases and the methods that are used for their diagnosis and discovery. For the infectious agents that commonly affect sheltered dogs and cats, including canine distemper virus, canine influenza virus, Streptococcus spp, parvoviruses, feline herpesvirus, feline caliciviruses, and feline infectious peritonitis virus, we present familiar as well as newly recognized lesions associated with infection. Preliminary studies on recently discovered viruses like canine circovirus, canine bocavirus, and feline norovirus

Emerging influenza virus: A global threat

Indian Academy of Sciences (India)

PRAKASH KUMAR

Emerging influenza virus: A global threat. 475. J. Biosci. ... pathogens and are of major global health concern. Recently, ..... cases among persons in 14 countries in Asia, the Middle ... of influenza, investment in pandemic vaccine research and.

Rapid detection, characterization, and enumeration of foodborne pathogens

DEFF Research Database (Denmark)

Hoorfar, Jeffrey

2011-01-01

. The present review discusses the reasons for the increasing interest in rapid methods; current developments in the field, the research needs, and the future trends. The advent of biotechnology has introduced new technologies that led to the emergence of rapid diagnostic methods and altered food testing...... of rapid methods is for fast screening of large number of samples, where most of them are expected to be test-negative, leading to faster product release for sale. This has been the main strength of rapid methods such as real-time Polymerase Chain Reaction (PCR). Enrichment PCR, where a primary culture...... of pathogen in a contaminated product. Another key issue is automation, where the key drivers are miniaturization and multiple testing, which mean that not only one instrument is flexible enough to test for many pathogens but also many pathogens can be detected with one test. The review is mainly based...

Modeling the intracellular pathogen-immune interaction with cure rate

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Dubey, Balram; Dubey, Preeti; Dubey, Uma S.

2016-09-01

Many common and emergent infectious diseases like Influenza, SARS, Hepatitis, Ebola etc. are caused by viral pathogens. These infections can be controlled or prevented by understanding the dynamics of pathogen-immune interaction in vivo. In this paper, interaction of pathogens with uninfected and infected cells in presence or absence of immune response are considered in four different cases. In the first case, the model considers the saturated nonlinear infection rate and linear cure rate without absorption of pathogens into uninfected cells and without immune response. The next model considers the effect of absorption of pathogens into uninfected cells while all other terms are same as in the first case. The third model incorporates innate immune response, humoral immune response and Cytotoxic T lymphocytes (CTL) mediated immune response with cure rate and without absorption of pathogens into uninfected cells. The last model is an extension of the third model in which the effect of absorption of pathogens into uninfected cells has been considered. Positivity and boundedness of solutions are established to ensure the well-posedness of the problem. It has been found that all the four models have two equilibria, namely, pathogen-free equilibrium point and pathogen-present equilibrium point. In each case, stability analysis of each equilibrium point is investigated. Pathogen-free equilibrium is globally asymptotically stable when basic reproduction number is less or equal to unity. This implies that control or prevention of infection is independent of initial concentration of uninfected cells, infected cells, pathogens and immune responses in the body. The proposed models show that introduction of immune response and cure rate strongly affects the stability behavior of the system. Further, on computing basic reproduction number, it has been found to be minimum for the fourth model vis-a-vis other models. The analytical findings of each model have been exemplified by

Detection of Pathogen Exposure in African Buffalo Using Non-Specific Markers of Inflammation

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Caroline K. Glidden

2018-01-01

Full Text Available Detecting exposure to new or emerging pathogens is a critical challenge to protecting human, domestic animal, and wildlife health. Yet, current techniques to detect infections typically target known pathogens of humans or economically important animals. In the face of the current surge in infectious disease emergence, non-specific disease surveillance tools are urgently needed. Tracking common host immune responses indicative of recent infection may have potential as a non-specific diagnostic approach for disease surveillance. The challenge to immunologists is to identify the most promising markers, which ideally should be highly conserved across pathogens and host species, become upregulated rapidly and consistently in response to pathogen invasion, and remain elevated beyond clearance of infection. This study combined an infection experiment and a longitudinal observational study to evaluate the utility of non-specific markers of inflammation [NSMI; two acute phase proteins (haptoglobin and serum amyloid A, two pro-inflammatory cytokines (IFNγ and TNF-α] as indicators of pathogen exposure in a wild mammalian species, African buffalo (Syncerus caffer. Specifically, in the experimental study, we asked (1 How quickly do buffalo mount NSMI responses upon challenge with an endemic pathogen, foot-and-mouth disease virus; (2 for how long do NSMI remain elevated after viral clearance and; (3 how pronounced is the difference between peak NSMI concentration and baseline NSMI concentration? In the longitudinal study, we asked (4 Are elevated NSMI associated with recent exposure to a suite of bacterial and viral respiratory pathogens in a wild population? Among the four NSMI that we tested, haptoglobin showed the strongest potential as a surveillance marker in African buffalo: concentrations quickly and consistently reached high levels in response to experimental infection, remaining elevated for almost a month. Moreover, elevated haptoglobin was

The Intriguing Evolutionary Journey of Enteroinvasive E. coli (EIEC) toward Pathogenicity.

Science.gov (United States)

Pasqua, Martina; Michelacci, Valeria; Di Martino, Maria Letizia; Tozzoli, Rosangela; Grossi, Milena; Colonna, Bianca; Morabito, Stefano; Prosseda, Gianni

2017-01-01

Among the intestinal pathogenic Escherichia coli , enteroinvasive E. coli (EIEC) are a group of intracellular pathogens able to enter epithelial cells of colon, multiplicate within them, and move between adjacent cells with a mechanism similar to Shigella , the ethiological agent of bacillary dysentery. Despite EIEC belong to the same pathotype of Shigella , they neither have the full set of traits that define Shigella nor have undergone the extensive gene decay observed in Shigella . Molecular analysis confirms that EIEC are widely distributed among E. coli phylogenetic groups and correspond to bioserotypes found in many E. coli serogroups. Like Shigella , also in EIEC the critical event toward a pathogenic life-style consisted in the acquisition by horizontal gene transfer of a large F-type plasmid (pINV) containing the genes required for invasion, intracellular survival, and spreading through the intestinal mucosa. In Shigella , the ample gain in virulence determinants has been counteracted by a substantial loss of functions that, although important for the survival in the environment, are redundant or deleterious for the life inside the host. The pathoadaptation process that has led Shigella to modify its metabolic profile and increase its pathogenic potential is still in infancy in EIEC, although maintenance of some features typical of E. coli might favor their emerging relevance as intestinal pathogens worldwide, as documented by recent outbreaks in industrialized countries. In this review, we will discuss the evolution of EIEC toward Shigella -like invasive forms going through the epidemiology, including the emergence of new virulent strains, their genome organization, and the complex interactions they establish with the host.

Pathogenic psychrotolerant sporeformers: an emerging challenge for low-temperature storage of minimally processed foods.

Science.gov (United States)

Markland, Sarah M; Farkas, Daniel F; Kniel, Kalmia E; Hoover, Dallas G

2013-05-01

Sporeforming bacteria are a significant problem in the food industry as they are ubiquitous in nature and capable of resisting inactivation by heat and chemical treatments designed to inactivate them. Beyond spoilage issues, psychrotolerant sporeformers are becoming increasingly recognized as a potential hazard given the ever-expanding demand for refrigerated processed foods with extended shelf-life. In these products, the sporeforming pathogens of concern are Bacillus cereus, Bacillus weihenstephanensis, and Clostridium botulinum type E. This review article examines the foods, conditions, and organisms responsible for the food safety issue caused by the germination and outgrowth of psychrotolerant sporeforming pathogens in minimally processed refrigerated foods.

The Vietnam Initiative on Zoonotic Infections (VIZIONS): A Strategic Approach to Studying Emerging Zoonotic Infectious Diseases.

Science.gov (United States)

Rabaa, Maia A; Tue, Ngo Tri; Phuc, Tran My; Carrique-Mas, Juan; Saylors, Karen; Cotten, Matthew; Bryant, Juliet E; Nghia, Ho Dang Trung; Cuong, Nguyen Van; Pham, Hong Anh; Berto, Alessandra; Phat, Voong Vinh; Dung, Tran Thi Ngoc; Bao, Long Hoang; Hoa, Ngo Thi; Wertheim, Heiman; Nadjm, Behzad; Monagin, Corina; van Doorn, H Rogier; Rahman, Motiur; Tra, My Phan Vu; Campbell, James I; Boni, Maciej F; Tam, Pham Thi Thanh; van der Hoek, Lia; Simmonds, Peter; Rambaut, Andrew; Toan, Tran Khanh; Van Vinh Chau, Nguyen; Hien, Tran Tinh; Wolfe, Nathan; Farrar, Jeremy J; Thwaites, Guy; Kellam, Paul; Woolhouse, Mark E J; Baker, Stephen

2015-12-01

The effect of newly emerging or re-emerging infectious diseases of zoonotic origin in human populations can be potentially catastrophic, and large-scale investigations of such diseases are highly challenging. The monitoring of emergence events is subject to ascertainment bias, whether at the level of species discovery, emerging disease events, or disease outbreaks in human populations. Disease surveillance is generally performed post hoc, driven by a response to recent events and by the availability of detection and identification technologies. Additionally, the inventory of pathogens that exist in mammalian and other reservoirs is incomplete, and identifying those with the potential to cause disease in humans is rarely possible in advance. A major step in understanding the burden and diversity of zoonotic infections, the local behavioral and demographic risks of infection, and the risk of emergence of these pathogens in human populations is to establish surveillance networks in populations that maintain regular contact with diverse animal populations, and to simultaneously characterize pathogen diversity in human and animal populations. Vietnam has been an epicenter of disease emergence over the last decade, and practices at the human/animal interface may facilitate the likelihood of spillover of zoonotic pathogens into humans. To tackle the scientific issues surrounding the origins and emergence of zoonotic infections in Vietnam, we have established The Vietnam Initiative on Zoonotic Infections (VIZIONS). This countrywide project, in which several international institutions collaborate with Vietnamese organizations, is combining clinical data, epidemiology, high-throughput sequencing, and social sciences to address relevant one-health questions. Here, we describe the primary aims of the project, the infrastructure established to address our scientific questions, and the current status of the project. Our principal objective is to develop an integrated approach to

Population dynamics of the critically endangered toad Atelopus cruciger and the fungal disease chytridiomycosis

Science.gov (United States)

Señaris, Celsa; García, Carmen Zulay

2017-01-01

Harlequin toads (Atelopus) are among the most severely impacted amphibians by the emergence of chytridiomycosis, a fungal disease caused by the pathogen Batrachochytrium dendrobatidis (Bd). Many species disappeared while others suffered drastic contractions of their geographic distribution to lower altitudes. A diminished virulence of Bd in warm habitats was proposed to explain the survival of lowland populations of harlequin toads (i.e. thermal refuge hypothesis). To understand the mechanisms that allow some populations to reach an endemic equilibrium with this pathogen, we estimated demographic and epidemiological parameters at one remnant population of Atelopus cruciger in Venezuela using mark-recapture data from 2007–2013. We demonstrated that Bd is highly virulent for A. cruciger, increasing the odds of dying of infected adults four times in relation to uninfected ones and reducing the life expectancy of reproductive toads to a few weeks. Despite an estimated annual loss of 18% of the reproductive population due to Bd-induced mortality, this population has persisted in an endemic equilibrium for the last decade through the large recruitment of healthy adults every year. Given the high vulnerability of harlequin toads to Bd in lowland populations, thermal refuges need to be redefined as habitats of reduced transmission rather than attenuated virulence. PMID:28570689

Plastic potential: how the phenotypes and adaptations of pathogens are influenced by microbial interactions within plants.

Science.gov (United States)

O'Keeffe, Kayleigh R; Carbone, Ignazio; Jones, Corbin D; Mitchell, Charles E

2017-08-01

Predicting the effects of plant-associated microbes on emergence, spread, and evolution of plant pathogens demands an understanding of how pathogens respond to these microbes at two levels of biological organization: that of an individual pathogen and that of a pathogen population across multiple individual plants. We first examine the plastic responses of individual plant pathogens to microbes within a shared host, as seen through changes in pathogen growth and multiplication. We then explore the limited understanding of how within-plant microbial interactions affect pathogen populations and discuss the need to incorporate population-level observations with population genomic techniques. Finally, we suggest that integrating across levels will further our understanding of the ecological and evolutionary impacts of within-plant microbial interactions on pathogens. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of 'atypical' Brucella in amphibians: are we facing novel emerging pathogens?

Science.gov (United States)

Mühldorfer, K; Wibbelt, G; Szentiks, C A; Fischer, D; Scholz, H C; Zschöck, M; Eisenberg, T

2017-01-01

To discuss together the novel cases of Brucella infections in frogs with the results of published reports to extend our current knowledge on 'atypical' brucellae isolated from amphibians and to discuss the challenges we face on this extraordinary emerging group of pathogens. Since our first description, an additional 14 isolates from four different frog species were collected. Novel isolates and a subset of Brucella isolates previously cultured from African bullfrogs were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), Fourier transform-infrared (FT-IR) spectroscopy and broth microdilution susceptibility testing. MALDI-TOF MS worked very efficiently for an accurate bacterial identification to the genus level. Within the cluster analysis, 'atypical' brucellae grouped distant from Brucella melitensis and were even more separated by FT-IR spectroscopy with respect to their geographical origin. Minimum inhibitory concentrations of 14 antimicrobial substances are provided as baseline data on antimicrobial susceptibility. The case history of Brucella infections in amphibians reveals a variety of pathologies ranging from localized manifestations to systemic infections. Some isolates seem to be capable of causing high mortality in zoological exhibitions putting higher demands on the management of endangered frog species. There is considerable risk in overlooking and misidentifying 'atypical' Brucella in routine diagnostics. Brucella have only recently been described in cold-blooded vertebrates. Their presence in frog species native to Africa, America and Australia indicates a more common occurrence in amphibians than previously thought. This study provides an extensive overview of amphibian brucellae by highlighting the main features of their clinical significance, diagnosis and zoonotic potential. © 2016 The Society for Applied Microbiology.

Elevated Corticosterone Levels and Changes in Amphibian Behavior Are Associated with Batrachochytrium dendrobatidis (Bd Infection and Bd Lineage.

Directory of Open Access Journals (Sweden)

Caitlin R Gabor

Full Text Available Few studies have examined the role hormones play in mediating clinical changes associated with infection by the parasite Batrachochytrium dendrobatidis (Bd. Glucocorticoid (GC hormones such as corticosteroids (CORT regulate homeostasis and likely play a key role in response to infection in amphibians. We explore the relationship between CORT release rates and Bd infection in tadpoles of the common midwife toad, Alytes obstetricians, using a non-invasive water-borne hormone collection method across seven populations. We further examined whether tadpoles of A. muletensis infected with a hypervirulent lineage of Bd, BdGPL, had greater CORT release rates than those infected with a hypovirulent lineage, BdCAPE. Finally, we examined the relationship between righting reflex and CORT release rates in infected metamorphic toads of A. obstetricans. We found an interaction between elevation and Bd infection status confirming that altitude is associated with the overall severity of infection. In tandem, increasing elevation was associated with increasing CORT release rates. Tadpoles infected with the hypervirulent BdGPL had significantly higher CORT release rates than tadpoles infected with BdCAPE showing that more aggressive infections lead to increased CORT release rates. Infected metamorphs with higher CORT levels had an impaired righting reflex, our defined experimental endpoint. These results provide evidence that CORT is associated with an amphibian's vulnerability to Bd infection, and that CORT is also affected by the aggressiveness of infection by Bd. Together these results indicate that CORT is a viable biomarker of amphibian stress.

An overview of various typing methods for clinical epidemiology of the emerging pathogen Stenotrophomonas maltophilia.

Science.gov (United States)

Gherardi, Giovanni; Creti, Roberta; Pompilio, Arianna; Di Bonaventura, Giovanni

2015-03-01

Typing of bacterial isolates has been used for decades to study local outbreaks as well as in national and international surveillances for monitoring newly emerging resistant clones. Despite being recognized as a nosocomial pathogen, the precise modes of transmission of Stenotrophomonas maltophilia in health care settings are unknown. Due to the high genetic diversity observed among S. maltophilia clinical isolates, the typing results might be better interpreted if also environmental strains were included. This could help to identify preventative measures to be designed and implemented for decreasing the possibility of outbreaks and nosocomial infections. In this review, we attempt to provide an overview on the most common typing methods used for clinical epidemiology of S. maltophilia strains, such as PCR-based fingerprinting analyses, pulsed-field gel electrophoresis, multilocus variable number tandem repeat analysis, and multilocus sequence type. Application of the proteomic-based mass spectrometry by matrix-assisted laser desorption ionization-time of flight is also described. Improvements of typing methods already in use have to be achieved to facilitate S. maltophilia infection control at any level. In the near future, when novel Web-based platforms for rapid data processing and analysis will be available, whole genome sequencing technologies will likely become a highly powerful tool for outbreak investigations and surveillance studies in routine clinical practices. Copyright © 2015 Elsevier Inc. All rights reserved.

Bacteriophage interactions with marine pathogenic Vibrios

DEFF Research Database (Denmark)

Kalatzis, Panagiotis

development and spreading of antibiotic resistant bacteria in the environment. Bacteriophage therapy, constitutes a potent alternative not only for treatment but also for prevention of vibriosis in aquaculture and the current thesis addresses the potential and challenges of using phages to control Vibrio...... pathogens. The combinatory administration of virulent bacteriophages φSt2 and φGrn1, isolated against Vibrio alginolyticus significantly reduced the Vibrio load in cultures of Artemia salina live prey, decreasing subsequently the risk of a vibriosis outbreak in the marine hatchery. During infection...... therapy applications. Lytic phage vB_VspP_pVa5 that has been isolated against the rapidly emerging pathogen V. splendidus is also a promising candidate for phage therapy application according to its gene content and in vitro performance against its host. The genetic features of vB_VspP_pVa5 provide also...

Genome of the carbapenemase-producing clinical isolate Elizabethkingia miricola EM_CHUV and comparative genomics with Elizabethkingia meningoseptica and Elizabethkingia anophelis: evidence for intrinsic multidrug resistance trait of emerging pathogens.

OpenAIRE

Opota, O.; Diene, S.M.; Bertelli, C.; Prod'hom, G.; Eckert, P.; Greub, G.

2017-01-01

Elizabethkingia miricola is a Gram-negative non-fermenting rod emerging as a life-threatening human pathogen. The multidrug-resistant (MDR) carbapenemase-producing clinical isolate E. miricola EM_CHUV was recovered in the setting of severe nosocomial pneumonia. In this study, the genome of E. miricola EM_CHUV was sequenced and a functional analysis was performed, including a comparative genomic study with Elizabethkingia meningoseptica and Elizabethkingia anophelis. The resistome of EM_CHUV r...

Emerging trends in the discovery of natural product antibacterials

DEFF Research Database (Denmark)

Bologa, Cristian G; Ursu, Oleg; Oprea, Tudor

2013-01-01

This article highlights current trends and advances in exploiting natural sources for the deployment of novel and potent anti-infective countermeasures. The key challenge is to therapeutically target bacterial pathogens that exhibit a variety of puzzling and evolutionarily complex resistance...... mechanisms. Special emphasis is given to the strengths, weaknesses, and opportunities in the natural product antibacterial drug discovery arena, and to emerging applications driven by advances in bioinformatics, chemical biology, and synthetic biology in concert with exploiting bacterial phenotypes....... These efforts have identified a critical mass of natural product antibacterial lead compounds and discovery technologies with high probability of successful implementation against emerging bacterial pathogens....

Streptococcus dysgalactiae subsp. dysgalactiae isolated from milk of the bovine udder as emerging pathogens: In vitro and in vivo infection of human cells and zebrafish as biological models.

Science.gov (United States)

Alves-Barroco, Cinthia; Roma-Rodrigues, Catarina; Raposo, Luís R; Brás, Catarina; Diniz, Mário; Caço, João; Costa, Pedro M; Santos-Sanches, Ilda; Fernandes, Alexandra R

2018-03-25

Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) is a major cause of bovine mastitis and has been regarded as an animal-restricted pathogen, although rare infections have been described in humans. Previous studies revealed the presence of virulence genes encoded by phages of the human pathogen Group A Streptococcus pyogenes (GAS) in SDSD isolated from the milk of bovine udder with mastitis. The isolates SDSD VSD5 and VSD13 could adhere and internalize human primary keratinocyte cells, suggesting a possible human infection potential of bovine isolates. In this work, the in vitro and in vivo potential of SDSD to internalize/adhere human cells of the respiratory track and zebrafish as biological models was evaluated. Our results showed that, in vitro, bovine SDSD strains could interact and internalize human respiratory cell lines and that this internalization was dependent on an active transport mechanism and that, in vivo, SDSD are able to cause invasive infections producing zebrafish morbidity and mortality. The infectious potential of these isolates showed to be isolate-specific and appeared to be independent of the presence or absence of GAS phage-encoded virulence genes. Although the infection ability of the bovine SDSD strains was not as strong as the human pathogenic S. pyogenes in the zebrafish model, results suggested that these SDSD isolates are able to interact with human cells and infect zebrafish, a vertebrate infectious model, emerging as pathogens with zoonotic capability. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Do wheelchairs spread pathogenic bacteria within hospital walls?

Science.gov (United States)

Peretz, Avi; Koiefman, Anna; Dinisman, Eleonora; Brodsky, Diana; Labay, Kozitta

2014-02-01

Transmission of nosocomial pathogens has been linked to transient colonization of health care workers, medical devices and other constituents of patients' environment. In this paper we present our findings concerning the presence of pathogenic bacteria on wheelchairs, and the possibility that wheelchairs constitute a reservoir of these bacteria and a means of spreading them. In this work we examined four wheelchairs, each from a different location: the internal medicine ward, the emergency department, the general surgery ward and wheelchair stockpile of the transportation unit of the hospital. The samples were collected and cultured on different media. Bacterial identification and antimicrobial sensitivity testing were carried out using accepted practices in the microbiology laboratory. We found that wheelchairs are contaminated with several pathogenic bacteria, among them antibiotic-resistant strains such as MRSA, Pseudomonas aeruginosa, Acinetobacter baumanni etc. Since there is no specific guideline protocol that deals with disinfection and cleaning frequency of wheelchairs in hospitals, we suggest each hospital to write one.

Immunity to intestinal pathogens: lessons learned from Salmonella

Science.gov (United States)

McSorley, Stephen J.

2014-01-01

Summary Salmonella are a common source of food or water-borne infection and cause a wide range of clinical disease in human and animal hosts. Salmonella are relatively easy to culture and manipulate in a laboratory setting, and the infection of laboratory animals induces robust innate and adaptive immune responses. Thus, immunologists have frequently turned to Salmonella infection models to expand understanding of immunity to intestinal pathogens. In this review, I summarize current knowledge of innate and adaptive immunity to Salmonella and highlight features of this response that have emerged from recent studies. These include the heterogeneity of the antigen-specific T-cell response to intestinal infection, the prominence of microbial mechanisms to impede T and B-cell responses, and the contribution of non-cognate pathways for elicitation of T-cell effector functions. Together, these different issues challenge an overly simplistic view of host-pathogen interaction during mucosal infection but also allow deeper insight into the real-world dynamic of protective immunity to intestinal pathogens. PMID:24942689

Aggressive chemotherapy and the selection of drug resistant pathogens.

Directory of Open Access Journals (Sweden)

Silvie Huijben

2013-09-01

Full Text Available Drug resistant pathogens are one of the key public health challenges of the 21st century. There is a widespread belief that resistance is best managed by using drugs to rapidly eliminate target pathogens from patients so as to minimize the probability that pathogens acquire resistance de novo. Yet strong drug pressure imposes intense selection in favor of resistance through alleviation of competition with wild-type populations. Aggressive chemotherapy thus generates opposing evolutionary forces which together determine the rate of drug resistance emergence. Identifying treatment regimens which best retard resistance evolution while maximizing health gains and minimizing disease transmission requires empirical analysis of resistance evolution in vivo in conjunction with measures of clinical outcomes and infectiousness. Using rodent malaria in laboratory mice, we found that less aggressive chemotherapeutic regimens substantially reduced the probability of onward transmission of resistance (by >150-fold, without compromising health outcomes. Our experiments suggest that there may be cases where resistance evolution can be managed more effectively with treatment regimens other than those which reduce pathogen burdens as fast as possible.

Capacity building efforts and perceptions for wildlife surveillance to detect zoonotic pathogens: comparing stakeholder perspectives.

Science.gov (United States)

Schwind, Jessica S; Goldstein, Tracey; Thomas, Kate; Mazet, Jonna A K; Smith, Woutrina A

2014-07-04

The capacity to conduct zoonotic pathogen surveillance in wildlife is critical for the recognition and identification of emerging health threats. The PREDICT project, a component of United States Agency for International Development's Emerging Pandemic Threats program, has introduced capacity building efforts to increase zoonotic pathogen surveillance in wildlife in global 'hot spot' regions where zoonotic disease emergence is likely to occur. Understanding priorities, challenges, and opportunities from the perspectives of the stakeholders is a key component of any successful capacity building program. A survey was administered to wildlife officials and to PREDICT-implementing in-country project scientists in 16 participating countries in order to identify similarities and differences in perspectives between the groups regarding capacity needs for zoonotic pathogen surveillance in wildlife. Both stakeholder groups identified some human-animal interfaces (i.e. areas of high contact between wildlife and humans with the potential risk for disease transmission), such as hunting and markets, as important for ongoing targeting of wildlife surveillance. Similarly, findings regarding challenges across stakeholder groups showed some agreement in that a lack of sustainable funding across regions was the greatest challenge for conducting wildlife surveillance for zoonotic pathogens (wildlife officials: 96% and project scientists: 81%). However, the opportunity for improving zoonotic pathogen surveillance capacity identified most frequently by wildlife officials as important was increasing communication or coordination among agencies, sectors, or regions (100% of wildlife officials), whereas the most frequent opportunities identified as important by project scientists were increasing human capacity, increasing laboratory capacity, and the growing interest or awareness regarding wildlife disease or surveillance programs (all identified by 69% of project scientists). A One

A Quantitative Prioritisation of Human and Domestic Animal Pathogens in Europe

Science.gov (United States)

McIntyre, K. Marie; Setzkorn, Christian; Hepworth, Philip J.; Morand, Serge; Morse, Andrew P.; Baylis, Matthew

2014-01-01

Disease or pathogen risk prioritisations aid understanding of infectious agent impact within surveillance or mitigation and biosecurity work, but take significant development. Previous work has shown the H-(Hirsch-)index as an alternative proxy. We present a weighted risk analysis describing infectious pathogen impact for human health (human pathogens) and well-being (domestic animal pathogens) using an objective, evidence-based, repeatable approach; the H-index. This study established the highest H-index European pathogens. Commonalities amongst pathogens not included in previous surveillance or risk analyses were examined. Differences between host types (humans/animals/zoonotic) in pathogen H-indices were explored as a One Health impact indicator. Finally, the acceptability of the H-index proxy for animal pathogen impact was examined by comparison with other measures. 57 pathogens appeared solely in the top 100 highest H-indices (1) human or (2) animal pathogens list, and 43 occurred in both. Of human pathogens, 66 were zoonotic and 67 were emerging, compared to 67 and 57 for animals. There were statistically significant differences between H-indices for host types (humans, animal, zoonotic), and there was limited evidence that H-indices are a reasonable proxy for animal pathogen impact. This work addresses measures outlined by the European Commission to strengthen climate change resilience and biosecurity for infectious diseases. The results include a quantitative evaluation of infectious pathogen impact, and suggest greater impacts of human-only compared to zoonotic pathogens or scientific under-representation of zoonoses. The outputs separate high and low impact pathogens, and should be combined with other risk assessment methods relying on expert opinion or qualitative data for priority setting, or could be used to prioritise diseases for which formal risk assessments are not possible because of data gaps. PMID:25136810

Elevated Genetic Diversity in the Emerging Blueberry Pathogen Exobasidium maculosum.

Science.gov (United States)

Stewart, Jane E; Brooks, Kyle; Brannen, Phillip M; Cline, William O; Brewer, Marin T

2015-01-01

Emerging diseases caused by fungi are increasing at an alarming rate. Exobasidium leaf and fruit spot of blueberry, caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA, severely reducing fruit quality in some plantings. The objectives of this study were to determine the genetic diversity of E. maculosum in the southeastern USA to elucidate the basis of disease emergence and to investigate if populations of E. maculosum are structured by geography, host species, or tissue type. We sequenced three conserved loci from 82 isolates collected from leaves and fruit of rabbiteye blueberry (Vaccinium virgatum), highbush blueberry (V. corymbosum), and southern highbush blueberry (V. corymbosum hybrids) from commercial fields in Georgia and North Carolina, USA, and 6 isolates from lowbush blueberry (V. angustifolium) from Maine, USA, and Nova Scotia, Canada. Populations of E. maculosum from the southeastern USA and from lowbush blueberry in Maine and Nova Scotia are distinct, but do not represent unique species. No difference in genetic structure was detected between different host tissues or among different host species within the southeastern USA; however, differentiation was detected between populations in Georgia and North Carolina. Overall, E. maculosum showed extreme genetic diversity within the conserved loci with 286 segregating sites among the 1,775 sequenced nucleotides and each isolate representing a unique multilocus haplotype. However, 94% of the nucleotide substitutions were silent, so despite the high number of mutations, selective constraints have limited changes to the amino acid sequences of the housekeeping genes. Overall, these results suggest that the emergence of Exobasidium leaf and fruit spot is not due to a recent introduction or host shift, or the recent evolution of aggressive genotypes of E. maculosum, but more likely as a result of an increasing host population

Elevated Genetic Diversity in the Emerging Blueberry Pathogen Exobasidium maculosum

Science.gov (United States)

Stewart, Jane E.; Brooks, Kyle; Brannen, Phillip M.; Cline, William O.; Brewer, Marin T.

2015-01-01

Emerging diseases caused by fungi are increasing at an alarming rate. Exobasidium leaf and fruit spot of blueberry, caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA, severely reducing fruit quality in some plantings. The objectives of this study were to determine the genetic diversity of E. maculosum in the southeastern USA to elucidate the basis of disease emergence and to investigate if populations of E. maculosum are structured by geography, host species, or tissue type. We sequenced three conserved loci from 82 isolates collected from leaves and fruit of rabbiteye blueberry (Vaccinium virgatum), highbush blueberry (V. corymbosum), and southern highbush blueberry (V. corymbosum hybrids) from commercial fields in Georgia and North Carolina, USA, and 6 isolates from lowbush blueberry (V. angustifolium) from Maine, USA, and Nova Scotia, Canada. Populations of E. maculosum from the southeastern USA and from lowbush blueberry in Maine and Nova Scotia are distinct, but do not represent unique species. No difference in genetic structure was detected between different host tissues or among different host species within the southeastern USA; however, differentiation was detected between populations in Georgia and North Carolina. Overall, E. maculosum showed extreme genetic diversity within the conserved loci with 286 segregating sites among the 1,775 sequenced nucleotides and each isolate representing a unique multilocus haplotype. However, 94% of the nucleotide substitutions were silent, so despite the high number of mutations, selective constraints have limited changes to the amino acid sequences of the housekeeping genes. Overall, these results suggest that the emergence of Exobasidium leaf and fruit spot is not due to a recent introduction or host shift, or the recent evolution of aggressive genotypes of E. maculosum, but more likely as a result of an increasing host population

Elevated Genetic Diversity in the Emerging Blueberry Pathogen Exobasidium maculosum.

Directory of Open Access Journals (Sweden)

Jane E Stewart

Full Text Available Emerging diseases caused by fungi are increasing at an alarming rate. Exobasidium leaf and fruit spot of blueberry, caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA, severely reducing fruit quality in some plantings. The objectives of this study were to determine the genetic diversity of E. maculosum in the southeastern USA to elucidate the basis of disease emergence and to investigate if populations of E. maculosum are structured by geography, host species, or tissue type. We sequenced three conserved loci from 82 isolates collected from leaves and fruit of rabbiteye blueberry (Vaccinium virgatum, highbush blueberry (V. corymbosum, and southern highbush blueberry (V. corymbosum hybrids from commercial fields in Georgia and North Carolina, USA, and 6 isolates from lowbush blueberry (V. angustifolium from Maine, USA, and Nova Scotia, Canada. Populations of E. maculosum from the southeastern USA and from lowbush blueberry in Maine and Nova Scotia are distinct, but do not represent unique species. No difference in genetic structure was detected between different host tissues or among different host species within the southeastern USA; however, differentiation was detected between populations in Georgia and North Carolina. Overall, E. maculosum showed extreme genetic diversity within the conserved loci with 286 segregating sites among the 1,775 sequenced nucleotides and each isolate representing a unique multilocus haplotype. However, 94% of the nucleotide substitutions were silent, so despite the high number of mutations, selective constraints have limited changes to the amino acid sequences of the housekeeping genes. Overall, these results suggest that the emergence of Exobasidium leaf and fruit spot is not due to a recent introduction or host shift, or the recent evolution of aggressive genotypes of E. maculosum, but more likely as a result of an increasing

Molecular Epidemiology and Genetic Variation of Pathogenic Vibrio parahaemolyticus in Peru

Science.gov (United States)

Gavilan, Ronnie G.; Zamudio, Maria L.; Martinez-Urtaza, Jaime

2013-01-01

Vibrio parahaemolyticus is a foodborne pathogen that has become a public health concern at the global scale. The epidemiological significance of V. parahaemolyticus infections in Latin America received little attention until the winter of 1997 when cases related to the pandemic clone were detected in the region, changing the epidemic dynamics of this pathogen in Peru. With the aim to assess the impact of the arrival of the pandemic clone on local populations of pathogenic V. parahaemolyticus in Peru, we investigated the population genetics and genomic variation in a complete collection of non-pandemic strains recovered from clinical sources in Peru during the pre- and post-emergence periods of the pandemic clone. A total of 56 clinical strains isolated in Peru during the period 1994 to 2007, 13 strains from Chile and 20 strains from Asia were characterized by Multilocus Sequence Typing (MLST) and checked for the presence of Variable Genomic Regions (VGRs). The emergence of O3:K6 cases in Peru implied a drastic disruption of the seasonal dynamics of infections and a shift in the serotype dominance of pathogenic V. parahaemolyticus. After the arrival of the pandemic clone, a great diversity of serovars not previously reported was detected in the country, which supports the introduction of additional populations cohabitating with the pandemic group. Moreover, the presence of genomic regions characteristic of the pandemic clone in other non-pandemic strains may represent early evidence of genetic transfer from the introduced population to the local communities. Finally, the results of this study stress the importance of population admixture, horizontal genetic transfer and homologous recombination as major events shaping the structure and diversity of pathogenic V. parahaemolyticus. PMID:23696906

The Intriguing Evolutionary Journey of Enteroinvasive E. coli (EIEC toward Pathogenicity

Directory of Open Access Journals (Sweden)

Martina Pasqua

2017-12-01

Full Text Available Among the intestinal pathogenic Escherichia coli, enteroinvasive E. coli (EIEC are a group of intracellular pathogens able to enter epithelial cells of colon, multiplicate within them, and move between adjacent cells with a mechanism similar to Shigella, the ethiological agent of bacillary dysentery. Despite EIEC belong to the same pathotype of Shigella, they neither have the full set of traits that define Shigella nor have undergone the extensive gene decay observed in Shigella. Molecular analysis confirms that EIEC are widely distributed among E. coli phylogenetic groups and correspond to bioserotypes found in many E. coli serogroups. Like Shigella, also in EIEC the critical event toward a pathogenic life-style consisted in the acquisition by horizontal gene transfer of a large F-type plasmid (pINV containing the genes required for invasion, intracellular survival, and spreading through the intestinal mucosa. In Shigella, the ample gain in virulence determinants has been counteracted by a substantial loss of functions that, although important for the survival in the environment, are redundant or deleterious for the life inside the host. The pathoadaptation process that has led Shigella to modify its metabolic profile and increase its pathogenic potential is still in infancy in EIEC, although maintenance of some features typical of E. coli might favor their emerging relevance as intestinal pathogens worldwide, as documented by recent outbreaks in industrialized countries. In this review, we will discuss the evolution of EIEC toward Shigella-like invasive forms going through the epidemiology, including the emergence of new virulent strains, their genome organization, and the complex interactions they establish with the host.

Phenotypic interactions between tree hosts and invasive forest pathogens in the light of globalization and climate change.

Science.gov (United States)

Stenlid, Jan; Oliva, Jonàs

2016-12-05

Invasive pathogens can cause considerable damage to forest ecosystems. Lack of coevolution is generally thought to enable invasive pathogens to bypass the defence and/or recognition systems in the host. Although mostly true, this argument fails to predict intermittent outcomes in space and time, underlining the need to include the roles of the environment and the phenotype in host-pathogen interactions when predicting disease impacts. We emphasize the need to consider host-tree imbalances from a phenotypic perspective, considering the lack of coevolutionary and evolutionary history with the pathogen and the environment, respectively. We describe how phenotypic plasticity and plastic responses to environmental shifts may become maladaptive when hosts are faced with novel pathogens. The lack of host-pathogen and environmental coevolution are aligned with two global processes currently driving forest damage: globalization and climate change, respectively. We suggest that globalization and climate change act synergistically, increasing the chances of both genotypic and phenotypic imbalances. Short moves on the same continent are more likely to be in balance than if the move is from another part of the world. We use Gremmeniella abietina outbreaks in Sweden to exemplify how host-pathogen phenotypic interactions can help to predict the impacts of specific invasive and emergent diseases.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Author(s).

Phenotypic interactions between tree hosts and invasive forest pathogens in the light of globalization and climate change

Science.gov (United States)

2016-01-01

Invasive pathogens can cause considerable damage to forest ecosystems. Lack of coevolution is generally thought to enable invasive pathogens to bypass the defence and/or recognition systems in the host. Although mostly true, this argument fails to predict intermittent outcomes in space and time, underlining the need to include the roles of the environment and the phenotype in host–pathogen interactions when predicting disease impacts. We emphasize the need to consider host–tree imbalances from a phenotypic perspective, considering the lack of coevolutionary and evolutionary history with the pathogen and the environment, respectively. We describe how phenotypic plasticity and plastic responses to environmental shifts may become maladaptive when hosts are faced with novel pathogens. The lack of host–pathogen and environmental coevolution are aligned with two global processes currently driving forest damage: globalization and climate change, respectively. We suggest that globalization and climate change act synergistically, increasing the chances of both genotypic and phenotypic imbalances. Short moves on the same continent are more likely to be in balance than if the move is from another part of the world. We use Gremmeniella abietina outbreaks in Sweden to exemplify how host–pathogen phenotypic interactions can help to predict the impacts of specific invasive and emergent diseases. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’. PMID:28080981

[Human plague and pneumonic plague : pathogenicity, epidemiology, clinical presentations and therapy].

Science.gov (United States)

Riehm, Julia M; Löscher, Thomas

2015-07-01

Yersinia pestis is a highly pathogenic gram-negative bacterium and the causative agent of human plague. In the last 1500 years and during three dreaded pandemics, millions of people became victims of Justinian's plague, the Black Death, or modern plague. Today, Y. pestis is endemic in natural foci of Asian, African and American countries. Due to its broad dissemination in mammal species and fleas, eradication of the pathogen will not be possible in the near future. In fact, plague is currently classified as a "re-emerging disease". Infection may occur after the bite of an infected flea, but also after oral ingestion or inhalation of the pathogen. The clinical presentations comprise the bubonic and pneumonic form, septicemia, rarely pharyngitis, and meningitis. Most human cases can successfully be treated with antibiotics. However, the high transmission rate and lethality of pneumonic plague require international and mandatory case notification and quarantine of patients. Rapid diagnosis, therapy and barrier nursing are not only crucial for the individual patient but also for the prevention of further spread of the pathogen or of epidemics. Therefore, WHO emergency schedules demand the isolation of cases, identification and surveillance of contacts as well as control of zoonotic reservoir animals and vectors. These sanctions and effective antibiotic treatment usually allow a rapid containment of outbreaks. However, multiple antibiotic resistant strains of Y. pestis have been isolated from patients in the past. So far, no outbreaks with such strains have been reported.

Evolution of two distinct phylogenetic lineages of the emerging human pathogen Mycobacterium ulcerans

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Portaels Francoise

2007-09-01

Full Text Available Abstract Background Comparative genomics has greatly improved our understanding of the evolution of pathogenic mycobacteria such as Mycobacterium tuberculosis. Here we have used data from a genome microarray analysis to explore insertion-deletion (InDel polymorphism among a diverse strain collection of Mycobacterium ulcerans, the causative agent of the devastating skin disease, Buruli ulcer. Detailed analysis of large sequence polymorphisms in twelve regions of difference (RDs, comprising irreversible genetic markers, enabled us to refine the phylogenetic succession within M. ulcerans, to define features of a hypothetical M. ulcerans most recent common ancestor and to confirm its origin from Mycobacterium marinum. Results M. ulcerans has evolved into five InDel haplotypes that separate into two distinct lineages: (i the "classical" lineage including the most pathogenic genotypes – those that come from Africa, Australia and South East Asia; and (ii an "ancestral" M. ulcerans lineage comprising strains from Asia (China/Japan, South America and Mexico. The ancestral lineage is genetically closer to the progenitor M. marinum in both RD composition and DNA sequence identity, whereas the classical lineage has undergone major genomic rearrangements. Conclusion Results of the InDel analysis are in complete accord with recent multi-locus sequence analysis and indicate that M. ulcerans has passed through at least two major evolutionary bottlenecks since divergence from M. marinum. The classical lineage shows more pronounced reductive evolution than the ancestral lineage, suggesting that there may be differences in the ecology between the two lineages. These findings improve the understanding of the adaptive evolution and virulence of M. ulcerans and pathogenic mycobacteria in general and will facilitate the development of new tools for improved diagnostics and molecular epidemiology.

Whole genome sequence of the emerging oomycete pathogen Pythium insidiosum strain CDC-B5653 isolated from an infected human in the USA

Directory of Open Access Journals (Sweden)

Marina S. Ascunce

2016-03-01

Full Text Available Pythium insidiosum ATCC 200269 strain CDC-B5653, an isolate from necrotizing lesions on the mouth and eye of a 2-year-old boy in Memphis, Tennessee, USA, was sequenced using a combination of Illumina MiSeq (300 bp paired-end, 14 millions reads and PacBio (10  Kb fragment library, 356,001 reads. The sequencing data were assembled using SPAdes version 3.1.0, yielding a total genome size of 45.6 Mb contained in 8992 contigs, N50 of 13 Kb, 57% G + C content, and 17,867 putative protein-coding genes. This Whole Genome Shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession JRHR00000000. Keywords: Oomycete, Pythium insidiosum, Pythiosis, Human emerging pathogen, Genome sequencing

Highly pathogenic avian influenza viruses and generation of novel reassortants,United States, 2014–2015

Science.gov (United States)

Dong-Hun Lee,; Justin Bahl,; Mia Kim Torchetti,; Mary Lea Killian,; Ip, Hon S.; David E Swayne,

2016-01-01

Asian highly pathogenic avian influenza A(H5N8) viruses spread into North America in 2014 during autumn bird migration. Complete genome sequencing and phylogenetic analysis of 32 H5 viruses identified novel H5N1, H5N2, and H5N8 viruses that emerged in late 2014 through reassortment with North American low-pathogenicity avian influenza viruses.

Combating highly resistant emerging pathogen Mycobacterium abscessus and Mycobacterium tuberculosis with novel salicylanilide esters and carbamates.

Science.gov (United States)

Baranyai, Zsuzsa; Krátký, Martin; Vinšová, Jarmila; Szabó, Nóra; Senoner, Zsuzsanna; Horváti, Kata; Stolaříková, Jiřina; Dávid, Sándor; Bősze, Szilvia

2015-08-28

In the Mycobacterium genus over one hundred species are already described and new ones are periodically reported. Species that form colonies in a week are classified as rapid growers, those requiring longer periods (up to three months) are the mostly pathogenic slow growers. More recently, new emerging species have been identified to lengthen the list, all rapid growers. Of these, Mycobacterium abscessus is also an intracellular pathogen and it is the most chemotherapy-resistant rapid-growing mycobacterium. In addition, the cases of multidrug-resistant Mycobacterium tuberculosis infection are also increasing. Therefore there is an urgent need to find new active molecules against these threatening strains. Based on previous results, a series of salicylanilides, salicylanilide 5-chloropyrazinoates and carbamates was designed, synthesized and characterised. The compounds were evaluated for their in vitro activity on M. abscessus, susceptible M. tuberculosis H37Rv, multidrug-resistant (MDR) M. tuberculosis MDR A8, M. tuberculosis MDR 9449/2006 and on the extremely-resistant Praha 131 (XDR) strains. All derivatives exhibited a significant activity with minimum inhibitory concentrations (MICs) in the low micromolar range. Eight salicylanilide carbamates and two salicylanilide esters exhibited an excellent in vitro activity on M. abscessus with MICs from 0.2 to 2.1 μM, thus being more effective than ciprofloxacin and gentamicin. This finding is potentially promising, particularly, as M. abscessus is a threateningly chemotherapy-resistant species. M. tuberculosis H37Rv was inhibited with MICs from 0.2 μM, and eleven compounds have lower MICs than isoniazid. Salicylanilide esters and carbamates were found that they were effective also on MDR and XDR M. tuberculosis strains with MICs ≥1.0 μM. The in vitro cytotoxicity (IC50) was also determined on human MonoMac-6 cells, and selectivity index (SI) of the compounds was established. In general, salicylanilide

Predators indirectly control vector-borne disease: linking predator-prey and host-pathogen models.

Science.gov (United States)

Moore, Sean M; Borer, Elizabeth T; Hosseini, Parviez R

2010-01-06

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of predators on vectored-pathogen dynamics, we developed a theoretical model that integrates predator-prey and host-pathogen theory. We used this model to determine whether predation can prevent pathogen persistence or alter the stability of host-pathogen dynamics. We found that, in the absence of predation, pathogen prevalence in the host increases with vector fecundity, whereas predation on the vector causes pathogen prevalence to decline, or even become extinct, with increasing vector fecundity. We also found that predation on a vector may drastically slow the initial spread of a pathogen. The predator can increase host abundance indirectly by reducing or eliminating infection in the host population. These results highlight the importance of studying interactions that, within the greater community, may alter our predictions when studying disease dynamics. From an applied perspective, these results also suggest situations where an introduced predator or the natural enemies of a vector may slow the rate of spread of an emerging vector-borne pathogen.

(Cucumis melo L.) cultivars to soil-borne plant pathogenic fungi in Iran

African Journals Online (AJOL)

ajl11

2012-10-30

Oct 30, 2012 ... resistance of melon cultivars to three important soil-borne plant pathogens found worldwide. Key words: Melon ... use of cultivars resistant to plant diseases is one of the ..... emerging disease of melons worldwide. Plant Dis.

A Framework for Modeling Emerging Diseases to Inform Management.

Science.gov (United States)

Russell, Robin E; Katz, Rachel A; Richgels, Katherine L D; Walsh, Daniel P; Grant, Evan H C

2017-01-01

The rapid emergence and reemergence of zoonotic diseases requires the ability to rapidly evaluate and implement optimal management decisions. Actions to control or mitigate the effects of emerging pathogens are commonly delayed because of uncertainty in the estimates and the predicted outcomes of the control tactics. The development of models that describe the best-known information regarding the disease system at the early stages of disease emergence is an essential step for optimal decision-making. Models can predict the potential effects of the pathogen, provide guidance for assessing the likelihood of success of different proposed management actions, quantify the uncertainty surrounding the choice of the optimal decision, and highlight critical areas for immediate research. We demonstrate how to develop models that can be used as a part of a decision-making framework to determine the likelihood of success of different management actions given current knowledge.

Inhibiting host-pathogen interactions using membrane-based nanostructures.

Science.gov (United States)

Bricarello, Daniel A; Patel, Mira A; Parikh, Atul N

2012-06-01

Virulent strains of bacteria and viruses recognize host cells by their plasma membrane receptors and often exploit the native translocation machinery to invade the cell. A promising therapeutic concept for early interruption of pathogen infection is to subvert this pathogenic trickery using exogenously introduced decoys that present high-affinity mimics of cellular receptors. This review highlights emerging applications of molecularly engineered lipid-bilayer-based nanostructures, namely (i) functionalized liposomes, (ii) supported colloidal bilayers or protocells and (iii) reconstituted lipoproteins, which display functional cellular receptors in optimized conformational and aggregative states. These decoys outcompete host cell receptors by preferentially binding to and neutralizing virulence factors of both bacteria and viruses, thereby promising a new approach to antipathogenic therapy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Current ecological understanding of fungal-like pathogens of fish: what lies beneath?

Directory of Open Access Journals (Sweden)

Rodolphe Elie Gozlan

2014-02-01

Full Text Available Despite increasingly sophisticated microbiological techniques, and long after the first discovery of microbes, basic knowledge is still lacking to fully appreciate the ecological importance of microbial parasites in fish. This is likely due to the nature of their habitats as many species of fish suffer from living beneath turbid water away from easy recording. However, fishes represent key ecosystem services for millions of people around the world and the absence of a functional ecological understanding of viruses, prokaryotes, and small eukaryotes in the maintenance of fish populations and of their diversity represents an inherent barrier to aquatic conservation and food security. Among recent emerging infectious diseases responsible for severe population declines in plant and animal taxa, fungal and fungal-like microbes have emerged as significant contributors. Here, we review the current knowledge gaps of fungal and fungal-like parasites and pathogens in fish and put them into an ecological perspective with direct implications for the monitoring of fungal fish pathogens in the wild, their phylogeography as well as their associated ecological impact on fish populations. With increasing fish movement around the world for farming, releases into the wild for sport fishing and human-driven habitat changes, it is expected, along with improved environmental monitoring of fungal and fungal-like infections, that the full extent of the impact of these pathogens on wild fish populations will soon emerge as a major threat to freshwater biodiversity.

West Africa - A Safe Haven for Frogs? A Sub-Continental Assessment of the Chytrid Fungus (Batrachochytrium dendrobatidis)

Science.gov (United States)

Penner, Johannes; Adum, Gilbert B.; McElroy, Matthew T.; Doherty-Bone, Thomas; Hirschfeld, Mareike; Sandberger, Laura; Weldon, Ché; Cunningham, Andrew A.; Ohst, Torsten; Wombwell, Emma; Portik, Daniel M.; Reid, Duncan; Hillers, Annika; Ofori-Boateng, Caleb; Oduro, William; Plötner, Jörg; Ohler, Annemarie; Leaché, Adam D.; Rödel, Mark-Oliver

2013-01-01

A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd). While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species) for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds) environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni (“Vulnerable”) and Petropedetes natator (“Near Threatened”)) as well as the “Critically Endangered” viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis). PMID:23426141

West Africa - a safe haven for frogs? A sub-continental assessment of the chytrid fungus (Batrachochytrium dendrobatidis.

Directory of Open Access Journals (Sweden)

Johannes Penner

Full Text Available A putative driver of global amphibian decline is the panzootic chytrid fungus Batrachochytrium dendrobatidis (Bd. While Bd has been documented across continental Africa, its distribution in West Africa remains ambiguous. We tested 793 West African amphibians (one caecilian and 61 anuran species for the presence of Bd. The samples originated from seven West African countries - Bénin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Liberia, Sierra Leone - and were collected from a variety of habitats, ranging from lowland rainforests to montane forests, montane grasslands to humid and dry lowland savannahs. The species investigated comprised various life-history strategies, but we focused particularly on aquatic and riparian species. We used diagnostic PCR to screen 656 specimen swabs and histology to analyse 137 specimen toe tips. All samples tested negative for Bd, including a widespread habitat generalist Hoplobatrachus occipitalis which is intensively traded on the West African food market and thus could be a potential dispersal agent for Bd. Continental fine-grained (30 arc seconds environmental niche models suggest that Bd should have a broad distribution across West Africa that includes most of the regions and habitats that we surveyed. The surprising apparent absence of Bd in West Africa indicates that the Dahomey Gap may have acted as a natural barrier. Herein we highlight the importance of this Bd-free region of the African continent - especially for the long-term conservation of several threatened species depending on fast flowing forest streams (Conraua alleni ("Vulnerable" and Petropedetes natator ("Near Threatened" as well as the "Critically Endangered" viviparous toad endemic to the montane grasslands of Mount Nimba (Nimbaphrynoides occidentalis.

Drivers for the emergence and re-emergence of vector-borne protozoal and bacterial diseases.

Science.gov (United States)

Harrus, S; Baneth, G

2005-10-01

In recent years, vector-borne parasitic and bacterial diseases have emerged or re-emerged in many geographical regions causing global health and economic problems that involve humans, livestock, companion animals and wild life. The ecology and epidemiology of vector-borne diseases are affected by the interrelations between three major factors comprising the pathogen, the host (human, animal or vector) and the environment. Important drivers for the emergence and spread of vector-borne parasites include habitat changes, alterations in water storage and irrigation habits, atmospheric and climate changes, immunosuppression by HIV, pollution, development of insecticide and drug resistance, globalization and the significant increase in international trade, tourism and travel. War and civil unrest, and governmental or global management failure are also major contributors to the spread of infectious diseases. The improvement of epidemic understanding and planning together with the development of new diagnostic molecular techniques in the last few decades have allowed researchers to better diagnose and trace pathogens, their origin and routes of infection, and to develop preventive public health and intervention programs. Health care workers, physicians, veterinarians and biosecurity officers should play a key role in future prevention of vector-borne diseases. A coordinated global approach for the prevention of vector-borne diseases should be implemented by international organizations and governmental agencies in collaboration with research institutions.

Contrasting introduction scenarios among continents in the worldwide invasion of the banana fungal pathogen Mycosphaerella fijiensis.

Science.gov (United States)

Robert, S; Ravigne, V; Zapater, M-F; Abadie, C; Carlier, J

2012-03-01

Reconstructing and characterizing introduction routes is a key step towards understanding the ecological and evolutionary factors underlying successful invasions and disease emergence. Here, we aimed to decipher scenarios of introduction and stochastic demographic events associated with the global spread of an emerging disease of bananas caused by the destructive fungal pathogen Mycosphaerella fijiensis. We analysed the worldwide population structure of this fungus using 21 microsatellites and 8 sequence-based markers on 735 individuals from 37 countries. Our analyses designated South-East Asia as the source of the global invasion and supported the location of the centre of origin of M. fijiensis within this area. We confirmed the occurrence of bottlenecks upon introduction into other continents followed by widespread founder events within continents. Furthermore, this study suggested contrasting introduction scenarios of the pathogen between the African and American continents. While potential signatures of admixture resulting from multiple introductions were detected in America, all the African samples examined seem to descend from a single successful founder event. In combination with historical information, our study reveals an original and unprecedented global scenario of invasion for this recently emerging disease caused by a wind-dispersed pathogen. © 2012 Blackwell Publishing Ltd.

75 FR 27237 - Regulatory Flexibility Act Review of the Bloodborne Pathogens Standard

Science.gov (United States)

2010-05-14

... shown that occupational exposure to bloodborne pathogens constituted a significant risk and that the... infectious substances on them) is prohibited; Employers must make HBV vaccinations available to employees... needlestick prevention; Effectiveness of needlestick prevention programs; New, emerging health risks from...

Lactococcus garvieae: where is it from? A first approach to explore the evolutionary history of this emerging pathogen.

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Chiara Ferrario

Full Text Available The population structure and diversity of Lactococcus garvieae, an emerging pathogen of increasing clinical significance, was determined at both gene and genome level. Selected lactococcal isolates of various origins were analyzed by a multi locus sequence typing (MLST. This gene-based analysis was compared to genomic characteristics, estimated through the complete genome sequences available in database. The MLST identified two branches containing the majority of the strains and two branches bearing one strain each. One strain was particularly differentiated from the other L. garvieae strains, showing a significant genetic distance. The genomic characteristics, correlated to the MLST-based phylogeny, indicated that this "separated strain" appeared first and could be considered the evolutionary intermediate between Lactococcus lactis and L. garvieae main clusters. A preliminary genome analysis of L. garvieae indicated a pan-genome constituted of about 4100 genes, which included 1341 core genes and 2760 genes belonging to the dispensable genome. A total of 1491 Clusters of Orthologous Genes (COGs were found to be specific to the 11 L. garvieae genomes, with the genome of the "separated strain" showing the highest presence of unique genes.

Methicillin-resistente Staphylococcus aureus (MRSA) in der Veterinärmedizin : ein "New Emerging Pathogen"?

NARCIS (Netherlands)

Walther, Birgit; Friedrich, Alexander W; Brunnberg, Leo; Wieler, Lothar H; Lübke-Becker, Antina

2006-01-01

The problem of nosocomial infections is of increasing importance in veterinary medicine. As an example, this review summarizes current knowledge regarding methicillin-resistant Staphylococcus aureus (MRSA) as a typical example, as these pathogens are the most important agents of nosocomial

Emerging infectious diseases of plants: pathogen pollution, climate change and agrotechnology drivers.

Science.gov (United States)

Anderson, Pamela K; Cunningham, Andrew A; Patel, Nikkita G; Morales, Francisco J; Epstein, Paul R; Daszak, Peter

2004-10-01

Emerging infectious diseases (EIDs) pose threats to conservation and public health. Here, we apply the definition of EIDs used in the medical and veterinary fields to botany and highlight a series of emerging plant diseases. We include EIDs of cultivated and wild plants, some of which are of significant conservation concern. The underlying cause of most plant EIDs is the anthropogenic introduction of parasites, although severe weather events are also important drivers of disease emergence. Much is known about crop plant EIDs, but there is little information about wild-plant EIDs, suggesting that their impact on conservation is underestimated. We conclude with recommendations for improving strategies for the surveillance and control of plant EIDs.

Timing of pathogen adaptation to a multicomponent treatment.

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Romain Bourget

Full Text Available The sustainable use of multicomponent treatments such as combination therapies, combination vaccines/chemicals, and plants carrying multigenic resistance requires an understanding of how their population-wide deployment affects the speed of the pathogen adaptation. Here, we develop a stochastic model describing the emergence of a mutant pathogen and its dynamics in a heterogeneous host population split into various types by the management strategy. Based on a multi-type Markov birth and death process, the model can be used to provide a basic understanding of how the life-cycle parameters of the pathogen population, and the controllable parameters of a management strategy affect the speed at which a pathogen adapts to a multicomponent treatment. Our results reveal the importance of coupling stochastic mutation and migration processes, and illustrate how their stochasticity can alter our view of the principles of managing pathogen adaptive dynamics at the population level. In particular, we identify the growth and migration rates that allow pathogens to adapt to a multicomponent treatment even if it is deployed on only small proportions of the host. In contrast to the accepted view, our model suggests that treatment durability should not systematically be identified with mutation cost. We show also that associating a multicomponent treatment with defeated monocomponent treatments can be more durable than associating it with intermediate treatments including only some of the components. We conclude that the explicit modelling of stochastic processes underlying evolutionary dynamics could help to elucidate the principles of the sustainable use of multicomponent treatments in population-wide management strategies intended to impede the evolution of harmful populations.

Two pathogenic species of Pythium: P. aphanidermatum and P. diclinum from a wheat field

OpenAIRE

Al-Sheikh, Hashem

2010-01-01

During a survey of pathogenic and non-pathogenic Pythium spp. in different localities in Egypt, several isolates of Pythia were obtained and maintained on corn meal agar. Among these isolates, Pythium aphanidermatum and Pythium diclinum were obtained from rhizosphere of wheat plants grown in Dear Attia village, Minia, Egypt. Identification was made using morphological and molecular analyses. P. aphanidermatum and P. diclinum were able to cause reductions in emergence and adulating in wheat in...

Comparative proteomic analysis of pathogenic and non-pathogenic strains from the swine pathogen Mycoplasma hyopneumoniae

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Klein Cátia S

2009-12-01

Full Text Available Abstract Background Mycoplasma hyopneumoniae is a highly infectious swine pathogen and is the causative agent of enzootic pneumonia (EP. Following the previous report of a proteomic survey of the pathogenic 7448 strain of swine pathogen, Mycoplasma hyopneumoniae, we performed comparative protein profiling of three M. hyopneumoniae strains, namely the non-pathogenic J strain and the two pathogenic strains 7448 and 7422. Results In 2DE comparisons, we were able to identify differences in expression levels for 67 proteins, including the overexpression of some cytoadherence-related proteins only in the pathogenic strains. 2DE immunoblot analyses allowed the identification of differential proteolytic cleavage patterns of the P97 adhesin in the three strains. For more comprehensive protein profiling, an LC-MS/MS strategy was used. Overall, 35% of the M. hyopneumoniae genome coding capacity was covered. Partially overlapping profiles of identified proteins were observed in the strains with 81 proteins identified only in one strain and 54 proteins identified in two strains. Abundance analysis of proteins detected in more than one strain demonstrates the relative overexpression of 64 proteins, including the P97 adhesin in the pathogenic strains. Conclusions Our results indicate the physiological differences between the non-pathogenic strain, with its non-infective proliferate lifestyle, and the pathogenic strains, with its constitutive expression of adhesins, which would render the bacterium competent for adhesion and infection prior to host contact.

Globally emerging hantaviruses: An overview

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Sara Chandy

2017-01-01

Full Text Available Hantaviruses are known to cause haemorrhagic fever with renal syndrome in Eurasia and hantavirus cardiopulmonary syndrome in the Americas. They are globally emerging pathogens as newer serotypes are routinely being reported. This review discusses hantavirus biology, clinical features and pathogenesis of hantavirus disease, its diagnostics, distribution and mammalian hosts. Hantavirus research in India is also summarised.

High levels of genetic and genotypic diversity in field populations of the barley pathogen Ramularia collo-cygni

DEFF Research Database (Denmark)

Hjortshøj, Rasmus Lund; Ravnshøj, A.R.; Nyman, M.

2013-01-01

The ascomycete pathogen Ramularia collo-cygni causes Ramularia leaf spot (RLS) on barley. Although R. collo-cygni is considerd an emerging disease of barley, little is known about genetic diversity or population genetic structure of this pathogen. We applied a set of polymorphic AFLP (Amplified F...

The community ecology of pathogens: coinfection, coexistence and community composition.

Science.gov (United States)

Seabloom, Eric W; Borer, Elizabeth T; Gross, Kevin; Kendig, Amy E; Lacroix, Christelle; Mitchell, Charles E; Mordecai, Erin A; Power, Alison G

2015-04-01

Disease and community ecology share conceptual and theoretical lineages, and there has been a resurgence of interest in strengthening links between these fields. Building on recent syntheses focused on the effects of host community composition on single pathogen systems, we examine pathogen (microparasite) communities using a stochastic metacommunity model as a starting point to bridge community and disease ecology perspectives. Such models incorporate the effects of core community processes, such as ecological drift, selection and dispersal, but have not been extended to incorporate host-pathogen interactions, such as immunosuppression or synergistic mortality, that are central to disease ecology. We use a two-pathogen susceptible-infected (SI) model to fill these gaps in the metacommunity approach; however, SI models can be intractable for examining species-diverse, spatially structured systems. By placing disease into a framework developed for community ecology, our synthesis highlights areas ripe for progress, including a theoretical framework that incorporates host dynamics, spatial structuring and evolutionary processes, as well as the data needed to test the predictions of such a model. Our synthesis points the way for this framework and demonstrates that a deeper understanding of pathogen community dynamics will emerge from approaches working at the interface of disease and community ecology. © 2015 John Wiley & Sons Ltd/CNRS.

Amphibian decline and extinction: what we know and what we need to learn.

Science.gov (United States)

Collins, James P

2010-11-01

For over 350 million yr, thousands of amphibian species have lived on Earth. Since the 1980s, amphibians have been disappearing at an alarming rate, in many cases quite suddenly. What is causing these declines and extinctions? In the modern era (post 1500) there are 6 leading causes of biodiversity loss in general, and all of these acting alone or together are responsible for modern amphibian declines: commercial use; introduced/exotic species that compete with, prey on, and parasitize native frogs and salamanders; land use change; contaminants; climate change; and infectious disease. The first 3 causes are historical in the sense that they have been operating for hundreds of years, although the rate of change due to each accelerated greatly after about the mid-20th century. Contaminants, climate change, and emerging infectious diseases are modern causes suspected of being responsible for the so-called 'enigmatic decline' of amphibians in protected areas. Introduced/exotic pathogens, land use change, and infectious disease are the 3 causes with a clear role in amphibian decline as well as extinction; thus far, the other 3 causes are only implicated in decline and not extinction. The present work is a review of the 6 causes with a focus on pathogens and suggested areas where new research is needed. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that is an emerging infectious disease causing amphibian population decline and species extinction. Historically, pathogens have not been seen as a major cause of extinction, but Bd is an exception, which is why it is such an interesting, important pathogen to understand. The late 20th and early 21st century global biodiversity loss is characterized as a sixth extinction event. Amphibians are a striking example of these losses as they disappear at a rate that greatly exceeds historical levels. Consequently, modern amphibian decline and extinction is a lens through which we can view the larger story of biodiversity

Diversity and role of cave-dwelling hematophagous insects in pathogen transmission in the Afrotropical region.

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Obame-Nkoghe, Judicaël; Leroy, Eric-Maurice; Paupy, Christophe

2017-04-12

The progressive anthropization of caves for food resources or economic purposes increases human exposure to pathogens that naturally infect cave-dwelling animals. The presence of wild or domestic animals in the immediate surroundings of caves also may contribute to increasing the risk of emergence of such pathogens. Some zoonotic pathogens are transmitted through direct contact, but many others require arthropod vectors, such as blood-feeding insects. In Africa, hematophagous insects often play a key role in the epidemiology of many pathogens; however, their ecology in cave habitats remains poorly known. During the last decades, several investigations carried out in Afrotropical caves suggested the medical and veterinary importance particularly of insect taxa of the Diptera order. Therefore, the role of some of these insects as vectors of pathogens that infect cave-dwelling vertebrates has been studied. The present review summarizes these findings, brings insights into the diversity of cave-dwelling hematophagous Diptera and their involvement in pathogen transmission, and finally discusses new challenges and future research directions.

Horizontal Gene Acquisitions, Mobile Element Proliferation, and Genome Decay in the Host-Restricted Plant Pathogen Erwinia Tracheiphila

Science.gov (United States)

Shapiro, Lori R.; Scully, Erin D.; Straub, Timothy J.; Park, Jihye; Stephenson, Andrew G.; Beattie, Gwyn A.; Gleason, Mark L.; Kolter, Roberto; Coelho, Miguel C.; De Moraes, Consuelo M.; Mescher, Mark C.; Zhaxybayeva, Olga

2016-01-01

Modern industrial agriculture depends on high-density cultivation of genetically similar crop plants, creating favorable conditions for the emergence of novel pathogens with increased fitness in managed compared with ecologically intact settings. Here, we present the genome sequence of six strains of the cucurbit bacterial wilt pathogen Erwinia tracheiphila (Enterobacteriaceae) isolated from infected squash plants in New York, Pennsylvania, Kentucky, and Michigan. These genomes exhibit a high proportion of recent horizontal gene acquisitions, invasion and remarkable amplification of mobile genetic elements, and pseudogenization of approximately 20% of the coding sequences. These genome attributes indicate that E. tracheiphila recently emerged as a host-restricted pathogen. Furthermore, chromosomal rearrangements associated with phage and transposable element proliferation contribute to substantial differences in gene content and genetic architecture between the six E. tracheiphila strains and other Erwinia species. Together, these data lead us to hypothesize that E. tracheiphila has undergone recent evolution through both genome decay (pseudogenization) and genome expansion (horizontal gene transfer and mobile element amplification). Despite evidence of dramatic genomic changes, the six strains are genetically monomorphic, suggesting a recent population bottleneck and emergence into E. tracheiphila’s current ecological niche. PMID:26992913

Has the time come for big science in wildlife health?

Science.gov (United States)

Sleeman, Jonathan M.

2013-01-01

The consequences of wildlife emerging diseases are global and profound with increased burden on the public health system, negative impacts on the global economy, declines and extinctions of wildlife species, and subsequent loss of ecological integrity. Examples of health threats to wildlife include Batrachochytrium dendrobatidis, which causes a cutaneous fungal infection of amphibians and is linked to declines of amphibians globally; and the recently discovered Pseudogymnoascus (Geomyces) destructans, the etiologic agent of white nose syndrome which has caused precipitous declines of North American bat species. Of particular concern are the novel pathogens that have emerged as they are particularly devastating and challenging to manage. A big science approach to wildlife health research is needed if we are to make significant and enduring progress in managing these diseases. The advent of new analytical models and bench assays will provide us with the mathematical and molecular tools to identify and anticipate threats to wildlife, and understand the ecology and epidemiology of these diseases. Specifically, new molecular diagnostic techniques have opened up avenues for pathogen discovery, and the application of spatially referenced databases allows for risk assessments that can assist in targeting surveillance. Long-term, systematic collection of data for wildlife health and integration with other datasets is also essential. Multidisciplinary research programs should be expanded to increase our understanding of the drivers of emerging diseases and allow for the development of better disease prevention and management tools, such as vaccines. Finally, we need to create a National Fish and Wildlife Health Network that provides the operational framework (governance, policies, procedures, etc.) by which entities with a stake in wildlife health cooperate and collaborate to achieve optimal outcomes for human, animal, and ecosystem health.

Cell wall modifications during conidial maturation of the human pathogenic fungus Pseudallescheria boydii

NARCIS (Netherlands)

Ghamrawi, Sarah; Rénier, Gilles; Saulnier, Patrick; Cuenot, Stéphane; Zykwinska, Agata; Dutilh, Bas E; Thornton, Christopher; Faure, Sébastien; Bouchara, Jean-Philippe

Progress in extending the life expectancy of cystic fibrosis (CF) patients remains jeopardized by the increasing incidence of fungal respiratory infections. Pseudallescheria boydii (P. boydii), an emerging pathogen of humans, is a filamentous fungus frequently isolated from the respiratory

Cell Wall Modifications during Conidial Maturation of the Human Pathogenic Fungus Pseudallescheria boydii

NARCIS (Netherlands)

Ghamrawi, S.; Renier, G.; Saulnier, P.; Cuenot, S.; Zykwinska, A.; Dutilh, B.E.; Thornton, C.; Faure, S.; Bouchara, J.P.

2014-01-01

Progress in extending the life expectancy of cystic fibrosis (CF) patients remains jeopardized by the increasing incidence of fungal respiratory infections. Pseudallescheria boydii (P. boydii), an emerging pathogen of humans, is a filamentous fungus frequently isolated from the respiratory

Evolutionary history of the plant pathogenic bacterium Xanthomonas axonopodis.

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Nadia Mhedbi-Hajri

Full Text Available Deciphering mechanisms shaping bacterial diversity should help to build tools to predict the emergence of infectious diseases. Xanthomonads are plant pathogenic bacteria found worldwide. Xanthomonas axonopodis is a genetically heterogeneous species clustering, into six groups, strains that are collectively pathogenic on a large number of plants. However, each strain displays a narrow host range. We address the question of the nature of the evolutionary processes--geographical and ecological speciation--that shaped this diversity. We assembled a large collection of X. axonopodis strains that were isolated over a long period, over continents, and from various hosts. Based on the sequence analysis of seven housekeeping genes, we found that recombination occurred as frequently as point mutation in the evolutionary history of X. axonopodis. However, the impact of recombination was about three times greater than the impact of mutation on the diversity observed in the whole dataset. We then reconstructed the clonal genealogy of the strains using coalescent and genealogy approaches and we studied the diversification of the pathogen using a model of divergence with migration. The suggested scenario involves a first step of generalist diversification that spanned over the last 25,000 years. A second step of ecology-driven specialization occurred during the past two centuries. Eventually, secondary contacts between host-specialized strains probably occurred as a result of agricultural development and intensification, allowing genetic exchanges of virulence-associated genes. These transfers may have favored the emergence of novel pathotypes. Finally, we argue that the largest ecological entity within X. axonopodis is the pathovar.

Landscape of emerging and re-emerging infectious diseases in China: impact of ecology, climate, and behavior.

Science.gov (United States)

Liu, Qiyong; Xu, Wenbo; Lu, Shan; Jiang, Jiafu; Zhou, Jieping; Shao, Zhujun; Liu, Xiaobo; Xu, Lei; Xiong, Yanwen; Zheng, Han; Jin, Sun; Jiang, Hai; Cao, Wuchun; Xu, Jianguo

2018-02-01

For the past several decades, the infectious disease profile in China has been shifting with rapid developments in social and economic aspects, environment, quality of food, water, housing, and public health infrastructure. Notably, 5 notifiable infectious diseases have been almost eradicated, and the incidence of 18 additional notifiable infectious diseases has been significantly reduced. Unexpectedly, the incidence of over 10 notifiable infectious diseases, including HIV, brucellosis, syphilis, and dengue fever, has been increasing. Nevertheless, frequent infectious disease outbreaks/events have been reported almost every year, and imported infectious diseases have increased since 2015. New pathogens and over 100 new genotypes or serotypes of known pathogens have been identified. Some infectious diseases seem to be exacerbated by various factors, including rapid urbanization, large numbers of migrant workers, changes in climate, ecology, and policies, such as returning farmland to forests. This review summarizes the current experiences and lessons from China in managing emerging and re-emerging infectious diseases, especially the effects of ecology, climate, and behavior, which should have merits in helping other countries to control and prevent infectious diseases.

Riding the wave: reconciling the roles of disease and climate change in amphibian declines.

Directory of Open Access Journals (Sweden)

Karen R Lips

2008-03-01

Full Text Available We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd, and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.

Riding the wave: reconciling the roles of disease and climate change in amphibian declines.

Science.gov (United States)

Lips, Karen R; Diffendorfer, Jay; Mendelson, Joseph R; Sears, Michael W

2008-03-25

We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd), and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.

Early emergence of Yersinia pestis as a severe respiratory pathogen.

Science.gov (United States)

Zimbler, Daniel L; Schroeder, Jay A; Eddy, Justin L; Lathem, Wyndham W

2015-06-30

Yersinia pestis causes the fatal respiratory disease pneumonic plague. Y. pestis recently evolved from the gastrointestinal pathogen Y. pseudotuberculosis; however, it is not known at what point Y. pestis gained the ability to induce a fulminant pneumonia. Here we show that the acquisition of a single gene encoding the protease Pla was sufficient for the most ancestral, deeply rooted strains of Y. pestis to cause pneumonic plague, indicating that Y. pestis was primed to infect the lungs at a very early stage in its evolution. As Y. pestis further evolved, modern strains acquired a single amino-acid modification within Pla that optimizes protease activity. While this modification is unnecessary to cause pneumonic plague, the substitution is instead needed to efficiently induce the invasive infection associated with bubonic plague. These findings indicate that Y. pestis was capable of causing pneumonic plague before it evolved to optimally cause invasive infections in mammals.

An emerging avian influenza A virus H5N7 is a genetic reassortant of highly pathogenic genes

DEFF Research Database (Denmark)

Bragstad, K.; Jørgensen, Poul Henrik; Handberg, Kurt

2006-01-01

We full genome characterised the newly discovered avian influenza virus H5N7 subtype combination isolated from a stock of Danish game ducks to investigate the composition of the genome and possible features of high pathogenicity. It was found that the haemagglutinin and the acidic polymerase gene...... low pathogenic avian influenza A viruses. (c) 2006 Elsevier Ltd. All rights reserved....

Shiga toxin-converting phages and the emergence of new pathogenic Escherichia coli: a world in motion

Science.gov (United States)

Tozzoli, Rosangela; Grande, Laura; Michelacci, Valeria; Ranieri, Paola; Maugliani, Antonella; Caprioli, Alfredo; Morabito, Stefano

2014-01-01

Shiga toxin (Stx)-producing Escherichia coli (STEC) are pathogenic E. coli causing diarrhea, hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). STEC are characterized by a constellation of virulence factors additional to Stx and have long been regarded as capable to cause HC and HUS when possessing the ability of inducing the attaching and effacing (A/E) lesion to the enterocyte, although strains isolated from such severe infections sometimes lack this virulence feature. Interestingly, the capability to cause the A/E lesion is shared with another E. coli pathogroup, the Enteropathogenic E. coli (EPEC). In the very recent times, a different type of STEC broke the scene causing a shift in the paradigm for HUS-associated STEC. In 2011, a STEC O104:H4 caused a large outbreak with more than 800 HUS and 50 deaths. Such a strain presented the adhesion determinants of Enteroaggregative E. coli (EAggEC). We investigated the possibility that, besides STEC and EAggEC, other pathogenic E. coli could be susceptible to infection with stx-phages. A panel of stx2-phages obtained from STEC isolated from human disease was used to infect experimentally E. coli strains representing all the known pathogenic types, including both diarrheagenic E. coli (DEC) and extra-intestinal pathogenic E. coli (ExPEC). We observed that all the E. coli pathogroups used in the infection experiments were susceptible to the infection. Our results suggest that the stx2-phages used may not have specificity for E. coli adapted to the intestinal environment, at least in the conditions used. Additionally, we could only observe transient lysogens suggesting that the event of stable stx2-phage acquisition occurs rarely. PMID:24999453

Resveratrol—Potential Antibacterial Agent against Foodborne Pathogens

Science.gov (United States)

Ma, Dexter S. L.; Tan, Loh Teng-Hern; Chan, Kok-Gan; Yap, Wei Hsum; Pusparajah, Priyia; Chuah, Lay-Hong; Ming, Long Chiau; Khan, Tahir Mehmood; Lee, Learn-Han; Goh, Bey-Hing

2018-01-01

Bacterial foodborne pathogens are a significant health burden and the recent emergence of pathogenic resistant strains due to the excessive use of antibiotics makes it more difficult to effectively treat infections as a result of contaminated food. Awareness of this impending health crisis has spurred the search for alternative antimicrobials with natural plant antimicrobials being among the more promising candidates as these substances have good acceptability and likely low toxicity levels as they have long been used in traditional medicines. Resveratrol (3,5,4′-trihydroxystilbene) is a naturally occurring stilbenoid which has been gaining considerable attention in medical field due to its diverse biological activities - it has been reported to exhibit antioxidant, cardioprotective, anti-diabetic, anticancer, and antiaging properties. Given that resveratrol is phytoalexin, with increased synthesis in response to infection by phytopathogens, there has been interest in exploring its antimicrobial activity. This review aims to provide an overview of the published data on the antibacterial activity of resveratrol against foodborne pathogens, its mechanisms of action as well as its possible applications in food packing and processing; in addition we also summarize the current data on its potential synergism with known antibacterials and future research and applications. PMID:29515440

Resveratrol—Potential Antibacterial Agent against Foodborne Pathogens

Directory of Open Access Journals (Sweden)

Dexter S. L. Ma

2018-02-01

Full Text Available Bacterial foodborne pathogens are a significant health burden and the recent emergence of pathogenic resistant strains due to the excessive use of antibiotics makes it more difficult to effectively treat infections as a result of contaminated food. Awareness of this impending health crisis has spurred the search for alternative antimicrobials with natural plant antimicrobials being among the more promising candidates as these substances have good acceptability and likely low toxicity levels as they have long been used in traditional medicines. Resveratrol (3,5,4′-trihydroxystilbene is a naturally occurring stilbenoid which has been gaining considerable attention in medical field due to its diverse biological activities - it has been reported to exhibit antioxidant, cardioprotective, anti-diabetic, anticancer, and antiaging properties. Given that resveratrol is phytoalexin, with increased synthesis in response to infection by phytopathogens, there has been interest in exploring its antimicrobial activity. This review aims to provide an overview of the published data on the antibacterial activity of resveratrol against foodborne pathogens, its mechanisms of action as well as its possible applications in food packing and processing; in addition we also summarize the current data on its potential synergism with known antibacterials and future research and applications.

Human pathogenic bacteria, fungi, and viruses in Drosophila

Science.gov (United States)

Panayidou, Stavria; Ioannidou, Eleni; Apidianakis, Yiorgos

2014-01-01

Drosophila has been the invertebrate model organism of choice for the study of innate immune responses during the past few decades. Many Drosophila–microbe interaction studies have helped to define innate immunity pathways, and significant effort has been made lately to decipher mechanisms of microbial pathogenesis. Here we catalog 68 bacterial, fungal, and viral species studied in flies, 43 of which are relevant to human health. We discuss studies of human pathogens in flies revealing not only the elicitation and avoidance of immune response but also mechanisms of tolerance, host tissue homeostasis, regeneration, and predisposition to cancer. Prominent among those is the emerging pattern of intestinal regeneration as a defense response induced by pathogenic and innocuous bacteria. Immunopathology mechanisms and many microbial virulence factors have been elucidated, but their relevance to human health conventionally necessitates validation in mammalian models of infection. PMID:24398387

Frontiers for research on the ecology of plant-pathogenic bacteria: fundamentals for sustainability: Challenges in Bacterial Molecular Plant Pathology.

Science.gov (United States)

Morris, Cindy E; Barny, Marie-Anne; Berge, Odile; Kinkel, Linda L; Lacroix, Christelle

2017-02-01

Methods to ensure the health of crops owe their efficacy to the extent to which we understand the ecology and biology of environmental microorganisms and the conditions under which their interactions with plants lead to losses in crop quality or yield. However, in the pursuit of this knowledge, notions of the ecology of plant-pathogenic microorganisms have been reduced to a plant-centric and agro-centric focus. With increasing global change, i.e. changes that encompass not only climate, but also biodiversity, the geographical distribution of biomes, human demographic and socio-economic adaptations and land use, new plant health problems will emerge via a range of processes influenced by these changes. Hence, knowledge of the ecology of plant pathogens will play an increasingly important role in the anticipation and response to disease emergence. Here, we present our opinion on the major challenges facing the study of the ecology of plant-pathogenic bacteria. We argue that the discovery of markedly novel insights into the ecology of plant-pathogenic bacteria is most likely to happen within a framework of more extensive scales of space, time and biotic interactions than those that currently guide much of the research on these bacteria. This will set a context that is more propitious for the discovery of unsuspected drivers of the survival and diversification of plant-pathogenic bacteria and of the factors most critical for disease emergence, and will set the foundation for new approaches to the sustainable management of plant health. We describe the contextual background of, justification for and specific research questions with regard to the following challenges: Development of terminology to describe plant-bacterial relationships in terms of bacterial fitness. Definition of the full scope of the environments in which plant-pathogenic bacteria reside or survive. Delineation of pertinent phylogenetic contours of plant-pathogenic bacteria and naming of strains

Molecular pathogenesis of H5 highly pathogenic avian influenza: the role of the haemagglutinin cleavage site motif

Science.gov (United States)

Luczo, Jasmina M.; Stambas, John; Durr, Peter A.; Michalski, Wojtek P.

2015-01-01

Summary The emergence of H5N1 highly pathogenic avian influenza has caused a heavy socio‐economic burden through culling of poultry to minimise human and livestock infection. Although human infections with H5N1 have to date been limited, concerns for the pandemic potential of this zoonotic virus have been greatly intensified following experimental evidence of aerosol transmission of H5N1 viruses in a mammalian infection model. In this review, we discuss the dominance of the haemagglutinin cleavage site motif as a pathogenicity determinant, the host‐pathogen molecular interactions driving cleavage activation, reverse genetics manipulations and identification of residues key to haemagglutinin cleavage site functionality and the mechanisms of cell and tissue damage during H5N1 infection. We specifically focus on the disease in chickens, as it is in this species that high pathogenicity frequently evolves and from which transmission to the human population occurs. With >75% of emerging infectious diseases being of zoonotic origin, it is necessary to understand pathogenesis in the primary host to explain spillover events into the human population. © 2015 The Authors. Reviews in Medical Virology published by John Wiley & Sons Ltd. PMID:26467906

Bacterial food-borne pathogens in Indian food

International Nuclear Information System (INIS)

Bandekar, J.R.

2015-01-01

Food technology and food processing techniques have made tremendous advances in preservation of food and ensuring safety of food by killing food-borne pathogens. In addition to old techniques such as pasteurization, canning, dehydration, fermentation and salting, a number of new techniques such as radiation processing, high pressure technology and pulsed electric field technology are being applied for preservation of food and to ensure food safety. Total Quality Management (TQM) concepts have been developed to take care of food safety from farm to table. Hazard Analysis at Critical Control Points (HACCP) is being applied for mass scale production of food to make food free from pathogens. Despite these advances, food-borne diseases have become one of the most widespread public health problems in the world. About two thirds of all the outbreaks are traced to microbial contaminated food. According to World Health Organization (WHO) estimates, food-borne and waterborne diarrhoeal diseases kill an estimated 2 million people annually, including many children. Food safety is a major concern not only for developing countries but also for the developed countries. A number of factors such as emergence of new food-borne pathogens, development of drug resistance in pathogens, changing life style, globalization of the food supply etc. are responsible for the continuous persistence of food-borne diseases. The food-borne disease outbreaks due to E. coli O157:H7, Listeria monocytogenes, Salmonella and Campylobacter, are responsible for recall of many foods resulting in heavy losses to food industry. Due to consumer demand, a number of Ready-To-Eat (RTE) minimally processed foods are increasingly marketed; however, there is increased risk of foodborne diseases with these products. Food Technology Division of Bhabha Atomic Research Centre, Mumbai, has been working on food-borne bacterial pathogens particularly Salmonella, Campylobacter, Listeria monocytogenes, Vibrio and Aeromonasf

Pelvic inflammatory disease: diagnosis and treatment in the emergency department [digest].

Science.gov (United States)

Bugg, Charles Walter; Taira, Taku; Zaurova, Milana

2016-12-22

Pelvic inflammatory disease is a common disease that is associated with significant complications including infertility, chronic pelvic pain, ruptured tubo-ovarian abscess, and ectopic pregnancy. The diagnosis may be delayed when the presentation has nonspecific signs and symptoms. Even when it is properly identified, pelvic inflammatory disease is often treated suboptimally. This review provides evidence-based recommendations for the diagnosis, treatment, disposition, and follow-up of patients with pelvic inflammatory disease. Arranging follow-up of patients within 48 to 72 hours and providing clear patient education are fundamental to ensuring good patient outcomes. Emerging issues, including new pathogens and evolving resistance patterns among pelvic inflammatory disease pathogens are reviewed. [Points & Pearls is a digest of Emergency Medicine Practice].

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira.

Science.gov (United States)

Fouts, Derrick E; Matthias, Michael A; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L; Haake, David A; Haft, Daniel H; Hartskeerl, Rudy; Ko, Albert I; Levett, Paul N; Matsunaga, James; Mechaly, Ariel E; Monk, Jonathan M; Nascimento, Ana L T; Nelson, Karen E; Palsson, Bernhard; Peacock, Sharon J; Picardeau, Mathieu; Ricaldi, Jessica N; Thaipandungpanit, Janjira; Wunder, Elsio A; Yang, X Frank; Zhang, Jun-Jie; Vinetz, Joseph M

2016-02-01

Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade's refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira.

Directory of Open Access Journals (Sweden)

Derrick E Fouts

2016-02-01

Full Text Available Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1 the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2 genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12 autotrophy as a bacterial virulence factor; 3 CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade's refractoriness to gene targeting; 4 finding Leptospira pathogen-specific specialized protein secretion systems; 5 novel virulence-related genes/gene families such as the Virulence Modifying (VM (PF07598 paralogs proteins and pathogen-specific adhesins; 6 discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7 and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately

Major emerging vector-borne zoonotic diseases of public health importance in Canada.

Science.gov (United States)

Kulkarni, Manisha A; Berrang-Ford, Lea; Buck, Peter A; Drebot, Michael A; Lindsay, L Robbin; Ogden, Nicholas H

2015-06-10

In Canada, the emergence of vector-borne diseases may occur via international movement and subsequent establishment of vectors and pathogens, or via northward spread from endemic areas in the USA. Re-emergence of endemic vector-borne diseases may occur due to climate-driven changes to their geographic range and ecology. Lyme disease, West Nile virus (WNV), and other vector-borne diseases were identified as priority emerging non-enteric zoonoses in Canada in a prioritization exercise conducted by public health stakeholders in 2013. We review and present the state of knowledge on the public health importance of these high priority emerging vector-borne diseases in Canada. Lyme disease is emerging in Canada due to range expansion of the tick vector, which also signals concern for the emergence of human granulocytic anaplasmosis, babesiosis, and Powassan virus. WNV has been established in Canada since 2001, with epidemics of varying intensity in following years linked to climatic drivers. Eastern equine encephalitis virus, Jamestown Canyon virus, snowshoe hare virus, and Cache Valley virus are other mosquito-borne viruses endemic to Canada with the potential for human health impact. Increased surveillance for emerging pathogens and vectors and coordinated efforts among sectors and jurisdictions will aid in early detection and timely public health response.

Electrochemical Methodologies for the Detection of Pathogens.

Science.gov (United States)

Amiri, Mandana; Bezaatpour, Abolfazl; Jafari, Hamed; Boukherroub, Rabah; Szunerits, Sabine

2018-05-25

Bacterial infections remain one of the principal causes of morbidity and mortality worldwide. The number of deaths due to infections is declining every year by only 1% with a forecast of 13 million deaths in 2050. Among the 1400 recognized human pathogens, the majority of infectious diseases is caused by just a few, about 20 pathogens only. While the development of vaccinations and novel antibacterial drugs and treatments are at the forefront of research, and strongly financially supported by policy makers, another manner to limit and control infectious outbreaks is targeting the development and implementation of early warning systems, which indicate qualitatively and quantitatively the presence of a pathogen. As toxin contaminated food and drink are a potential threat to human health and consequently have a significant socioeconomic impact worldwide, the detection of pathogenic bacteria remains not only a big scientific challenge but also a practical problem of enormous significance. Numerous analytical methods, including conventional culturing and staining techniques as well as molecular methods based on polymerase chain reaction amplification and immunological assays, have emerged over the years and are used to identify and quantify pathogenic agents. While being highly sensitive in most cases, these approaches are highly time, labor, and cost consuming, requiring trained personnel to perform the frequently complex assays. A great challenge in this field is therefore to develop rapid, sensitive, specific, and if possible miniaturized devices to validate the presence of pathogens in cost and time efficient manners. Electrochemical sensors are well accepted powerful tools for the detection of disease-related biomarkers and environmental and organic hazards. They have also found widespread interest in the last years for the detection of waterborne and foodborne pathogens due to their label free character and high sensitivity. This Review is focused on the current

The microbial detection array for detection of emerging viruses in clinical samples--a useful panmicrobial diagnostic tool

DEFF Research Database (Denmark)

Rosenstierne, Maiken W; McLoughlin, Kevin S; Olesen, Majken Lindholm

2014-01-01

Emerging viruses are usually endemic to tropical and sub-tropical regions of the world, but increased global travel, climate change and changes in lifestyle are believed to contribute to the spread of these viruses into new regions. Many of these viruses cause similar disease symptoms as other...... emerging viruses or common infections, making these unexpected pathogens difficult to diagnose. Broad-spectrum pathogen detection microarrays containing probes for all sequenced viruses and bacteria can provide rapid identification of viruses, guiding decisions about treatment and appropriate case...... of emerging viruses present in both non-clinical and clinical samples using two different microarray data analysis methods....

Self-disseminating vaccines for emerging infectious diseases.

Science.gov (United States)

Murphy, Aisling A; Redwood, Alec J; Jarvis, Michael A

2016-01-01

Modern human activity fueled by economic development is profoundly altering our relationship with microorganisms. This altered interaction with microbes is believed to be the major driving force behind the increased rate of emerging infectious diseases from animals. The spate of recent infectious disease outbreaks, including Ebola virus disease and Middle East respiratory syndrome, emphasize the need for development of new innovative tools to manage these emerging diseases. Disseminating vaccines are one such novel approach to potentially interrupt animal to human (zoonotic) transmission of these pathogens.

Abundance and co-occurrence of extracellular capsules increase environmental breadth: Implications for the emergence of pathogens.

Science.gov (United States)

Rendueles, Olaya; Garcia-Garcerà, Marc; Néron, Bertrand; Touchon, Marie; Rocha, Eduardo P C

2017-07-01

Extracellular capsules constitute the outermost layer of many bacteria, are major virulence factors, and affect antimicrobial therapies. They have been used as epidemiological markers and recently became vaccination targets. Despite the efforts to biochemically serotype capsules in a few model pathogens, little is known of their taxonomic and environmental distribution. We developed, validated, and made available a computational tool, CapsuleFinder, to identify capsules in genomes. The analysis of over 2500 prokaryotic genomes, accessible in a database, revealed that ca. 50% of them-including Archaea-encode a capsule. The Wzx/Wzy-dependent capsular group was by far the most abundant. Surprisingly, a fifth of the genomes encode more than one capsule system-often from different groups-and their non-random co-occurrence suggests the existence of negative and positive epistatic interactions. To understand the role of multiple capsules, we queried more than 6700 metagenomes for the presence of species encoding capsules and showed that their distribution varied between environmental categories and, within the human microbiome, between body locations. Species encoding capsules, and especially those encoding multiple capsules, had larger environmental breadths than the other species. Accordingly, capsules were more frequent in environmental bacteria than in pathogens and, within the latter, they were more frequent among facultative pathogens. Nevertheless, capsules were frequent in clinical samples, and were usually associated with fast-growing bacteria with high infectious doses. Our results suggest that capsules increase the environmental range of bacteria and make them more resilient to environmental perturbations. Capsules might allow opportunistic pathogens to profit from empty ecological niches or environmental perturbations, such as those resulting from antibiotic therapy, to colonize the host. Capsule-associated virulence might thus be a by-product of environmental

Abundance and co-occurrence of extracellular capsules increase environmental breadth: Implications for the emergence of pathogens.

Directory of Open Access Journals (Sweden)

Olaya Rendueles

2017-07-01

Full Text Available Extracellular capsules constitute the outermost layer of many bacteria, are major virulence factors, and affect antimicrobial therapies. They have been used as epidemiological markers and recently became vaccination targets. Despite the efforts to biochemically serotype capsules in a few model pathogens, little is known of their taxonomic and environmental distribution. We developed, validated, and made available a computational tool, CapsuleFinder, to identify capsules in genomes. The analysis of over 2500 prokaryotic genomes, accessible in a database, revealed that ca. 50% of them-including Archaea-encode a capsule. The Wzx/Wzy-dependent capsular group was by far the most abundant. Surprisingly, a fifth of the genomes encode more than one capsule system-often from different groups-and their non-random co-occurrence suggests the existence of negative and positive epistatic interactions. To understand the role of multiple capsules, we queried more than 6700 metagenomes for the presence of species encoding capsules and showed that their distribution varied between environmental categories and, within the human microbiome, between body locations. Species encoding capsules, and especially those encoding multiple capsules, had larger environmental breadths than the other species. Accordingly, capsules were more frequent in environmental bacteria than in pathogens and, within the latter, they were more frequent among facultative pathogens. Nevertheless, capsules were frequent in clinical samples, and were usually associated with fast-growing bacteria with high infectious doses. Our results suggest that capsules increase the environmental range of bacteria and make them more resilient to environmental perturbations. Capsules might allow opportunistic pathogens to profit from empty ecological niches or environmental perturbations, such as those resulting from antibiotic therapy, to colonize the host. Capsule-associated virulence might thus be a by

Zoonotic pathogens in Atlantic Forest wild rodents in Brazil: Bartonella and Coxiella infections.

Science.gov (United States)

Rozental, Tatiana; Ferreira, Michelle Santos; Guterres, Alexandro; Mares-Guia, Maria Angélica; Teixeira, Bernardo R; Gonçalves, Jonathan; Bonvicino, Cibele Rodrigues; D'Andrea, Paulo Sergio; de Lemos, Elba Regina Sampaio

2017-04-01

Zoonotic pathogens comprise a significant and increasing fraction of all emerging and re-emerging infectious diseases that plague humans. Identifying host species is one of the keys to controlling emerging infectious diseases. From March 2007 until April 2012, we collected a total of 131 wild rodents in eight municipalities of Rio de Janeiro, Brazil. We investigated these rodents for infection with Coxiella burnetii, Bartonella spp. and Rickettsia spp. In total, 22.1% (29/131) of the rodents were infected by at least one pathogen; co-infection was detected in 1.5% (2/131) of rodents. Coxiella burnetii was detected in 4.6% (6/131) of the wild animals, 17.6% of the rodents harbored Bartonella spp. No cases of Rickettsia were identified. Bartonella doshiae and Bartonella vinsonii were the species found on the wild mammals. This report is the first to note C. burnetii, B. doshiae and B. vinsonii natural infections in Atlantic Forest wild rodents in Brazil. Our work highlights the potential risk of transmission to humans, since most of the infected specimens belong to generalist species that live near human dwellings. Copyright © 2017 Elsevier B.V. All rights reserved.

Photobacterium damselae subsp damselae, an emerging pathogen in Danish rainbow trout, Oncorhynchus mykiss (Walbaum), mariculture

DEFF Research Database (Denmark)

Pedersen, Karl; Skall, Helle Frank; Lassen-Nielsen, Anne Marie

2009-01-01

A selection of 16 field isolates of Photobacterium damselae from marine rainbow trout farms in Denmark was subjected to phenotypic and genotypic characterization and pathogenicity to fish. All isolates belonged to the subspecies damselae, being positive for haemolysis, motility and urease...

Diversity of aquatic Pseudomonas species and their activity against the fish pathogenic oomycete Saprolegnia

NARCIS (Netherlands)

Liu, Y.; Rzeszutek, E.; Voort, van der M.; Wu, C.H.; Thoen, E.; Skaar, I.; Bulone, V.; Dorrestein, P.C.; Raaijmakers, J.M.; Bruijn, de I.

2015-01-01

Emerging fungal and oomycete pathogens are increasingly threatening animals and plants globally. Amongst oomycetes, Saprolegnia species adversely affect wild and cultivated populations of amphibians and fish, leading to substantial reductions in biodiversity and food productivity. With the ban of

Combating Pathogenic Microorganisms Using Plant-Derived Antimicrobials: A Minireview of the Mechanistic Basis

Directory of Open Access Journals (Sweden)

Abhinav Upadhyay

2014-01-01

Full Text Available The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plant-derived antimicrobials (PDAs as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed.

Emergence of highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) in medium-scale swine farms in southeastern Cambodia.

Science.gov (United States)

Tornimbene, B; Frossard, J-P; Chhim, V; Sorn, S; Guitian, J; Drew, T W

2015-01-01

Since 2006, reports from China and Viet Nam have alerted of an emergent highly pathogenic variant of porcine reproductive and respiratory syndrome virus (HP-PRRSV) in that region. The frequent occurrence of outbreaks in these countries puts Cambodian pig farms at high risk of infection, but no study had been conducted to investigate the presence of HP-PRRS in Cambodian farms. We investigated the presence of HP-PRRS in medium-scale (semi-commercial) swine farms in the Cambodian southeastern region. Specifically, one province bordering Viet Nam (Takeo) was selected due to the concentration of most semi-commercial farms in that province. A cross-sectional study was carried out, between July and September 2010 to assess whether the prevalence of infection in these farms was indicative of recent spread of PPRSV and to identify risk factors for infection. The number of farms to be sampled was established using methods for Lot Quality Assurance Surveys (LQAS), in order to achieve a pre-established ability to discriminate between two different prevalence settings. The target population comprised all semi-commercial farms in Takeo province from which a random sample of 35 farms was selected. Selected farms were visited and questionnaires administered to gather information on farm characteristics and husbandry practices. Blood samples from individual pigs were collected in each of the study farms and tested for PRRSV, along with a number of other swine respiratory pathogens in order to investigate potential interactions. Our results showed that the virus was already present in Takeo semi-commercial pig population (LQAS herd prevalence ≥85%) at the time of sampling. The presence of sows in the farm and farm density were significantly associated (P<0.05) with the introduction and the presence of PRRS - but this was an unadjusted association as small sample size precluded multivariate analysis. Spatiotemporal description of the supposed pattern of infection revealed that the

Periodontal Pathogens and Atherosclerosis: Implications of Inflammation and Oxidative Modification of LDL

Directory of Open Access Journals (Sweden)

Tomoko Kurita-Ochiai

2014-01-01

Full Text Available Inflammation is well accepted to play a crucial role in the development of atherosclerotic lesions, and recent studies have demonstrated an association between periodontal disease and cardiovascular disease. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, causative agents of destructive chronic inflammation in the periodontium, can accelerate atheroma deposition in animal models. Emerging evidence suggests that vaccination against virulence factors of these pathogens and anti-inflammatory therapy may confer disease resistance. In this review, we focus on the role of inflammatory mechanisms and oxidative modification in the formation and activation of atherosclerotic plaques accelerated by P. gingivalis or A. actinomycetemcomitans in an ApoE-deficient mouse model and high-fat-diet-fed mice. Furthermore, we examine whether mucosal vaccination with a periodontal pathogen or the anti-inflammatory activity of catechins can reduce periodontal pathogen-accelerated atherosclerosis.

Host-Induced Gene Silencing of Rice Blast Fungus Magnaporthe oryzae Pathogenicity Genes Mediated by the Brome Mosaic Virus.

Science.gov (United States)

Zhu, Lin; Zhu, Jian; Liu, Zhixue; Wang, Zhengyi; Zhou, Cheng; Wang, Hong

2017-09-26

Magnaporthe oryzae is a devastating plant pathogen, which has a detrimental impact on rice production worldwide. Despite its agronomical importance, some newly-emerging pathotypes often overcome race-specific disease resistance rapidly. It is thus desirable to develop a novel strategy for the long-lasting resistance of rice plants to ever-changing fungal pathogens. Brome mosaic virus (BMV)-induced RNA interference (RNAi) has emerged as a useful tool to study host-resistance genes for rice blast protection. Planta-generated silencing of targeted genes inside biotrophic pathogens can be achieved by expression of M. oryzae -derived gene fragments in the BMV-mediated gene silencing system, a technique termed host-induced gene silencing (HIGS). In this study, the effectiveness of BMV-mediated HIGS in M. oryzae was examined by targeting three predicted pathogenicity genes, MoABC1, MoMAC1 and MoPMK1 . Systemic generation of fungal gene-specific small interfering RNA (siRNA) molecules induced by inoculation of BMV viral vectors inhibited disease development and reduced the transcription of targeted fungal genes after subsequent M. oryzae inoculation. Combined introduction of fungal gene sequences in sense and antisense orientation mediated by the BMV silencing vectors significantly enhanced the efficiency of this host-generated trans-specific RNAi, implying that these fungal genes played crucial roles in pathogenicity. Collectively, our results indicated that BMV-HIGS system was a great strategy for protecting host plants against the invasion of pathogenic fungi.

AMPK in Pathogens.

Science.gov (United States)

Mesquita, Inês; Moreira, Diana; Sampaio-Marques, Belém; Laforge, Mireille; Cordeiro-da-Silva, Anabela; Ludovico, Paula; Estaquier, Jérôme; Silvestre, Ricardo

2016-01-01

During host-pathogen interactions, a complex web of events is crucial for the outcome of infection. Pathogen recognition triggers powerful cellular signaling events that is translated into the induction and maintenance of innate and adaptive host immunity against infection. In opposition, pathogens employ active mechanisms to manipulate host cell regulatory pathways toward their proliferation and survival. Among these, subversion of host cell energy metabolism by pathogens is currently recognized to play an important role in microbial growth and persistence. Extensive studies have documented the role of AMP-activated protein kinase (AMPK) signaling, a central cellular hub involved in the regulation of energy homeostasis, in host-pathogen interactions. Here, we highlight the most recent advances detailing how pathogens hijack cellular metabolism by suppressing or increasing the activity of the host energy sensor AMPK. We also address the role of lower eukaryote AMPK orthologues in the adaptive process to the host microenvironment and their contribution for pathogen survival, differentiation, and growth. Finally, we review the effects of pharmacological or genetic AMPK modulation on pathogen growth and persistence.

Quorum sensing Inhibitors as anti-pathogenic drugs

DEFF Research Database (Denmark)

Rasmussen, Thomas Bovbjerg; Givskov, Michael Christian

2006-01-01

as well as elevated tolerance to the activity of the innate immune system. Gram-negative bacteria commonly use N-acyl homoserine lactones (AHL) as QS signal molecules. The use of signal molecule based drugs to attenuate bacterial pathogenecity rather than bacterial growth is attractive for several reasons......, particularly considering the emergence of increasingly antibiotic-resistant bacteria. Compounds capable of this type of interference have been termed anti-pathogenic drugs. A large variety of synthetic AHL analogues and natural products libraries have been screened and a number of QS inhibitors (QSI) have been...

Multidrug-resistant opportunistic pathogens challenging veterinary infection control.

Science.gov (United States)

Walther, Birgit; Tedin, Karsten; Lübke-Becker, Antina

2017-02-01

Although the problems associated with healthcare-associated infections (HAI) and the emergence of zoonotic and multidrug-resistant pathogens in companion animal (dogs, cats and horses) medicine have been well-known for decades, current progress with respect to practical implementation of infection control programs in veterinary clinics has been limited. Clinical outbreak events reported for methicillin-resistant Staphylooccus aureus (MRSA) and Staphylococcus pseudintermedius (MRSP), extended spectrum beta-lactamase (ESBL)-producing Escherichia coli and multidrug-resistant (MDR) Salmonella Serovars indicate the necessity of infection control strategies for protecting animal patients at risk as well as veterinary personnel. The close bond between humans and their companion animals provides opportunities for exchange of microorganisms, including MDR pathogens. This particular aspect of the "One Health" idea requires more representative surveillance efforts and infection control strategies with respect to animal-species specific characters. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

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Wen Shan Yew

2013-08-01

Full Text Available Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria.

Pathogen reduction of blood components.

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Solheim, Bjarte G

2008-08-01

Thanks to many blood safety interventions introduced in developed countries the risk of transfusion transmitted infections has become exceedingly small in these countries. However, emerging pathogens still represent a serious challenge, as demonstrated by West Nile virus in the US and more recently by Chikungunya virus in the Indian Ocean. In addition bacterial contamination, particularly in platelets, and protozoa transmitted by blood components still represent sizeable risks in developed countries. In developing countries the risk of all transfusion transmitted infections is still high due to insufficient funding and organisation of the health service. Pathogen reduction of pooled plasma products has virtually eliminated the risk of transfusion transmitted infections, without compromising the quality of the products significantly. Pathogen reduction of blood components has been much more challenging. Solvent detergent treatment which has been so successfully applied for plasma products dissolves cell membranes, and can, therefore, only be applied for plasma and not for cellular blood components. Targeting of nucleic acids has been another method for pathogen inactivation of plasma and the only approach possible for cellular blood products. As documented in more than 15 year's track record, solvent detergent treatment of pooled plasma can yield high quality plasma. The increased risk for contamination by unknown viruses due to pooling is out weighed by elimination of TRALI, significant reduction in allergic reactions and standardisation of the product. Recently, a promising method for solvent detergent treatment of single donor plasma units has been published. Methylene blue light treatment of single donor plasma units has a similar long track record as pooled solvent detergent treated plasma; but the method is less well documented and affects coagulation factor activity more. Psoralen light treated plasma has only recently been introduced (CE marked in Europe

Fight Fungi with Fungi: Antifungal Properties of the Amphibian Mycobiome

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Patrick J. Kearns

2017-12-01

Full Text Available Emerging infectious diseases caused by fungal taxa are increasing and are placing a substantial burden on economies and ecosystems worldwide. Of the emerging fungal diseases, chytridomycosis caused by the fungus Batrachochytrium dendrobatidis (hereafter Bd is linked to global amphibian declines. Amphibians have innate immunity, as well as additional resistance through cutaneous microbial communities. Despite the targeting of bacteria as potential probiotics, the role of fungi in the protection against Bd infection in unknown. We used a four-part approach, including high-throughput sequencing of bacterial and fungal communities, cultivation of fungi, Bd challenge assays, and experimental additions of probiotic to Midwife Toads (Altyes obstetricans, to examine the overlapping roles of bacterial and fungal microbiota in pathogen defense in captive bred poison arrow frogs (Dendrobates sp.. Our results revealed that cutaneous fungal taxa differed from environmental microbiota across three species and a subspecies of Dendrobates spp. frogs. Cultivation of host-associated and environmental fungi realved numerous taxa with the ability to inhibit or facilitate the growth of Bd. The abundance of cutaneous fungi contributed more to Bd defense (~45% of the fungal community, than did bacteria (~10% and frog species harbored distinct inhibitory communities that were distinct from the environment. Further, we demonstrated that a fungal probiotic therapy did not induce an endocrine-immune reaction, in contrast to bacterial probiotics that stressed amphibian hosts and suppressed antimicrobial peptide responses, limiting their long-term colonization potential. Our results suggest that probiotic strategies against amphibian fungal pathogens should, in addition to bacterial probiotics, focus on host-associated and environmental fungi such as Penicillium and members of the families Chaetomiaceae and Lasiosphaeriaceae.

Citrobacter rodentium is an unstable pathogen showing evidence of significant genomic flux.

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Nicola K Petty

2011-04-01

Full Text Available Citrobacter rodentium is a natural mouse pathogen that causes attaching and effacing (A/E lesions. It shares a common virulence strategy with the clinically significant human A/E pathogens enteropathogenic E. coli (EPEC and enterohaemorrhagic E. coli (EHEC and is widely used to model this route of pathogenesis. We previously reported the complete genome sequence of C. rodentium ICC168, where we found that the genome displayed many characteristics of a newly evolved pathogen. In this study, through PFGE, sequencing of isolates showing variation, whole genome transcriptome analysis and examination of the mobile genetic elements, we found that, consistent with our previous hypothesis, the genome of C. rodentium is unstable as a result of repeat-mediated, large-scale genome recombination and because of active transposition of mobile genetic elements such as the prophages. We sequenced an additional C. rodentium strain, EX-33, to reveal that the reference strain ICC168 is representative of the species and that most of the inactivating mutations were common to both isolates and likely to have occurred early on in the evolution of this pathogen. We draw parallels with the evolution of other bacterial pathogens and conclude that C. rodentium is a recently evolved pathogen that may have emerged alongside the development of inbred mice as a model for human disease.

Novel aptamer-linked nanoconjugate approach for detection of waterborne bacterial pathogens: an update

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Singh, Gulshan; Manohar, Murli; Adegoke, Anthony Ayodeji; Stenström, Thor Axel; Shanker, Rishi

2017-01-01

The lack of microbiologically safe water in underdeveloped nations is the prime cause of infectious disease outbreaks. The need for the specific identification and detection of microorganisms encourages the development of advanced, rapid, sensitive and highly specific methods for the monitoring of pathogens and management of potential risk to human health. The rapid molecular assays based on detection of specific molecular signatures offer advantages over conventional methods in terms of specificity and sensitivity but require complex instrumentation and skilled personnel. Nanotechnology is an emerging area and provides a robust approach for the identification of pathogenic microorganism utilizing the peculiar properties of nanomaterials, i.e. small size (1-100 nm) and large surface area. This emerging technology promises to fulfill the urgent need of a novel strategy to enhance the bacterial identification and quantitation in the environment. In this context, the peculiar properties of gold nanoparticles, their plasmonic shifts, and changes in magnetic properties have been utilized for the simple and cost-effective detection of bacterial nucleic acids, antigens and toxins with quite improved sensitivity. One of the promising leads to develop an advance detection method might be the coupling of nucleic acid aptamers (capable of interacting specifically with bacteria, protozoa, and viruses) with nanomaterials. Such aptamer-nano conjugate can be used for the specific recognition of infectious agents in different environmental matrices. This review summarizes the application of nanotechnology in the area of pathogen detection and discusses the prospects of coupling nucleic acid aptamers with nanoparticles for the specific detection of targeted pathogens.

Novel aptamer-linked nanoconjugate approach for detection of waterborne bacterial pathogens: an update

International Nuclear Information System (INIS)

Singh, Gulshan; Manohar, Murli; Adegoke, Anthony Ayodeji; Stenström, Thor Axel; Shanker, Rishi

2017-01-01

The lack of microbiologically safe water in underdeveloped nations is the prime cause of infectious disease outbreaks. The need for the specific identification and detection of microorganisms encourages the development of advanced, rapid, sensitive and highly specific methods for the monitoring of pathogens and management of potential risk to human health. The rapid molecular assays based on detection of specific molecular signatures offer advantages over conventional methods in terms of specificity and sensitivity but require complex instrumentation and skilled personnel. Nanotechnology is an emerging area and provides a robust approach for the identification of pathogenic microorganism utilizing the peculiar properties of nanomaterials, i.e. small size (1–100 nm) and large surface area. This emerging technology promises to fulfill the urgent need of a novel strategy to enhance the bacterial identification and quantitation in the environment. In this context, the peculiar properties of gold nanoparticles, their plasmonic shifts, and changes in magnetic properties have been utilized for the simple and cost-effective detection of bacterial nucleic acids, antigens and toxins with quite improved sensitivity. One of the promising leads to develop an advance detection method might be the coupling of nucleic acid aptamers (capable of interacting specifically with bacteria, protozoa, and viruses) with nanomaterials. Such aptamer-nano conjugate can be used for the specific recognition of infectious agents in different environmental matrices. This review summarizes the application of nanotechnology in the area of pathogen detection and discusses the prospects of coupling nucleic acid aptamers with nanoparticles for the specific detection of targeted pathogens.

Novel aptamer-linked nanoconjugate approach for detection of waterborne bacterial pathogens: an update

Energy Technology Data Exchange (ETDEWEB)

Singh, Gulshan, E-mail: gsingh.gulshan@gmail.com [Durban University of Technology, Institute for Water and Wastewater Technology (IWWT) (South Africa); Manohar, Murli [Jamia Hamdard (Hamdard University), Department of Biochemistry (India); Adegoke, Anthony Ayodeji; Stenström, Thor Axel [Durban University of Technology, Institute for Water and Wastewater Technology (IWWT) (South Africa); Shanker, Rishi [Ahmedabad University, Division of Biological & Life Sciences, School of Arts & Sciences (India)

2017-01-15

The lack of microbiologically safe water in underdeveloped nations is the prime cause of infectious disease outbreaks. The need for the specific identification and detection of microorganisms encourages the development of advanced, rapid, sensitive and highly specific methods for the monitoring of pathogens and management of potential risk to human health. The rapid molecular assays based on detection of specific molecular signatures offer advantages over conventional methods in terms of specificity and sensitivity but require complex instrumentation and skilled personnel. Nanotechnology is an emerging area and provides a robust approach for the identification of pathogenic microorganism utilizing the peculiar properties of nanomaterials, i.e. small size (1–100 nm) and large surface area. This emerging technology promises to fulfill the urgent need of a novel strategy to enhance the bacterial identification and quantitation in the environment. In this context, the peculiar properties of gold nanoparticles, their plasmonic shifts, and changes in magnetic properties have been utilized for the simple and cost-effective detection of bacterial nucleic acids, antigens and toxins with quite improved sensitivity. One of the promising leads to develop an advance detection method might be the coupling of nucleic acid aptamers (capable of interacting specifically with bacteria, protozoa, and viruses) with nanomaterials. Such aptamer-nano conjugate can be used for the specific recognition of infectious agents in different environmental matrices. This review summarizes the application of nanotechnology in the area of pathogen detection and discusses the prospects of coupling nucleic acid aptamers with nanoparticles for the specific detection of targeted pathogens.

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot

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Hirschfeld, Mareike; Blackburn, David C.; Doherty-Bone, Thomas M.; Gonwouo, LeGrand Nono; Ghose, Sonia; Rödel, Mark-Oliver

2016-01-01

Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004–2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon’s frog diversity. PMID:27149624

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot.

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Mareike Hirschfeld

Full Text Available Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd. In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004-2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon's frog diversity.

Network Analysis Highlights Complex Interactions between Pathogen, Host and Commensal Microbiota

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Boutin, Sébastien; Bernatchez, Louis; Audet, Céline; Derôme, Nicolas

2013-01-01

Interactions between bacteria and their host represent a full continuum from pathogenicity to mutualism. From an evolutionary perspective, host-bacteria relationships are no longer considered a two-component system but rather a complex network. In this study, we focused on the relationship between brook charr (Salvelinus fontinalis) and bacterial communities developing on skin mucus. We hypothesized that stressful conditions such as those occurring in aquaculture production induce shifts in the bacterial community of healthy fish, thus allowing pathogens to cause infections. The results showed that fish skin mucus microbiota taxonomical structure is highly specific, its diversity being partly influenced by the surrounding water bacterial community. Two types of taxonomic co-variation patterns emerged across 121 contrasted communities’ samples: one encompassing four genera well known for their probiotic properties, the other harboring five genera mostly associated with pathogen species. The homeostasis of fish bacterial community was extensively disturbed by induction of physiological stress in that both: 1) the abundance of probiotic-like bacteria decreased after stress exposure; and 2) pathogenic bacteria increased following stress exposure. This study provides further insights regarding the role of mutualistic bacteria as a primary host protection barrier. PMID:24376845

Network analysis highlights complex interactions between pathogen, host and commensal microbiota.

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Sébastien Boutin

Full Text Available Interactions between bacteria and their host represent a full continuum from pathogenicity to mutualism. From an evolutionary perspective, host-bacteria relationships are no longer considered a two-component system but rather a complex network. In this study, we focused on the relationship between brook charr (Salvelinus fontinalis and bacterial communities developing on skin mucus. We hypothesized that stressful conditions such as those occurring in aquaculture production induce shifts in the bacterial community of healthy fish, thus allowing pathogens to cause infections. The results showed that fish skin mucus microbiota taxonomical structure is highly specific, its diversity being partly influenced by the surrounding water bacterial community. Two types of taxonomic co-variation patterns emerged across 121 contrasted communities' samples: one encompassing four genera well known for their probiotic properties, the other harboring five genera mostly associated with pathogen species. The homeostasis of fish bacterial community was extensively disturbed by induction of physiological stress in that both: 1 the abundance of probiotic-like bacteria decreased after stress exposure; and 2 pathogenic bacteria increased following stress exposure. This study provides further insights regarding the role of mutualistic bacteria as a primary host protection barrier.

Vaccines for emerging infectious diseases: Lessons from MERS coronavirus and Zika virus.

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Maslow, Joel N

2017-12-02

The past decade and a half has been characterized by numerous emerging infectious diseases. With each new threat, there has been a call for rapid vaccine development. Pathogens such as the Middle East Respiratory Syndrome coronavirus (MERS-CoV) and the Zika virus represent either new viral entities or viruses emergent in new geographic locales and characterized by novel complications. Both serve as paradigms for the global spread that can accompany new pathogens. In this paper, we review the epidemiology and pathogenesis of MERS-CoV and Zika virus with respect to vaccine development. The challenges in vaccine development and the approach to clinical trial design to test vaccine candidates for disease entities with a changing epidemiology are discussed.

Two pathogenic species of Pythium: P. aphanidermatum and P. diclinum from a wheat field.

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Al-Sheikh, Hashem

2010-10-01

During a survey of pathogenic and non-pathogenic Pythium spp. in different localities in Egypt, several isolates of Pythia were obtained and maintained on corn meal agar. Among these isolates, Pythium aphanidermatum and Pythium diclinum were obtained from rhizosphere of wheat plants grown in Dear Attia village, Minia, Egypt. Identification was made using morphological and molecular analyses. P. aphanidermatum and P. diclinum were able to cause reductions in emergence and adulating in wheat in laboratory scale. P. aphanidermatum appeared to be the most aggressive parasite under agar and pot experimental conditions.

A functional collagen adhesin gene, acm, in clinical isolates of Enterococcus faecium correlates with the recent success of this emerging nosocomial pathogen.

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Nallapareddy, Sreedhar R; Singh, Kavindra V; Okhuysen, Pablo C; Murray, Barbara E

2008-09-01

Enterococcus faecium recently evolved from a generally avirulent commensal into a multidrug-resistant health care-associated pathogen causing difficult-to-treat infections, but little is known about the factors responsible for this change. We previously showed that some E. faecium strains express a cell wall-anchored collagen adhesin, Acm. Here we analyzed 90 E. faecium isolates (99% acm(+)) and found that the Acm protein was detected predominantly in clinically derived isolates, while the acm gene was present as a transposon-interrupted pseudogene in 12 of 47 isolates of nonclinical origin. A highly significant association between clinical (versus fecal or food) origin and collagen adherence (P Acm detected by whole-cell enzyme-linked immunosorbent assay and flow cytometry. Thirty-seven of 41 sera from patients with E. faecium infections showed reactivity with recombinant Acm, while only 4 of 30 community and hospitalized patient control group sera reacted (P Acm were present in all 14 E. faecium endocarditis patient sera. Although pulsed-field gel electrophoresis indicated that multiple strains expressed collagen adherence, multilocus sequence typing demonstrated that the majority of collagen-adhering isolates, as well as 16 of 17 endocarditis isolates, are part of the hospital-associated E. faecium genogroup referred to as clonal complex 17 (CC17), which has emerged globally. Taken together, our findings support the hypothesis that Acm has contributed to the emergence of E. faecium and CC17 in nosocomial infections.

Pathogen inactivation techniques.

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Pelletier, J P R; Transue, S; Snyder, E L

2006-01-01

The desire to rid the blood supply of pathogens of all types has led to the development of many technologies aimed at the same goal--eradication of the pathogen(s) without harming the blood cells or generating toxic chemical agents. This is a very ambitious goal, and one that has yet to be achieved. One approach is to shun the 'one size fits all' concept and to target pathogen-reduction agents at the Individual component types. This permits the development of technologies that might be compatible with, for example, plasma products but that would be cytocidal and thus incompatible with platelet concentrates or red blood cell units. The technologies to be discussed include solvent detergent and methylene blue treatments--designed to inactivate plasma components and derivatives; psoralens (S-59--amotosalen) designed to pathogen-reduce units of platelets; and two products aimed at red blood cells, S-303 (a Frale--frangible anchor-linker effector compound) and Inactine (a binary ethyleneimine). A final pathogen-reduction material that might actually allow one material to inactivate all three blood components--riboflavin (vitamin B2)--is also under development. The sites of action of the amotosalen (S-59), the S-303 Frale, Inactine, and riboflavin are all localized in the nucleic acid part of the pathogen. Solvent detergent materials act by dissolving the plasma envelope, thus compromising the integrity of the pathogen membrane and rendering it non-infectious. By disrupting the pathogen's ability to replicate or survive, its infectivity is removed. The degree to which bacteria and viruses are affected by a particular pathogen-reducing technology relates to its Gram-positive or Gram-negative status, to the sporulation characteristics for bacteria, and the presence of lipid or protein envelopes for viruses. Concerns related to photoproducts and other breakdown products of these technologies remain, and the toxicology of pathogen-reduction treatments is a major ongoing area

Effect of chipping on emergence of the redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae) and recovery of the laurel wilt pathogen from infested wood chips.

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Spence, D J; Smith, J A; Ploetz, R; Hulcr, J; Stelinski, L L

2013-10-01

Significant mortality ofredbay trees (Persea borbonia (L.) Spreng.) in the southeastern United States has been caused by Raffaelea lauricola, T.C. Harr., Fraedrich, & Aghayeva (Harrington et al. 2008), a fungal symbiont of the exotic redbay ambrosia beetle, Xyleborus glabratus, Eichhoff (Fraedrich et al. 2008). This pathogen causes laurel wilt, which is an irreversible disease that can kill mature trees within a few weeks in summer. R. lauricola has been shown to be lethal to most native species of Lauraceae and cultivated avocado (Persea americana Mill.) in the southeastern United States. In this study, we examined the survival of X. glabratus and R. lauricola in wood chips made from infested trees by using a standard tree chipper over a 10-wk period. After 2 wk, 14 X. glabratus were recovered from wood chips, whereas 339 X. glabratus emerged from nonchipped bolts. R. lauricola was not found 2 d postchipping from wood chips, indicating that the pathogen is not likely to survive for long inside wood chips. In contrast, R. lauricola persisted in dead, standing redbay trees for 14 mo. With large volumes of wood, the potential for infested logs to be moved between states or across U.S. borders is significant. Results demonstrated that chipping wood from laurel wilt-killed trees can significantly reduce the number of X. glabratus and limit the persistence of R. lauricola, which is important for sanitation strategies aimed at limiting the spread of this disease.

Interactions between intestinal pathogens, enteropathy and malnutrition in developing countries.

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Prendergast, Andrew J; Kelly, Paul

2016-06-01

This review focuses on recent data highlighting the interactions between intestinal pathogens, enteropathy and malnutrition in developing countries, which drive morbidity and mortality and hinder the long-term developmental potential of children. Diarrhoea remains the second commonest cause of death in children below 5 years, and malnutrition underlies 45% of all child deaths. Even in the absence of diarrhoea, subclinical pathogen carriage and enteropathy are almost universal in developing countries. Here, we review recent studies addressing the causes and consequences of diarrhoea; emerging data on environmental influences that govern postnatal development of the gut and microbiota; current concepts of environmental enteric dysfunction; and recent intervention trials in the field. We highlight the interactions between these processes, whereby intestinal pathogens drive a cycle of gut damage, malabsorption, chronic inflammation and failed mucosal regeneration, leading to malnutrition and susceptibility to further enteric infections. Efforts to improve child survival and long-term developmental potential need to address the overlapping and interacting effects of diarrhoea, enteropathy and malnutrition. Recent insights from human and animal studies suggest potential targets for intervention.

AMPK in Pathogens

OpenAIRE

Mesquita, Inês Morais; Moreira, Diana; Marques, Belém Sampaio; Laforge, Mireille; Cordeiro-da-Silva, Anabela; Ludovico, Paula; Estaquier, Jérôme; Silvestre, Ricardo Jorge Leal

2016-01-01

During host–pathogen interactions, a complex web of events is crucial for the outcome of infection. Pathogen recognition triggers powerful cellular signaling events that is translated into the induction and maintenance of innate and adaptive host immunity against infection. In opposition, pathogens employ active mechanisms to manipulate host cell regulatory pathways toward their proliferation and survival. Among these, subversion of host cell energy metabolism by pathogens is currently recogn...

Antimicrobial resistance of mastitis pathogens.

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Oliver, Stephen P; Murinda, Shelton E

2012-07-01

Antibiotics are used extensively in the dairy industry to combat disease and to improve animal performance. Antibiotics such as penicillin, cephalosporin, streptomycin, and tetracycline are used for the treatment and prevention of diseases affecting dairy cows caused by a variety of gram-positive and gram-negative bacteria. Antibiotics are often administrated routinely to entire herds to prevent mastitis during the dry period. An increase in the incidence of disease in a herd generally results in increased use of antimicrobials, which in turn increases the potential for antibiotic residues in milk and the potential for increased bacterial resistance to antimicrobials. Continued use of antibiotics in the treatment and prevention of diseases of dairy cows will continue to be scrutinized. It is clear that strategies employing the prudent use of antimicrobials are needed. This clearly illustrates the importance of effective herd disease prevention and control programs. Based on studies published to date, scientific evidence does not support widespread, emerging resistance among mastitis pathogens to antibacterial drugs even though many of these antibiotics have been used in the dairy industry for treatment and prevention of disease for several decades. However, it is clear that use of antibiotics in dairy cows can contribute to increased antimicrobial resistance. While antimicrobial resistance does occur, we are of the opinion that the advantages of using antibiotics for the treatment of mastitis far outweigh the disadvantages. The clinical consequences of antimicrobial resistance of dairy pathogens affecting humans appear small. Antimicrobial resistance among dairy pathogens, particularly those found in milk, is likely not a human health concern as long as the milk is pasteurized. However, there are an increasing number of people who choose to consume raw milk. Transmission of an antimicrobial-resistant mastitis pathogen and/or foodborne pathogen to humans could occur

Genomic Organization and Expression of Iron Metabolism Genes in the Emerging Pathogenic Mold Scedosporium apiospermum

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Yohann Le Govic

2018-04-01

Full Text Available The ubiquitous mold Scedosporium apiospermum is increasingly recognized as an emerging pathogen, especially among patients with underlying disorders such as immunodeficiency or cystic fibrosis (CF. Indeed, it ranks the second among the filamentous fungi colonizing the respiratory tract of CF patients. However, our knowledge about virulence factors of this fungus is still limited. The role of iron-uptake systems may be critical for establishment of Scedosporium infections, notably in the iron-rich environment of the CF lung. Two main strategies are employed by fungi to efficiently acquire iron from their host or from their ecological niche: siderophore production and reductive iron assimilation (RIA systems. The aim of this study was to assess the existence of orthologous genes involved in iron metabolism in the recently sequenced genome of S. apiospermum. At first, a tBLASTn analysis using A. fumigatus iron-related proteins as query revealed orthologs of almost all relevant loci in the S. apiospermum genome. Whereas the genes putatively involved in RIA were randomly distributed, siderophore biosynthesis and transport genes were organized in two clusters, each containing a non-ribosomal peptide synthetase (NRPS whose orthologs in A. fumigatus have been described to catalyze hydroxamate siderophore synthesis. Nevertheless, comparative genomic analysis of siderophore-related clusters showed greater similarity between S. apiospermum and phylogenetically close molds than with Aspergillus species. The expression level of these genes was then evaluated by exposing conidia to iron starvation and iron excess. The expression of several orthologs of A. fumigatus genes involved in siderophore-based iron uptake or RIA was significantly induced during iron starvation, and conversely repressed in iron excess conditions. Altogether, these results indicate that S. apiospermum possesses the genetic information required for efficient and competitive iron uptake

Bacterial genome engineering and synthetic biology: combating pathogens.

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Krishnamurthy, Malathy; Moore, Richard T; Rajamani, Sathish; Panchal, Rekha G

2016-11-04

The emergence and prevalence of multidrug resistant (MDR) pathogenic bacteria poses a serious threat to human and animal health globally. Nosocomial infections and common ailments such as pneumonia, wound, urinary tract, and bloodstream infections are becoming more challenging to treat due to the rapid spread of MDR pathogenic bacteria. According to recent reports by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), there is an unprecedented increase in the occurrence of MDR infections worldwide. The rise in these infections has generated an economic strain worldwide, prompting the WHO to endorse a global action plan to improve awareness and understanding of antimicrobial resistance. This health crisis necessitates an immediate action to target the underlying mechanisms of drug resistance in bacteria. The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic and treatment plans to monitor and treat widespread recalcitrant bacterial infections. Key advances in genetic engineering approaches can successfully aid in targeting and editing pathogenic bacterial genomes for understanding and mitigating drug resistance mechanisms. In this review, we discuss the application of specific genome engineering and SB methods such as recombineering, clustered regularly interspaced short palindromic repeats (CRISPR), and bacterial cell-cell signaling mechanisms for pathogen targeting. The utility of these tools in developing antibacterial strategies such as novel antibiotic production, phage therapy, diagnostics and vaccine production to name a few, are also highlighted. The prevalent use of antibiotics and the spread of MDR bacteria raise the prospect of a post-antibiotic era, which underscores the need for developing novel therapeutics to target MDR pathogens. The development of enabling SB technologies offers promising solutions to deliver safe and effective antibacterial therapies.

Arginase activity in pathogenic and non-pathogenic species of Leishmania parasites.

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Badirzadeh, Alireza; Taheri, Tahereh; Taslimi, Yasaman; Abdossamadi, Zahra; Heidari-Kharaji, Maryam; Gholami, Elham; Sedaghat, Baharehsadat; Niyyati, Maryam; Rafati, Sima

2017-07-01

Proliferation of Leishmania (L.) parasites depends on polyamine availability, which can be generated by the L-arginine catabolism and the enzymatic activity of arginase (ARG) of the parasites and of the mammalian hosts. In the present study, we characterized and compared the arginase (arg) genes from pathogenic L. major and L. tropica and from non-pathogenic L. tarentolae. We quantified the level of the ARG activity in promastigotes and macrophages infected with pathogenic L. major and L. tropica and non-pathogenic L. tarentolae amastigotes. The ARG's amino acid sequences of the pathogenic and non-pathogenic Leishmania demonstrated virtually 98.6% and 88% identities with the reference L. major Friedlin ARG. Higher ARG activity was observed in all pathogenic promastigotes as compared to non-pathogenic L. tarentolae. In vitro infection of human macrophage cell line (THP1) with pathogenic and non-pathogenic Leishmania spp. resulted in increased ARG activities in the infected macrophages. The ARG activities present in vivo were assessed in susceptible BALB/c and resistant C57BL/6 mice infected with L. major, L. tropica and L. tarentolae. We demonstrated that during the development of the infection, ARG is induced in both strains of mice infected with pathogenic Leishmania. However, in L. major infected BALB/c mice, the induction of ARG and parasite load increased simultaneously according to the time course of infection, whereas in C57BL/6 mice, the enzyme is upregulated solely during the period of footpad swelling. In L. tropica infected mice, the footpads' swellings were slow to develop and demonstrated minimal cutaneous pathology and ARG activity. In contrast, ARG activity was undetectable in mice inoculated with the non-pathogenic L. tarentolae. Our data suggest that infection by Leishmania parasites can increase ARG activity of the host and provides essential polyamines for parasite salvage and its replication. Moreover, the ARG of Leishmania is vital for parasite

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

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Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Transcriptional regulation by Ferric Uptake Regulator (Fur) in pathogenic bacteria.

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Troxell, Bryan; Hassan, Hosni M

2013-01-01

In the ancient anaerobic environment, ferrous iron (Fe(2+)) was one of the first metal cofactors. Oxygenation of the ancient world challenged bacteria to acquire the insoluble ferric iron (Fe(3+)) and later to defend against reactive oxygen species (ROS) generated by the Fenton chemistry. To acquire Fe(3+), bacteria produce low-molecular weight compounds, known as siderophores, which have extremely high affinity for Fe(3+). However, during infection the host restricts iron from pathogens by producing iron- and siderophore-chelating proteins, by exporting iron from intracellular pathogen-containing compartments, and by limiting absorption of dietary iron. Ferric Uptake Regulator (Fur) is a transcription factor which utilizes Fe(2+) as a corepressor and represses siderophore synthesis in pathogens. Fur, directly or indirectly, controls expression of enzymes that protect against ROS damage. Thus, the challenges of iron homeostasis and defense against ROS are addressed via Fur. Although the role of Fur as a repressor is well-documented, emerging evidence demonstrates that Fur can function as an activator. Fur activation can occur through three distinct mechanisms (1) indirectly via small RNAs, (2) binding at cis regulatory elements that enhance recruitment of the RNA polymerase holoenzyme (RNAP), and (3) functioning as an antirepressor by removing or blocking DNA binding of a repressor of transcription. In addition, Fur homologs control defense against peroxide stress (PerR) and control uptake of other metals such as zinc (Zur) and manganese (Mur) in pathogenic bacteria. Fur family members are important for virulence within bacterial pathogens since mutants of fur, perR, or zur exhibit reduced virulence within numerous animal and plant models of infection. This review focuses on the breadth of Fur regulation in pathogenic bacteria.

Epigenetics of host-pathogen interactions: the road ahead and the road behind.

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Elena Gómez-Díaz

Full Text Available A growing body of evidence points towards epigenetic mechanisms being responsible for a wide range of biological phenomena, from the plasticity of plant growth and development to the nutritional control of caste determination in honeybees and the etiology of human disease (e.g., cancer. With the (partial elucidation of the molecular basis of epigenetic variation and the heritability of certain of these changes, the field of evolutionary epigenetics is flourishing. Despite this, the role of epigenetics in shaping host-pathogen interactions has received comparatively little attention. Yet there is plenty of evidence supporting the implication of epigenetic mechanisms in the modulation of the biological interaction between hosts and pathogens. The phenotypic plasticity of many key parasite life-history traits appears to be under epigenetic control. Moreover, pathogen-induced effects in host phenotype may have transgenerational consequences, and the bases of these changes and their heritability probably have an epigenetic component. The significance of epigenetic modifications may, however, go beyond providing a mechanistic basis for host and pathogen plasticity. Epigenetic epidemiology has recently emerged as a promising area for future research on infectious diseases. In addition, the incorporation of epigenetic inheritance and epigenetic plasticity mechanisms to evolutionary models and empirical studies of host-pathogen interactions will provide new insights into the evolution and coevolution of these associations. Here, we review the evidence available for the role epigenetics on host-pathogen interactions, and the utility and versatility of the epigenetic technologies available that can be cross-applied to host-pathogen studies. We conclude with recommendations and directions for future research on the burgeoning field of epigenetics as applied to host-pathogen interactions.

Early detection surveillance for an emerging plant pathogen: a rule of thumb to predict prevalence at first discovery.

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Parnell, S; Gottwald, T R; Cunniffe, N J; Alonso Chavez, V; van den Bosch, F

2015-09-07

Emerging plant pathogens are a significant problem for conservation and food security. Surveillance is often instigated in an attempt to detect an invading epidemic before it gets out of control. Yet in practice many epidemics are not discovered until already at a high prevalence, partly due to a lack of quantitative understanding of how surveillance effort and the dynamics of an invading epidemic relate. We test a simple rule of thumb to determine, for a surveillance programme taking a fixed number of samples at regular intervals, the distribution of the prevalence an epidemic will have reached on first discovery (discovery-prevalence) and its expectation E(q*). We show that E(q*) = r/(N/Δ), i.e. simply the rate of epidemic growth divided by the rate of sampling; where r is the epidemic growth rate, N is the sample size and Δ is the time between sampling rounds. We demonstrate the robustness of this rule of thumb using spatio-temporal epidemic models as well as data from real epidemics. Our work supports the view that, for the purposes of early detection surveillance, simple models can provide useful insights in apparently complex systems. The insight can inform decisions on surveillance resource allocation in plant health and has potential applicability to invasive species generally. © 2015 The Author(s).

Identification and characterization of novel natural pathogen of Drosophila melanogaster isolated from wild captured Drosophila spp.

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Singh, Karan; Zulkifli, Mohammad; Prasad, N G

2016-12-01

Drosophila melanogaster is an emerging model system for the study of evolutionary ecology of immunity. However, a large number of studies have used non natural pathogens as very few natural pathogens have been isolated and identified. Our aim was to isolate and characterize natural pathogen/s of D. melanogaster. A bacterial pathogen was isolated from wild caught Drosophila spp., identified as a new strain of Staphylococcus succinus subsp. succinus and named PK-1. This strain induced substantial mortality (36-62%) in adults of several laboratory populations of D. melanogaster. PK-1 grew rapidly within the body of the flies post infection and both males and females had roughly same number of colony forming units. Mortality was affected by mode of infection and dosage of the pathogen. However mating status of the host had no effect on mortality post infection. Given that there are very few known natural bacterial pathogens of D. melanogaster and that PK-1 can establish a sustained infection across various outbred and inbred populations of D. melanogaster this new isolate is a potential resource for future studies on immunity. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Emergence of Stenotrophomonas maltophilia nosocomial isolates in a Saudi children's hospital. Risk factors and clinical characteristics.

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Alqahtani, Jobran M

2017-05-01

  To describe the clinical characteristics of pediatric patients colonized or infected by Stenotrophomonas maltophilia (S. maltophilia) at a Saudi children's hospital, to identify risk factors associated with infection, and to investigate the antimicrobial resistance patterns of this emerging pathogen.  Methods: In this cross-sectional observational study, 64 non-duplicating S. maltophilia strains were isolated  in Najran Maternity and Children's Hospital, Najran,  Saudi Arabia between January 2015 to February 2016. Antimicrobial susceptibility testing was performed using the reference broth microdilution method.  Results: In this study, 48 (75%) isolates were identified in true infections and 16 (25%) isolates were considered colonization. The main types of S. maltophilia infection were pneumonia in 22 (45.8%) patients and bloodstream infection in 14 (29.2%) patients. The significant risk factors included exposure to invasive procedure (p=0.02), and presence of acute leukemia as an underlying disease (p=0.02). The most active antimicrobials were trimethoprim/sulfamethoxazole (100% sensitivity) and tigecycline (93.7% sensitivity). Conclusions: Stenotrophomonas maltophilia is an emerging nosocomial pathogen among pediatric patients. Accurate identification and susceptibility testing of this emerging pathogen are crucial for the management of infected patients and prevention of spread of this nosocomial pathogen.

Genomic analyses of the microsporidian Nosema ceranae, an emergent pathogen of honey bees.

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R Scott Cornman

2009-06-01

Full Text Available Recent steep declines in honey bee health have severely impacted the beekeeping industry, presenting new risks for agricultural commodities that depend on insect pollination. Honey bee declines could reflect increased pressures from parasites and pathogens. The incidence of the microsporidian pathogen Nosema ceranae has increased significantly in the past decade. Here we present a draft assembly (7.86 MB of the N. ceranae genome derived from pyrosequence data, including initial gene models and genomic comparisons with other members of this highly derived fungal lineage. N. ceranae has a strongly AT-biased genome (74% A+T and a diversity of repetitive elements, complicating the assembly. Of 2,614 predicted protein-coding sequences, we conservatively estimate that 1,366 have homologs in the microsporidian Encephalitozoon cuniculi, the most closely related published genome sequence. We identify genes conserved among microsporidia that lack clear homology outside this group, which are of special interest as potential virulence factors in this group of obligate parasites. A substantial fraction of the diminutive N. ceranae proteome consists of novel and transposable-element proteins. For a majority of well-supported gene models, a conserved sense-strand motif can be found within 15 bases upstream of the start codon; a previously uncharacterized version of this motif is also present in E. cuniculi. These comparisons provide insight into the architecture, regulation, and evolution of microsporidian genomes, and will drive investigations into honey bee-Nosema interactions.

PATHOGENICITY, DEVELOPMENT AND REPRODUCTION OF THE ENTOMOPATHOGENIC NEMATODE Steinernema sp., IN MEALWORM Tenebrio molitor

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Yuliantoro Baliadi

2011-10-01

Full Text Available The pathogenicity, development and reproduction of Steinernema sp., isolate Skpr-20/Str, were studied using Tenebrio molitor. Results revealed that pathogenicity, development and reproduction were significantly influenced by nematode doses. Although the number of invading IJs increased with increasing dose, percentage penetration declined. The IJs reached adulthood within 3 days. Females laid eggs from day 4-7. All eggs remaining inside uterus develop inside the maternal body. The first female bearing endotokia matricida was observed on day 5. In a sand-based assay, nematode was more pathogenic at lower dose instead of higher ones, where optimum dose was 80 nematodes per larva and average number of progeny per female was 5438. Under crowded conditions, development proceeds to IJ stage instead of the J3. The average length and width decreased with increasing of nematode doses. The IJ produced in cadavers infested with 640 nematodes per larva was significantly smaller (492 ± 6.4 µm than offspring from other doses. The number of days which nematodes first emerged from the cadavers decreased with increasing dose. IJ first emerged at the average of 10-13 days at high IJ densities. It is concluded that the wide experimental characteristic of EPNs is also true for Steinernema sp., isolate Skpr-20/Str.

Genome analyses of an aggressive and invasive lineage of the Irish potato famine pathogen.

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David E L Cooke

Full Text Available Pest and pathogen losses jeopardise global food security and ever since the 19(th century Irish famine, potato late blight has exemplified this threat. The causal oomycete pathogen, Phytophthora infestans, undergoes major population shifts in agricultural systems via the successive emergence and migration of asexual lineages. The phenotypic and genotypic bases of these selective sweeps are largely unknown but management strategies need to adapt to reflect the changing pathogen population. Here, we used molecular markers to document the emergence of a lineage, termed 13_A2, in the European P. infestans population, and its rapid displacement of other lineages to exceed 75% of the pathogen population across Great Britain in less than three years. We show that isolates of the 13_A2 lineage are among the most aggressive on cultivated potatoes, outcompete other aggressive lineages in the field, and overcome previously effective forms of plant host resistance. Genome analyses of a 13_A2 isolate revealed extensive genetic and expression polymorphisms particularly in effector genes. Copy number variations, gene gains and losses, amino-acid replacements and changes in expression patterns of disease effector genes within the 13_A2 isolate likely contribute to enhanced virulence and aggressiveness to drive this population displacement. Importantly, 13_A2 isolates carry intact and in planta induced Avrblb1, Avrblb2 and Avrvnt1 effector genes that trigger resistance in potato lines carrying the corresponding R immune receptor genes Rpi-blb1, Rpi-blb2, and Rpi-vnt1.1. These findings point towards a strategy for deploying genetic resistance to mitigate the impact of the 13_A2 lineage and illustrate how pathogen population monitoring, combined with genome analysis, informs the management of devastating disease epidemics.

Rapid extirpation of a North American frog coincides with an increase in fungal pathogen prevalence: Historical analysis and implications for reintroduction.

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Adams, Andrea J; Pessier, Allan P; Briggs, Cheryl J

2017-12-01

As extinctions continue across the globe, conservation biologists are turning to species reintroduction programs as one optimistic tool for addressing the biodiversity crisis. For repatriation to become a viable strategy, fundamental prerequisites include determining the causes of declines and assessing whether the causes persist in the environment. Invasive species-especially pathogens-are an increasingly significant factor contributing to biodiversity loss. We hypothesized that Batrachochytrium dendrobatidis (Bd), the causative agent of the deadly amphibian disease chytridiomycosis, was important in the rapid (herpetological experts, analysis of archived field notes and museum specimen collections, and field sampling of the extant amphibian assemblage to examine (1) historical relative abundance of R. boylii ; (2) potential causes of R. boylii declines; and (3) historical and contemporary prevalence of Bd. We found that R. boylii were relatively abundant prior to their rapid extirpation, and an increase in Bd prevalence coincided with R. boylii declines during a time of rapid change in the region, wherein backcountry recreation, urban development, and the amphibian pet trade were all on the rise. In addition, extreme flooding during the winter of 1969 coincided with localized extirpations in R. boylii populations observed by interview respondents. We conclude that Bd likely played an important role in the rapid extirpation of R. boylii from southern California and that multiple natural and anthropogenic factors may have worked in concert to make this possible in a relatively short period of time. This study emphasizes the importance of recognizing historical ecological contexts in making future management and reintroduction decisions.

Analysis of the synonymous codon usage bias in recently emerged enterovirus D68 strains.

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Karniychuk, Uladzimir U

2016-09-02

Understanding the codon usage pattern of a pathogen and relationship between pathogen and host's codon usage patterns has fundamental and applied interests. Enterovirus D68 (EV-D68) is an emerging pathogen with a potentially high public health significance. In the present study, the synonymous codon usage bias of 27 recently emerged, and historical EV-D68 strains was analyzed. In contrast to previously studied enteroviruses (enterovirus 71 and poliovirus), EV-D68 and human host have a high discrepancy between favored codons. Analysis of viral synonymous codon usage bias metrics, viral nucleotide/dinucleotide compositional parameters, and viral protein properties showed that mutational pressure is more involved in shaping the synonymous codon usage bias of EV-D68 than translation selection. Computation of codon adaptation indices allowed to estimate expression potential of the EV-D68 genome in several commonly used laboratory animals. This approach requires experimental validation and may provide an auxiliary tool for the rational selection of laboratory animals to model emerging viral diseases. Enterovirus D68 genome compositional and codon usage data can be useful for further pathogenesis, animal model, and vaccine design studies. Copyright © 2016 Elsevier B.V. All rights reserved.

The relationship between host lifespan and pathogen reservoir potential: an analysis in the system Arabidopsis thaliana--cucumber mosaic virus.

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Jean Michel Hily

2014-11-01

Full Text Available Identification of the determinants of pathogen reservoir potential is central to understand disease emergence. It has been proposed that host lifespan is one such determinant: short-lived hosts will invest less in costly defenses against pathogens, so that they will be more susceptible to infection, more competent as sources of infection and/or will sustain larger vector populations, thus being effective reservoirs for the infection of long-lived hosts. This hypothesis is sustained by analyses of different hosts of multihost pathogens, but not of different genotypes of the same host species. Here we examined this hypothesis by comparing two genotypes of the plant Arabidopsis thaliana that differ largely both in life-span and in tolerance to its natural pathogen Cucumber mosaic virus (CMV. Experiments with the aphid vector Myzus persicae showed that both genotypes were similarly competent as sources for virus transmission, but the short-lived genotype was more susceptible to infection and was able to sustain larger vector populations. To explore how differences in defense against CMV and its vector relate to reservoir potential, we developed a model that was run for a set of experimentally-determined parameters, and for a realistic range of host plant and vector population densities. Model simulations showed that the less efficient defenses of the short-lived genotype resulted in higher reservoir potential, which in heterogeneous host populations may be balanced by the longer infectious period of the long-lived genotype. This balance was modulated by the demography of both host and vector populations, and by the genetic composition of the host population. Thus, within-species genetic diversity for lifespan and defenses against pathogens will result in polymorphisms for pathogen reservoir potential, which will condition within-population infection dynamics. These results are relevant for a better understanding of host-pathogen co-evolution, and of

The role of compensatory mutations in the emergence of drug resistance.

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Andreas Handel

2006-10-01

Full Text Available Pathogens that evolve resistance to drugs usually have reduced fitness. However, mutations that largely compensate for this reduction in fitness often arise. We investigate how these compensatory mutations affect population-wide resistance emergence as a function of drug treatment. Using a model of gonorrhea transmission dynamics, we obtain generally applicable, qualitative results that show how compensatory mutations lead to more likely and faster resistance emergence. We further show that resistance emergence depends on the level of drug use in a strongly nonlinear fashion. We also discuss what data need to be obtained to allow future quantitative predictions of resistance emergence.

Properties of Gluten Intolerance: Gluten Structure, Evolution, Pathogenicity and Detoxification Capabilities

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Balakireva, Anastasia V.; Zamyatnin, Andrey A.

2016-01-01

Theterm gluten intolerance may refer to three types of human disorders: autoimmune celiac disease (CD), allergy to wheat and non-celiac gluten sensitivity (NCGS). Gluten is a mixture of prolamin proteins present mostly in wheat, but also in barley, rye and oat. Gluten can be subdivided into three major groups: S-rich, S-poor and high molecular weight proteins. Prolamins within the groups possess similar structures and properties. All gluten proteins are evolutionarily connected and share the same ancestral origin. Gluten proteins are highly resistant to hydrolysis mediated by proteases of the human gastrointestinal tract. It results in emergence of pathogenic peptides, which cause CD and allergy in genetically predisposed people. There is a hierarchy of peptide toxicity and peptide recognition by T cells. Nowadays, there are several ways to detoxify gluten peptides: the most common is gluten-free diet (GFD), which has proved its effectiveness; prevention programs, enzymatic therapy, correction of gluten pathogenicity pathways and genetically modified grains with reduced immunotoxicity. A deep understanding of gluten intolerance underlying mechanisms and detailed knowledge of gluten properties may lead to the emergence of novel effective approaches for treatment of gluten-related disorders. PMID:27763541

Properties of Gluten Intolerance: Gluten Structure, Evolution, Pathogenicity and Detoxification Capabilities

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Anastasia V. Balakireva

2016-10-01

Full Text Available Theterm gluten intolerance may refer to three types of human disorders: autoimmune celiac disease (CD, allergy to wheat and non-celiac gluten sensitivity (NCGS. Gluten is a mixture of prolamin proteins present mostly in wheat, but also in barley, rye and oat. Gluten can be subdivided into three major groups: S-rich, S-poor and high molecular weight proteins. Prolamins within the groups possess similar structures and properties. All gluten proteins are evolutionarily connected and share the same ancestral origin. Gluten proteins are highly resistant to hydrolysis mediated by proteases of the human gastrointestinal tract. It results in emergence of pathogenic peptides, which cause CD and allergy in genetically predisposed people. There is a hierarchy of peptide toxicity and peptide recognition by T cells. Nowadays, there are several ways to detoxify gluten peptides: the most common is gluten-free diet (GFD, which has proved its effectiveness; prevention programs, enzymatic therapy, correction of gluten pathogenicity pathways and genetically modified grains with reduced immunotoxicity. A deep understanding of gluten intolerance underlying mechanisms and detailed knowledge of gluten properties may lead to the emergence of novel effective approaches for treatment of gluten-related disorders.

Morphological and molecular characterization of Fusarium spp pathogenic to pecan tree in Brazil.

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Lazarotto, M; Milanesi, P M; Muniz, M F B; Reiniger, L R S; Beltrame, R; Harakava, R; Blume, E

2014-11-11

The occurrence of Fusarium spp associated with pecan tree (Carya illinoinensis) diseases in Brazil has been observed in recent laboratory analyses in Rio Grande do Sul State. Thus, in this study, we i) obtained Fusarium isolates from plants with disease symptoms; ii) tested the pathogenicity of these Fusarium isolates to pecan; iii) characterized and grouped Fusarium isolates that were pathogenic to the pecan tree based on morphological characteristics; iv) identified Fusarium spp to the species complex level through TEF-1α sequencing; and v) compared the identification methods used in the study. Fifteen isolates collected from the inflorescences, roots, and seeds of symptomatic plants (leaf necrosis or root rot) were used for pathogenicity tests. Morphological characterization was conducted using only pathogenic isolates, for a total of 11 isolates, based on the mycelial growth rate, sporulation, colony pigmentation, and conidial length and width variables. Pathogenic isolates were grouped based on morphological characteristics, and molecular characterization was performed by sequencing TEF-1α genes. Pathogenic isolates belonging to the Fusarium chlamydosporum species complex, Fusarium graminearum species complex, Fusarium proliferatum, and Fusarium oxysporum were identified based on the TEF-1α region. Morphological characteristics were used to effectively differentiate isolates and group the isolates according to genetic similarity, particularly conidial width, which emerged as a key morphological descriptor in this study.

Candida glabrata Esophagitis: Are We Seeing the Emergence of a New Azole-Resistant Pathogen?

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Aze Wilson

2014-01-01

Full Text Available Background. Candida glabrata (C. glabrata has become a recognized pathogen in fungal esophagitis. A proportion of these isolates are azole-resistant which may have treatment implications. Variability in the prevalence of this organism exists in the limited data available. Objective. To determine the incidence of C. glabrata esophagitis in a North American hospital setting and to highlight factors that may predispose patients to this condition. Methods. Patient charts were collected from January 1, 2009 to July 30, 2011. Any charts of patients identified as having esophagitis with a positive fungal culture were reviewed for the species of Candida and the presence of factors that would predispose them to esophageal candidiasis. Results. The prevalence of Candida esophagitis based on culture was 2.2% (37 subjects. C. glabrata was the 2nd most prevalent pathogen identified (24.3% or 9 subjects. Of the C. glabrata cohort, all patients had at least one factor predisposing them to candidiasis. Conclusion. C. glabrata esophagitis makes up a large portion of the candidal esophagitis seen in hospital. C. glabrata infections were associated with at least one risk factor for candidal infection. Given its resistance to azole-based therapy, this may have treatment implications for how candidal esophagitis is approached by the clinician.

Vaccines for emerging infectious diseases: Lessons from MERS coronavirus and Zika virus

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Maslow, Joel N.

2017-01-01

ABSTRACT The past decade and a half has been characterized by numerous emerging infectious diseases. With each new threat, there has been a call for rapid vaccine development. Pathogens such as the Middle East Respiratory Syndrome coronavirus (MERS-CoV) and the Zika virus represent either new viral entities or viruses emergent in new geographic locales and characterized by novel complications. Both serve as paradigms for the global spread that can accompany new pathogens. In this paper, we review the epidemiology and pathogenesis of MERS-CoV and Zika virus with respect to vaccine development. The challenges in vaccine development and the approach to clinical trial design to test vaccine candidates for disease entities with a changing epidemiology are discussed. PMID:28846484

Comparative genomics of emerging human ehrlichiosis agents.

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Julie C Dunning Hotopp

2006-02-01

Full Text Available Anaplasma (formerly Ehrlichia phagocytophilum, Ehrlichia chaffeensis, and Neorickettsia (formerly Ehrlichia sennetsu are intracellular vector-borne pathogens that cause human ehrlichiosis, an emerging infectious disease. We present the complete genome sequences of these organisms along with comparisons to other organisms in the Rickettsiales order. Ehrlichia spp. and Anaplasma spp. display a unique large expansion of immunodominant outer membrane proteins facilitating antigenic variation. All Rickettsiales have a diminished ability to synthesize amino acids compared to their closest free-living relatives. Unlike members of the Rickettsiaceae family, these pathogenic Anaplasmataceae are capable of making all major vitamins, cofactors, and nucleotides, which could confer a beneficial role in the invertebrate vector or the vertebrate host. Further analysis identified proteins potentially involved in vacuole confinement of the Anaplasmataceae, a life cycle involving a hematophagous vector, vertebrate pathogenesis, human pathogenesis, and lack of transovarial transmission. These discoveries provide significant insights into the biology of these obligate intracellular pathogens.

Opportunities for mitigating pathogen contamination during on-farm food production.

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Doyle, Michael P; Erickson, Marilyn C

2012-01-16

Fruits, vegetables, and meat are susceptible to contamination by foodborne pathogens at many points from production through preparation in the home. This review will largely highlight approaches and progress made in the last five years to address strategies to reduce pathogen contamination in animal production but will also touch on the emerging field of preharvest produce food safety. Mitigation strategies can be divided into those that address pathogen reduction in the environment and those that target reduction/elimination of pathogen contamination in animals or plants. The former strategy has been encompassed in studies evaluating sanitation treatments of facilities as well as in numerous epidemiologic risk assessment studies (both on-farm assessments and computer simulation models) that identify management practices that impact pathogen prevalence in animals. Interventions to significantly reduce pathogen exposure via feed or water are dependent on their role as a significant contributor to pathogen contamination in the animal production system. In addition, inconsistent results obtained with interventions of dietary additives or formulation modifications (grain versus forage; inclusion of distiller's grains) on pathogen prevalence in animals have been attributed to a range of factors including target organism, grain type, level of inclusion, the animal's health or stress level, and ability to survive the gastric acidic conditions. Recent attempts to microencapsulate organic acids or bacteriophage within feed have met with only marginal improvements in reducing pathogen carriage in animals but this approach may have greater potential with other antimicrobial additives (i.e., essential oils). Bacteriophage therapy, in general, can significantly reduce pathogen carriage in animals but based on its transient nature and the potential for development of phage-resistant subpopulations, this approach should be administered to animals just prior to slaughter and

Computational analyses of ancient pathogen DNA from herbarium samples: challenges and prospects.

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Yoshida, Kentaro; Sasaki, Eriko; Kamoun, Sophien

2015-01-01

The application of DNA sequencing technology to the study of ancient DNA has enabled the reconstruction of past epidemics from genomes of historically important plant-associated microbes. Recently, the genome sequences of the potato late blight pathogen Phytophthora infestans were analyzed from 19th century herbarium specimens. These herbarium samples originated from infected potatoes collected during and after the Irish potato famine. Herbaria have therefore great potential to help elucidate past epidemics of crops, date the emergence of pathogens, and inform about past pathogen population dynamics. DNA preservation in herbarium samples was unexpectedly good, raising the possibility of a whole new research area in plant and microbial genomics. However, the recovered DNA can be extremely fragmented resulting in specific challenges in reconstructing genome sequences. Here we review some of the challenges in computational analyses of ancient DNA from herbarium samples. We also applied the recently developed linkage method to haplotype reconstruction of diploid or polyploid genomes from fragmented ancient DNA.

Meeting the Challenge of Zoonotic Emerging Infectious Diseases in ...

International Development Research Centre (IDRC) Digital Library (Canada)

Over one third of the world's EIDs have emerged there, including severe acute respiratory syndrome (SARS), highly pathogenic avian influenza (HPAI) or bird flu, and the Nipah ... L'Initiative des conseils subventionnaires de la recherche scientifique en Afrique subsaharienne remporte le prix de la diplomatie scientifique.

Metabolic principles of persistence and pathogenicity in Mycobacterium tuberculosis.

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Ehrt, Sabine; Schnappinger, Dirk; Rhee, Kyu Y

2018-04-24

Metabolism was once relegated to the supply of energy and biosynthetic precursors, but it has now become clear that it is a specific mediator of nearly all physiological processes. In the context of microbial pathogenesis, metabolism has expanded outside its canonical role in bacterial replication. Among human pathogens, this expansion has emerged perhaps nowhere more visibly than for Mycobacterium tuberculosis, the causative agent of tuberculosis. Unlike most pathogens, M. tuberculosis has evolved within humans, which are both host and reservoir. This makes unrestrained replication and perpetual quiescence equally incompatible strategies for survival as a species. In this Review, we summarize recent work that illustrates the diversity of metabolic functions that not only enable M. tuberculosis to establish and maintain a state of chronic infection within the host but also facilitate its survival in the face of drug pressure and, ultimately, completion of its life cycle.

The neglected intrinsic resistome of bacterial pathogens.

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Alicia Fajardo

Full Text Available Bacteria with intrinsic resistance to antibiotics are a worrisome health problem. It is widely believed that intrinsic antibiotic resistance of bacterial pathogens is mainly the consequence of cellular impermeability and activity of efflux pumps. However, the analysis of transposon-tagged Pseudomonas aeruginosa mutants presented in this article shows that this phenotype emerges from the action of numerous proteins from all functional categories. Mutations in some genes make P. aeruginosa more susceptible to antibiotics and thereby represent new targets. Mutations in other genes make P. aeruginosa more resistant and therefore define novel mechanisms for mutation-driven acquisition of antibiotic resistance, opening a new research field based in the prediction of resistance before it emerges in clinical environments. Antibiotics are not just weapons against bacterial competitors, but also natural signalling molecules. Our results demonstrate that antibiotic resistance genes are not merely protective shields and offer a more comprehensive view of the role of antibiotic resistance genes in the clinic and in nature.

Emergence of Stenotrophomonas maltophilia nosocomial isolates in a Saudi children’s hospital. Risk factors and clinical characteristics

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Jobran M. Alqahtani

2017-05-01

Full Text Available Objectives: To describe the clinical characteristics of pediatric patients colonized or infected by Stenotrophomonas maltophilia (S. maltophilia at a Saudi children’s hospital, to identify risk factors associated with infection, and to investigate the antimicrobial resistance patterns of this emerging pathogen. Methods: In this cross-sectional observational study, 64 non-duplicating S. maltophilia strains were isolated in Najran Maternity and Children’s Hospital, Najran, Saudi Arabia between January 2015 to February 2016. Antimicrobial susceptibility testing was performed using the reference broth microdilution method. Results: In this study, 48 (75% isolates were identified in true infections and 16 (25% isolates were considered colonization. The main types of S. maltophilia infection were pneumonia in 22 (45.8% patients and bloodstream infection in 14 (29.2% patients. The significant risk factors included exposure to invasive procedure (p=0.02, and presence of acute leukemia as an underlying disease (p=0.02. The most active antimicrobials were trimethoprim/sulfamethoxazole (100% sensitivity and tigecycline (93.7% sensitivity. Conclusions: Stenotrophomonas maltophilia is an emerging nosocomial pathogen among pediatric patients. Accurate identification and susceptibility testing of this emerging pathogen are crucial for the management of infected patients and prevention of spread of this nosocomial pathogen.

Constructing rigorous and broad biosurveillance networks for detecting emerging zoonotic outbreaks.

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Mac Brown

Full Text Available Determining optimal surveillance networks for an emerging pathogen is difficult since it is not known beforehand what the characteristics of a pathogen will be or where it will emerge. The resources for surveillance of infectious diseases in animals and wildlife are often limited and mathematical modeling can play a supporting role in examining a wide range of scenarios of pathogen spread. We demonstrate how a hierarchy of mathematical and statistical tools can be used in surveillance planning help guide successful surveillance and mitigation policies for a wide range of zoonotic pathogens. The model forecasts can help clarify the complexities of potential scenarios, and optimize biosurveillance programs for rapidly detecting infectious diseases. Using the highly pathogenic zoonotic H5N1 avian influenza 2006-2007 epidemic in Nigeria as an example, we determined the risk for infection for localized areas in an outbreak and designed biosurveillance stations that are effective for different pathogen strains and a range of possible outbreak locations. We created a general multi-scale, multi-host stochastic SEIR epidemiological network model, with both short and long-range movement, to simulate the spread of an infectious disease through Nigerian human, poultry, backyard duck, and wild bird populations. We chose parameter ranges specific to avian influenza (but not to a particular strain and used a Latin hypercube sample experimental design to investigate epidemic predictions in a thousand simulations. We ranked the risk of local regions by the number of times they became infected in the ensemble of simulations. These spatial statistics were then complied into a potential risk map of infection. Finally, we validated the results with a known outbreak, using spatial analysis of all the simulation runs to show the progression matched closely with the observed location of the farms infected in the 2006-2007 epidemic.

Water Microbiology. Bacterial Pathogens and Water

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João P. S. Cabral

2010-10-01

Full Text Available Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water—cholera, typhoid fever and bacillary dysentery—is presented, focusing on the biology and ecology of the causal agents and on the diseases’ characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers. Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters.

Water microbiology. Bacterial pathogens and water.

Science.gov (United States)

Cabral, João P S

2010-10-01

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water-cholera, typhoid fever and bacillary dysentery-is presented, focusing on the biology and ecology of the causal agents and on the diseases' characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters.

Antibacterial resistance: an emerging 'zoonosis'?

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Labro, Marie-Thérèse; Bryskier, Jean-Marie

2014-12-01

Antibacterial resistance is a worldwide threat, and concerns have arisen about the involvement of animal commensal and pathogenic bacteria in the maintenance and spread of resistance genes. However, beyond the facts related to the occurrence of resistant microorganisms in food, food-producing animals and companion animals and their transmission to humans, it is important to consider the vast environmental 'resistome', the selective pathways underlying the emergence of antibacterial resistance and how we can prepare answers for tomorrow.

Echinococcus multilocularis: An Emerging Pathogen in Hungary and Central Eastern Europe?

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Sréter, Tamás; Széll, Zoltán; Egyed, Zsuzsa

2003-01-01

Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, is reported for the first time in Red Foxes (Vulpes vulpes) in Hungary. This parasite may be spreading eastward because the population of foxes has increased because of human interventions, and this spread may result in the emergence of alveolar echinococcosis in Central Eastern Europe. PMID:12643838

Widespread dispersal of the microsporidian Nosema ceranae, an emergent pathogen of the western honey bee, Apis mellifera.

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Klee, Julia; Besana, Andrea M; Genersch, Elke; Gisder, Sebastian; Nanetti, Antonio; Tam, Dinh Quyet; Chinh, Tong Xuan; Puerta, Francisco; Ruz, José Maria; Kryger, Per; Message, Dejair; Hatjina, Fani; Korpela, Seppo; Fries, Ingemar; Paxton, Robert J

2007-09-01

The economically most important honey bee species, Apis mellifera, was formerly considered to be parasitized by one microsporidian, Nosema apis. Recently, [Higes, M., Martín, R., Meana, A., 2006. Nosema ceranae, a new microsporidian parasite in honeybees in Europe, J. Invertebr. Pathol. 92, 93-95] and [Huang, W.-F., Jiang, J.-H., Chen, Y.-W., Wang, C.-H., 2007. A Nosema ceranae isolate from the honeybee Apis mellifera. Apidologie 38, 30-37] used 16S (SSU) rRNA gene sequences to demonstrate the presence of Nosema ceranae in A. mellifera from Spain and Taiwan, respectively. We developed a rapid method to differentiate between N. apis and N. ceranae based on PCR-RFLPs of partial SSU rRNA. The reliability of the method was confirmed by sequencing 29 isolates from across the world (N =9 isolates gave N. apis RFLPs and sequences, N =20 isolates gave N. ceranae RFLPs and sequences; 100% correct classification). We then employed the method to analyze N =115 isolates from across the world. Our data, combined with N =36 additional published sequences demonstrate that (i) N. ceranae most likely jumped host to A. mellifera, probably within the last decade, (ii) that host colonies and individuals may be co-infected by both microsporidia species, and that (iii) N. ceranae is now a parasite of A. mellifera across most of the world. The rapid, long-distance dispersal of N. ceranae is likely due to transport of infected honey bees by commercial or hobbyist beekeepers. We discuss the implications of this emergent pathogen for worldwide beekeeping.

Deciphering microbial landscapes of fish eggs to mitigate emerging diseases

NARCIS (Netherlands)

Liu, Y.; Bruijn, de I.; Jack, A.L.H.; Drynan, K.; Berg, van den A.H.; Thoen, E.; Sandoval-Sierra, V.; Skaar, I.; West, van P.; Diéguez-Uribeondo, J.; Voort, van der M.; Mendez, R.; Mazzola, M.; Raaijmakers, J.M.

2014-01-01

Animals and plants are increasingly suffering from diseases caused by fungi and oomycetes. These emerging pathogens are now recognized as a global threat to biodiversity and food security. Among oomycetes, Saprolegnia species cause significant declines in fish and amphibian populations. Fish eggs

Emerging mosquito-borne viruses: transmission and modulation of host defence

NARCIS (Netherlands)

Fros, J.J.

2015-01-01

Summary

Two highly pathogenic arthropod-borne (arbo)viruses, West Nile virus (WNV) and chikungunya virus (CHIKV), recently (re-)emerged in both Europe and the Americas. This resulted in large-scale epidemics of severe encephalitic and arthritogenic human disease,

Genomic evidence for the evolution of Streptococcus equi: host restriction, increased virulence, and genetic exchange with human pathogens.

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Matthew T G Holden

2009-03-01

Full Text Available The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus. These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A(2 toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci.

Vibrio tapetis Displays an Original Type IV Secretion System in Strains Pathogenic for Bivalve Molluscs

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Graciela M. Dias

2018-02-01

Full Text Available The Brown Ring Disease (BRD caused high mortality rates since 1986 in the Manila clam Venerupis philippinarum introduced and cultured in Western Europe from the 1970s. The causative agent of BRD is a Gram-Negative bacterium, Vibrio tapetis, which is also pathogenic to fish. Here we report the first assembly of the complete genome of V. tapetis CECT4600T, together with the genome sequences of 16 additional strains isolated across a broad host and geographic range. Our extensive genome dataset allowed us to describe the pathogen pan- and core genomes and to identify putative virulence factors. The V. tapetis core genome consists of 3,352 genes, including multiple potential virulence factors represented by haemolysins, transcriptional regulators, Type I restriction modification system, GGDEF domain proteins, several conjugative plasmids, and a Type IV secretion system. Future research on the coevolutionary arms race between V. tapetis virulence factors and host resistance mechanisms will improve our understanding of how pathogenicity develops in this emerging pathogen.

Evaluation of a new T2 Magnetic Resonance assay for rapid detection of emergent fungal pathogen Candida auris on clinical skin swab samples.

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Sexton, D Joseph; Bentz, Meghan L; Welsh, Rory M; Litvintseva, Anastasia P

2018-06-25

Candida auris is a multidrug-resistant pathogenic yeast whose recent emergence is of increasing public-health concern. C. auris can colonize multiple body sites, including patients' skin, and survive for weeks in the healthcare environment, facilitating patient-to-patient transmission and fueling healthcare-associated outbreaks. Rapid and accurate detection of C. auris colonization is essential for timely implementation of infection control measures and prevent transmission. Currently, axilla/groin composite swabs, used to assess colonization status, are processed using a culture-based method that is sensitive and specific but requires 14 days. This delay limits the opportunity to respond and highlights the need for a faster alternative. The culture-independent T2 Magnetic Resonance (T2MR) system is a rapid diagnostic platform shown to detect target pathogens of interest from unprocessed blood samples in T2 assay was evaluated for screening of the skin surveillance samples. Inclusivity and limit of detection of the T2 C. auris assay were assessed with spiked samples in a representative skin flora background. The T2 C. auris assay recognized isolates from each of the 4 known clades of C. auris and consistently detected cells at 5 CFU/mL. Finally, 89 clinical axilla/groin swab samples were processed with the T2 C. auris assay. The culture-based diagnostic assay was used as a gold standard to determine performance statistics including sensitivity (0.89) and specificity (0.98). Overall, the T2 C. auris assay performed well as a rapid diagnostic and could help expedite the detection of C. auris in patient skin swabs. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Diagnosis, Treatment, and Prevention of Hemodialysis Emergencies.

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Saha, Manish; Allon, Michael

2017-02-07

Given the high comorbidity in patients on hemodialysis and the complexity of the dialysis treatment, it is remarkable how rarely a life-threatening complication occurs during dialysis. The low rate of dialysis emergencies can be attributed to numerous safety features in modern dialysis machines; meticulous treatment and testing of the dialysate solution to prevent exposure to trace elements, toxins, and pathogens; adherence to detailed treatment protocols; and extensive training of dialysis staff to handle medical emergencies. Most hemodialysis emergencies can be attributed to human error. A smaller number are due to rare idiosyncratic reactions. In this review, we highlight major emergencies that may occur during hemodialysis treatments, describe their pathogenesis, offer measures to minimize them, and provide specific interventions to prevent catastrophic consequences on the rare occasions when such emergencies arise. These emergencies include dialysis disequilibrium syndrome, venous air embolism, hemolysis, venous needle dislodgement, vascular access hemorrhage, major allergic reactions to the dialyzer or treatment medications, and disruption or contamination of the dialysis water system. Finally, we describe root cause analysis after a dialysis emergency has occurred to prevent a future recurrence. Copyright © 2017 by the American Society of Nephrology.

Host and pathogen ecology drive the seasonal dynamics of a fungal disease, white-nose syndrome.

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Langwig, Kate E; Frick, Winifred F; Reynolds, Rick; Parise, Katy L; Drees, Kevin P; Hoyt, Joseph R; Cheng, Tina L; Kunz, Thomas H; Foster, Jeffrey T; Kilpatrick, A Marm

2015-01-22

Seasonal patterns in pathogen transmission can influence the impact of disease on populations and the speed of spatial spread. Increases in host contact rates or births drive seasonal epidemics in some systems, but other factors may occasionally override these influences. White-nose syndrome, caused by the emerging fungal pathogen Pseudogymnoascus destructans, is spreading across North America and threatens several bat species with extinction. We examined patterns and drivers of seasonal transmission of P. destructans by measuring infection prevalence and pathogen loads in six bat species at 30 sites across the eastern United States. Bats became transiently infected in autumn, and transmission spiked in early winter when bats began hibernating. Nearly all bats in six species became infected by late winter when infection intensity peaked. In summer, despite high contact rates and a birth pulse, most bats cleared infections and prevalence dropped to zero. These data suggest the dominant driver of seasonal transmission dynamics was a change in host physiology, specifically hibernation. Our study is the first, to the best of our knowledge, to describe the seasonality of transmission in this emerging wildlife disease. The timing of infection and fungal growth resulted in maximal population impacts, but only moderate rates of spatial spread. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Insights on the Horizontal Gene Transfer of Carbapenemase Determinants in the Opportunistic Pathogen Acinetobacter baumannii

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Da Silva, Gabriela Jorge; Domingues, Sara

2016-01-01

Horizontal gene transfer (HGT) is a driving force to the evolution of bacteria. The fast emergence of antimicrobial resistance reflects the ability of genetic adaptation of pathogens. Acinetobacter baumannii has emerged in the last few decades as an important opportunistic nosocomial pathogen, in part due to its high capacity of acquiring resistance to diverse antibiotic families, including to the so-called last line drugs such as carbapenems. The rampant selective pressure and genetic exchange of resistance genes hinder the effective treatment of resistant infections. A. baumannii uses all the resistance mechanisms to survive against carbapenems but production of carbapenemases are the major mechanism, which may act in synergy with others. A. baumannii appears to use all the mechanisms of gene dissemination. Beyond conjugation, the mostly reported recent studies point to natural transformation, transduction and outer membrane vesicles-mediated transfer as mechanisms that may play a role in carbapenemase determinants spread. Understanding the genetic mobilization of carbapenemase genes is paramount in preventing their dissemination. Here we review the carbapenemases found in A. baumannii and present an overview of the current knowledge of contributions of the various HGT mechanisms to the molecular epidemiology of carbapenem resistance in this relevant opportunistic pathogen. PMID:27681923

A novel approach for differentiating pathogenic and non-pathogenic Leptospira based on molecular fingerprinting.

Science.gov (United States)

Xiao, Di; Zhang, Cuicai; Zhang, Huifang; Li, Xiuwen; Jiang, Xiugao; Zhang, Jianzhong

2015-04-24

Leptospirosis is a worldwide, deadly zoonotic disease. Pathogenic Leptospira causes leptospirosis. The rapid and accurate identification of pathogenic and non-pathogenic Leptospira strains is essential for appropriate therapeutic management and timely intervention for infection control. The molecular fingerprint is a simple and rapid alternative tool for microorganisms identification, which is based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In this study, molecular fingerprint was performed to identify pathogenic strains of Leptospira. Phylogenetic analysis based on 16S rRNA gene sequences was used as the reference method. In addition, a label-free technique was used to reveal the different proteins of pathogenic or non-pathogenic Leptospira. A reference database was constructed using 30 Leptospira strains, including 16 pathogenic strains and 14 non-pathogenic strains. Two super reference spectra that were associated with pathogenicity were established. Overall, 33 Leptospira strains were used for validation, and 32 of 33 Leptospira strains could be identified on the species level and all the 33 could be classified as pathogenic or non-pathogenic. The super reference spectra and the major spectra projection (MSP) dendrogram correctly categorized the Leptospira strains into pathogenic and non-pathogenic groups, which was consistent with the 16S rRNA reference methods. Between the pathogenic and non-pathogenic strains, 108 proteins were differentially expressed. molecular fingerprint is an alternative to conventional molecular identification and can rapidly distinguish between pathogenic and non-pathogenic Leptospira strains. Therefore, molecular fingerprint may play an important role in the clinical diagnosis, treatment, surveillance, and tracking of epidemic outbreaks of leptospirosis. Leptospirosis is a worldwide zoonosis that is caused by spirochetes of the genus Leptospira. Leptospirosis is a serious zoonotic

One Health, emerging infectious diseases and wildlife: two decades of progress?

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Cunningham, Andrew A; Daszak, Peter; Wood, James L N

2017-07-19

Infectious diseases affect people, domestic animals and wildlife alike, with many pathogens being able to infect multiple species. Fifty years ago, following the wide-scale manufacture and use of antibiotics and vaccines, it seemed that the battle against infections was being won for the human population. Since then, however, and in addition to increasing antimicrobial resistance among bacterial pathogens, there has been an increase in the emergence of, mostly viral, zoonotic diseases from wildlife, sometimes causing fatal outbreaks of epidemic proportions. Concurrently, infectious disease has been identified as an increasing threat to wildlife conservation. A synthesis published in 2000 showed common anthropogenic drivers of disease threats to biodiversity and human health, including encroachment and destruction of wildlife habitat and the human-assisted spread of pathogens. Almost two decades later, the situation has not changed and, despite improved knowledge of the underlying causes, little has been done at the policy level to address these threats. For the sake of public health and wellbeing, human-kind needs to work better to conserve nature and preserve the ecosystem services, including disease regulation, that biodiversity provides while also understanding and mitigating activities which lead to disease emergence. We consider that holistic, One Health approaches to the management and mitigation of the risks of emerging infectious diseases have the greatest chance of success.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'. © 2017 The Authors.

Cytosolic access of intracellular bacterial pathogens: the Shigella paradigm

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Nora eMellouk

2016-04-01

Full Text Available Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Adaption of wild-bird origin H5Nx highly pathogenic avian influenza virus Clade 2.3.4.4 in vaccinated poultry

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The 2014-2015 incursion of H5Nx clade 2.3.4.4 high pathogenicity avian influenza (HPAI) virus caused the largest animal health emergency in U.S. history and renewed interest in developing vaccines against these newly emergent viruses. Our previous research demonstrated several H5 vaccines with varyi...

Dual RNA-seq of the plant pathogen phytophthora ramorum and its tanoak host

Science.gov (United States)

Katherine J. Hayden; Matteo Garbelotto; Brian J. Knaus; Richard C. Cronn; Hardeep Rai; Jessica W. Wright

2014-01-01

Emergent diseases are an ever-increasing threat to forests and forest ecosystems and necessitate the development of research tools for species that often may have few preexisting resources. We sequenced the mRNA expressed by the sudden oak death pathogen Phytophthora ramorum and its most susceptible forest host, tanoak, within the same tissue at two time points after...

The evolution of plant secretory structures and emergence of terpenoid chemical diversity.

Science.gov (United States)

Lange, Bernd Markus

2015-01-01

Secretory structures in terrestrial plants appear to have first emerged as intracellular oil bodies in liverworts. In vascular plants, internal secretory structures, such as resin ducts and laticifers, are usually found in conjunction with vascular bundles, whereas subepidermal secretory cavities and epidermal glandular trichomes generally have more complex tissue distribution patterns. The primary function of plant secretory structures is related to defense responses, both constitutive and induced, against herbivores and pathogens. The ability to sequester secondary (or specialized) metabolites and defense proteins in secretory structures was a critical adaptation that shaped plant-herbivore and plant-pathogen interactions. Although this review places particular emphasis on describing the evolution of pathways leading to terpenoids, it also assesses the emergence of other metabolite classes to outline the metabolic capabilities of different plant lineages.

Novel Eurasian Highly Pathogenic Influenza A H5 Viruses in Wild Birds, Washington, USA, 2014

Centers for Disease Control (CDC) Podcasts

2015-03-24

Sarah Gregory reads an abridged version of the article, Novel Eurasian Highly Pathogenic Influenza A H5 Viruses in Wild Birds, Washington, USA, 2014.  Created: 3/24/2015 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 4/13/2015.

The Natural Evolutionary Potential of Tree Populations to Cope with Newly Introduced Pests and Pathogens

DEFF Research Database (Denmark)

Budde, Katharina Birgit; Nielsen, Lene Rostgaard; Ravn, Hans Peter

2016-01-01

Emerging diseases often originate from host shifts of introduced pests or pathogens. Genetic resistance of the host to such diseases might be limited or absent due to the lack of coevolutionary history. We review six examples of major disease outbreaks on native tree species caused by different...

DEVELOPMENT OF A MOLECULAR METHOD TO IDENTIFY THE MERGING PATHOGEN HEPATITIS E IN WATER SAMPLES

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Hepatitis E virus (HEV) is an emerging pathogen that causes significant illness in the developing world. Like the hepatitis A virus, it is transmitted via the fecal-oral route and can cause short-term, acute hepatitis. In addition, hepatitis E has been found to cause a signific...

Novel genetic reassortants in H9N2 influenza A viruses and their diverse pathogenicity to mice

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Bi Yuhai

2011-11-01

Full Text Available Abstract Background H9N2 influenza A viruses have undergone extensive reassortments in different host species, and could lead to the epidemics or pandemics with the potential emergence of novel viruses. Methods To understand the genetic and pathogenic features of early and current circulating H9N2 viruses, 15 representative H9N2 viruses isolated from diseased chickens in northern China between 1998 and 2010 were characterized and compared with all Chinese H9N2 viruses available in the NCBI database. Then, the representative viruses of different genotypes were selected to study the pathogenicity in mice with the aim to investigate the adaptation and the potential pathogenicity of the novel H9N2 reassortants to mammals. Results Our results demonstrated that most of the 15 isolates were reassortants and generated four novel genotypes (B62-B65, which incorporated the gene segments from Eurasian H9N2 lineage, North American H9N2 branch, and H5N1 viruses. It was noteworthy that the newly identified genotype B65 has been prevalent in China since 2007, and more importantly, different H9N2 influenza viruses displayed a diverse pathogenicity to mice. The isolates of the 2008-2010 epidemic (genotypes B55 and B65 were lowly infectious, while two representative viruses of genotypes B0 and G2 isolated from the late 1990s were highly pathogenic to mice. In addition, Ck/SD/LY-1/08 (genotype 63, containing H5N1-like NP and PA genes was able to replicate well in mouse lungs with high virus titers but caused mild clinical signs. Conclusion Several lines of evidence indicated that the H9N2 influenza viruses constantly change their genetics and pathogenicity. Thus, the genetic evolution of H9N2 viruses and their pathogenicity to mammals should be closely monitored to prevent the emergence of novel pandemic viruses.

Rapid Identification of Emerging Human-Pathogenic Sporothrix Species with Rolling Circle Amplification

NARCIS (Netherlands)

Rodrigues, Anderson M; Najafzadeh, Mohammad J; de Hoog, G Sybren; de Camargo, Zoilo P

2015-01-01

Sporothrix infections are emerging as an important human and animal threat among otherwise healthy patients, especially in Brazil and China. Correct identification of sporotrichosis agents is beneficial for epidemiological surveillance, enabling implementation of adequate public-health policies and

Complete genome and comparative analysis of Streptococcus gallolyticus subsp. gallolyticus, an emerging pathogen of infective endocarditis

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Dreier Jens

2011-08-01

Full Text Available Abstract Background Streptococcus gallolyticus subsp. gallolyticus is an important causative agent of infectious endocarditis, while the pathogenicity of this species is widely unclear. To gain insight into the pathomechanisms and the underlying genetic elements for lateral gene transfer, we sequenced the entire genome of this pathogen. Results We sequenced the whole genome of S. gallolyticus subsp. gallolyticus strain ATCC BAA-2069, consisting of a 2,356,444 bp circular DNA molecule with a G+C-content of 37.65% and a novel 20,765 bp plasmid designated as pSGG1. Bioinformatic analysis predicted 2,309 ORFs and the presence of 80 tRNAs and 21 rRNAs in the chromosome. Furthermore, 21 ORFs were detected on the plasmid pSGG1, including tetracycline resistance genes telL and tet(O/W/32/O. Screening of 41 S. gallolyticus subsp. gallolyticus isolates revealed one plasmid (pSGG2 homologous to pSGG1. We further predicted 21 surface proteins containing the cell wall-sorting motif LPxTG, which were shown to play a functional role in the adhesion of bacteria to host cells. In addition, we performed a whole genome comparison to the recently sequenced S. gallolyticus subsp. gallolyticus strain UCN34, revealing significant differences. Conclusions The analysis of the whole genome sequence of S. gallolyticus subsp. gallolyticus promotes understanding of genetic factors concerning the pathogenesis and adhesion to ECM of this pathogen. For the first time we detected the presence of the mobilizable pSGG1 plasmid, which may play a functional role in lateral gene transfer and promote a selective advantage due to a tetracycline resistance.

Repurposing Clinical Molecule Ebselen to Combat Drug Resistant Pathogens.

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Thangamani, Shankar; Younis, Waleed; Seleem, Mohamed N

2015-01-01

Without a doubt, our current antimicrobials are losing the battle in the fight against newly-emerged multidrug-resistant pathogens. There is a pressing, unmet need for novel antimicrobials and novel approaches to develop them; however, it is becoming increasingly difficult and costly to develop new antimicrobials. One strategy to reduce the time and cost associated with antimicrobial innovation is drug repurposing, which is to find new applications outside the scope of the original medical indication of the drug. Ebselen, an organoselenium clinical molecule, possesses potent antimicrobial activity against clinical multidrug-resistant Gram-positive pathogens, including Staphylococcus, Streptococcus, and Enterococcus, but not against Gram-negative pathogens. Moreover, the activity of ebselen against Gram-positive pathogens exceeded those activities determined for vancomycin and linezolid, drugs of choice for treatment of Enterococcus and Staphylococcus infections. The minimum inhibitory concentrations of ebselen at which 90% of clinical isolates of Enterococcus and Staphylococcus were inhibited (MIC90) were found to be 0.5 and 0.25 mg/L, respectively. Ebselen showed significant clearance of intracellular methicillin-resistant S. aureus (MRSA) in comparison to vancomycin and linezolid. We demonstrated that ebselen inhibits the bacterial translation process without affecting mitochondrial biogenesis. Additionally, ebselen was found to exhibit excellent activity in vivo in a Caenorhabditis elegans MRSA-infected whole animal model. Finally, ebselen showed synergistic activities with conventional antimicrobials against MRSA. Taken together, our results demonstrate that ebselen, with its potent antimicrobial activity and safety profiles, can be potentially used to treat multidrug resistant Gram-positive bacterial infections alone or in combination with other antibiotics and should be further clinically evaluated.

Decay Of Bacterial Pathogens, Fecal Indicators, And Real-Time Quantitative PCR Genetic Markers In Manure-Amended Soils

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This study examined persistence and decay of bacterial pathogens, fecal indicator bacteria (FIB), and emerging real-time quantitative PCR (qPCR) genetic markers for rapid detection of fecal pollution in manure-amended agricultural soils. Known concentrations of transformed green...

Decay Of Bacterial Pathogen, Fecal Indicators, And Real-Time Quantitative PCR Genetic Markers In Manure Amended Soils

Science.gov (United States)

This study examined persistence and decay of bacterial pathogens, fecal indicator bacteria, and emerging real-time quantitative PCR (qPCR) genetic markers for rapid detection of fecal pollution in manre-amended agricultural soils. Known concentrations of transformed green fluore...

The varieties of immunological experience: of pathogens, stress, and dendritic cells.

Science.gov (United States)

Pulendran, Bali

2015-01-01

In the 40 years since their discovery, dendritic cells (DCs) have been recognized as central players in immune regulation. DCs sense microbial stimuli through pathogen-recognition receptors (PRRs) and decode, integrate, and present information derived from such stimuli to T cells, thus stimulating immune responses. DCs can also regulate the quality of immune responses. Several functionally specialized subsets of DCs exist, but DCs also display functional plasticity in response to diverse stimuli. In addition to sensing pathogens via PRRs, emerging evidence suggests that DCs can also sense stress signals, such as amino acid starvation, through ancient stress and nutrient sensing pathways, to stimulate adaptive immunity. Here, I discuss these exciting advances in the context of a historic perspective on the discovery of DCs and their role in immune regulation. I conclude with a discussion of emerging areas in DC biology in the systems immunology era and suggest that the impact of DCs on immunity can be usefully contextualized in a hierarchy-of-organization model in which DCs, their receptors and signaling networks, cell-cell interactions, tissue microenvironment, and the host macroenvironment represent different levels of the hierarchy. Immunity or tolerance can then be represented as a complex function of each of these hierarchies.

Ensuring privacy in the study of pathogen genetics.

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Mehta, Sanjay R; Vinterbo, Staal A; Little, Susan J

2014-08-01

Rapid growth in the genetic sequencing of pathogens in recent years has led to the creation of large sequence databases. This aggregated sequence data can be very useful for tracking and predicting epidemics of infectious diseases. However, the balance between the potential public health benefit and the risk to personal privacy for individuals whose genetic data (personal or pathogen) are included in such work has been difficult to delineate, because neither the true benefit nor the actual risk to participants has been adequately defined. Existing approaches to minimise the risk of privacy loss to participants are based on de-identification of data by removal of a predefined set of identifiers. These approaches neither guarantee privacy nor protect the usefulness of the data. We propose a new approach to privacy protection that will quantify the risk to participants, while still maximising the usefulness of the data to researchers. This emerging standard in privacy protection and disclosure control, which is known as differential privacy, uses a process-driven rather than data-centred approach to protecting privacy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Encephalitis Caused by Pathogens Transmitted through Organ Transplants, United States, 2002–2013

Centers for Disease Control (CDC) Podcasts

2014-10-21

Dr. Mike Miller reads an abridged version of the article, Encephalitis Caused by Pathogens Transmitted through Organ Transplants, United States, 2002–2013.  Created: 10/21/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 10/23/2014.

Intervention strategies for control of foodborne pathogens

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Juneja, Vijay K.

2004-03-01

The increasing numbers of illnesses associated with foodborne pathogens such as Listeria monocytogenes and Escherichia coli O157:H7, has renewed concerns about food safety because of consumer preferences for minimally processed foods that offer convenience in availability and preparation. Accordingly, the need for better control of foodborne pathogens has been paramount in recent years. Mechanical removal of microorganisms from food can be accomplished by centrifugation, filtration, trimming and washing. Cleaning and sanitation strategies can be used for minimizing the access of microorganisms in foods from various sources. Other strategies for control of foodborne pathogens include established physical microbiocidal treatments such as ionizing radiation and heating. Research has continued to demonstrate that food irradiation is a suitable process to control and possibly eliminate foodborne pathogens, for example Listeria monocytogenes and Escherichia coli O157:H7, from a number of raw and cooked meat and poultry products. Heat treatment is the most common method in use today for the inactivation of microorganisms. Microorganisms can also be destroyed by nonthermal treatments, such as application of high hydrostatic pressure, pulsed electric fields, oscillating magnetic fields or a combination of physical processes such as heat-irradiation, or heat-high hydrostatic pressure, etc. Each of the non-thermal technologies has specific applications in terms of the types of food that can be processed. Both conventional and newly developed physical treatments can be used in combination for controlling foodborne pathogens and enhancing the safety and shelf life of foods. Recent research has focused on combining traditional preservation factors with emerging intervention technologies. However, many key issues still need to be addressed for combination preservation factors or technologies to be useful in the food industry to meet public demands for foods with enhanced safety

Reservoir-host amplification of disease impact in an endangered amphibian.

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Scheele, Ben C; Hunter, David A; Brannelly, Laura A; Skerratt, Lee F; Driscoll, Don A

2017-06-01

Emerging wildlife pathogens are an increasing threat to biodiversity. One of the most serious wildlife diseases is chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which has been documented in over 500 amphibian species. Amphibians vary greatly in their susceptibility to Bd; some species tolerate infection, whereas others experience rapid mortality. Reservoir hosts-species that carry infection while maintaining high abundance but are rarely killed by disease-can increase extinction risk in highly susceptible, sympatric species. However, whether reservoir hosts amplify Bd in declining amphibian species has not been examined. We investigated the role of reservoir hosts in the decline of the threatened northern corroboree frog (Pseudophryne pengilleyi) in an amphibian community in southeastern Australia. In the laboratory, we characterized the response of a potential reservoir host, the (nondeclining) common eastern froglet (Crinia signifera), to Bd infection. In the field, we conducted frog abundance surveys and Bd sampling for both P. pengilleyi and C. signifera. We built multinomial logistic regression models to test whether Crinia signifera and environmental factors were associated with P. pengilleyi decline. C. signifera was a reservoir host for Bd. In the laboratory, many individuals maintained intense infections (>1000 zoospore equivalents) over 12 weeks without mortality, and 79% of individuals sampled in the wild also carried infections. The presence of C. signifera at a site was strongly associated with increased Bd prevalence in sympatric P. pengilleyi. Consistent with disease amplification by a reservoir host, P. pengilleyi declined at sites with high C. signifera abundance. Our results suggest that when reservoir hosts are present, population declines of susceptible species may continue long after the initial emergence of Bd, highlighting an urgent need to assess extinction risk in remnant populations of other declined

Community-acquired methicillin-resistant Staphylococcus aureus: an emerging pathogen in orthopaedics.

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Marcotte, Anthony L; Trzeciak, Marc A

2008-02-01

Staphylococcus aureus (S aureus) remains one of the most common pathogens for skin and soft-tissue infections encountered by the orthopaedic surgeon. Community-acquired methicillin-resistant S aureus (CA-MRSA) has become increasingly prevalent, particularly among athletes, children in day care, homeless persons, intravenous drug users, men who have sex with men, military recruits, certain minorities (ie, Alaskan Natives, Native Americans, Pacific Islanders), and prison inmates. Risk factors include antibiotic use within the preceding year, crowded living conditions, compromised skin integrity, contaminated surfaces, frequent skin-to-skin contact, shared items, and suboptimal cleanliness. When a patient presents with a skin or soft-tissue infection, the clinician should determine whether an abscess or other infection needs to be surgically incised and drained. Cultures should be performed. When the patient is a member of an at-risk group or has any of the risk factors for CA-MRSA, beta-lactam antibiotics (eg, methicillin) are no longer a reasonable choice for treatment. Empiric treatment should consist of non-beta-lactam antibiotics active against CA-MRSA.

Public health implications of emerging zoonoses.

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Meslin, F X; Stöhr, K; Heymann, D

2000-04-01

Many new, emerging and re-emerging diseases of humans are caused by pathogens which originate from animals or products of animal origin. A wide variety of animal species, both domestic and wild, act as reservoirs for these pathogens, which may be viruses, bacteria or parasites. Given the extensive distribution of the animal species affected, the effective surveillance, prevention and control of zoonotic diseases pose a significant challenge. The authors describe the direct and indirect implications for public health of emerging zoonoses. Direct implications are defined as the consequences for human health in terms of morbidity and mortality. Indirect implications are defined as the effect of the influence of emerging zoonotic disease on two groups of people, namely: health professionals and the general public. Professional assessment of the importance of these diseases influences public health practices and structures, the identification of themes for research and allocation of resources at both national and international levels. The perception of the general public regarding the risks involved considerably influences policy-making in the health field. Extensive outbreaks of zoonotic disease are not uncommon, especially as the disease is often not recognised as zoonotic at the outset and may spread undetected for some time. However, in many instances, the direct impact on health of these new, emerging or re-emerging zoonoses has been small compared to that of other infectious diseases affecting humans. To illustrate the tremendous indirect impact of emerging zoonotic diseases on public health policy and structures and on public perception of health risks, the authors provide a number of examples, including that of the Ebola virus, avian influenza, monkeypox and bovine spongiform encephalopathy. Recent epidemics of these diseases have served as a reminder of the existence of infectious diseases and of the capacity of these diseases to occur unexpectedly in new

Development and application of an oligonucleotide microarray and real-time quantitative PCR for detection of wastewater bacterial pathogens

Energy Technology Data Exchange (ETDEWEB)

Lee, Dae-Young [National Water Research Institute, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, L7R 4A6 (Canada)], E-mail: daeyoung.lee@ec.gc.ca; Lauder, Heather; Cruwys, Heather; Falletta, Patricia [National Water Research Institute, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, L7R 4A6 (Canada); Beaudette, Lee A. [Environmental Science and Technology Centre, Environment Canada, 335 River Road South, Ottawa, Ontario, K1A 0H3 (Canada)], E-mail: lee.beaudette@ec.gc.ca

2008-07-15

Conventional microbial water quality test methods are well known for their technical limitations, such as lack of direct pathogen detection capacity and low throughput capability. The microarray assay has recently emerged as a promising alternative for environmental pathogen monitoring. In this study, bacterial pathogens were detected in municipal wastewater using a microarray equipped with short oligonucleotide probes targeting 16S rRNA sequences. To date, 62 probes have been designed against 38 species, 4 genera, and 1 family of pathogens. The detection sensitivity of the microarray for a waterborne pathogen Aeromonas hydrophila was determined to be approximately 1.0% of the total DNA, or approximately 10{sup 3}A. hydrophila cells per sample. The efficacy of the DNA microarray was verified in a parallel study where pathogen genes and E. coli cells were enumerated using real-time quantitative PCR (qPCR) and standard membrane filter techniques, respectively. The microarray and qPCR successfully detected multiple wastewater pathogen species at different stages of the disinfection process (i.e. secondary effluents vs. disinfected final effluents) and at two treatment plants employing different disinfection methods (i.e. chlorination vs. UV irradiation). This result demonstrates the effectiveness of the DNA microarray as a semi-quantitative, high throughput pathogen monitoring tool for municipal wastewater.

Minimizing the Risk of Disease Transmission in Emergency Settings: Novel In Situ Physico-Chemical Disinfection of Pathogen-Laden Hospital Wastewaters.

Directory of Open Access Journals (Sweden)

Emanuele Sozzi

Full Text Available The operation of a health care facility, such as a cholera or Ebola treatment center in an emergency setting, results in the production of pathogen-laden wastewaters that may potentially lead to onward transmission of the disease. The research presented here evaluated the design and operation of a novel treatment system, successfully used by Médecins Sans Frontières in Haiti to disinfect CTC wastewaters in situ, eliminating the need for road haulage and disposal of the waste to a poorly-managed hazardous waste facility, thereby providing an effective barrier to disease transmission through a novel but simple sanitary intervention. The physico-chemical protocols eventually successfully treated over 600 m3 of wastewater, achieving coagulation/flocculation and disinfection by exposure to high pH (Protocol A and low pH (Protocol B environments, using thermotolerant coliforms as a disinfection efficacy index. In Protocol A, the addition of hydrated lime resulted in wastewater disinfection and coagulation/flocculation of suspended solids. In Protocol B, disinfection was achieved by the addition of hydrochloric acid, followed by pH neutralization and coagulation/flocculation of suspended solids using aluminum sulfate. Removal rates achieved were: COD >99%; suspended solids >90%; turbidity >90% and thermotolerant coliforms >99.9%. The proposed approach is the first known successful attempt to disinfect wastewater in a disease outbreak setting without resorting to the alternative, untested, approach of 'super chlorination' which, it has been suggested, may not consistently achieve adequate disinfection. A basic analysis of costs demonstrated a significant saving in reagent costs compared with the less reliable approach of super-chlorination. The proposed approach to in situ sanitation in cholera treatment centers and other disease outbreak settings represents a timely response to a UN call for onsite disinfection of wastewaters generated in such

Processes for managing pathogens.

Science.gov (United States)

Godfree, Alan; Farrell, Joseph

2005-01-01

Wastewater contains human, animal, and plant pathogens capable of causing viral, bacterial, or parasitic infections. There are several routes whereby sewage pathogens may affect human health, including direct contact, contamination of food crops, zoonoses, and vectors. The range and numbers of pathogens in municipal wastewater vary with the level of endemic disease in the community, discharges from commercial activities, and seasonal factors. Regulations to control pathogen risk in the United States and Europe arising from land application of biosolids are based on the concept of multiple barriers to the prevention of transmission. The barriers are (i) treatment to reduce pathogen content and vector attraction, (ii) restrictions on crops grown on land to which biosolids have been applied, and (iii) minimum intervals following application and grazing or harvesting. Wastewater treatment reduces number of pathogens in the wastewater by concentrating them with the solids in the sludge. Although some treatment processes are designed specifically to inactivate pathogens, many are not, and the actual mechanisms of microbial inactivation are not fully understood for all processes. Vector attraction is reduced by stabilization (reduction of readily biodegradable material) and/or incorporation immediately following application. Concerns about health risks have renewed interest in the effects of treatment (on pathogens) and advanced treatment methods, and work performed in the United States suggests that Class A pathogen reduction can be achieved less expensively than previously thought. Effective pathogen risk management requires control to the complete chain of sludge treatment, biosolids handling and application, and post-application activities. This may be achieved by adherence to quality management systems based on hazard analysis critical control point (HACCP) principles.

Genome-wide transcriptional response of Silurana (Xenopus tropicalis to infection with the deadly chytrid fungus.

Directory of Open Access Journals (Sweden)

Erica Bree Rosenblum

Full Text Available Emerging infectious diseases are of great concern for both wildlife and humans. Several highly virulent fungal pathogens have recently been discovered in natural populations, highlighting the need for a better understanding of fungal-vertebrate host-pathogen interactions. Because most fungal pathogens are not fatal in the absence of other predisposing conditions, host-pathogen dynamics for deadly fungal pathogens are of particular interest. The chytrid fungus Batrachochytrium dendrobatidis (hereafter Bd infects hundreds of species of frogs in the wild. It is found worldwide and is a significant contributor to the current global amphibian decline. However, the mechanism by which Bd causes death in amphibians, and the response of the host to Bd infection, remain largely unknown. Here we use whole-genome microarrays to monitor the transcriptional responses to Bd infection in the model frog species, Silurana (Xenopus tropicalis, which is susceptible to chytridiomycosis. To elucidate the immune response to Bd and evaluate the physiological effects of chytridiomycosis, we measured gene expression changes in several tissues (liver, skin, spleen following exposure to Bd. We detected a strong transcriptional response for genes involved in physiological processes that can help explain some clinical symptoms of chytridiomycosis at the organismal level. However, we detected surprisingly little evidence of an immune response to Bd exposure, suggesting that this susceptible species may not be mounting efficient innate and adaptive immune responses against Bd. The weak immune response may be partially explained by the thermal conditions of the experiment, which were optimal for Bd growth. However, many immune genes exhibited decreased expression in Bd-exposed frogs compared to control frogs, suggesting a more complex effect of Bd on the immune system than simple temperature-mediated immune suppression. This study generates important baseline data for ongoing

[Eradication of poliomyelitis and emergence of pathogenic vaccine-derived polioviruses: from Madagascar to Cameroon].

Science.gov (United States)

Delpeyroux, Francis; Colbère-Garapin, Florence; Razafindratsimandresy, Richter; Sadeuh-Mba, Serge; Joffret, Marie-Line; Rousset, Dominique; Blondel, Bruno

2013-11-01

The oral poliovaccine, a live vaccine made of attenuated poliovirus strains, is the main tool of the vaccination campaigns organised for eradicating poliomyelitis. these campaigns had led to the decline and, thereafter, to the disappearance of wild poliovirus strains of the three serotypes (1-3) in most parts of the world. However, when the poliovaccine coverage becomes too low, vaccine polioviruses can circulate in insufficiently immunized populations and become then pathogenic by mutations and genetic recombination with other enteroviruses of the same species, in particular some coxsackievirus A. These mutated and recombinant vaccine strains have been implicated in several epidemics of paralytic poliomyelitis. Two polio outbreaks associated with these pathogenic circulating vaccine-derived poliovirus (cVDPV) occurred in 2001-2002 and 2005 in the South of Madagascar where vaccine coverage was low. These cVDPV, of serotype 2 or 3, were isolated from paralyzed children and some of their healthy contacts. Other cVDPV were isolated in the same region from healthy children in 2011, indicating that these viruses were circulating again. Vaccination campaigns could stop the outbreaks in 2002 and 2005, and most probably prevent another one in 2011. Therefore, the genetic plasticity of poliovaccine strains that threatens the benefit of vaccination campaigns is the target of an accurate surveillance and an important theme of studies in the virology laboratories of the Institut Pasteur international network. © 2013 médecine/sciences – Inserm.

Migrating microbes: what pathogens can tell us about population movements and human evolution.

Science.gov (United States)

Houldcroft, Charlotte J; Ramond, Jean-Baptiste; Rifkin, Riaan F; Underdown, Simon J

2017-08-01

The biology of human migration can be observed from the co-evolutionary relationship with infectious diseases. While many pathogens are brief, unpleasant visitors to human bodies, others have the ability to become life-long human passengers. The story of a pathogen's genetic code may, therefore, provide insight into the history of its human host. The evolution and distribution of disease in Africa is of particular interest, because of the deep history of human evolution in Africa, the presence of a variety of non-human primates, and tropical reservoirs of emerging infectious diseases. This study explores which pathogens leave traces in the archaeological record, and whether there are realistic prospects that these pathogens can be recovered from sub-Saharan African archaeological contexts. Three stories are then presented of germs on a journey. The first is the story of HIV's spread on the back of colonialism and the railway networks over the last 150 years. The second involves the spread of Schistosoma mansoni, a parasite which shares its history with the trans-Atlantic slave trade and the origins of fresh-water fishing. Finally, we discuss the tantalising hints of hominin migration and interaction found in the genome of human herpes simplex virus 2. Evidence from modern African pathogen genomes can provide data on human behaviour and migration in deep time and contribute to the improvement of human quality-of-life and longevity.

The science and fiction of emerging rickettsioses.

Science.gov (United States)

Paddock, Christopher D

2009-05-01

As newly recognized rickettsial diseases and rickettsial pathogens increase in scope and magnitude, several elements related to the concept of emerging rickettsioses deserve consideration. Newly identified rickettsiae may be mildly pathogenic, or perhaps even nonpathogenic, and have little direct impact on human or animal health, yet nonetheless wield considerable influence on the epidemiology and ecology of historically recognized diseases. In this context "new" rickettsioses provide a lens through which "old" rickettsioses are more accurately represented. Predicting pathogen from nonpathogen is not an exact science, particularly as so few rickettsiae have been broadly accepted as nonpathogenic by contemporary rickettsiologists. However, various factors relating to specific physiologic requirements and molecular machinery of the particular rickettsia, as well as characteristics of its invertebrate host that either position or exclude the rickettsia from infecting a human host, must be considered. Close inspection of mild or atypical forms of historically recognized rickettsioses and a greater emphasis on culture- and molecular-based diagnostic techniques are the keys to identifying future rickettsial agents of disease.

From Insect to Man: Photorhabdus Sheds Light on the Emergence of Human Pathogenicity.

Directory of Open Access Journals (Sweden)

Geraldine Mulley

Full Text Available Photorhabdus are highly effective insect pathogenic bacteria that exist in a mutualistic relationship with Heterorhabditid nematodes. Unlike other members of the genus, Photorhabdus asymbiotica can also infect humans. Most Photorhabdus cannot replicate above 34°C, limiting their host-range to poikilothermic invertebrates. In contrast, P. asymbiotica must necessarily be able to replicate at 37°C or above. Many well-studied mammalian pathogens use the elevated temperature of their host as a signal to regulate the necessary changes in gene expression required for infection. Here we use RNA-seq, proteomics and phenotype microarrays to examine temperature dependent differences in transcription, translation and phenotype of P. asymbiotica at 28°C versus 37°C, relevant to the insect or human hosts respectively. Our findings reveal relatively few temperature dependant differences in gene expression. There is however a striking difference in metabolism at 37°C, with a significant reduction in the range of carbon and nitrogen sources that otherwise support respiration at 28°C. We propose that the key adaptation that enables P. asymbiotica to infect humans is to aggressively acquire amino acids, peptides and other nutrients from the human host, employing a so called "nutritional virulence" strategy. This would simultaneously cripple the host immune response while providing nutrients sufficient for reproduction. This might explain the severity of ulcerated lesions observed in clinical cases of Photorhabdosis. Furthermore, while P. asymbiotica can invade mammalian cells they must also resist immediate killing by humoral immunity components in serum. We observed an increase in the production of the insect Phenol-oxidase inhibitor Rhabduscin normally deployed to inhibit the melanisation immune cascade. Crucially we demonstrated this molecule also facilitates protection against killing by the alternative human complement pathway.

Xenosurveillance reflects traditional sampling techniques for the identification of human pathogens: A comparative study in West Africa.

Directory of Open Access Journals (Sweden)

Joseph R Fauver

2018-03-01

Full Text Available Novel surveillance strategies are needed to detect the rapid and continuous emergence of infectious disease agents. Ideally, new sampling strategies should be simple to implement, technologically uncomplicated, and applicable to areas where emergence events are known to occur. To this end, xenosurveillance is a technique that makes use of blood collected by hematophagous arthropods to monitor and identify vertebrate pathogens. Mosquitoes are largely ubiquitous animals that often exist in sizable populations. As well, many domestic or peridomestic species of mosquitoes will preferentially take blood-meals from humans, making them a unique and largely untapped reservoir to collect human blood.We sought to take advantage of this phenomenon by systematically collecting blood-fed mosquitoes during a field trail in Northern Liberia to determine whether pathogen sequences from blood engorged mosquitoes accurately mirror those obtained directly from humans. Specifically, blood was collected from humans via finger-stick and by aspirating bloodfed mosquitoes from the inside of houses. Shotgun metagenomic sequencing of RNA and DNA derived from these specimens was performed to detect pathogen sequences. Samples obtained from xenosurveillance and from finger-stick blood collection produced a similar number and quality of reads aligning to two human viruses, GB virus C and hepatitis B virus.This study represents the first systematic comparison between xenosurveillance and more traditional sampling methodologies, while also demonstrating the viability of xenosurveillance as a tool to sample human blood for circulating pathogens.

Natural disturbance reduces disease risk in endangered rainforest frog populations.

Science.gov (United States)

Roznik, Elizabeth A; Sapsford, Sarah J; Pike, David A; Schwarzkopf, Lin; Alford, Ross A

2015-08-21

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11-28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.

Emerging Infectious Diseases in Pregnancy.

Science.gov (United States)