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Sample records for dynamic hiv epidemic

  1. The evolutionary rate dynamically tracks changes in HIV-1 epidemics

    Energy Technology Data Exchange (ETDEWEB)

    Maljkovic-berry, Irina [Los Alamos National Laboratory; Athreya, Gayathri [Los Alamos National Laboratory; Daniels, Marcus [Los Alamos National Laboratory; Bruno, William [Los Alamos National Laboratory; Korber, Bette [Los Alamos National Laboratory; Kuiken, Carla [Los Alamos National Laboratory; Ribeiro, Ruy M [Los Alamos National Laboratory

    2009-01-01

    Large-sequence datasets provide an opportunity to investigate the dynamics of pathogen epidemics. Thus, a fast method to estimate the evolutionary rate from large and numerous phylogenetic trees becomes necessary. Based on minimizing tip height variances, we optimize the root in a given phylogenetic tree to estimate the most homogenous evolutionary rate between samples from at least two different time points. Simulations showed that the method had no bias in the estimation of evolutionary rates and that it was robust to tree rooting and topological errors. We show that the evolutionary rates of HIV-1 subtype B and C epidemics have changed over time, with the rate of evolution inversely correlated to the rate of virus spread. For subtype B, the evolutionary rate slowed down and tracked the start of the HAART era in 1996. Subtype C in Ethiopia showed an increase in the evolutionary rate when the prevalence increase markedly slowed down in 1995. Thus, we show that the evolutionary rate of HIV-1 on the population level dynamically tracks epidemic events.

  2. The role of recombination in the emergence of a complex and dynamic HIV epidemic

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    Morgenstern Burkhard

    2010-03-01

    Full Text Available Abstract Background Inter-subtype recombinants dominate the HIV epidemics in three geographical regions. To better understand the role of HIV recombinants in shaping the current HIV epidemic, we here present the results of a large-scale subtyping analysis of 9435 HIV-1 sequences that involve subtypes A, B, C, G, F and the epidemiologically important recombinants derived from three continents. Results The circulating recombinant form CRF02_AG, common in West Central Africa, appears to result from recombination events that occurred early in the divergence between subtypes A and G, followed by additional recent recombination events that contribute to the breakpoint pattern defining the current recombinant lineage. This finding also corrects a recent claim that G is a recombinant and a descendant of CRF02, which was suggested to be a pure subtype. The BC and BF recombinants in China and South America, respectively, are derived from recent recombination between contemporary parental lineages. Shared breakpoints in South America BF recombinants indicate that the HIV-1 epidemics in Argentina and Brazil are not independent. Therefore, the contemporary HIV-1 epidemic has recombinant lineages of both ancient and more recent origins. Conclusions Taken together, we show that these recombinant lineages, which are highly prevalent in the current HIV epidemic, are a mixture of ancient and recent recombination. The HIV pandemic is moving towards having increasing complexity and higher prevalence of recombinant forms, sometimes existing as "families" of related forms. We find that the classification of some CRF designations need to be revised as a consequence of (1 an estimated > 5% error in the original subtype assignments deposited in the Los Alamos sequence database; (2 an increasing number of CRFs are defined while they do not readily fit into groupings for molecular epidemiology and vaccine design; and (3 a dynamic HIV epidemic context.

  3. Phylodynamic analysis of HIV sub-epidemics in Mochudi, Botswana

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    Vlad Novitsky

    2015-12-01

    Real-time HIV genotyping and breaking down local HIV epidemics into phylogenetically distinct sub-epidemics may help to reveal the structure and dynamics of HIV transmission networks in communities, and aid in the design of targeted interventions for members of the acute sub-epidemics that likely fuel local HIV/AIDS epidemics.

  4. Emergence of recombinant forms in geographic regions with co-circulating HIV subtypes in the dynamic HIV-1 epidemic

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ming [Los Alamos National Laboratory; Letiner, Thomas K [Los Alamos National Laboratory; Korber, Bette T [Los Alamos National Laboratory; Foley, Brian [Los Alamos National Laboratory

    2009-01-01

    We have reexamined the subtype designations of {approx}10,000 subtype A, B, C, G, and AG, BC, BF recombinant sequences, and compared the results of the new analysis with their published designations. Intersubtype recombinants dominate HIV epidemics in three different geographical regions. The circulating recombinant from (CRF) CRF02-AG, common in West Central Africa, appears to result from a recombination event that occurred early in the divergence between subtypes A and G, although additional more recent recombination events may have contributed to the breakpoint pattern in this recombinant lineage as well. The Chinese recombinant epidemic strains CRF07 and CRF08, in contrast, result from recent recombinations between more contemporary strains. Nevertheless, CRF07 and CRF08 contributed to many subsequent recombination events. The BF recombinant epidemics in two HIV-1 epicenters in South America are not independent and BF epidemics in South America have an unusually high fraction of unique recombinant forms (URFs) that have each been found only once and carry distinctive breakpoints. Taken together, these analyses reveal a complex and dynamic picture of the current HIV-1 epidemic, and suggest a means of grouping and tracking relationships between viruses through preservation of shared breakpints.

  5. The dispersion of age differences between partners and the asymptotic dynamics of the HIV epidemic.

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    d'Albis, Hippolyte; Augeraud-Véron, Emmanuelle; Djemai, Elodie; Ducrot, Arnaud

    2012-01-01

    In this paper, the effect of a change in the distribution of age differences between sexual partners on the dynamics of the HIV epidemic is studied. In a gender- and age-structured compartmental model, it is shown that if the variance of the distribution is small enough, an increase in this variance strongly increases the basic reproduction number. Moreover, if the variance is large enough, the mean age difference barely affects the basic reproduction number. We, therefore, conclude that the local stability of the disease-free equilibrium relies more on the variance than on the mean.

  6. Spatiotemporal dynamics of the HIV-1 CRF06_cpx epidemic in Western Africa.

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    Delatorre, Edson; Bello, Gonzalo

    2013-05-15

    To investigate the origin and spatiotemporal dynamics of dissemination of the HIV-1 CRF06_cpx clade in western Africa. A total of 180 HIV-1 CRF06_cpx-like pol sequences isolated from 12 different countries from west and west-central Africa over a period of 16 years (1995-2010) were analyzed. Evolutionary, phylogeographic and demographic parameters were jointly estimated from sequence data using a Bayesian coalescent-based method and combined with molecular epidemiology and spatial accessibility data. The CRF06_cpx most probably emerged in Burkina Faso in 1979 (1970-1985). From Burkina Faso, the virus was first disseminated to Mali and Nigeria during the 1980s and later to other countries from west and west-central Africa. Demographic reconstruction indicates that the CRF06_cpx epidemic grew exponentially during the 1980s, with a median growth rate of 0.82 year (0.60-1.09 year), and after stabilize. We found a negative correlation between CRF06_cpx prevalence and the geographical distance to Burkina Faso's capital. Regional accessibility information agrees with the overall geographical range of the CRF06_cpx, but not fully explains the highly heterogeneous distribution pattern of this CRF at regional level. The CRF06_cpx epidemic in western Africa probably emerged at the late 1970s and grew during the 1980s at a rate comparable to the HIV-1 epidemics in the United States and Europe. Burkina Faso seems to be the most important epicenter of dissemination of the HIV-1 CRF06_cpx strain at regional level. The explanation for the current geographical distribution of CRF06_cpx is probably multifactorial.

  7. The Epidemic Dynamics of Four Major Lineages of HIV-1 CRF01_AE Strains After Their Introduction into China.

    Science.gov (United States)

    Zeng, Haiyan; Li, Tingting; Wang, Yan; Sun, Binlian; Yang, Rongge

    2016-05-01

    The epidemic of HIV-1 CRF01_AE in China was driven by multiple lineages of HIV-1 viruses introduced in the 1990s and increasing; it is important to investigate their epidemic status in China. In this study, we download all available CRF01_AE sequences (n = 2,931) from China and their associated epidemiological information in the Los Alamos HIV database for our analysis to explore their epidemic status in China. The results showed there were 11 distinct clusters of CRF01_AE strains in China, and 4 major clusters that accounted for 80.0% (1,793/2,241) of Chinese CRF01_AE strains in total had led a real epidemic. Clusters 1 and 2 were epidemic among heterosexuals and injecting drug users in southern and southwestern China, while Clusters 3 and 4 were predominant among homosexuals in eastern and central China and northeastern China, respectively. HIV-1 CRF01_AE strains detected in heterosexuals had the most complex characteristic, underscoring its important role in the occurrence of multiple CRF01_AE lineages. Furthermore, epidemic history reconstruction analysis using the birth-death susceptible-infected-removed package revealed that the four clusters had gone through varying epidemic stages. Clusters 2 and 3 were near the peak of the local epidemic, while Clusters 1 and 4 were just in the very early stage of their epidemic. The epidemic status of CRF01_AE clusters in the future is mainly determined by the effect of prevention and control. Our study provides new insights into the understanding of the epidemic dynamics of CRF01_AE in China.

  8. Understanding the effects of different HIV transmission models in individual-based microsimulation of HIV epidemic dynamics in people who inject drugs.

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    Monteiro, J F G; Escudero, D J; Weinreb, C; Flanigan, T; Galea, S; Friedman, S R; Marshall, B D L

    2016-06-01

    We investigated how different models of HIV transmission, and assumptions regarding the distribution of unprotected sex and syringe-sharing events ('risk acts'), affect quantitative understanding of HIV transmission process in people who inject drugs (PWID). The individual-based model simulated HIV transmission in a dynamic sexual and injecting network representing New York City. We constructed four HIV transmission models: model 1, constant probabilities; model 2, random number of sexual and parenteral acts; model 3, viral load individual assigned; and model 4, two groups of partnerships (low and high risk). Overall, models with less heterogeneity were more sensitive to changes in numbers risk acts, producing HIV incidence up to four times higher than that empirically observed. Although all models overestimated HIV incidence, micro-simulations with greater heterogeneity in the HIV transmission modelling process produced more robust results and better reproduced empirical epidemic dynamics.

  9. Using System Dynamics to model the HIV/AIDS epidemic in Botswana and Uganda

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    Howell, R.; Wesselink, O.; Pruyt, E.

    2013-01-01

    Uganda and Botswana present two interesting and contrasting cases in the AIDS epidemic. System dynamics models of the AIDS epidemic in Botswana and Uganda were created to examine the future development of the virus in both countries and evaluate existing and future policy measures. The effect of exi

  10. An HIV epidemic model based on viral load dynamics: value in assessing empirical trends in HIV virulence and community viral load.

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    Herbeck, Joshua T; Mittler, John E; Gottlieb, Geoffrey S; Mullins, James I

    2014-06-01

    Trends in HIV virulence have been monitored since the start of the AIDS pandemic, as studying HIV virulence informs our understanding of HIV epidemiology and pathogenesis. Here, we model changes in HIV virulence as a strictly evolutionary process, using set point viral load (SPVL) as a proxy, to make inferences about empirical SPVL trends from longitudinal HIV cohorts. We develop an agent-based epidemic model based on HIV viral load dynamics. The model contains functions for viral load and transmission, SPVL and disease progression, viral load trajectories in multiple stages of infection, and the heritability of SPVL across transmissions. We find that HIV virulence evolves to an intermediate level that balances infectiousness with longer infected lifespans, resulting in an optimal SPVL∼4.75 log10 viral RNA copies/mL. Adaptive viral evolution may explain observed HIV virulence trends: our model produces SPVL trends with magnitudes that are broadly similar to empirical trends. With regard to variation among studies in empirical SPVL trends, results from our model suggest that variation may be explained by the specific epidemic context, e.g. the mean SPVL of the founding lineage or the age of the epidemic; or improvements in HIV screening and diagnosis that results in sampling biases. We also use our model to examine trends in community viral load, a population-level measure of HIV viral load that is thought to reflect a population's overall transmission potential. We find that community viral load evolves in association with SPVL, in the absence of prevention programs such as antiretroviral therapy, and that the mean community viral load is not necessarily a strong predictor of HIV incidence.

  11. An HIV epidemic model based on viral load dynamics: value in assessing empirical trends in HIV virulence and community viral load.

    Directory of Open Access Journals (Sweden)

    Joshua T Herbeck

    2014-06-01

    Full Text Available Trends in HIV virulence have been monitored since the start of the AIDS pandemic, as studying HIV virulence informs our understanding of HIV epidemiology and pathogenesis. Here, we model changes in HIV virulence as a strictly evolutionary process, using set point viral load (SPVL as a proxy, to make inferences about empirical SPVL trends from longitudinal HIV cohorts. We develop an agent-based epidemic model based on HIV viral load dynamics. The model contains functions for viral load and transmission, SPVL and disease progression, viral load trajectories in multiple stages of infection, and the heritability of SPVL across transmissions. We find that HIV virulence evolves to an intermediate level that balances infectiousness with longer infected lifespans, resulting in an optimal SPVL∼4.75 log10 viral RNA copies/mL. Adaptive viral evolution may explain observed HIV virulence trends: our model produces SPVL trends with magnitudes that are broadly similar to empirical trends. With regard to variation among studies in empirical SPVL trends, results from our model suggest that variation may be explained by the specific epidemic context, e.g. the mean SPVL of the founding lineage or the age of the epidemic; or improvements in HIV screening and diagnosis that results in sampling biases. We also use our model to examine trends in community viral load, a population-level measure of HIV viral load that is thought to reflect a population's overall transmission potential. We find that community viral load evolves in association with SPVL, in the absence of prevention programs such as antiretroviral therapy, and that the mean community viral load is not necessarily a strong predictor of HIV incidence.

  12. Short-Term Dynamic and Local Epidemiological Trends in the South American HIV-1B Epidemic.

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    Junqueira, Dennis Maletich; de Medeiros, Rubia Marília; Gräf, Tiago; Almeida, Sabrina Esteves de Matos

    2016-01-01

    The human displacement and sexual behavior are the main factors driving the HIV-1 pandemic to the current profile. The intrinsic structure of the HIV transmission among different individuals has valuable importance for the understanding of the epidemic and for the public health response. The aim of this study was to characterize the HIV-1 subtype B (HIV-1B) epidemic in South America through the identification of transmission links and infer trends about geographical patterns and median time of transmission between individuals. Sequences of the protease and reverse transcriptase coding regions from 4,810 individuals were selected from GenBank. Maximum likelihood phylogenies were inferred and submitted to ClusterPicker to identify transmission links. Bayesian analyses were applied only for clusters including ≥5 dated samples in order to estimate the median maximum inter-transmission interval. This study analyzed sequences sampled from 12 South American countries, from individuals of different exposure categories, under different antiretroviral profiles, and from a wide period of time (1989-2013). Continentally, Brazil, Argentina and Venezuela were revealed important sites for the spread of HIV-1B among countries inside South America. Of note, from all the clusters identified about 70% of the HIV-1B infections are primarily occurring among individuals living in the same geographic region. In addition, these transmissions seem to occur early after the infection of an individual, taking in average 2.39 years (95% CI 1.48-3.30) to succeed. Homosexual/Bisexual individuals transmit the virus as quickly as almost half time of that estimated for the general population sampled here. Public health services can be broadly benefitted from this kind of information whether to focus on specific programs of response to the epidemic whether as guiding of prevention campaigns to specific risk groups.

  13. Short-Term Dynamic and Local Epidemiological Trends in the South American HIV-1B Epidemic.

    Directory of Open Access Journals (Sweden)

    Dennis Maletich Junqueira

    Full Text Available The human displacement and sexual behavior are the main factors driving the HIV-1 pandemic to the current profile. The intrinsic structure of the HIV transmission among different individuals has valuable importance for the understanding of the epidemic and for the public health response. The aim of this study was to characterize the HIV-1 subtype B (HIV-1B epidemic in South America through the identification of transmission links and infer trends about geographical patterns and median time of transmission between individuals. Sequences of the protease and reverse transcriptase coding regions from 4,810 individuals were selected from GenBank. Maximum likelihood phylogenies were inferred and submitted to ClusterPicker to identify transmission links. Bayesian analyses were applied only for clusters including ≥5 dated samples in order to estimate the median maximum inter-transmission interval. This study analyzed sequences sampled from 12 South American countries, from individuals of different exposure categories, under different antiretroviral profiles, and from a wide period of time (1989-2013. Continentally, Brazil, Argentina and Venezuela were revealed important sites for the spread of HIV-1B among countries inside South America. Of note, from all the clusters identified about 70% of the HIV-1B infections are primarily occurring among individuals living in the same geographic region. In addition, these transmissions seem to occur early after the infection of an individual, taking in average 2.39 years (95% CI 1.48-3.30 to succeed. Homosexual/Bisexual individuals transmit the virus as quickly as almost half time of that estimated for the general population sampled here. Public health services can be broadly benefitted from this kind of information whether to focus on specific programs of response to the epidemic whether as guiding of prevention campaigns to specific risk groups.

  14. Dynamics of beneficial epidemics

    CERN Document Server

    Berdahl, Andrew; De Bacco, Caterina; Dumas, Marion; Ferdinand, Vanessa; Grochow, Joshua A; Hébert-Dufresne, Laurent; Kallus, Yoav; Kempes, Christopher P; Kolchinsky, Artemy; Larremore, Daniel B; Libby, Eric; Power, Eleanor A; Stern, Caitlin A; Tracey, Brendan

    2016-01-01

    Pathogens can spread epidemically through populations. Beneficial contagions, such as viruses that enhance host survival or technological innovations that improve quality of life, also have the potential to spread epidemically. How do the dynamics of beneficial biological and social epidemics differ from those of detrimental epidemics? We investigate this question using three theoretical approaches as well as an empirical analysis of concept propagation. First, in evolutionary models, we show that a beneficial horizontally-transmissible element, such as viral DNA, spreads super-exponentially through a population, substantially more quickly than a beneficial mutation. Second, in an epidemiological social network approach, we show that infections that cause increased connectivity lead to faster-than-exponential fixation in the population. Third, in a sociological model with strategic rewiring, we find that preferences for increased global infection accelerate spread and produce super-exponential fixation rates,...

  15. An epidemic model for the transmission dynamics of HIV/AIDS with different clinical stages

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    Sandip Omar

    2010-06-01

    Full Text Available In this paper, a five–dimensional mathematical model is proposed for the transmission dynamics of HIV/AIDS within a population of varying size. In writing the model, we have divided the population under consideration into five sub classes of susceptible, infective, pre-AIDS, AIDS related complex and that of AIDS patients. The model has two non- negative equilibria namely, a disease free and the endemic equilibrium. The model has been studied using stability theory. It is shown that the positive non-trivial equilibrium is always locally stable but it may become globally stable under certain condition showing that the disease becomes endemic due to constant migration of the population into the habitat. The effect of various parameters on the spread of the disease has also been discussed.

  16. HIV/AIDS and Drug Abuse: Intertwined Epidemics

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    ... DrugFacts » HIV/AIDS and Drug Abuse: Intertwined Epidemics HIV/AIDS and Drug Abuse: Intertwined Epidemics Email Facebook ... to AIDS, greatly prolonging lives. What Exactly Is HIV/AIDS? HIV stands for human immunodeficiency virus. This ...

  17. Phylogenetics of the Danish HIV epidemic

    DEFF Research Database (Denmark)

    Audelin, Anne Margrethe; Cowan, Susan A; Obel, Niels

    2013-01-01

    BACKGROUND:: In Denmark 300 new individuals are diagnosed with HIV every year, despite decades of public health campaigns aimed to raise awareness of potential risk behaviour for HIV transmission. It is important to identify the driving forces of the epidemic, to enable more targeted campaigns...

  18. Monitoring linked epidemics: the case of tuberculosis and HIV.

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    María S Sánchez

    Full Text Available BACKGROUND: The tight epidemiological coupling between HIV and its associated opportunistic infections leads to challenges and opportunities for disease surveillance. METHODOLOGY/PRINCIPAL FINDINGS: We review efforts of WHO and collaborating agencies to track and fight the TB/HIV co-epidemic, and discuss modeling--via mathematical, statistical, and computational approaches--as a means to identify disease indicators designed to integrate data from linked diseases in order to characterize how co-epidemics change in time and space. We present R(TB/HIV, an index comparing changes in TB incidence relative to HIV prevalence, and use it to identify those sub-Saharan African countries with outlier TB/HIV dynamics. R(TB/HIV can also be used to predict epidemiological trends, investigate the coherency of reported trends, and cross-check the anticipated impact of public health interventions. Identifying the cause(s responsible for anomalous R(TB/HIV values can reveal information crucial to the management of public health. CONCLUSIONS/SIGNIFICANCE: We frame our suggestions for integrating and analyzing co-epidemic data within the context of global disease monitoring. Used routinely, joint disease indicators such as R(TB/HIV could greatly enhance the monitoring and evaluation of public health programs.

  19. HIV epidemic in Russia and neighbouring countries

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    Vadim Pokrovskiy

    2014-11-01

    Full Text Available Reports of HIV/AIDS cases attributed to sexual transmission from foreigners were published in the USSR in the mid of 80s. In the initial decade of the epidemic, the subtype B was found in men who have sex with men (MSM population and several non-B subtypes were identified in heterosexual persons. The first case of HIV infection in intravenous drug users (IVDU was reported in 1993 and since then a specific subtype A and its recombinants invaded the intravenous drug users (IVDU populations of the region with the highest rate in Estonia, Russia and Ukraine. The concentrated HIV epidemic in IVDUs is still the main problem in the Eastern Europe; however, the rate of heterosexual transmission is increasing and many evidences of HIV prevalence rise in MSM are published. UNAIDS estimations for the number of HIV-positive persons living in the region range from 980,000 to 1,300,000 but distribution of HIV-cases is uneven and the prevalence rate of HIV infection in separate regions is over 1%. Mass seasonal labour migration from Central Asia and Caucasian republics to Russia transmits HIV to these countries. Prevention programs in the region are limited, and ART coverage is not more than 20% of the total HIV-positive population. The lack of concern about the epidemic, absence of effective national strategies and limited allocated resources are the main barriers to prevention and care in many countries. Local conflicts, rising religiosity and discrimination are adverse factors. The near-term forecast for the epidemic in the region is pessimistic and further international advocacy is needed to improve the situation.

  20. Epidemic dynamics on complex networks

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tao; FU Zhongqian; WANG Binghong

    2006-01-01

    Recently, motivated by the pioneer work in revealing the small-world effect and scale-free property of various real-life networks, many scientists devote themselves to studying complex networks. One of the ultimate goals is to understand how the topological structures affect the dynamics upon networks. In this paper, we give a brief review on the studies of epidemic dynamics on complex networks, including the description of classical epidemic models, the epidemic spread on small-world and scale-free networks, and network immunization. Finally, perspectives and some interesting problems are proposed.

  1. Global HIV/AIDS Epidemic

    Science.gov (United States)

    ... to text United Nations. Transforming our world: the 2030 Agenda for Sustainable Development ; 2015. ← Return to text UNAIDS. 2011 Political Declaration on HIV/AIDS; 2011, available at: ... 2030 ; 2014. ← Return to text Global Fund. Grants Portfolio; ...

  2. Global HIV/AIDS Epidemic

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    ... Annual new HIV infections decreased by 50% in Thailand since 2010, but increased by 141% in the ... 27, 2003. ← Return to text U.S. Congress. Public Law No: 113-56; December 2, 2013. ← Return to ...

  3. HIV epidemic in South Africa: A comparison of HIV epidemic ...

    African Journals Online (AJOL)

    2014-08-26

    Aug 26, 2014 ... Results: Even though KwaZulu-Natal has the highest HIV prevalence ... amongst youth in KwaZulu-Natal compared with an increase in the same age group in .... expectation that increased access to ART will increase survival.

  4. The origin and emergence of an HIV-1 epidemic:

    DEFF Research Database (Denmark)

    Bruhn, Christian Anders Wathne; Audelin, Anne M.; Helleberg, Marie;

    2014-01-01

    To describe, at patient-level detail, the determining events and factors involved in the development of a country's HIV-1 epidemic.......To describe, at patient-level detail, the determining events and factors involved in the development of a country's HIV-1 epidemic....

  5. Abia State HIV epidemic and response: challenges and prospects.

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    Onyeonoro, Ugochukwu Uchenna; Emelumadu, Obiageli Fidelia; Nwamoh, Uche Ngozi; Ukegbu, Andrew Ugwunna; Okafor, Godwin Oc

    2014-11-13

    Since the first seroprevalence survey in 1999, the HIV prevalence in Abia State has increased from 1.8% to 7.3% in 2010. The state is currently experiencing a generalized epidemic, with most transmission occurring through heterosexual low-risk sex. Drivers of the epidemic include low knowledge of HIV prevention, low risk perception, predominantly male factor-driven risky sexual behavior, and low condom use. This study reviewed the state HIV epidemic trend in relation to response, sought to identify the gaps between the epidemic and response, and recommended measures to strengthen the state response.

  6. Untangling the Interplay between Epidemic Spread and Transmission Network Dynamics.

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    Christel Kamp

    Full Text Available The epidemic spread of infectious diseases is ubiquitous and often has a considerable impact on public health and economic wealth. The large variability in the spatio-temporal patterns of epidemics prohibits simple interventions and requires a detailed analysis of each epidemic with respect to its infectious agent and the corresponding routes of transmission. To facilitate this analysis, we introduce a mathematical framework which links epidemic patterns to the topology and dynamics of the underlying transmission network. The evolution, both in disease prevalence and transmission network topology, is derived from a closed set of partial differential equations for infections without allowing for recovery. The predictions are in excellent agreement with complementarily conducted agent-based simulations. The capacity of this new method is demonstrated in several case studies on HIV epidemics in synthetic populations: it allows us to monitor the evolution of contact behavior among healthy and infected individuals and the contributions of different disease stages to the spreading of the epidemic. This gives both direction to and a test bed for targeted intervention strategies for epidemic control. In conclusion, this mathematical framework provides a capable toolbox for the analysis of epidemics from first principles. This allows for fast, in silico modeling--and manipulation--of epidemics and is especially powerful if complemented with adequate empirical data for parameterization.

  7. The HIV-1 Epidemic: Low- to Middle-Income Countries

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    Shao, Yiming; Williamson, Carolyn

    2012-01-01

    Low- to middle-income countries bear the overwhelming burden of the human immunodeficiency virus type 1 (HIV-1) epidemic in terms of the numbers of their citizens living with HIV/AIDS (acquired immunodeficiency syndrome), the high degrees of viral diversity often involving multiple HIV-1 clades circulating within their populations, and the social and economic factors that compromise current control measures. Distinct epidemics have emerged in different geographical areas. These epidemics differ in their severity, the population groups they affect, their associated risk behaviors, and the viral strains that drive them. In addition to inflicting great human cost, the high burden of HIV infection has a major impact on the social and economic development of many low- to middle-income countries. Furthermore, the high degrees of viral diversity associated with multiclade HIV epidemics impacts viral diagnosis and pathogenicity and treatment and poses daunting challenges for effective vaccine development. PMID:22393534

  8. Paediatric HIV treatment failure: a silent epidemic

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    Jonathan M Bernheimer

    2015-07-01

    Full Text Available Paediatric antiretroviral treatment (ART failure is an under-recognized issue that receives inadequate attention in the field of paediatrics and within HIV treatment programmes. With paediatric ART failure rates ranging from 19.3% to over 32% in resource limited settings, a comprehensive evaluation of the causes of failure along with approaches to address barriers to treatment adherence are urgently needed.In partnership with the local Department of Health, a pilot programme has been established by Medecins Sans Frontieres (MSF in Khayelitsha, South Africa, to identify and support paediatric HIV patients with high viral loads and potential treatment failure. Through detailed clinical and psychosocial evaluations and adherence support with an innovative counselling model, treatment barriers are identified and addressed.Demographic and clinical characteristics from the cohort show a delayed median start date for ART, prolonged viraemia including a large number of patients who have never achieved viral load (VL suppression, a low rate of regimen changes despite failure, and a high percentage of pre-adolescent and adolescent patients who have not gone through the disclosure process.Stemming this epidemic of paediatric treatment failure requires programmatic responses to high viral loads in children, starting with improved “case finding” of previously undiagnosed HIV-infected children and adolescents. Viral load testing needs to be prioritized over CD4 count monitoring, and flagging systems to identify high VL results should be developed in clinics. Clinicians must understand that successful treatment begins with good adherence, and that simple adherence support strategies can often dramatically improve adherence. Moreover, appropriate adherence counselling should begin not when the child fails to respond to treatment. Establishing good adherence from the beginning of treatment, and supporting ongoing adherence during the milestones in these

  9. HIV/AIDS in Asia: The Shape of Epidemics and Their Molecular Epidemiology

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Asia-Pacific region is a home to 60% of the population in the world and to approximately one quarter of people with HIV/AIDS. Close to a million of people has been infected and a half million people died of AIDS annually in Asia, becoming the second largest epicenter of global AIDS epidemic. Molecular epidemiology has been useful tool to track a course of HIV spread. In-depth knowledge from the studies on molecular epidemiology elucidates the dynamics of HIV spread and the interrelationship of epidemics in the different regions in Asia.

  10. Know your epidemic, know your response: targeting HIV in Asia

    DEFF Research Database (Denmark)

    Lazarus, Jeff; Curth, Nadja; Bridge, Jamie

    2010-01-01

    prevention and treatment services. In order to reach the Millennium Development Goal of halting and reversing the spread of HIV by 2015 and to achieve universal access to HIV treatment, these barriers must be overcome across Asia. High-impact programs must be targeted at those in need, with continuous......This article provides an overview of the HIV epidemic in Asia, the context within which the epidemic is evolving, and the key actions to address the challenges faced by countries and risk groups. HIV epidemics across Asia are predominantly concentrated among most-at-risk populations. Although...... there have been many successes in the HIV response in Asia over the past decade, great challenges clearly remain - especially when addressing most-at-risk populations, who are often criminalized, marginalized, and discriminated against. These groups face significant legal and social barriers to accessing HIV...

  11. Fitting the HIV epidemic in Zambia: a two-sex micro-simulation model.

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    Pauline M Leclerc

    Full Text Available BACKGROUND: In describing and understanding how the HIV epidemic spreads in African countries, previous studies have not taken into account the detailed periods at risk. This study is based on a micro-simulation model (individual-based of the spread of the HIV epidemic in the population of Zambia, where women tend to marry early and where divorces are not frequent. The main target of the model was to fit the HIV seroprevalence profiles by age and sex observed at the Demographic and Health Survey conducted in 2001. METHODS AND FINDINGS: A two-sex micro-simulation model of HIV transmission was developed. Particular attention was paid to precise age-specific estimates of exposure to risk through the modelling of the formation and dissolution of relationships: marriage (stable union, casual partnership, and commercial sex. HIV transmission was exclusively heterosexual for adults or vertical (mother-to-child for children. Three stages of HIV infection were taken into account. All parameters were derived from empirical population-based data. Results show that basic parameters could not explain the dynamics of the HIV epidemic in Zambia. In order to fit the age and sex patterns, several assumptions were made: differential susceptibility of young women to HIV infection, differential susceptibility or larger number of encounters for male clients of commercial sex workers, and higher transmission rate. The model allowed to quantify the role of each type of relationship in HIV transmission, the proportion of infections occurring at each stage of disease progression, and the net reproduction rate of the epidemic (R(0 = 1.95. CONCLUSIONS: The simulation model reproduced the dynamics of the HIV epidemic in Zambia, and fitted the age and sex pattern of HIV seroprevalence in 2001. The same model could be used to measure the effect of changing behaviour in the future.

  12. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    G. Magiorkinis (Gkikas); K. Angelis (Konstantinos); I. Mamais (Ioannis); Katzourakis, A. (Aris); A. Hatzakis (Angelos); J. Albert (Jan); Lawyer, G. (Glenn); O. Hamouda (Osamah); D. Struck (Daniel); J. Vercauteren (Jurgen); A. Wensing (Amj); I. Alexiev (Ivailo); B. Åsjö (Birgitta); C. Balotta (Claudia); Gomes, P. (Perpétua); R.J. Camacho (Ricardo Jorge); S. Coughlan (Suzie); A. Griskevicius (Algirdas); Z. Grossman (Zehava); Horban, A. (Anders); L.G. Kostrikis (Leondios); Lepej, S.J. (Snjezana J.); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen; D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.C. Schmit; A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); Stylianou, D.C. (Dora C.); C.A. Boucher (Charles); Nikolopoulos, G. (Georgios); Vasylyeva, T. (Tetyana); Friedman, S.R. (Samuel R.); D.A.M.C. van de Vijver (David); G. Angarano (Guiseppe); M.L. Chaix (Marie Laure); A. de Luca (Andrea); K. Korn (Klaus); Loveday, C. (Clive); V. Soriano (Virtudes); S. Yerly (Sabine); M. Zazzi; A.M. Vandamme (Anne Mieke); D. Paraskevis (Dimitrios)

    2016-01-01

    textabstractHuman immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa

  13. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J.; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G.; Lepej, Snjezana J.; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C.; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R.; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne Mieke; Paraskevis, Dimitrios

    2016-01-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti

  14. The global spread of HIV-1 subtype B epidemic

    NARCIS (Netherlands)

    G. Magiorkinis (Gkikas); K. Angelis (Konstantinos); I. Mamais (Ioannis); Katzourakis, A. (Aris); A. Hatzakis (Angelos); J. Albert (Jan); Lawyer, G. (Glenn); O. Hamouda (Osamah); D. Struck (Daniel); J. Vercauteren (Jurgen); A. Wensing (Amj); I. Alexiev (Ivailo); B. Åsjö (Birgitta); C. Balotta (Claudia); Gomes, P. (Perpétua); R.J. Camacho (Ricardo Jorge); S. Coughlan (Suzie); A. Griskevicius (Algis); Z. Grossman (Zehava); Horban, A. (Anders); L.G. Kostrikis (Leondios); Lepej, S.J. (Snjezana J.); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen; D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.C. Schmit; A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); Stylianou, D.C. (Dora C.); C.A. Boucher (Charles); Nikolopoulos, G. (Georgios); Vasylyeva, T. (Tetyana); Friedman, S.R. (Samuel R.); D.A.M.C. van de Vijver (David); G. Angarano (Guiseppe); M.L. Chaix (Marie Laure); A. de Luca (Andrea); K. Korn (Klaus); Loveday, C. (Clive); V. Soriano (Virtudes); S. Yerly (Sabine); M. Zazzi; A.M. Vandamme (Anne Mieke); D. Paraskevis (Dimitrios)

    2016-01-01

    textabstractHuman immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa th

  15. HIV-1 epidemic in Warao Amerindians from Venezuela: spatial phylodynamics and epidemiological patterns.

    Science.gov (United States)

    Villalba, Julian A; Bello, Gonzalo; Maes, Mailis; Sulbaran, Yoneira F; Garzaro, Domingo; Loureiro, Carmen L; Rangel, Hector R; de Waard, Jacobus H; Pujol, Flor H

    2013-07-17

    We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities. HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic. HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities. A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.

  16. A qualitative view of the HIV epidemic in coastal Ecuador.

    Science.gov (United States)

    Beckman, Adam L; Wilson, Magdalena M; Prabhu, Vishaal; Soekoe, Nicola; Mata, Humberto; Grau, Lauretta E

    2016-01-01

    In 2013 approximately 37,000 people were living with HIV in Ecuador (prevalence 0.4%), representing a generalized epidemic where most new infections arise from sexual interactions in the general population. Studies that examine attitudes towards people living with HIV (PLWH), individual risk perception of acquiring HIV amongst Ecuadorians, and the ways in which levels of risk perception may affect risk behaviors are lacking. This qualitative study aimed to fill this gap in the literature by investigating these issues in the rural, coastal community of Manglaralto, Ecuador, which has among the highest incidence of HIV in Ecuador. We conducted interviews with 15 patients at Manglaralto Hospital. Analysis of interview transcripts revealed widespread negative attitudes towards PLWH, prevalent risk behaviors such as multiple sex partners and lack of condom use, and low individual risk-perception of contracting HIV. These findings underscore the need for increased efforts to prevent further growth of the HIV epidemic in Ecuador.

  17. HIV and AIDS: where is the epidemic going?

    OpenAIRE

    Mertens, T.E.; Low-Beer, D.

    1996-01-01

    Routine surveillance of HIV (human immunodeficiency virus) infection and AIDS has been established over the past decade in many countries around the world. HIV estimates derived from empirical data are essential to the assessment of the HIV situation in different parts of the world and trends are used in tracking the development of regional epidemics, thereby keeping intervention activities focused on realities. As of the end of 1995, and following an extensive country-by-country review of HI...

  18. The HIV/AIDS epidemic in Cuba: description and tentative explanation of its low HIV prevalence

    OpenAIRE

    Clémençon Stéphan; Legeai Camille; Lounes Rachid; Joanes Jose; de Arazoza Héctor; Pérez Jorge; Auvert Bertran

    2007-01-01

    Abstract Background The Cuban HIV/AIDS epidemic has the lowest prevalence rate of the Caribbean region. The objective of this paper is to give an overview of the HIV/AIDS epidemic in Cuba and to explore the reasons for this low prevalence. Methods Data were obtained from the Cuban HIV/AIDS programme established in 1983. This programme has an extensive adult HIV testing policy, including testing of all pregnant women. HIV and AIDS cases have been recorded since 1986. Persons found to be HIV-po...

  19. An HIV epidemic is ready to emerge in the Philippines

    Directory of Open Access Journals (Sweden)

    Farr Anna C

    2010-04-01

    Full Text Available Abstract Background The state of the HIV epidemic in the Philippines has been described as "low and slow", which is in stark contrast to many other countries in the region. A review of the conditions for HIV spread in the Philippines is necessary. Methods We evaluated the current epidemiology, trends in behaviour and public health response in the Philippines to identify factors that could account for the current HIV epidemic, as well as to review conditions that may be of concern for facilitating an emerging epidemic. Results The past control of HIV in the Philippines cannot be attributed to any single factor, nor is it necessarily a result of the actions of the Filipino government or other stakeholders. Likely reasons for the epidemic's slow development include: the country's geography is complicated; injecting drug use is relatively uncommon; a culture of sexual conservatism exists; sex workers tend to have few clients; anal sex is relatively uncommon; and circumcision rates are relatively high. In contrast, there are numerous factors suggesting that HIV is increasing and ready to emerge at high rates, including: the lowest documented rates of condom use in Asia; increasing casual sexual activity; returning overseas Filipino workers from high-prevalence settings; widespread misconceptions about HIV/AIDS; and high needle-sharing rates among injecting drug users. There was a three-fold increase in the rate of HIV diagnoses in the Philippines between 2003 and 2008, and this has continued over the past year. HIV diagnoses rates have noticeably increased among men, particularly among bisexual and homosexual men (114% and 214% respective increases over 2003-2008. The average age of diagnosis has also significantly decreased, from approximately 36 to 29 years. Conclusions Young adults, men who have sex with men, commercial sex workers, injecting drug users, overseas Filipino workers, and the sexual partners of people in these groups are particularly

  20. The HIV/AIDS epidemic in Cuba: description and tentative explanation of its low HIV prevalence.

    Science.gov (United States)

    de Arazoza, Héctor; Joanes, Jose; Lounes, Rachid; Legeai, Camille; Clémençon, Stéphan; Pérez, Jorge; Auvert, Bertran

    2007-11-09

    The Cuban HIV/AIDS epidemic has the lowest prevalence rate of the Caribbean region. The objective of this paper is to give an overview of the HIV/AIDS epidemic in Cuba and to explore the reasons for this low prevalence. Data were obtained from the Cuban HIV/AIDS programme established in 1983. This programme has an extensive adult HIV testing policy, including testing of all pregnant women. HIV and AIDS cases have been recorded since 1986. Persons found to be HIV-positive are interviewed on their sexual behaviour and partners. Tracing and voluntary testing of these partners are organised. Epidemiological description of this epidemic was obtained from analysis of this data set. Using elementary mathematical analyses, we estimated the coverage of the detection system (percentage of HIV-positive adults detected) and the average period between HIV infection and detection. Estimated HIV prevalence rates were corrected to account for the coverage. HIV prevalence has increased since 1996. In 2005, the prevalence among pregnant women was 1.2 per 10,000 (16/137000). Estimated HIV prevalence among 15- to 49-year-olds was 8.1 per 10,000 (4913/6065000; 95%CI: 7.9 per 10,000 - 8.3 per 10,000). Most (77%) of the HIV-positive adults were men, most (85.1%) of the detected HIV-positive men were reported as having sex with men (MSM), and most of the HIV-positive women reported having had sex with MSM. The average period between HIV infection and detection was estimated to be 2.1 years (IQR = 1.7 - 2.2 years). We estimated that, for the year 2005, 79.6% (IQR: 77.3 - 81.4%) of the HIV-positive persons were detected. MSM drive the HIV epidemic in Cuba. The extensive HIV testing policy may be an important factor in explaining the low HIV prevalence. To reduce the HIV epidemic in Cuba, the epidemic among MSM should be addressed. To understand this epidemic further, data on sexual behaviour should be collected. Now that antiretroviral therapy is more widely available, the Cuban policy

  1. The HIV/AIDS epidemic in Cuba: description and tentative explanation of its low HIV prevalence

    Directory of Open Access Journals (Sweden)

    Clémençon Stéphan

    2007-11-01

    Full Text Available Abstract Background The Cuban HIV/AIDS epidemic has the lowest prevalence rate of the Caribbean region. The objective of this paper is to give an overview of the HIV/AIDS epidemic in Cuba and to explore the reasons for this low prevalence. Methods Data were obtained from the Cuban HIV/AIDS programme established in 1983. This programme has an extensive adult HIV testing policy, including testing of all pregnant women. HIV and AIDS cases have been recorded since 1986. Persons found to be HIV-positive are interviewed on their sexual behaviour and partners. Tracing and voluntary testing of these partners are organised. Epidemiological description of this epidemic was obtained from analysis of this data set. Using elementary mathematical analyses, we estimated the coverage of the detection system (percentage of HIV-positive adults detected and the average period between HIV infection and detection. Estimated HIV prevalence rates were corrected to account for the coverage. Results HIV prevalence has increased since 1996. In 2005, the prevalence among pregnant women was 1.2 per 10,000 (16/137000. Estimated HIV prevalence among 15- to 49-year-olds was 8.1 per 10,000 (4913/6065000; 95%CI: 7.9 per 10,000 – 8.3 per 10,000. Most (77% of the HIV-positive adults were men, most (85.1% of the detected HIV-positive men were reported as having sex with men (MSM, and most of the HIV-positive women reported having had sex with MSM. The average period between HIV infection and detection was estimated to be 2.1 years (IQR = 1.7 – 2.2 years. We estimated that, for the year 2005, 79.6% (IQR: 77.3 – 81.4% of the HIV-positive persons were detected. Conclusion MSM drive the HIV epidemic in Cuba. The extensive HIV testing policy may be an important factor in explaining the low HIV prevalence. To reduce the HIV epidemic in Cuba, the epidemic among MSM should be addressed. To understand this epidemic further, data on sexual behaviour should be collected. Now that

  2. The global HIV epidemic: current status and challenges.

    Science.gov (United States)

    Abdool Karim, Quarraisha

    2013-06-01

    Three decades after the first reported cases of AIDS we have within our reach sufficient evidence to substantially alter the HIV epidemic at a country level regardless of mode of transmission of HIV. There are a growing number of countries demonstrating control of the epidemic. Human rights violations and/or legislation relating to sexual orientation, status of minors, injecting drug use and sex work together with stigma and discrimination remain key barriers to knowledge of HIV status and access to appropriate services. The use of anti-retrovirals prophylactically to reduce sexual and vertical transmission and systemically to treat infected infants and adults is central to the optimism in responses to the epidemic. In the current fiscal climate careful thought needs to be given to how to efficiently optimise combinations of what is available to have the biggest impact in the context of limited human and infrastructure resources.

  3. HIV epidemic appraisals for assisting in the design of effective prevention programmes: shifting the paradigm back to basics.

    Directory of Open Access Journals (Sweden)

    Sharmistha Mishra

    Full Text Available BACKGROUND: To design HIV prevention programmes, it is critical to understand the temporal and geographic aspects of the local epidemic and to address the key behaviours that drive HIV transmission. Two methods have been developed to appraise HIV epidemics and guide prevention strategies. The numerical proxy method classifies epidemics based on current HIV prevalence thresholds. The Modes of Transmission (MOT model estimates the distribution of incidence over one year among risk-groups. Both methods focus on the current state of an epidemic and provide short-term metrics which may not capture the epidemiologic drivers. Through a detailed analysis of country and sub-national data, we explore the limitations of the two traditional methods and propose an alternative approach. METHODS AND FINDINGS: We compared outputs of the traditional methods in five countries for which results were published, and applied the numeric and MOT model to India and six districts within India. We discovered three limitations of the current methods for epidemic appraisal: (1 their results failed to identify the key behaviours that drive the epidemic; (2 they were difficult to apply to local epidemics with heterogeneity across district-level administrative units; and (3 the MOT model was highly sensitive to input parameters, many of which required extraction from non-regional sources. We developed an alternative decision-tree framework for HIV epidemic appraisals, based on a qualitative understanding of epidemiologic drivers, and demonstrated its applicability in India. The alternative framework offered a logical algorithm to characterize epidemics; it required minimal but key data. CONCLUSIONS: Traditional appraisals that utilize the distribution of prevalent and incident HIV infections in the short-term could misguide prevention priorities and potentially impede efforts to halt the trajectory of the HIV epidemic. An approach that characterizes local transmission

  4. A hidden HIV epidemic among women in Vietnam

    NARCIS (Netherlands)

    T.A. Nguyen; P. Oosterhoff; A. Hardon; H.N. Tran; R.A. Coutinho; P. Wright

    2008-01-01

    Background: The HIV epidemic in Vietnam is still concentrated among high risk populations, including IDU and FSW. The response of the government has focused on the recognized high risk populations, mainly young male drug users. This concentration on one high risk population may leave other populatio

  5. Understanding the epidemic of HIV in South Africa

    African Journals Online (AJOL)

    growth rate and probable asymptotic prevalence of HIV among women attending ... intrinsic growth rate of the epidemic in different provinces and the ..... A pharma meta-anal. Fran'rois W. Osman Eb. Objectives assess the antibiotic ... treatment assumptio. Outcome. Franyois. Anderson. A Nixon A. Roche Pr. Osman E.

  6. COURSE FEATURES EPIDEMIC PROCESS HIV INFECTION IN KHARKIV REGION

    Directory of Open Access Journals (Sweden)

    Nikolaeva LG

    2016-03-01

    Full Text Available Introduction. In the context of the transformation of the spheres of human living epidemic HIV-infection continues. According to the intensity of the epidemic process of HIV-infection, Ukraine takes one of the first places among the European countries. The epidemic process of the infection is concentrated mainly on the high-risk groups, and there is uneven prevalence. Besides in most cases this distribution can not be explained by the social and economic characteristics of certain territories. Kharkiv region belongs to the territory of Ukraine with the lowest prevalence level of HIV-infection. Though in terms of the social and economic crisis due to hostilities in the east of the country, which the region borders, the epidemic situation may significantly become worse. Work objective: to study the peculiarities of the course of the epidemic process of HIV-infection for the period from 1987 till 2015 in Kharkiv region that will improve the epidemiological surveillance of the infection and develop appropriate preventive measures in modern conditions. Material & methods. The studies were conducted in Kharkiv region, which is a big industrial and administrative center. The city of Kharkiv is located at the crossroads of drug trafficking from Asia and Russia. The reportings and analytics of the Kharkiv regional center for prevention and control of AIDS and the Ministry of Health of Ukraine for the period of 1987 – 2015 were used in the research. The analysis of incidence of HIV prevalence, structure of transmission routes and sex-age groups were carried out using descriptive and evaluative and analytical ways of epidemiological research method. Results & discussion. During 1987 – 2015 in Kharkiv region there were officially registered 7868 cases of HIV-infection what was equal to 4.0 % of the registered cases in Ukraine. Since 1996 a marked upward tendency of the incidence of HIV infection in Kharkiv region (growth rate – +7.0 %, and on the

  7. The global spread of HIV-1 subtype B epidemic.

    Science.gov (United States)

    Magiorkinis, Gkikas; Angelis, Konstantinos; Mamais, Ioannis; Katzourakis, Aris; Hatzakis, Angelos; Albert, Jan; Lawyer, Glenn; Hamouda, Osamah; Struck, Daniel; Vercauteren, Jurgen; Wensing, Annemarie; Alexiev, Ivailo; Åsjö, Birgitta; Balotta, Claudia; Gomes, Perpétua; Camacho, Ricardo J; Coughlan, Suzie; Griskevicius, Algirdas; Grossman, Zehava; Horban, Anders; Kostrikis, Leondios G; Lepej, Snjezana J; Liitsola, Kirsi; Linka, Marek; Nielsen, Claus; Otelea, Dan; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elizabeth; Schmit, Jean Claude; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Stylianou, Dora C; Boucher, Charles A B; Nikolopoulos, Georgios; Vasylyeva, Tetyana; Friedman, Samuel R; van de Vijver, David; Angarano, Gioacchino; Chaix, Marie-Laure; de Luca, Andrea; Korn, Klaus; Loveday, Clive; Soriano, Vincent; Yerly, Sabine; Zazzi, Mauricio; Vandamme, Anne-Mieke; Paraskevis, Dimitrios

    2016-12-01

    Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti to United States. However, the pattern of the subsequent spread still remains poorly understood. Here we analyze a large dataset of globally representative HIV-1 subtype B strains to map their spread around the world over the last 50years and describe significant spread patterns. We show that subtype B travelled from North America to Western Europe in different occasions, while Central/Eastern Europe remained isolated for the most part of the early epidemic. Looking with more detail in European countries we see that the United Kingdom, France and Switzerland exchanged viral isolates with non-European countries than with European ones. The observed pattern is likely to mirror geopolitical landmarks in the post-World War II era, namely the rise and the fall of the Iron Curtain and the European colonialism. In conclusion, HIV-1 spread through specific migration routes which are consistent with geopolitical factors that affected human activities during the last 50years, such as migration, tourism and trade. Our findings support the argument that epidemic control policies should be global and incorporate political and socioeconomic factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  8. HIV/AIDS in Vancouver, British Columbia: a growing epidemic

    Directory of Open Access Journals (Sweden)

    Lima Viviane D

    2009-03-01

    Full Text Available Abstract The prevalence of HIV in Vancouver, British Columbia was subject to two distinct periods of rapid increase. The first occurred in the 1980s due to high incidence among men who have sex with men (MSM, and the second occurred in the 1990s due to high incidence among injection drug users (IDU. The purpose of this study was to estimate and model the trends in HIV prevalence in Vancouver from 1980 to 2006. HIV prevalence data were entered into the UNAIDS/WHO Estimation and Projection Package (EPP where prevalence trends were estimated by fitting an epidemiological model to the data. Epidemic curves were fit for IDU, MSM, street-based female sex trade workers (FSW, and the general population. Using EPP, these curves were then aggregated to produce a model of Vancouver's overall HIV prevalence. Of the 505 000 people over the age of 15 that reside in Vancouver, 6108 (ranging from 4979 to 7237 were living with HIV in the year 2006, giving an overall prevalence of 1.21 percent (ranging from 0.99 to 1.43 percent. The subgroups of IDU and MSM account for the greatest proportion of HIV infections. Our model estimates that the prevalence of HIV in Vancouver is greater than one percent, roughly 6 times higher than Canada's national prevalence. These results suggest that HIV infection is having a relatively large impact in Vancouver and that evidence-based prevention and harm reduction strategies should be expanded.

  9. Phylodynamics of the HIV-1 epidemic in Cuba.

    Science.gov (United States)

    Delatorre, Edson; Bello, Gonzalo

    2013-01-01

    Previous studies have shown that the HIV-1 epidemic in Cuba displayed a complex molecular epidemiologic profile with circulation of several subtypes and circulating recombinant forms (CRF); but the evolutionary and population history of those viral variants remains unknown. HIV-1 pol sequences of the most prevalent Cuban lineages (subtypes B, C and G, CRF18_cpx, CRF19_cpx, and CRFs20/23/24_BG) isolated between 1999 and 2011 were analyzed. Maximum-likelihood analyses revealed multiple introductions of subtype B (n≥66), subtype C (n≥10), subtype G (n≥8) and CRF18_cpx (n≥2) viruses in Cuba. The bulk of HIV-1 infections in this country, however, was caused by dissemination of a few founder strains probably introduced from North America/Europe (clades B(CU-I) and B(CU-II)), east Africa (clade C(CU-I)) and central Africa (clades G(CU), CRF18(CU) and CRF19(CU)), or locally generated (clades CRFs20/23/24_BG). Bayesian-coalescent analyses show that the major HIV-1 founder strains were introduced into Cuba during 1985-1995; whereas the CRFs_BG strains emerged in the second half of the 1990s. Most HIV-1 Cuban clades appear to have experienced an initial period of fast exponential spread during the 1990s and early 2000s, followed by a more recent decline in growth rate. The median initial growth rate of HIV-1 Cuban clades ranged from 0.4 year⁻¹ to 1.6 year⁻¹. Thus, the HIV-1 epidemic in Cuba has been a result of the successful introduction of a few viral strains that began to circulate at a rather late time of the AIDS pandemic, but then were rapidly disseminated through local transmission networks.

  10. Phylodynamics of the HIV-1 epidemic in Cuba.

    Directory of Open Access Journals (Sweden)

    Edson Delatorre

    Full Text Available Previous studies have shown that the HIV-1 epidemic in Cuba displayed a complex molecular epidemiologic profile with circulation of several subtypes and circulating recombinant forms (CRF; but the evolutionary and population history of those viral variants remains unknown. HIV-1 pol sequences of the most prevalent Cuban lineages (subtypes B, C and G, CRF18_cpx, CRF19_cpx, and CRFs20/23/24_BG isolated between 1999 and 2011 were analyzed. Maximum-likelihood analyses revealed multiple introductions of subtype B (n≥66, subtype C (n≥10, subtype G (n≥8 and CRF18_cpx (n≥2 viruses in Cuba. The bulk of HIV-1 infections in this country, however, was caused by dissemination of a few founder strains probably introduced from North America/Europe (clades B(CU-I and B(CU-II, east Africa (clade C(CU-I and central Africa (clades G(CU, CRF18(CU and CRF19(CU, or locally generated (clades CRFs20/23/24_BG. Bayesian-coalescent analyses show that the major HIV-1 founder strains were introduced into Cuba during 1985-1995; whereas the CRFs_BG strains emerged in the second half of the 1990s. Most HIV-1 Cuban clades appear to have experienced an initial period of fast exponential spread during the 1990s and early 2000s, followed by a more recent decline in growth rate. The median initial growth rate of HIV-1 Cuban clades ranged from 0.4 year⁻¹ to 1.6 year⁻¹. Thus, the HIV-1 epidemic in Cuba has been a result of the successful introduction of a few viral strains that began to circulate at a rather late time of the AIDS pandemic, but then were rapidly disseminated through local transmission networks.

  11. An agent-based epidemic simulation of social behaviors affecting HIV transmission among Taiwanese homosexuals.

    Science.gov (United States)

    Huang, Chung-Yuan

    2015-01-01

    Computational simulations are currently used to identify epidemic dynamics, to test potential prevention and intervention strategies, and to study the effects of social behaviors on HIV transmission. The author describes an agent-based epidemic simulation model of a network of individuals who participate in high-risk sexual practices, using number of partners, condom usage, and relationship length to distinguish between high- and low-risk populations. Two new concepts-free links and fixed links-are used to indicate tendencies among individuals who either have large numbers of short-term partners or stay in long-term monogamous relationships. An attempt was made to reproduce epidemic curves of reported HIV cases among male homosexuals in Taiwan prior to using the agent-based model to determine the effects of various policies on epidemic dynamics. Results suggest that when suitable adjustments are made based on available social survey statistics, the model accurately simulates real-world behaviors on a large scale.

  12. HIV Epidemic in Asia: Implications for HIV Vaccine and Other Prevention Trials

    Science.gov (United States)

    Phanuphak, Nittaya; Lo, Ying-Ru; Shao, Yiming; Solomon, Sunil Suhas; O'Connell, Robert J.; Tovanabutra, Sodsai; Chang, David; Kim, Jerome H.

    2015-01-01

    Abstract An overall decrease of HIV prevalence is now observed in several key Asian countries due to effective prevention programs. The decrease in HIV prevalence and incidence may further improve with the scale-up of combination prevention interventions. The implementation of future prevention trials then faces important challenges. The opportunity to identify heterosexual populations at high risk such as female sex workers may rapidly wane. With unabating HIV epidemics among men who have sex with men (MSM) and transgender (TG) populations, an effective vaccine would likely be the only option to turn the epidemic. It is more likely that efficacy trials will occur among MSM and TG because their higher HIV incidence permits smaller and less costly trials. The constantly evolving patterns of HIV-1 diversity in the region suggest close monitoring of the molecular HIV epidemic in potential target populations for HIV vaccine efficacy trials. CRF01_AE remains predominant in southeast Asian countries and MSM populations in China. This relatively steady pattern is conducive to regional efficacy trials, and as efficacy warrants, to regional licensure. While vaccines inducing nonneutralizing antibodies have promise against HIV acquisition, vaccines designed to induce broadly neutralizing antibodies and cell-mediated immune responses of greater breadth and depth in the mucosal compartments should be considered for testing in MSM and TG. The rationale and design of efficacy trials of combination prevention modalities such as HIV vaccine and preexposure prophylaxis (PrEP) remain hypothetical, require high adherence to PrEP, are more costly, and present new regulatory challenges. The prioritization of prevention interventions should be driven by the HIV epidemic and decided by the country-specific health and regulatory authorities. Modeling the impact and cost–benefit may help this decision process. PMID:26107771

  13. The HIV epidemic in Eastern Europe and Central Asia.

    Science.gov (United States)

    DeHovitz, Jack; Uuskula, Anneli; El-Bassel, Nabila

    2014-06-01

    Eastern Europe and Central Asia represent one of the few regions globally where there is a continued increase in the incidence of HIV infection. For example, in Eastern Europe the rate of diagnosed cases of HIV infection per 100 000 population has increased from 11.7 in 2004 to 22.5 in 2011. Initially propelled by injection drug use, heterosexual transmission has now become a major driver of new infections in the region. Nonetheless substance use remains an important factor, with its control limited by challenges in scaling up harm reduction efforts. While most countries have implemented opioid substitution therapy programs, their scale remains very limited. Similarly, coverage of needles syringe programs across the region is variable. Complicating the control of HIV has been the emergence of non-injection drugs and inadequate access to antiretroviral therapy. In addition, structural barriers and stigma toward HIV infected people may contribute to the high proportion of late presentations for HIV care. Finally in the wake of the HIV epidemic, high rates of hepatitis C infection and tuberculosis have been noted.

  14. HIV Epidemic situation among Small Indigenous Populations of Northeast Russia

    Directory of Open Access Journals (Sweden)

    L. Yu. Volova

    2014-01-01

    Full Text Available The aim of the study was to analyze and assess the real situation of HIV infection among indigenous peoples established , to investigate the prevalence of risky behavior in relation to HIV also determine the level of awareness of the indigenous population about HIV / AIDS.Materials and Methods 1. Analysis of the data cards of the epidemical investigation hearth HIV data form number 283 «About measures on prevention of HIV , hepatitis B and C , detection and treatment of HIV» , form number 61 «Information on the groups of HIV», outpatients patient. 2. The analysis of the statistical prevalence of HIV infection among men and women , including among indigenous representatives , the structure of HIV transmission , coverage of clinical examination. 3. Data analysis of the sociological study among indigenous representatives. The proposed questionnaire contained both closed and open-ended questions to assess the risk factors of respondents’ behavior and their level of awareness of HIV infection. Evaluation of the reliability of the data performed using Student t-test. Results. In 2000, HIV infection in region penetrated into the population of indigenous peoples and continues to spread. Particular way of life and living conditions, such as seasonal migration within the county, early sexual activity, lack of skills in safe sexual behavior , bad habits contributed to the spread of HIV among this ethnic group. Link transition of HIV infection in a group of indigenous peoples is a high incidence of working shifts and workers, among them 30% are already infected with HIV. In connection with this, the spread of HIV infection among women occurs rapidly. Special role in the spread of HIV infection among women of indigenous peoples plays lifestyle and delated psychosocial problems.Conclusion 1. The most vulnerable to HIV infection and sexually transmitted infections by representatives of indigenous peoples living in the

  15. A hidden HIV epidemic among women in Vietnam

    Directory of Open Access Journals (Sweden)

    Tran Hien

    2008-01-01

    Full Text Available Abstract Background The HIV epidemic in Vietnam is still concentrated among high risk populations, including IDU and FSW. The response of the government has focused on the recognized high risk populations, mainly young male drug users. This concentration on one high risk population may leave other populations under-protected or unprepared for the risk and the consequences of HIV infection. In particular, attention to women's risks of exposure and needs for care may not receive sufficient attention as long as the perception persists that the epidemic is predominantly among young males. Without more knowledge of the epidemic among women, policy makers and planners cannot ensure that programs will also serve women's needs. Methods More than 300 documents appearing in the period 1990 to 2005 were gathered and reviewed to build an understanding of HIV infection and related risk behaviors among women and of the changes over time that may suggest needed policy changes. Results It appears that the risk of HIV transmission among women in Vietnam has been underestimated; the reported data may represent as little as 16% of the real number. Although modeling predicted that there would be 98,500 cases of HIV-infected women in 2005, only 15,633 were accounted for in reports from the health system. That could mean that in 2005, up to 83,000 women infected with HIV have not been detected by the health care system, for a number of possible reasons. For both detection and prevention, these women can be divided into sub-groups with different risk characteristics. They can be infected by sharing needles and syringes with IDU partners, or by having unsafe sex with clients, husbands or lovers. However, most new infections among women can be traced to sexual relations with young male injecting drug users engaged in extramarital sex. Each of these groups may need different interventions to increase the detection rate and thus ensure that the women receive the care they

  16. The Prevalence of HIV/AIDS Epidemic in Anambra State, Nigeria ...

    African Journals Online (AJOL)

    The Prevalence of HIV/AIDS Epidemic in Anambra State, Nigeria: Exploring Gender, ... AFRREV IJAH: An International Journal of Arts and Humanities ... domestic violence etc. are gender related factors that exacerbate prevalence of HIV.

  17. A Population-Structured HIV Epidemic in Israel: Roles of Risk and Ethnicity

    Science.gov (United States)

    Grossman, Zehava; Avidor, Boaz; Mor, Zohar; Chowers, Michal; Levy, Itzchak; Shahar, Eduardo; Riesenberg, Klaris; Sthoeger, Zev; Maayan, Shlomo; Shao, Wei; Lorber, Margalit; Olstein-Pops, Karen; Elbirt, Daniel; Elinav, Hila; Asher, Ilan; Averbuch, Diana; Istomin, Valery; Gottesman, Bat Sheva; Kedem, Eynat; Girshengorn, Shirley; Kra-Oz, Zipi; Shemer Avni, Yonat; Radian Sade, Sara; Turner, Dan; Maldarelli, Frank

    2015-01-01

    Background HIV in Israel started with a subtype-B epidemic among men who have sex with men, followed in the 1980s and 1990s by introductions of subtype C from Ethiopia (predominantly acquired by heterosexual transmission) and subtype A from the former Soviet Union (FSU, most often acquired by intravenous drug use). The epidemic matured over the last 15 years without additional large influx of exogenous infections. Between 2005 and 2013 the number of infected men who have sex with men (MSM) increased 2.9-fold, compared to 1.6-fold and 1.3-fold for intravenous drug users (IVDU) and Ethiopian-origin residents. Understanding contemporary spread is essential for effective public health planning. Methods We analyzed demographic and virologic data from 1,427 HIV-infected individuals diagnosed with HIV-I during 1998–2012. HIV phylogenies were reconstructed with maximum-likelihood and Bayesian methods. Results Subtype-B viruses, but not A or C, demonstrated a striking number of large clusters with common ancestors having posterior probability ≥0.95, including some suggesting presence of transmission networks. Transmitted drug resistance was highest in subtype B (13%). MSM represented a frequent risk factor in cross-ethnic transmission, demonstrated by the presence of Israeli-born with non-B virus infections and FSU immigrants with non-A subtypes. Conclusions Reconstructed phylogenetic trees demonstrated substantial grouping in subtype B, but not in non-MSM subtype-A or in subtype-C, reflecting differences in transmission dynamics linked to HIV transmission categories. Cross-ethnic spread occurred through multiple independent introductions, with MSM playing a prevalent role in the transmission of the virus. Such data provide a baseline to track epidemic trends and will be useful in informing and quantifying efforts to reduce HIV transmission. PMID:26302493

  18. The HIV epidemic in China: history, response, and challenge

    Institute of Scientific and Technical Information of China (English)

    Na HE; Roger DETELS

    2005-01-01

    The first case of AIDS was reported in 1985 in China, but by the early 21st century, the government estimated that there were 840,000 citizens living with HIV/AIDS. The number is increasing rapidly. The major risk groups are injection drug users (IDUSs; 43%) and former plasma donors (27%), but rates among heterosexual groups are rising rapidly.Sentinel surveillance was initiated in 1986, and now includes IDUs, men-who-have-sex-with-men, sexually transmitted disease clinic attendees, antenatal women, long-distance truck drivers, and .sex workers. Although the government was slow to respond to the epidemic in the late 20th century, it has made a vigorous response in the early 21st century.Components of that response include implementation and evaluation of harm reduction programs for IDUs, education to increase knowledge and reduce stigma, treatment and social support for rural and poor HIV/AIDS patients, widespread testing, and increased funding for HIV/AIDS programs. International agencies have been generous in their support of the government initiatives. To successfully combat the epidemic, China needs to develop and train the necessary infrastructure to implement its intervention programs, particularly in the rural areas, to vigorously combat stigma and discrimination, support research especially in the universities and research institutions other than the China Centers for Disease Control, develop a system for efficient exchange of research and program information, and update legislation to reflect the current situation.

  19. The HIV epidemic in Greenland - a slow spreading infection among adult heterosexual Greenlanders

    DEFF Research Database (Denmark)

    Bjørn-Mortensen, Karen; Ladefoged, Karin; Obel, Niels;

    2013-01-01

    We aimed to characterise the HIV epidemic in Greenland and to determine incidence, prevalence, mortality rates (MR) and specific causes of deaths.......We aimed to characterise the HIV epidemic in Greenland and to determine incidence, prevalence, mortality rates (MR) and specific causes of deaths....

  20. Towards an Integrated Framework for Accelerating the End of the Global HIV Epidemic among Young People

    Science.gov (United States)

    DiClemente, Ralph J.; Jackson, Jerrold M.

    2014-01-01

    For decades, the HIV epidemic has exacted an enormous toll worldwide. However, trend analyses have discerned significant declines in the overall prevalence of HIV over the last two decades. More recently, advances in biomedical, behavioural, and structural interventions offer considerable promise in the battle against generalised epidemics.…

  1. Dynamics of Dengue epidemics using optimal control

    CERN Document Server

    Rodrigues, Helena Sofia; Torres, Delfim F M

    2010-01-01

    We present an application of optimal control theory to Dengue epidemics. This epidemiologic disease is an important theme in tropical countries due to the growing number of infected individuals. The dynamic model is described by a set of nonlinear ordinary differential equations, that depend on the dynamic of the Dengue mosquito, the number of infected individuals, and the people's motivation to combat the mosquito. The cost functional depends not only on the costs of medical treatment of the infected people but also on the costs related to educational and sanitary campaigns. Two approaches to solve the problem are considered: one using optimal control theory, another one by discretizing first the problem and then solving it with nonlinear programming. The results obtained with OC-ODE and IPOPT solvers are given and discussed. We observe that with current computational tools it is easy to obtain, in an efficient way, better solutions to Dengue problems, leading to a decrease of infected mosquitoes and individ...

  2. Modeling the HIV epidemic in Novgorod region, Russia

    Directory of Open Access Journals (Sweden)

    Azovtseva OV

    2017-11-01

    Full Text Available The purpose of this study is designed for predicting the epidemic process and to improve preventive measures, clinical examination and treatment of HIV-infected patients at both the regional and national level. Morbidity indicators for the last 25 years were studied; prevailing ways of transmission, age pattern, and main causes of death among HIV-infected persons. A comparative analysis of morbidity was carried out. Microsoft Excel 2007 was used to analyse obtained data statistically. The significance of “clinical outcomes” was assessed by analysing confidence indexes of frequency distribution by the χ2 test with Fisher’s angular transformation or the Mantel-Haenszel test. The sequential recognition procedure by Bayes’ method was used as the basis for mathematical modelling. There are observed the declining role of transmission through injection and the increasing role of sexual transmission. HIV is diagnosed most frequently in young people aged 15–30. However, an increased morbidity rate of older people has been discovered during the last 2-3 years. The mathematical modelling of the epidemiological situation discovered that this infection spreading among the socially safe population against the backdrop of intensifying sexual transmission, accompanied by a rising female morbidity rate and the percentage of children born by HIV-infected mothers. Obtained results substantiate the need for a unified personalized registration system for HIV-infected individuals, which would include information about the scope and effectiveness of treatment, diagnostic, preventive, and rehabilitation measures that were taken when providing medical and social assistance to this category of patients.

  3. HIV status awareness, partnership dissolution and HIV transmission in generalized epidemics.

    Directory of Open Access Journals (Sweden)

    Georges Reniers

    Full Text Available OBJECTIVES: HIV status aware couples with at least one HIV positive partner are characterized by high separation and divorce rates. This phenomenon is often described as a corollary of couples HIV Testing and Counseling (HTC that ought to be minimized. In this contribution, we demonstrate the implications of partnership dissolution in serodiscordant couples for the propagation of HIV. METHODS: We develop a compartmental model to study epidemic outcomes of elevated partnership dissolution rates in serodiscordant couples and parameterize it with estimates from population-based data (Rakai, Uganda. RESULTS: Via its effect on partnership dissolution, every percentage point increase in HIV status awareness reduces HIV incidence in monogamous populations by 0.27 percent for women and 0.63 percent for men. These effects are even larger when the assumption of monogamy can be relaxed, but are moderated by other behavior changes (e.g., increased condom use in HIV status aware serodiscordant partnerships. When these behavior changes are taken into account, each percentage point increase in HIV status awareness reduces HIV incidence by 0.13 and 0.32 percent for women and men, respectively (assuming monogamy. The partnership dissolution effect exists because it decreases the fraction of serodiscordant couples in the population and prolongs the time that individuals spend outside partnerships. CONCLUSION: Our model predicts that elevated partnership dissolution rates in HIV status aware serodiscordant couples reduce the spread of HIV. As a consequence, the full impact of couples HTC for HIV prevention is probably larger than recognized to date. Particularly high partnership dissolution rates in female positive serodiscordant couples contribute to the gender imbalance in HIV infections.

  4. Inferring epidemiological parameters from phylogenetic information for the HIV-1 epidemic among MSM

    Science.gov (United States)

    Quax, Rick; van de Vijver, David A. M. C.; Frentz, Dineke; Sloot, Peter M. A.

    2013-09-01

    The HIV-1 epidemic in Europe is primarily sustained by a dynamic topology of sexual interactions among MSM who have individual immune systems and behavior. This epidemiological process shapes the phylogeny of the virus population. Both fields of epidemic modeling and phylogenetics have a long history, however it remains difficult to use phylogenetic data to infer epidemiological parameters such as the structure of the sexual network and the per-act infectiousness. This is because phylogenetic data is necessarily incomplete and ambiguous. Here we show that the cluster-size distribution indeed contains information about epidemiological parameters using detailed numberical experiments. We simulate the HIV epidemic among MSM many times using the Monte Carlo method with all parameter values and their ranges taken from literature. For each simulation and the corresponding set of parameter values we calculate the likelihood of reproducing an observed cluster-size distribution. The result is an estimated likelihood distribution of all parameters from the phylogenetic data, in particular the structure of the sexual network, the per-act infectiousness, and the risk behavior reduction upon diagnosis. These likelihood distributions encode the knowledge provided by the observed cluster-size distrbution, which we quantify using information theory. Our work suggests that the growing body of genetic data of patients can be exploited to understand the underlying epidemiological process.

  5. Strengthening HIV surveillance: measurements to track the epidemic in real time.

    Science.gov (United States)

    Buthelezi, Usangiphile E; Davidson, Candace L; Kharsany, Ayesha Bm

    2016-07-01

    Surveillance for HIV as a public health initiative requires timely, detailed and robust data to systematically understand burden of infection, transmission patterns, direct prevention efforts, guide funding, identify new infections and predict future trends in the epidemic. The methods for HIV surveillance have evolved to reliably track the epidemic and identify new infections in real time. Initially HIV surveillance relied primarily on the reporting of AIDS cases followed by measuring antibodies to HIV to determine prevalence in key populations. With the roll-out of antiretroviral therapy (ART) resulting in better survival and the corresponding increase in HIV prevalence, the landscape of surveillance shifted further to track HIV prevalence and incidence within the context of programmes. Recent developments in laboratory assays that potentially measure and differentiate recent versus established HIV infection offer a cost-effective method for the rapid estimation of HIV incidence. These tests continue to be validated and are increasingly useful in informing the status of the epidemic in real time. Surveillance of heterogeneity of infections contributing to sub-epidemics requires methods to identify affected populations, density, key geographical locations and phylogenetically linked or clustered infections. Such methods could provide a nuanced understanding of the epidemic and prioritise prevention efforts to those most vulnerable. This paper brings together recent developments and challenges facing HIV surveillance, together with the application of newer assays and methods to fast-track the HIV prevention and treatment response.

  6. A dynamic epidemic control model on uncorrelated complex networks

    Institute of Scientific and Technical Information of China (English)

    Pei Wei-Dong; Chen Zeng-Qiang; Yuan Zhu-Zhi

    2008-01-01

    In this paper,a dynamic epidemic control model on the uncorrelated complex networks is proposed.By means of theoretical analysis,we found that the new model has a similar epidemic threshold as that of the susceptible-infectedrecovered (SIR) model on the above networks,but it can reduce the prevalence of the infected individuals remarkably.This result may help us understand epidemic spreading phenomena on real networks and design appropriate strategies to control infections.

  7. Stability analysis of an HIV/AIDS epidemic model with treatment

    Science.gov (United States)

    Cai, Liming; Li, Xuezhi; Ghosh, Mini; Guo, Baozhu

    2009-07-01

    An HIV/AIDS epidemic model with treatment is investigated. The model allows for some infected individuals to move from the symptomatic phase to the asymptomatic phase by all sorts of treatment methods. We first establish the ODE treatment model with two infective stages. Mathematical analyses establish that the global dynamics of the spread of the HIV infectious disease are completely determined by the basic reproduction number [real]0. If [real]01. Then, we introduce a discrete time delay to the model to describe the time from the start of treatment in the symptomatic stage until treatment effects become visible. The effect of the time delay on the stability of the endemically infected equilibrium is investigated. Moreover, the delay model exhibits Hopf bifurcations by using the delay as a bifurcation parameter. Finally, numerical simulations are presented to illustrate the results.

  8. Epidemic impacts of a community empowerment intervention for HIV prevention among female sex workers in generalized and concentrated epidemics.

    Science.gov (United States)

    Wirtz, Andrea L; Pretorius, Carel; Beyrer, Chris; Baral, Stefan; Decker, Michele R; Sherman, Susan G; Sweat, Michael; Poteat, Tonia; Butler, Jennifer; Oelrichs, Robert; Semini, Iris; Kerrigan, Deanna

    2014-01-01

    Sex workers have endured a high burden of HIV infection in and across HIV epidemics. A comprehensive, community empowerment-based HIV prevention intervention emphasizes sex worker organization and mobilization to address HIV risk and often includes community-led peer education, condom distribution, and other activities. Meta-analysis of such interventions suggests a potential 51% reduction in inconsistent condom use. Mathematical modeling exercises provide theoretical insight into potential impacts of the intervention on HIV incidence and burden in settings where interventions have not yet been implemented. We used a deterministic model, Goals, to project the impact on HIV infections when the community empowerment interventions were scaled up among female sex workers in Kenya, Thailand, Brazil, and Ukraine. Modeling scenarios included expansion of the comprehensive community empowerment-based HIV prevention intervention from baseline coverage over a 5-year period (5-65% in Kenya and Ukraine; 10-70% in Thailand and Brazil), while other interventions were held at baseline levels. A second exercise increased the intervention coverage simultaneously with equitable access to ART for sex workers. Impacts on HIV outcomes among sex workers and adults are observed from 2012-2016 and, compared to status quo when all interventions are held constant. Optimistic but feasible coverage (65%-70%) of the intervention demonstrated a range of impacts on HIV: 220 infections averted over 5 yrs. among sex workers in Thailand, 1,830 in Brazil, 2,220 in Ukraine, and 10,800 infections in Kenya. Impacts of the intervention for female sex workers extend to the adult population, cumulatively averting 730 infections in Thailand to 20,700 adult infections in Kenya. Impacts vary by country, influenced by HIV prevalence in risk groups, risk behaviors, intervention use, and population size. A community empowerment approach to HIV prevention and access to universal ART for female sex workers is a

  9. A Direct Comparison of Two Densely Sampled HIV Epidemics: The UK and Switzerland

    Science.gov (United States)

    Ragonnet-Cronin, Manon L.; Shilaih, Mohaned; Günthard, Huldrych F.; Hodcroft, Emma B.; Böni, Jürg; Fearnhill, Esther; Dunn, David; Yerly, Sabine; Klimkait, Thomas; Aubert, Vincent; Yang, Wan-Lin; Brown, Alison E.; Lycett, Samantha J.; Kouyos, Roger; Brown, Andrew J. Leigh

    2016-09-01

    Phylogenetic clustering approaches can elucidate HIV transmission dynamics. Comparisons across countries are essential for evaluating public health policies. Here, we used a standardised approach to compare the UK HIV Drug Resistance Database and the Swiss HIV Cohort Study while maintaining data-protection requirements. Clusters were identified in subtype A1, B and C pol phylogenies. We generated degree distributions for each risk group and compared distributions between countries using Kolmogorov-Smirnov (KS) tests, Degree Distribution Quantification and Comparison (DDQC) and bootstrapping. We used logistic regression to predict cluster membership based on country, sampling date, risk group, ethnicity and sex. We analysed >8,000 Swiss and >30,000 UK subtype B sequences. At 4.5% genetic distance, the UK was more clustered and MSM and heterosexual degree distributions differed significantly by the KS test. The KS test is sensitive to variation in network scale, and jackknifing the UK MSM dataset to the size of the Swiss dataset removed the difference. Only heterosexuals varied based on the DDQC, due to UK male heterosexuals who clustered exclusively with MSM. Their removal eliminated this difference. In conclusion, the UK and Swiss HIV epidemics have similar underlying dynamics and observed differences in clustering are mainly due to different population sizes.

  10. A Direct Comparison of Two Densely Sampled HIV Epidemics: The UK and Switzerland.

    Science.gov (United States)

    Ragonnet-Cronin, Manon L; Shilaih, Mohaned; Günthard, Huldrych F; Hodcroft, Emma B; Böni, Jürg; Fearnhill, Esther; Dunn, David; Yerly, Sabine; Klimkait, Thomas; Aubert, Vincent; Yang, Wan-Lin; Brown, Alison E; Lycett, Samantha J; Kouyos, Roger; Brown, Andrew J Leigh

    2016-09-19

    Phylogenetic clustering approaches can elucidate HIV transmission dynamics. Comparisons across countries are essential for evaluating public health policies. Here, we used a standardised approach to compare the UK HIV Drug Resistance Database and the Swiss HIV Cohort Study while maintaining data-protection requirements. Clusters were identified in subtype A1, B and C pol phylogenies. We generated degree distributions for each risk group and compared distributions between countries using Kolmogorov-Smirnov (KS) tests, Degree Distribution Quantification and Comparison (DDQC) and bootstrapping. We used logistic regression to predict cluster membership based on country, sampling date, risk group, ethnicity and sex. We analysed >8,000 Swiss and >30,000 UK subtype B sequences. At 4.5% genetic distance, the UK was more clustered and MSM and heterosexual degree distributions differed significantly by the KS test. The KS test is sensitive to variation in network scale, and jackknifing the UK MSM dataset to the size of the Swiss dataset removed the difference. Only heterosexuals varied based on the DDQC, due to UK male heterosexuals who clustered exclusively with MSM. Their removal eliminated this difference. In conclusion, the UK and Swiss HIV epidemics have similar underlying dynamics and observed differences in clustering are mainly due to different population sizes.

  11. Epidemic model of HIV infection and AIDS in Argentina. Status in 1990 and predictive estimates.

    Science.gov (United States)

    Raggi, R; Blanco, G A

    1992-01-01

    The purpose of this paper was to evaluate the prevalence of HIV infection and AIDS in Argentina, to study the dynamics of the spread of HIV and to predict the future course by means of an epidemic model. The model was constructed using differential equations to describe the interactions between members of the various groups at risk. The functional form of the solutions was used in a back calculation procedure using data from cohort studies which were done in other countries (U.S.A. and France) together with data of AIDS cases reported to the National AIDS Program, to determine the time evolution of HIV-infection in each of the groups at risk defined. Results show that HIV was introduced in Argentina during the early 80's and affected persons of the homosexual/bisexual group in a first stage. In April 1990 it was estimated that there were a total of 34,131 HIV-infected persons. Intravenous drug users (IVDU) represented 39.5%, homosexual/bisexual men 47.6% and heterosexual adults 11%. It is estimated that in December 1992 there will be 107,946 HIV-infected persons where heterosexuals contribute with more than 20% of that value. AIDS cases predicted for the same period are 4130, with 1958 among homosexual/bisexual, 1483 among IVDU, 449 in heterosexual adults, 153 in children under 4 years old and 87 among hemophiliacs or patients with blood coagulation disorders. By the end of 1994 the model predicts more than 200,000 HIV infected persons with an important proportion of heterosexual adults and more than 12,000 AIDS cases. The values of this period must be considered as a future possible scenario if the present spread conditions are preserved. Infection among heterosexual adults is at the present time in a first and exponential phase of spread and dominated by transmission from IVDU group and bisexual men. It is concluded that the future course of AIDS epidemic in Argentina may be particularly influenced by changes in the heterosexual behavior particularly in those

  12. Complex Agent Networks explaining the HIV epidemic among homosexual men in Amsterdam

    CERN Document Server

    Mei, Shan; Quax, Rick; van de Vijver, David; Zhu, Yifan

    2008-01-01

    Simulating the evolution of the Human Immunodeficiency Virus (HIV) epidemic requires a detailed description of the population network, especially for small populations in which individuals can be represented in detail and accuracy. In this paper, we introduce the concept of a Complex Agent Network(CAN) to model the HIV epidemics by combining agent-based modelling and complex networks, in which agents represent individuals that have sexual interactions. The applicability of CANs is demonstrated by constructing and executing a detailed HIV epidemic model for men who have sex with men (MSM) in Amsterdam, including a distinction between steady and casual relationships. We focus on MSM contacts because they play an important role in HIV epidemics and have been tracked in Amsterdam for a long time. Our experiments show good correspondence between the historical data of the Amsterdam cohort and the simulation results.

  13. HIV/AIDS epidemic in the State of Amazonas: characteristics and trends from 2001 to 2012

    OpenAIRE

    Romina do Socorro Marques de Oliveira; Adele Schwartz Benzaken; Valeria Saraceni; Meritxell Sabidó

    2015-01-01

    A scoping review was conducted to describe the epidemiological characteristics of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in the State of Amazonas, Brazil, from 2001 to 2012, and temporary patterns were estimated from surveillance data. The results suggest that in its third decade, the Amazon HIV/AIDS epidemic is far from being stabilized and displays rising AIDS incidence and mortality rates and late diagnoses. The data suggest that AIDS cases ...

  14. Defining and measuring the costs of the HIV epidemic to business firms.

    OpenAIRE

    Farnham, P G

    1994-01-01

    Most published estimates of the costs of the epidemic of human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) have been developed from the societal perspective, attempting to measure the burden of the epidemic to society in this country. Although societal cost analysis is well-developed, relatively little is known about many of the factors influencing the costs of the epidemic to business firms. The business community may bear a substantial portion of tho...

  15. Responding to the HIV/AIDS epidemic : lessons from the case of Eritrea

    NARCIS (Netherlands)

    Müller, T.R.

    2005-01-01

    This paper discusses the political response to HIV/AIDS in Eritrea, a country where the epidemic appears to have stabilized at an average prevalence rate of around 3%. It shows that Eritrea has mobilized an effective multisectoral response to cope with the epidemic and its impact under conditions of

  16. Vaccination intervention on epidemic dynamics in networks

    CERN Document Server

    Peng, Xiao-Long; Fu, Xinchu; Zhou, Tao

    2013-01-01

    Vaccination is an important measure available for preventing or reducing the spread of infectious diseases. In this paper, an epidemic model including susceptible, infected, and imperfectly vaccinated compartments is studied on Watts-Strogatz small-world, Barab\\'asi-Albert scale-free, and random scale-free networks. The epidemic threshold and prevalence are analyzed. For small-world networks, the effective vaccination intervention is suggested and its influence on the threshold and prevalence is analyzed. For scale-free networks, the threshold is found to be strongly dependent both on the effective vaccination rate and on the connectivity distribution. Moreover, so long as vaccination is effective, it can linearly decrease the epidemic prevalence in small-world networks, whereas for scale-free networks it acts exponentially. These results can help in adopting pragmatic treatment upon diseases in structured populations.

  17. A Candle Lit from Both Sides : The Epidemic of HIV Infection In Central and Eastern Europe

    NARCIS (Netherlands)

    J-P.C. Grund (Jean-Paul)

    2002-01-01

    textabstractUntil 1995 central and eastern Europe as well as the Asian republics of the former Soviet Union have been more-or-less devoid of epidemic outbreaks of HIV infection. In this region with more than 450 million inhabitants (United Nations 1997), the total number of HIV infections was estima

  18. HIV epidemics and prevention responses in Asia and Eastern Europe: lessons to be learned?

    DEFF Research Database (Denmark)

    Bridge, Jamie; Lazarus, Jeff; Atun, Rifat

    2010-01-01

    This paper describes characteristics of the HIV epidemics in Eastern Europe and Central Asia (EECA) and Asia and Central Asia, and draws comparisons between these regions. It focuses on the role that key populations continue to play in HIV transmission in both regions, the challenges that this po...

  19. Women with HIV in Indonesia: are they bridging a concentrated epidemic to the wider community?

    NARCIS (Netherlands)

    Rahmalia, A.; Wisaksana, R.; Meijerink, H.; Indrati, A.R.; Alisjahbana, B.; Roeleveld, N.; Ven, A.J.A.M. van der; Laga, M.; Crevel, R. van

    2015-01-01

    BACKGROUND: Male injecting drug users drove the onset of the HIV epidemic in Indonesia but over time more women have been diagnosed. We examined the relative proportion of female patients in an HIV cohort and characterized their probable transmission route and reproductive profile. DESIGNS: Prospect

  20. The changing epidemiology of the global paediatric HIV epidemic: keeping track of perinatally HIV-infected adolescents

    OpenAIRE

    Sohn, Annette H.; Rohan Hazra

    2013-01-01

    The global paediatric HIV epidemic is shifting into a new phase as children on antiretroviral therapy (ART) move into adolescence and adulthood, and face new challenges of living with HIV. UNAIDS reports that 3.4 million children aged below 15 years and 2 million adolescents aged between 10 and 19 years have HIV. Although the vast majority of children were perinatally infected, older children are combined with behaviourally infected adolescents and youth in global reporting, making it difficu...

  1. New evidence on the HIV epidemic in Libya: why countries must implement prevention programs among people who inject drugs.

    Science.gov (United States)

    Mirzoyan, Lusine; Berendes, Sima; Jeffery, Caroline; Thomson, Joanna; Ben Othman, Hussain; Danon, Leon; Turki, Abdullah A; Saffialden, Rabea; Valadez, Joseph J

    2013-04-15

    Libya had one of the world's largest nosocomial HIV outbreaks in the late 1990 s leading to the detention of 6 foreign medical workers. They were released in 2007 after the Libyan Government and the European Union agreed to humanitarian cooperation that included the development of Libya's first National HIV Strategy and the research reported in this article. Despite the absence of sound evidence on the status and dynamics of Libya's HIV epidemic, some officials posited that injecting drug use was the main mode of transmission. We therefore sought to assess HIV prevalence and related risk factors among people who inject drugs (PWID) in Tripoli. We conducted a cross-sectional survey among 328 PWID in Tripoli using respondent-driven sampling. We collected behavioral data and blood samples for HIV, hepatitis C virus, and hepatitis B virus testing. We estimate an HIV prevalence of 87%, hepatitis C virus prevalence of 94%, and hepatitis B virus prevalence of 5%. We detected injecting drug use-related and sexual risk factors in the context of poor access to comprehensive services for HIV prevention and mitigation. For example, most respondents (85%) reported having shared needles. In this first biobehavioral survey among PWID in Libya, we detected one of the highest (or even the highest) levels of HIV infection worldwide in the absence of a comprehensive harm-reduction program. There is an urgent need to implement an effective National HIV Strategy informed by the results of this research, especially because recent military events and related sociopolitical disruption and migration might lead to a further expansion of the epidemic.

  2. Dynamics of epidemic diseases on a growing adaptive network

    Science.gov (United States)

    Demirel, Güven; Barter, Edmund; Gross, Thilo

    2017-02-01

    The study of epidemics on static networks has revealed important effects on disease prevalence of network topological features such as the variance of the degree distribution, i.e. the distribution of the number of neighbors of nodes, and the maximum degree. Here, we analyze an adaptive network where the degree distribution is not independent of epidemics but is shaped through disease-induced dynamics and mortality in a complex interplay. We study the dynamics of a network that grows according to a preferential attachment rule, while nodes are simultaneously removed from the network due to disease-induced mortality. We investigate the prevalence of the disease using individual-based simulations and a heterogeneous node approximation. Our results suggest that in this system in the thermodynamic limit no epidemic thresholds exist, while the interplay between network growth and epidemic spreading leads to exponential networks for any finite rate of infectiousness when the disease persists.

  3. Review: [corrected] The changing face of the HIV epidemic in sub-Saharan Africa.

    Science.gov (United States)

    Mutevedzi, Portia C; Newell, Marie-Louise

    2014-09-01

    The widespread roll-out of antiretroviral therapy (ART) has substantially changed the face of human immunodeficiency virus (HIV). Timely initiation of ART in HIV-infected individuals dramatically reduces mortality and improves employment rates to levels prior to HIV infection. Recent findings from several studies have shown that ART reduces HIV transmission risk even with modest ART coverage of the HIV-infected population and imperfect ART adherence. While condoms are highly effective in the prevention of HIV acquisition, they are compromised by low and inconsistent usage; male medical circumcision substantially reduces HIV transmission but uptake remains relatively low; ART during pregnancy, delivery and breastfeeding can virtually eliminate mother-to-child transmission but implementation is challenging, especially in resource-limited settings. The current HIV prevention recommendations focus on a combination of preventions approach, including ART as treatment or pre- or post-exposure prophylaxis together with condoms, circumcision and sexual behaviour modification. Improved survival in HIV-infected individuals and reduced HIV transmission risk is beginning to result in limited HIV incidence decline at population level and substantial increases in HIV prevalence. However, achievements in HIV treatment and prevention are threatened by the challenges of lifelong adherence to preventive and therapeutic methods and by the ageing of the HIV-infected cohorts potentially complicating HIV management. Although current thinking suggests prevention of HIV transmission through early detection of infection immediately followed by ART could eventually result in elimination of the HIV epidemic, controversies remain as to whether we can treat our way out of the HIV epidemic. © 2014 John Wiley & Sons Ltd.

  4. Epidemic Impacts of a Community Empowerment Intervention for HIV Prevention among Female Sex Workers in Generalized and Concentrated Epidemics

    Science.gov (United States)

    Wirtz, Andrea L.; Pretorius, Carel; Beyrer, Chris; Baral, Stefan; Decker, Michele R.; Sherman, Susan G.; Sweat, Michael; Poteat, Tonia; Butler, Jennifer; Oelrichs, Robert; Semini, Iris; Kerrigan, Deanna

    2014-01-01

    Introduction Sex workers have endured a high burden of HIV infection in and across HIV epidemics. A comprehensive, community empowerment-based HIV prevention intervention emphasizes sex worker organization and mobilization to address HIV risk and often includes community-led peer education, condom distribution, and other activities. Meta-analysis of such interventions suggests a potential 51% reduction in inconsistent condom use. Mathematical modeling exercises provide theoretical insight into potential impacts of the intervention on HIV incidence and burden in settings where interventions have not yet been implemented. Methods We used a deterministic model, Goals, to project the impact on HIV infections when the community empowerment interventions were scaled up among female sex workers in Kenya, Thailand, Brazil, and Ukraine. Modeling scenarios included expansion of the comprehensive community empowerment-based HIV prevention intervention from baseline coverage over a 5-year period (5–65% in Kenya and Ukraine; 10–70% in Thailand and Brazil), while other interventions were held at baseline levels. A second exercise increased the intervention coverage simultaneously with equitable access to ART for sex workers. Impacts on HIV outcomes among sex workers and adults are observed from 2012–2016 and, compared to status quo when all interventions are held constant. Results Optimistic but feasible coverage (65%–70%) of the intervention demonstrated a range of impacts on HIV: 220 infections averted over 5 yrs. among sex workers in Thailand, 1,830 in Brazil, 2,220 in Ukraine, and 10,800 infections in Kenya. Impacts of the intervention for female sex workers extend to the adult population, cumulatively averting 730 infections in Thailand to 20,700 adult infections in Kenya. Impacts vary by country, influenced by HIV prevalence in risk groups, risk behaviors, intervention use, and population size. Discussion A community empowerment approach to HIV prevention and

  5. Epidemic impacts of a community empowerment intervention for HIV prevention among female sex workers in generalized and concentrated epidemics.

    Directory of Open Access Journals (Sweden)

    Andrea L Wirtz

    Full Text Available INTRODUCTION: Sex workers have endured a high burden of HIV infection in and across HIV epidemics. A comprehensive, community empowerment-based HIV prevention intervention emphasizes sex worker organization and mobilization to address HIV risk and often includes community-led peer education, condom distribution, and other activities. Meta-analysis of such interventions suggests a potential 51% reduction in inconsistent condom use. Mathematical modeling exercises provide theoretical insight into potential impacts of the intervention on HIV incidence and burden in settings where interventions have not yet been implemented. METHODS: We used a deterministic model, Goals, to project the impact on HIV infections when the community empowerment interventions were scaled up among female sex workers in Kenya, Thailand, Brazil, and Ukraine. Modeling scenarios included expansion of the comprehensive community empowerment-based HIV prevention intervention from baseline coverage over a 5-year period (5-65% in Kenya and Ukraine; 10-70% in Thailand and Brazil, while other interventions were held at baseline levels. A second exercise increased the intervention coverage simultaneously with equitable access to ART for sex workers. Impacts on HIV outcomes among sex workers and adults are observed from 2012-2016 and, compared to status quo when all interventions are held constant. RESULTS: Optimistic but feasible coverage (65%-70% of the intervention demonstrated a range of impacts on HIV: 220 infections averted over 5 yrs. among sex workers in Thailand, 1,830 in Brazil, 2,220 in Ukraine, and 10,800 infections in Kenya. Impacts of the intervention for female sex workers extend to the adult population, cumulatively averting 730 infections in Thailand to 20,700 adult infections in Kenya. Impacts vary by country, influenced by HIV prevalence in risk groups, risk behaviors, intervention use, and population size. DISCUSSION: A community empowerment approach to HIV

  6. Impact of age at marriage and migration on HIV and AIDS epidemics in Japan

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    Ohkusa Yasushi

    2009-06-01

    Full Text Available Abstract The causes of wide variation in the rates of HIV and AIDS epidemics among Japanese and non-Japanese nationals are not well understood. So, this paper examines the associations and assesses the potential roles of mean age at marriage, and migration in the HIV and AIDS epidemics in Japan. For the purpose, bivariate and multivariate regression analysis have been performed using epidemiological panel data to build up the relationships among overall HIV and AIDS prevalence, mean age at marriage, and migration. The same analyses have done for non-Japanese nationals living with HIV and AIDS separately. These indicators were significantly correlated with mean age at marriage, and migration. Multivariate linear regression analysis identified non-Japanese nationals' HIV and AIDS prevalence and mean age at marriage as the two most prominent factors linked with the national HIV and AIDS epidemics. The findings of this study supported the hypotheses that a high average age at marriage in the population leads to long period of premarital sex and the non-Japanese nationals' high prevalence facilitating the spread of the HIV and AIDS epidemics in Japan.

  7. Impact of age at marriage and migration on HIV and AIDS epidemics in Japan.

    Science.gov (United States)

    Mondal, Nazrul Islam; Takaku, Hiroshi; Ohkusa, Yasushi

    2009-06-10

    The causes of wide variation in the rates of HIV and AIDS epidemics among Japanese and non-Japanese nationals are not well understood. So, this paper examines the associations and assesses the potential roles of mean age at marriage, and migration in the HIV and AIDS epidemics in Japan. For the purpose, bivariate and multivariate regression analysis have been performed using epidemiological panel data to build up the relationships among overall HIV and AIDS prevalence, mean age at marriage, and migration. The same analyses have done for non-Japanese nationals living with HIV and AIDS separately. These indicators were significantly correlated with mean age at marriage, and migration. Multivariate linear regression analysis identified non-Japanese nationals' HIV and AIDS prevalence and mean age at marriage as the two most prominent factors linked with the national HIV and AIDS epidemics. The findings of this study supported the hypotheses that a high average age at marriage in the population leads to long period of premarital sex and the non-Japanese nationals' high prevalence facilitating the spread of the HIV and AIDS epidemics in Japan.

  8. Heterogeneity of the HIV epidemic in the general population of Karnataka state, south India

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    Banandur Pradeep

    2011-12-01

    Full Text Available Abstract Background In the context of AVAHAN, the India AIDS Initiative of the Bill & Melinda Gates Foundation, general population surveys (GPS were carried out between 2006 and 2008 in Belgaum (northern, Bellary (mid-state and Mysore (southern districts of Karnataka state, south India. Data from these three surveys were analysed to understand heterogeneity in HIV risk. Methods Outcome variables were the prevalence of HIV and sexually transmitted infections (STIs. Independent variables included age, district, place of residence, along with socio-demographic, medical and behavioural characteristics. Multivariate logistic regression was undertaken to identify characteristics associated with HIV and differences between districts, incorporating survey statistics to consider weights and cluster effects. Results The participation rate was 79.0% for the interview and 72.5% for providing a blood or urine sample that was tested for HIV. Belgaum had the highest overall HIV (1.43% and Herpes simplex type-2 (HSV-2 (16.93% prevalence, and the lowest prevalence of curable STIs. In Belgaum, the HIV epidemic is predominantly rural, and among women. In Bellary, the epidemic is predominantly in urban areas and among men, and HIV prevalence was 1.18%. Mysore had the lowest prevalence of HIV (0.80% and HSV-2 (10.89% and the highest prevalence of curable STIs. Higher HIV prevalence among men was associated with increasing age (p25-29years=11.22,95%CI:1.42-88.74, AOR30-34years=13.13,95%CI:1.67-103.19 and AOR35-39years=11.33,95%CI:1.32-96.83, having more than one lifetime sexual partner (AOR=4.61,95%CI:1.26-16.91 and having ever used a condom (AOR=3.32,95%CI:1.38-7.99. Having a dissolved marriage (being widowed/divorced/separated was the strongest predictor (AOR=10.98,95%CI: 5.35-22.57 of HIV among women. Being a muslim woman was associated with lower HIV prevalence (AOR=0.27,95%CI:0.08-0.87. Conclusion The HIV epidemic in Karnataka shows considerable heterogeneity

  9. Genetic and phylogenetic evolution of HIV-1 in a low subtype heterogeneity epidemic: the Italian example

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    Tornesello Maria

    2007-05-01

    Full Text Available Abstract The Human Immunodeficiency Virus type 1 (HIV-1 is classified into genetic groups, subtypes and sub-subtypes which show a specific geographic distribution pattern. The HIV-1 epidemic in Italy, as in most of the Western Countries, has traditionally affected the Intra-venous drug user (IDU and Homosexual (Homo risk groups and has been sustained by the genetic B subtype. In the last years, however, the HIV-1 transmission rate among heterosexuals has dramatically increased, becoming the prevalent transmission route. In fact, while the traditional risk groups have high levels of knowledge and avoid high-risk practices, the heterosexuals do not sufficiently perceive the risk of HIV-1 infection. This misperception, linked to the growing number of immigrants from non-Western Countries, where non-B clades and circulating recombinant forms (CRFs are prevalent, is progressively introducing HIV-1 variants of non-B subtype in the Italian epidemic. This is in agreement with reports from other Western European Countries. In this context, the Italian HIV-1 epidemic is still characterized by low subtype heterogeneity and represents a paradigmatic example of the European situation. The continuous molecular evolution of the B subtype HIV-1 isolates, characteristic of a long-lasting epidemic, together with the introduction of new subtypes as well as recombinant forms may have significant implications for diagnostic, treatment, and vaccine development. The study and monitoring of the genetic evolution of the HIV-1 represent, therefore, an essential strategy for controlling the local as well as global HIV-1 epidemic and for developing efficient preventive and therapeutic strategies.

  10. HIV/AIDS epidemic and the development of comprehensive surveillance system in China with challenges

    Institute of Scientific and Technical Information of China (English)

    WANG Lu; WANG Ning

    2010-01-01

    @@ AIDS is the most severe infectious disease that has appeared in the second half of the 20th century.Since the United States Center of Disease Control & Prevention (US CDC) reported the first case of HIV carrier in the men who had sex with men (MSM)population in 1981, HIV/AIDS had spread globally. By the end of December 2008, UNAIDS and WHO estimated that there were 3340 million (3110-3580 million)infected with HIV/AIDS worldwide.1 While the HIV/AIDS epidemic in Asia began later than the epidemic in Europe, America and Africa, experts predict that countries in Asia, especially in three countries, China,India and Indonesia, which have a population of more than 100 million, will have the world's largest number of HIV/AIDS in the near future.

  11. The contributing role of tourism in the HIV/AIDS epidemic in the Caribbean.

    Science.gov (United States)

    Orisatoki, R O; Oguntibeju, O O; Truter, E J

    2009-01-01

    The first confirmed case of HIV/AIDS in the Caribbean was reported in 1982, however a recent report by UNAIDS shows that the epidemic has risen to over 250,000 persons living with the virus with the highest prevalence rates shown to be in the Dominican Republic and Haiti. Various factors ranging from commercial sex trading to unsafe injection employed for drug abuse have been identified to play a contributing role in this increase. Also, the role and impact of tourism on the spread of HIV infection has been reported. Due to concerns shown by countries and territories who are dependent on tourism and that they rank amongst the most highly affected by HIV/AIDS in the region, this paper endeavours to examine the impact of HIV/AIDS and the contributing role of tourism to HIV/AIDS epidemic in the Caribbean.

  12. Changing patterns of HIV epidemic in 30 years in East Asia.

    Science.gov (United States)

    Suguimoto, S Pilar; Techasrivichien, Teeranee; Musumari, Patou Masika; El-saaidi, Christina; Lukhele, Bhekumusa Wellington; Ono-Kihara, Masako; Kihara, Masahiro

    2014-06-01

    The HIV epidemic in East Asia started relatively late compared to the rest of the world. All countries or areas, except for North Korea, had reported HIV and AIDS cases, with China being the major contributor to the epidemic. Though initially driven by injecting drug use in China, East Asia did not experience an explosive spread. Strong commitment in China and early harm reduction programs in Taiwan managed to reduce transmission substantially among injecting drug users. In contrast to China and Taiwan, injection drug use has accounted just a little, if not at all, for the spread of HIV in other East Asian counties. However, following a global trend, sexual contact has become a major route of infection across the region. While much progress has been achieved in this region, with the epidemic among other key populations relatively stable, the emerging epidemic through sex between men is a growing concern. Recent estimates suggest that HIV prevalence among men who have sex with men (MSM) has reached 6.3 % in China, 7.5 % in Mongolia, and ranges between 8.1 %-10.7 % in Taiwan and between 2.7 %- 6.5 % in South Korea. In Japan, 74 % of male HIV cases were among MSM in 2012, while Hong Kong has witnessed a sharp increase of HIV cases among MSM since 2004. There is urgent need to address issues of discrimination and stigma toward homosexuality, and to strengthen the strategies to reach and care for this population.

  13. Is the HIV epidemic stable among MSM in Mexico? HIV prevalence and risk behavior results from a nationally representative survey among men who have sex with men.

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    Sergio Bautista-Arredondo

    Full Text Available BACKGROUND: Recent evidence points to the apparent increase of HIV prevalence among men who have sex with men (MSM in different settings with concentrated epidemics, including the Latin American region. In 2011, Mexico implemented an ambitious HIV prevention program in all major cities, funded by the Global Fund to Fight Aids, Tuberculosis and Malaria. The program was intended to strengthen the prevention response for the most at risk populations: MSM and injecting drug users. This paper presents the HIV prevalence results of a nationally representative baseline survey in 24 Mexican cities throughout the 5 regions in the country and reports the socio-demographic and sexual risk behaviors that predict the probability of infection. METHODS: The survey was implemented in two phases. We first identified and characterized places where MSM gather in each city and then conducted in a second phase, a seroprevalence survey that included rapid HIV testing and a self-administered questionnaire. The prevalence of HIV was estimated by adjusting for positive predicted value. We applied a probit model to estimate the probability of having a positive result from the HIV test as a function of socio-demographic characteristics and self-reported sexual risk behaviors. RESULTS: We found an overall HIV prevalence among MSM gathering in meeting points of 16.9% [95% CI: 15.6-18.3], significantly higher than previously reported estimates. Our regression results suggest that the risk of infection increases with age, with the number of sexual partners, and among those who play a receptive sexual role, and the risk decreases with higher education. DISCUSSION: Our findings suggest a higher HIV prevalence among MSM than previously acknowledged and that a significant regional variability exist throughout the country. These two findings combined, signal an important dynamic in the epidemic that should be better understood and promptly addressed with strong prevention efforts

  14. HIV type 2 epidemic in Spain: challenges and missing opportunities.

    Science.gov (United States)

    de Mendoza, Carmen; Cabezas, Teresa; Caballero, Estrella; Requena, Silvia; Amengual, María J; Peñaranda, María; Sáez, Ana; Tellez, Raquel; Lozano, Ana B; Treviño, Ana; Ramos, José M; Pérez, José L; Barreiro, Pablo; Soriano, Vicente

    2017-06-19

    : HIV type 2 (HIV-2) is a neglected virus despite estimates of 1-2 million people infected worldwide. HIV-2 is less efficiently transmitted than HIV-1 by sex and from mother to child. Although AIDS may develop in HIV-2 carriers, it takes longer than in HIV-1-infected patients. In contrast with HIV-1 infection, there is no global pandemic caused by HIV-2, as the virus is largely confined to West Africa. In a less extent and due to socioeconomic ties and wars, HIV-2 is prevalent in Portugal and its former colonies in Brazil, India, Mozambique and Angola. Globally, HIV-2 infections are steadily declining over time. A total of 338 cases of HIV-2 infection had been reported at the Spanish HIV-2 registry until December 2016, of whom 63% were men. Overall 72% were sub-Saharan Africans, whereas 16% were native Spaniards. Dual HIV-1 and HIV-2 coinfection was found in 9% of patients. Heterosexual contact was the most likely route of HIV-2 acquisition in more than 90% of cases. Roughly one-third presented with CD4 cell counts less than 200 cells/μl and/or AIDS clinical events. Plasma HIV-2 RNA was undetectable at baseline in 40% of patients. To date, one-third of HIV-2 carriers have received antiretroviral therapy, using integrase inhibitors 32 individuals. New diagnoses of HIV-2 in Spain have remained stable since 2010 with an average of 15 cases yearly. Illegal immigration from Northwestern African borders accounts for over 75% of new HIV-2 diagnoses. Given the relatively large community of West Africans already living in Spain and the continuous flux of immigration from endemic regions, HIV-2 infection either alone or as coinfection with HIV-1 should be excluded once in all HIV-seroreactive persons, especially when showing atypical HIV serological profiles, immunovirological disconnect (CD4 cell count loss despite undetectable HIV-1 viremia) and/or high epidemiological risks (birth in or sex partners from endemic regions).

  15. [A recombinant HIV-1 strain causing an epidemic among injection drug addicts in Kaliningrad].

    Science.gov (United States)

    Korovina, G I; Smol'skaia, T T; Tashkinova, I P; Momot, O F; Kevlova, N A; Liitsola, K; Leinikki, P; Salminen, M

    1999-01-01

    The analysis of the genetic structure of HIV causing the epidemic in Kaliningrad Province. A new recombinant virus of subtype A/B was detected with the use of the polymerase chain reaction, the cloning of amplified fragments, sequencing and the phylogenetic analysis of the obtained data. The results thus obtained indicate that the epidemic in Kaliningrad was caused by a recombinant strain, and not due to co-infection caused by two HIV strains of different subtypes. The study of HIV-1 DNA revealed the divergence between the samples was extremely low, which was characteristic of epidemics connected with the transmission of the virus in the process of the intravenous use of narcotic drugs.

  16. HIV/AIDS Epidemic in the United States

    Science.gov (United States)

    ... 30 , 31 However, looking across the spectrum from HIV diagnosis to viral suppression reveals missed opportunities for addressing ... half (44%) of deaths among people with an HIV diagnosis in 2014. 47 Survival after an AIDS diagnosis ...

  17. The impact of vaccine success and awareness on epidemic dynamics

    Science.gov (United States)

    Juang, Jonq; Liang, Yu-Hao

    2016-11-01

    The role of vaccine success is introduced into an epidemic spreading model consisting of three states: susceptible, infectious, and vaccinated. Moreover, the effect of three types, namely, contact, local, and global, of infection awareness and immunization awareness is also taken into consideration. The model generalizes those considered in Pastor-Satorras and Vespignani [Phys. Rev. E 63, 066117 (2001)], Pastor-Satorras and Vespignani [Phys. Rev. E 65, 036104 (2002)], Moreno et al. [Eur. Phys. J. B 26, 521-529 (2002)], Wu et al. [Chaos 22, 013101 (2012)], and Wu et al. [Chaos 24, 023108 (2014)]. Our main results contain the following. First, the epidemic threshold is explicitly obtained. In particular, we show that, for any initial conditions, the epidemic eventually dies out regardless of what other factors are whenever some type of immunization awareness is considered, and vaccination has a perfect success. Moreover, the threshold is independent of the global type of awareness. Second, we compare the effect of contact and local types of awareness on the epidemic thresholds between heterogeneous networks and homogeneous networks. Specifically, we find that the epidemic threshold for the homogeneous network can be lower than that of the heterogeneous network in an intermediate regime for intensity of contact infection awareness while it is higher otherwise. In summary, our results highlight the important and crucial roles of both vaccine success and contact infection awareness on epidemic dynamics.

  18. Epidemic Dynamics On Information-Driven Adaptive Networks

    CERN Document Server

    Zhan, Xiu-Xiu; Sun, Gui-Quan; Zhang, Zi-Ke

    2015-01-01

    can evolve simultaneously. For the information-driven adaptive process, susceptible (infected) individuals who have abilities to recognize the disease would break the links of their infected (susceptible) neighbors to prevent the epidemic from further spreading. Simulation results and numerical analyses based on the pairwise approach indicate that the information-driven adaptive process can not only slow down the speed of epidemic spreading, but can also diminish the epidemic prevalence at the final state significantly. In addition, the disease spreading and information diffusion pattern on the lattice give a visual representation about how the disease is trapped into an isolated field with the information-driven adaptive process. Furthermore, we perform the local bifurcation analysis on four types of dynamical regions, including healthy, oscillatory, bistable and endemic, to understand the evolution of the observed dynamical behaviors. This work may shed some lights on understanding how information affects h...

  19. Temporal Dynamics of Connectivity and Epidemic Properties of Growing Networks

    CERN Document Server

    Fotouhi, Babak

    2015-01-01

    Traditional mathematical models of epidemic disease had for decades conventionally considered static structure for contacts. Recently, an upsurge of theoretical inquiry has strived towards rendering the models more realistic by incorporating the temporal aspects of networks of contacts, societal and online, that are of interest in the study of epidemics (and other similar diffusion processes). However, temporal dynamics have predominantly focused on link fluctuations and nodal activities, and less attention has been paid to the growth of the underlying network. Many real networks grow: online networks are evidently in constant growth, and societal networks can grow due to migration flux and reproduction. The effect of network growth on the epidemic properties of networks is hitherto unknown---mainly due to the predominant focus of the network growth literature on the so-called steady-state. This paper takes a step towards alleviating this gap. We analytically study the degree dynamics of a given arbitrary net...

  20. The hepatitis C epidemic among HIV-positive MSM

    DEFF Research Database (Denmark)

    van der Helm, Jannie J; Prins, Maria; del Amo, Julia

    2011-01-01

    Outbreaks of acute hepatitis C virus (HCV) infection among HIV-infected MSM have been described since 2000. However, phylogenetic analysis suggests that the spread of HCV started around 1996. We estimated the incidence of HCV in HIV-infected MSM with well estimated dates of HIV seroconversion from...

  1. The epidemic of HIV/AIDS in developing countries; the current scenario in Pakistan

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    Babar Masroor E

    2011-08-01

    Full Text Available Abstract HIV (Human Immunodeficiency virus causes (acquired immunodeficiency syndrome AIDS, in which the immune system of body totally fails to develop any defense against the foreign invaders. Infection with HIV occurs by transfer of blood, semen, and breast milk. HIV/AIDS is a global problem and it results nearly 25 million deaths worldwide. Developing countries like Pakistan have issues regarding Public Health. Currently, epidemic of HIV/AIDS is established in Pakistan and there is a threat of an expanded HIV/AIDS outbreak in the country. The major reason is that population is engaging in high-risk practices, low awareness about HIV/AIDS, and treacherous blood transfusion practices. A supplementary threat to Pakistan is India because both sharing a border and India is facing a rapidly growing HIV/AIDS epidemic. Local NGOs, National and International organizations are warning that in near future Pakistan may experiences bad situation regarding HIV/AIDS. In the present article we focused current situation of surveillance of HIV/AIDS, its virology, genotype, diagnostics, high-risk groups, reasons of vulnerability in Pakistani population, and the role of different national and international organizations in this situation.

  2. The relatedness of HIV epidemics in the United States-Mexico border region.

    Science.gov (United States)

    Mehta, Sanjay R; Delport, Wayne; Brouwer, Kimberly C; Espitia, Stephen; Patterson, Thomas; Pond, Sergei Kosakovsky; Strathdee, Steffanie A; Smith, Davey M

    2010-12-01

    Phylogeography can improve the understanding of local and worldwide HIV epidemics, including the migration of subepidemics across national borders. We analyzed HIV-1 sequences sampled from Mexico and San Diego, California to determine the relatedness of these epidemics. We sampled the HIV epidemics in (1) Mexico by downloading all publicly available HIV-1 pol sequences from antiretroviral-naive individuals in GenBank (n = 100) and generating similar sequences from cohorts of injection drug users and female sex workers in Tijuana, Mexico (n = 27) and (2) in San Diego, California by pol sequencing well-characterized primary (n = 395) and chronic (n = 267) HIV infection cohorts. Estimates of population structure (F(ST)), genetic distance cluster analysis, and a cladistic measure of migration events (Slatkin-Maddison test) were used to assess the relatedness of the epidemics. Both a test of population differentiation (F(ST) = 0.06; p cluster analysis identified 72 clusters (two or more sequences), with two clusters containing both Mexican and San Diego sequences (permutation p Mexico are distinct. Larger epidemiological studies are needed to quantify the magnitude and associations of cross-border mixing.

  3. Learning Lessons through Data Triangulation: Vulnerability of Surat City to HIV epidemic

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    Anjali Modi, J K Kosambiya, H K Sondharwa, Manish Kumar

    2013-01-01

    Results: The prevalence of HIV among ANC clinic attendees in HIV Sentinel Surveillance (HSS and PPTCT 2008 was 0.76% and 0.9%. The HSS 2008 showed 14.40%, 4.4% and 10.00% positivity among high-risk groups (HRG; STI Clinic attendees, Female Sex Workers (FSW and Men having Sex with Men (MSM. The observation of yearly trends showed stable to declining trends among general population and HRGs. Service (41.75% and Treatment (21.42% gaps at the program level for identifying and treating PLHIVs were found. Conclusion: The high HIV positivity of Surat city in comparison to the Gujarat state and India indicates its vulnerability towards HIV epidemic. The program officers and policy makers need to formulate special strategies to halt and reverse epidemic in Surat.

  4. HIV Stages Contributions to the Epidemic, Due to a Changing Viral Load

    Science.gov (United States)

    Combadão, Jaime; Gomes, M. Gabriela M.

    2009-09-01

    It is very important to understand the contribution of the various HIV progression stages -acute, asymptomatic, late-, so as to optimize the fight against the HIV epidemic. In the last recent years, some have given the acute phase the responsibility for the majority of the new infections, while others thought that the late phase was more important, no doubt because these two phases are more infectious. More recently, it was argued that no HIV stage is dominant in the HIV epidemic in sub-Saharan Africa. Here, by a simple population model with continuous influx of susceptible individuals, and using known relationships between the viral load, the duration of the asymptomatic infection and transmission probability, we calculated the contributions of each stage to the spreading of the disease in a high risk group. Also, we analyzed some evolutionary scenarios, in which the virulence of the virus can evolve.

  5. Modeling the dynamical interaction between epidemics on overlay networks

    CERN Document Server

    Marceau, Vincent; Hébert-Dufresne, Laurent; Allard, Antoine; Dubé, Louis J

    2011-01-01

    Epidemics seldom occur as isolated phenomena. Typically, two or more viral agents spread within the same host population and may interact dynamically with each other. We present a general model where two viral agents interact via an immunity mechanism as they propagate simultaneously on two networks connecting the same set of nodes. Exploiting a correspondence between the propagation dynamics and a dynamical process performing progressive network generation, we develop an analytic approach that accurately captures the dynamical interaction between epidemics on overlay networks. The formalism allows for overlay networks with arbitrary joint degree distribution and overlap. To illustrate the versatility of our approach, we consider a hypothetical delayed intervention scenario in which an immunizing agent is disseminated in a host population to hinder the propagation of an undesirable agent (e.g. the spread of preventive information in the context of an emerging infectious disease).

  6. Dynamic optimization model for allocating medical resources in epidemic controlling

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    Ming Liu

    2013-03-01

    Full Text Available Purpose: The model proposed in this paper addresses a dynamic optimization model for allocating medical resources in epidemic controlling.Design/methodology/approach: In this work, a three-level and dynamic linear programming model for allocating medical resources based on epidemic diffusion model is proposed. The epidemic diffusion model is used to construct the forecasting mechanism for dynamic demand of medical resources. Heuristic algorithm coupled with MTLAB mathematical programming solver is adopted to solve the model. A numerical example is presented for testing the model’s practical applicability.Findings: The main contribution of the present study is that a discrete time-space network model to study the medical resources allocation problem when an epidemic outbreak is formulated. It takes consideration of the time evolution and dynamic nature of the demand, which is different from most existing researches on medical resources allocation.Practical implications: In our model, the medicine logistics operation problem has been decomposed into several mutually correlated sub-problems, and then be solved systematically in the same decision scheme. Thus, the result will be much more suitable for real operations.Originality/value: In our model, the rationale that the medical resources allocated in early periods will take effect in subduing the spread of the epidemic spread and thus impact the demand in later periods has been for the first time incorporated. A win-win emergency rescue effect is achieved by the integrated and dynamic optimization model. The total rescue cost is controlled effectively, and meanwhile, inventory level in each urban health departments is restored and raised gradually.

  7. Monitoring HIV Epidemic in Pregnant Women: Are the Current Measures Enough?

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    Purva Sarkate

    2015-01-01

    Full Text Available Introduction. Burden of HIV in pregnant women follows overall epidemic in India. Hence, it is imperative that prevalence calculations in this group be accurate. The present study was carried out to determine prevalence of HIV in pregnant women attending our hospital, to determine trend of HIV infection and to compare our results with reported prevalence. Methods. All pregnant women are routinely counselled for HIV testing using opt-out strategy. Year-wise positivity and trend were determined in these patients over a period of five years. The positivity in different age groups was determined. Results. 31,609 women were tested of which 279 (0.88% were positive. Positivity showed a declining trend over study period and significant quadratic trend (biphasic, P<0.05 was observed. The positivity in older age group ≥35 years (1.64% was significantly more than younger age groups (0.76% in 15–24-year and 0.94% in 25–34-year age group (P=0.0052. Conclusion. A significant decline in HIV positivity was seen over the study period. Taking into account heterogeneous nature of HIV epidemic even within the same district, analysis at local levels especially using the prevention of parent to child transmission of HIV program data is critical for HIV programming and resource allocation.

  8. Characterizing the HIV/AIDS Epidemic in the United States and China.

    Science.gov (United States)

    Huang, Ming-Bo; Ye, Li; Liang, Bing-Yu; Ning, Chuan-Yi; Roth, William W; Jiang, Jun-Jun; Huang, Jie-Gang; Zhou, Bo; Zang, Ning; Powell, Michael D; Liang, Hao; Bond, Vincent C

    2015-12-22

    The HIV/AIDS data from the national surveillance systems of China and the United States from 1985 to 2014 were compared to characterize the HIV/AIDS epidemic in both countries. The current estimated national HIV prevalence rate in China and the United States are 0.0598% and 0.348%, respectively. In the United States, the annual number of new HIV infections has remained relatively stable (~50,000 each year) and has shown a downward trend in recent years. The Chinese national HIV prevalence is still low, and new HIV infections have been contained at a low level (50,000-100,000 each year). However, the epidemic has showed an increasing trend since 2012. By risk group, in both countries, men who have sex with men (MSM), heterosexual sex, and injection drug use (IDU) are the most common modes of transmission of new HIV infections. However, in the United States, MSM is the dominant transmission route, accounting for >60% of new infections; whereas in China, heterosexual sex has now become the dominant route, also accounting for >60% of new infections. A rapid increase in the proportion of HIV cases that were attributed to MSM and an obvious decrease in the proportion of HIV cases attributed to IDU in China in recent years imply that the China's epidemic is still evolving, to some extent, copying what was experienced in the United States. By age group, the proportions of HIV cases that were attributed to the age group 25-59 were comparable between the two countries. However, the United States had a higher proportion of cases that were attributed to age groups 15-19 and 20-24 than China, indicating that youth account for more infections in the United States. One other fact worth noting: in China there is a significant increase in the number of HIV new infections in individuals over 50 years of age, which results in much higher proportion of cases that were attributed to age groups 60-64 and over 65 in China than those in the United States. By race/ethnicity, in the United

  9. Characterizing the HIV/AIDS Epidemic in the United States and China

    Directory of Open Access Journals (Sweden)

    Ming-Bo Huang

    2015-12-01

    Full Text Available The HIV/AIDS data from the national surveillance systems of China and the United States from 1985 to 2014 were compared to characterize the HIV/AIDS epidemic in both countries. The current estimated national HIV prevalence rate in China and the United States are 0.0598% and 0.348%, respectively. In the United States, the annual number of new HIV infections has remained relatively stable (~50,000 each year and has shown a downward trend in recent years. The Chinese national HIV prevalence is still low, and new HIV infections have been contained at a low level (50,000–100,000 each year. However, the epidemic has showed an increasing trend since 2012. By risk group, in both countries, men who have sex with men (MSM, heterosexual sex, and injection drug use (IDU are the most common modes of transmission of new HIV infections. However, in the United States, MSM is the dominant transmission route, accounting for >60% of new infections; whereas in China, heterosexual sex has now become the dominant route, also accounting for >60% of new infections. A rapid increase in the proportion of HIV cases that were attributed to MSM and an obvious decrease in the proportion of HIV cases attributed to IDU in China in recent years imply that the China’s epidemic is still evolving, to some extent, copying what was experienced in the United States. By age group, the proportions of HIV cases that were attributed to the age group 25–59 were comparable between the two countries. However, the United States had a higher proportion of cases that were attributed to age groups 15–19 and 20–24 than China, indicating that youth account for more infections in the United States. One other fact worth noting: in China there is a significant increase in the number of HIV new infections in individuals over 50 years of age, which results in much higher proportion of cases that were attributed to age groups 60–64 and over 65 in China than those in the United States. By

  10. Expanding HIV testing efforts in concentrated epidemic settings: a population-based survey from rural Vietnam.

    Directory of Open Access Journals (Sweden)

    Anastasia Pharris

    Full Text Available BACKGROUND: To improve HIV prevention and care programs, it is important to understand the uptake of HIV testing and to identify population segments in need of increased HIV testing. This is particularly crucial in countries with concentrated HIV epidemics, where HIV prevalence continues to rise in the general population. This study analyzes determinants of HIV testing in a rural Vietnamese population in order to identify potential access barriers and areas for promoting HIV testing services. METHODS: A population-based cross-sectional survey of 1874 randomly sampled adults was linked to pregnancy, migration and economic cohort data from a demographic surveillance site (DSS. Multivariate logistic regression analysis was used to determine which factors were associated with having tested for HIV. RESULTS: The age-adjusted prevalence of ever-testing for HIV was 7.6%; however 79% of those who reported feeling at-risk of contracting HIV had never tested. In multivariate analysis, younger age (aOR 1.85, 95% CI 1.14-3.01, higher economic status (aOR 3.4, 95% CI 2.21-5.22, and semi-urban residence (aOR 2.37, 95% CI 1.53-3.66 were associated with having been tested for HIV. HIV testing rates did not differ between women of reproductive age who had recently been pregnant and those who had not. CONCLUSIONS: We found low testing uptake (6% among pregnant women despite an existing prevention of mother-to-child HIV testing policy, and lower-than-expected testing among persons who felt that they were at-risk of HIV. Poverty and residence in a more geographically remote location were associated with less HIV testing. In addition to current HIV testing strategies focusing on high-risk groups, we recommend targeting HIV testing in concentrated HIV epidemic settings to focus on a scaled-up provision of antenatal testing. Additional recommendations include removing financial and geographic access barriers to client-initiated testing, and encouraging provider

  11. SIS model of epidemic spreading on dynamical networks with community

    Institute of Scientific and Technical Information of China (English)

    Chengyi XIA; Shiwen SUN; Feng RAO; Junqing SUN; Jinsong WANG; Zengqiang CHEN

    2009-01-01

    We present a new epidemic Susceptible-Infected-Susceptible (SIS) model to investigate the spreading behav-ior on networks with dynamical topology and community structure. Individuals in the model are mobile agents who are allowed to perform the inter-community (i.e., long-range) motion with the probability p. The mean-field theory is uti-lized to derive the critical threshold (λ_C) of epidemic spread-ing inside separate communities and the influence of the long-range motion on the epidemic spreading. The results indicate that λ_C is only related with the population density within the community, and the long-range motion will make the original disease-free community become the endemic state. Large-scale numerical simulations also demonstrate the theoretical approximations based on our new epidemic model. The current model and analysis will help us to fur-ther understand the propagation behavior of real epidemics taking place on social networks.

  12. Evolving uses of oral reverse transcriptase inhibitors in the HIV-1 epidemic: From treatment to prevention

    NARCIS (Netherlands)

    R.K. Gupta (Ravindra); D.A.M.C. van de Vijver (David); S. Manicklal (Sheetal); M.A. Wainberg (Mark)

    2013-01-01

    textabstractThe HIV epidemic continues unabated, with no highly effective vaccine and no cure. Each new infection has significant economic, social and human costs and prevention efforts are now as great a priority as global antiretroviral therapy (ART) scale up. Reverse transcriptase inhibitors, the

  13. The Impact of HIV/AIDS Epidemic on the Choice of Specialties ...

    African Journals Online (AJOL)

    The Impact of HIV/AIDS Epidemic on the Choice of Specialties among ... Fifty three percent (53.3%) and sixteen Percent (16.3%) based their choice of specialty on job satisfaction and favourable work schedule respectively. ... We recommend improvements in the work environment and adherence to universal precautions to

  14. A transmission model for HIV with application to the Australian epidemic.

    Science.gov (United States)

    Becker, N G; Egerton, L R

    1994-02-01

    An age-specific transmission model is proposed to describe the spread of HIV in a homosexual population. The model incorporates developments in the treatment of patients and the change in the surveillance definition of AIDS. The model is applied to the Australian epidemic with the aim of determining the extent of behavioral changes during the epidemic and assessing the extent to which therapy has changed the course of the epidemic. It is found that therapy and the adoption of totally safe sex practices by individuals who have tested HIV positive cannot explain the recent downturn in the rate of increase of observed AIDS incidence. A significant change in behavior within the general homosexual community is indicated.

  15. Ending the HIV/AIDS epidemic in low- and middle-income countries by 2030: is it possible?

    Science.gov (United States)

    Harries, Anthony D; Suthar, Amitabh B; Takarinda, Kudakwashe C; Tweya, Hannock; Kyaw, Nang Thu Thu; Tayler-Smith, Katie; Zachariah, Rony

    2016-01-01

    The international community has committed to ending the epidemics of HIV/AIDS, tuberculosis, malaria, and neglected tropical infections by 2030, and this bold stance deserves universal support. In this paper, we discuss whether this ambitious goal is achievable for HIV/AIDS and what is needed to further accelerate progress. The joint United Nations Program on HIV/AIDS (UNAIDS) 90-90-90 targets and the related strategy are built upon currently available health technologies that can diagnose HIV infection and suppress viral replication in all people with HIV. Nonetheless, there is much work to be done in ensuring equitable access to these HIV services for key populations and those who remain outside the rims of the traditional health services. Identifying a cure and a preventive vaccine would further help accelerate progress in ending the epidemic. Other disease control programmes could learn from the response to the HIV/AIDS epidemic.

  16. Behavioral Risk Reduction in a Declining HIV Epidemic: Injection Drug Users in New York City, 1990-1997.

    Science.gov (United States)

    Des Jarlais, Don C.; Perlis, Theresa; Friedman, Samuel R.; Chapman, Timothy; Kwok, John; Rockwell, Russell; Paone, Denise; Milliken, Judith; Monterroso, Edgar

    2000-01-01

    Assessed trends in HIV risk behaviors among New York City injection drug users from 1990-97. Interviews at a drug detoxification program and a research storefront in a high drug-use area showed continuing risk reduction among users that indicated a declining phase in the large HIV epidemic in New York City. HIV prevention programs appeared to be…

  17. The impact of antiretroviral treatment on the age composition of the HIV epidemic in sub-Saharan Africa

    NARCIS (Netherlands)

    J.A.C. Hontelez (Jan A.C.); S.J. de Vlas (Sake); R.M.P.M. Baltussen (Rob); M.-L. Newell (Marie-Louise); R. Bakker (Roel); F. Tanser (Frank); M.N. Lurie (Mark N.); T. Bärnighausen (Till)

    2012-01-01

    textabstractIntroduction: Antiretroviral treatment (ART) coverage is rapidly expanding in sub-Saharan Africa (SSA). Based on the effect of ART on survival of HIV-infected people and HIV transmission, the age composition of the HIV epidemic in the region is expected to change in the coming decades. W

  18. The impact of antiretroviral treatment on the age composition of the HIV epidemic in sub-Saharan Africa

    NARCIS (Netherlands)

    Hontelez, J.A.C.; Vlas, S.J. de; Baltussen, R.; Newell, M.L.; Bakker, R.; Tanser, F.; Lurie, M.; Barnighausen, T.

    2012-01-01

    INTRODUCTION: Antiretroviral treatment (ART) coverage is rapidly expanding in sub-Saharan Africa (SSA). Based on the effect of ART on survival of HIV-infected people and HIV transmission, the age composition of the HIV epidemic in the region is expected to change in the coming decades. We quantify t

  19. The HIV/AIDS Epidemic in the Dominican Republic: Key Contributing Factors.

    Science.gov (United States)

    Rojas, Patria; Malow, Robert; Ruffin, Beverly; Rothe, Eugenio M; Rosenberg, Rhonda

    2011-01-01

    This article reviews HIV/AIDS epidemiological data and recent research conducted in the Dominican Republic, with a focus on explaining the variability in estimated seroincidence and prevalence within the country. HIV seroprevalence estimates range from 1.0% (in the general population) to 11.0% among men who have sex with men (MSM). Some have indicated that the highest HIV seroprevalence occurs in Haitian enclaves called bateyes (US Agency for International Development [USAID], 2008), which are migrant worker shantytowns primarily serving the sugar industry in the Dominican Republic. Others report higher or comparable rates to the bateyes in areas related to the tourism and sex industries. As in other Caribbean and Latin American countries, reported HIV transmission in the Dominican Republic is predominantly due to unprotected heterosexual sex and the infection rate has been increasing disproportionally among women. The Dominican Republic represents two thirds of the Hispaniola island; the western one third is occupied by Haiti, the nation with the highest HIV prevalence in the western hemisphere. Although data is limited, it shows important differences in seroprevalence and incidence between these two countries, but commonalities such as poverty, gender inequalities, and stigma appear to be pivotal factors driving the epidemic. This article will discuss these and other factors that may contribute to the HIV epidemic in the Dominican Republic, as well as highlight the gaps in the literature and provide recommendations to guide further work in this area, particularly in the role of governance in sustainable HIV prevention.

  20. The Silent Epidemic – Frailty and Aging with HIV

    Science.gov (United States)

    Willig, Amanda L.; Overton, Edgar T.; Saag, Michael S.

    2017-01-01

    As the number of older adults with HIV increases, this population is experiencing an increased risk for frailty. While there is no single definition or diagnostic criteria for frailty, it is generally recognized as an accumulation of deficits in functional capacity and ability to perform activities of daily living. Frailty may be present in up to half of older adults living with HIV, and is associated with significant morbidity and mortality risk in this group. Frailty in HIV can either be transient, and linked to the status of HIV infection, or resemble a more typical gradual decline in functional capacity. Frailty risk in HIV may be exacerbated by mitochondrial dysfunction, chronic inflammation, and oxidative stress. Several tools have been developed and adapted to assess different domains of frailty, yet medical treatment of this condition can be complex and should consider management of polypharmacy as well as nutrition and exercise interventions. However, few concrete strategies have been developed to prevent or treat frailty in the context of HIV infection. This review summarizes what is currently known about the prevalence, diagnosis, and management of frailty among older adults living with HIV.

  1. Modeling epidemics dynamics on heterogenous networks.

    Science.gov (United States)

    Ben-Zion, Yossi; Cohen, Yahel; Shnerb, Nadav M

    2010-05-21

    The dynamics of the SIS process on heterogenous networks, where different local communities are connected by airlines, is studied. We suggest a new modeling technique for travelers movement, in which the movement does not affect the demographic parameters characterizing the metapopulation. A solution to the deterministic reaction-diffusion equations that emerges from this model on a general network is presented. A typical example of a heterogenous network, the star structure, is studied in detail both analytically and using agent-based simulations. The interplay between demographic stochasticity, spatial heterogeneity and the infection dynamics is shown to produce some counterintuitive effects. In particular it was found that, while movement always increases the chance of an outbreak, it may decrease the steady-state fraction of sick individuals. The importance of the modeling technique in estimating the outcomes of a vaccination campaign is demonstrated.

  2. A neglected epidemic: fungal infections in HIV/AIDS.

    Science.gov (United States)

    Armstrong-James, Darius; Meintjes, Graeme; Brown, Gordon D

    2014-03-01

    Invasive fungal infections (IFIs) are a major cause of HIV-related mortality globally. Despite widespread rollout of combined antiretroviral therapy, there are still up to 1 million deaths annually from IFIs, accounting for 50% of all AIDS-related death. A historic failure to focus efforts on the IFIs that kill so many HIV patients has led to fundamental flaws in the management of advanced HIV infection. This review, based on the EMBO AIDS-Related Mycoses Workshop in Cape Town in July 2013, summarizes the current state of the-art in AIDS-related mycoses, and the key action points required to improve outcomes from these devastating infections.

  3. The HIV epidemic in Southern Africa - Is an AIDS-free generation possible?

    Science.gov (United States)

    Delva, Wim; Abdool Karim, Quarraisha

    2014-06-01

    Southern Africa, home to about 20 % of the global burden of infection continues to experience high rates of new HIV infection despite substantial programmatic scale-up of treatment and prevention interventions. While several countries in the region have had substantial reductions in HIV infection, almost half a million new infections occurred in this region in 2012. Sexual transmission remains the dominant mode of transmission. A recent national household survey in Swaziland revealed an HIV prevalence of 14.3 % among 18-19 year old girls, compared to 0.8 % among their male peers. Expanded ART programmes in Southern Africa have resulted in dramatically decreased HIV incidence and HIV mortality rates. In South Africa alone, it is estimated that more than 2.1 million of the 6.1 million HIV-positive people were receiving ART by the end of 2012, and that this resulted in more than 2.7 million life-years saved, and hundreds of thousands of HIV infections averted. Biological, behavioural and structural factors all contribute to the ongoing high rates of new HIV infection; however, as the epidemic matures and mortality is reduced from increased ART coverage, epidemiological trends become hard to quantify. What is clear is that a key driver of the Southern African epidemic is the high incidence rate of infection in young women, a vulnerable population with limited prevention options. Moreover, whilst ongoing trials of combination prevention, microbicides and behavioural economics hold promise for further epidemic control, an AIDS-free generation will not be realised unless incident infections in key populations are reduced.

  4. Increasing clinical virulence in two decades of the Italian HIV epidemic.

    Science.gov (United States)

    Müller, Viktor; Maggiolo, Franco; Suter, Fredy; Ladisa, Nicoletta; De Luca, Andrea; Antinori, Andrea; Sighinolfi, Laura; Quiros-Roldan, Eugenia; Carosi, Giampiero; Torti, Carlo

    2009-05-01

    The recent origin and great evolutionary potential of HIV imply that the virulence of the virus might still be changing, which could greatly affect the future of the pandemic. However, previous studies of time trends of HIV virulence have yielded conflicting results. Here we used an established methodology to assess time trends in the severity (virulence) of untreated HIV infections in a large Italian cohort. We characterized clinical virulence by the decline slope of the CD4 count (n = 1423 patients) and the viral setpoint (n = 785 patients) in untreated patients with sufficient data points. We used linear regression models to detect correlations between the date of diagnosis (ranging 1984-2006) and the virulence markers, controlling for gender, exposure category, age, and CD4 count at entry. The decline slope of the CD4 count and the viral setpoint displayed highly significant correlation with the date of diagnosis pointing in the direction of increasing virulence. A detailed analysis of riskgroups revealed that the epidemics of intravenous drug users started with an apparently less virulent virus, but experienced the strongest trend towards steeper CD4 decline among the major exposure categories. While our study did not allow us to exclude the effect of potential time trends in host factors, our findings are consistent with the hypothesis of increasing HIV virulence. Importantly, the use of an established methodology allowed for a comparison with earlier results, which confirmed that genuine differences exist in the time trends of HIV virulence between different epidemics. We thus conclude that there is not a single global trend of HIV virulence, and results obtained in one epidemic cannot be extrapolated to others. Comparison of discordant patterns between riskgroups and epidemics hints at a converging trend, which might indicate that an optimal level of virulence might exist for the virus.

  5. Krokodile Injectors in Ukraine: Fueling the HIV Epidemic?

    Science.gov (United States)

    Booth, Robert E; Davis, Jonathan M; Brewster, John T; Lisovska, Oksana; Dvoryak, Sergey

    2016-02-01

    This study was designed to assess the characteristics of krokodile injectors, a recent phenomenon in Ukraine, and HIV-related risk factors among people who inject drugs (PWID). In three Ukraine cities, Odessa, Donetsk and Nikolayev, 550 PWID were recruited between December 2012 and October 2013 using modified targeted sampling methods. The sample averaged 31 years of age and they had been injecting for over 12 years. Overall, 39 % tested positive for HIV, including 45 % of krokodile injectors. In the past 30 days, 25 % reported injecting krokodile. Those who injected krokodile injected more frequently (p < 0.001) and they injected more often with others (p = 0.005). Despite knowing their HIV status to be positive, krokodile users did not reduce their injection frequency, indeed, they injected as much as 85 % (p = 0.016) more frequently than those who did not know their HIV status or thought they were negative. This behavior was not seen in non-krokodile using PWID. Although only a small sample of knowledgeable HIV positive krokodile users was available (N = 12), this suggests that krokodile users may disregard their HIV status more so than nonkrokodile users. In spite of widespread knowledge of its harmful physical consequences, a growing number of PWID are turning to injecting krokodile in Ukraine. Given the recency of krokodile use the country, the associated higher frequency of injecting, a propensity to inject more often with others, and what could be a unique level of disregard of HIV among krokodile users, HIV incidence could increase in future years.

  6. Temporal dynamics of connectivity and epidemic properties of growing networks

    Science.gov (United States)

    Fotouhi, Babak; Shirkoohi, Mehrdad Khani

    2016-01-01

    Traditional mathematical models of epidemic disease had for decades conventionally considered static structure for contacts. Recently, an upsurge of theoretical inquiry has strived towards rendering the models more realistic by incorporating the temporal aspects of networks of contacts, societal and online, that are of interest in the study of epidemics (and other similar diffusion processes). However, temporal dynamics have predominantly focused on link fluctuations and nodal activities, and less attention has been paid to the growth of the underlying network. Many real networks grow: Online networks are evidently in constant growth, and societal networks can grow due to migration flux and reproduction. The effect of network growth on the epidemic properties of networks is hitherto unknown, mainly due to the predominant focus of the network growth literature on the so-called steady state. This paper takes a step towards alleviating this gap. We analytically study the degree dynamics of a given arbitrary network that is subject to growth. We use the theoretical findings to predict the epidemic properties of the network as a function of time. We observe that the introduction of new individuals into the network can enhance or diminish its resilience against endemic outbreaks and investigate how this regime shift depends upon the connectivity of newcomers and on how they establish connections to existing nodes. Throughout, theoretical findings are corroborated with Monte Carlo simulations over synthetic and real networks. The results shed light on the effects of network growth on the future epidemic properties of networks and offers insights for devising a priori immunization strategies.

  7. Population mobility and the changing epidemics of HIV-2 in Portugal

    DEFF Research Database (Denmark)

    Carvalho, A C; Valadas, E; França, L

    2012-01-01

    Portugal is the European country with the highest frequency of HIV-2 infection, which is mainly concentrated in West Africa. The cumulative number of notified HIV-2 infections in Portugal was 1813 by the end of December 2008. To better characterize the dynamics of HIV-2 infection in the country a...

  8. Stochastic epidemic dynamics on extremely heterogeneous networks

    CERN Document Server

    Parra-Rojas, César; McKane, Alan J

    2016-01-01

    Networks of contacts capable of spreading infectious diseases are often observed to be highly heterogeneous, with the majority of individuals having fewer contacts than the mean, and a significant minority having relatively very many contacts. We derive a two-dimensional diffusion model for the full temporal behavior of the stochastic susceptible-infectious-recovered (SIR) model on such a network, by making use of a time-scale separation in the deterministic limit of the dynamics. This low-dimensional process is an accurate approximation to the full model in the limit of large populations, even for cases when the time-scale separation is not too pronounced, provided the maximum degree is not of the order of the population size.

  9. Stochastic epidemic dynamics on extremely heterogeneous networks

    Science.gov (United States)

    Parra-Rojas, César; House, Thomas; McKane, Alan J.

    2016-12-01

    Networks of contacts capable of spreading infectious diseases are often observed to be highly heterogeneous, with the majority of individuals having fewer contacts than the mean, and a significant minority having relatively very many contacts. We derive a two-dimensional diffusion model for the full temporal behavior of the stochastic susceptible-infectious-recovered (SIR) model on such a network, by making use of a time-scale separation in the deterministic limit of the dynamics. This low-dimensional process is an accurate approximation to the full model in the limit of large populations, even for cases when the time-scale separation is not too pronounced, provided the maximum degree is not of the order of the population size.

  10. Dynamic Forecasting of Zika Epidemics Using Google Trends

    Science.gov (United States)

    Jin, Yuan; Huang, Yong; Lin, Baihan; An, Xiaoping; Feng, Dan; Tong, Yigang

    2017-01-01

    We developed a dynamic forecasting model for Zika virus (ZIKV), based on real-time online search data from Google Trends (GTs). It was designed to provide Zika virus disease (ZVD) surveillance and detection for Health Departments, and predictive numbers of infection cases, which would allow them sufficient time to implement interventions. In this study, we found a strong correlation between Zika-related GTs and the cumulative numbers of reported cases (confirmed, suspected and total cases; p<0.001). Then, we used the correlation data from Zika-related online search in GTs and ZIKV epidemics between 12 February and 20 October 2016 to construct an autoregressive integrated moving average (ARIMA) model (0, 1, 3) for the dynamic estimation of ZIKV outbreaks. The forecasting results indicated that the predicted data by ARIMA model, which used the online search data as the external regressor to enhance the forecasting model and assist the historical epidemic data in improving the quality of the predictions, are quite similar to the actual data during ZIKV epidemic early November 2016. Integer-valued autoregression provides a useful base predictive model for ZVD cases. This is enhanced by the incorporation of GTs data, confirming the prognostic utility of search query based surveillance. This accessible and flexible dynamic forecast model could be used in the monitoring of ZVD to provide advanced warning of future ZIKV outbreaks. PMID:28060809

  11. Women hold up half the sky - and half the burden of the HIV epidemic.

    Science.gov (United States)

    Heidari, Shirin; Kippax, Susan; Sow, Papa Salif; Wainberg, Mark A

    2013-03-08

    It has been said that women hold up half the sky. In the HIV epidemic, women carry half the burden of the epidemic, perhaps even more. The HIV burden on women is dramatically higher in some regions, certain age groups and among marginalized groups, such as female sex workers. Women's vulnerability to HIV is exacerbated by gender inequality and domestic violence. The global effort towards elimination of paediatric HIV and keeping mothers alive deserves applause. However, the needs of women go beyond their child-bearing age or potentials and/or reproductive desires and must be recognized in the global HIV agenda. In particular, more female-controlled prevention tools are urgently required to allow women to protect themselves. It is time to turn the tide through promoting gender equality and genuinely committing to gender-responsive policies and programmes, and encouraging a more gender-aware research agenda that can generate necessary evidence. In recognition of International Women's Day, the Journal of the International AIDS Society is pleased to launch a thematic series to highlight articles that address the different dimensions of HIV as they relate to women.

  12. Women hold up half the sky – and half the burden of the HIV epidemic

    Directory of Open Access Journals (Sweden)

    Shirin Heidari

    2013-03-01

    Full Text Available It has been said that women hold up half the sky. In the HIV epidemic, women carry half the burden of the epidemic, perhaps even more. The HIV burden on women is dramatically higher in some regions, certain age groups and among marginalized groups, such as female sex workers. Women's vulnerability to HIV is exacerbated by gender inequality and domestic violence. The global effort towards elimination of paediatric HIV and keeping mothers alive deserves applause. However, the needs of women go beyond their child-bearing age or potentials and/or reproductive desires and must be recognized in the global HIV agenda. In particular, more female-controlled prevention tools are urgently required to allow women to protect themselves. It is time to turn the tide through promoting gender equality and genuinely committing to gender-responsive policies and programmes, and encouraging a more gender-aware research agenda that can generate necessary evidence. In recognition of International Women's Day, the Journal of the International AIDS Society is pleased to launch a thematic series to highlight articles that address the different dimensions of HIV as they relate to women.

  13. Reconstructing the timing and dispersion routes of HIV-1 subtype B epidemics in the Caribbean and Central America: a phylogenetic story.

    Science.gov (United States)

    Pagán, Israel; Holguín, Africa

    2013-01-01

    The Caribbean and Central America are among the regions with highest HIV-1B prevalence worldwide. Despite of this high virus burden, little is known about the timing and the migration patterns of HIV-1B in these regions. Migration is one of the major processes shaping the genetic structure of virus populations. Thus, reconstruction of epidemiological network may contribute to understand HIV-1B evolution and reduce virus prevalence. We have investigated the spatio-temporal dynamics of the HIV-1B epidemic in The Caribbean and Central America using 1,610 HIV-1B partial pol sequences from 13 Caribbean and 5 Central American countries. Timing of HIV-1B introduction and virus evolutionary rates, as well as the spatial genetic structure of the HIV-1B populations and the virus migration patterns were inferred. Results revealed that in The Caribbean and Central America most of the HIV-1B variability was generated since the 80 s. At odds with previous data suggesting that Haiti was the origin of the epidemic in The Caribbean, our reconstruction indicated that the virus could have been disseminated from Puerto Rico and Antigua. These two countries connected two distinguishable migration areas corresponding to the (mainly Spanish-colonized) Easter and (mainly British-colonized) Western islands, which indicates that virus migration patterns are determined by geographical barriers and by the movement of human populations among culturally related countries. Similar factors shaped the migration of HIV-1B in Central America. The HIV-1B population was significantly structured according to the country of origin, and the genetic diversity in each country was associated with the virus prevalence in both regions, which suggests that virus populations evolve mainly through genetic drift. Thus, our work contributes to the understanding of HIV-1B evolution and dispersion pattern in the Americas, and its relationship with the geography of the area and the movements of human populations.

  14. Reconstructing the timing and dispersion routes of HIV-1 subtype B epidemics in the Caribbean and Central America: a phylogenetic story.

    Directory of Open Access Journals (Sweden)

    Israel Pagán

    Full Text Available The Caribbean and Central America are among the regions with highest HIV-1B prevalence worldwide. Despite of this high virus burden, little is known about the timing and the migration patterns of HIV-1B in these regions. Migration is one of the major processes shaping the genetic structure of virus populations. Thus, reconstruction of epidemiological network may contribute to understand HIV-1B evolution and reduce virus prevalence. We have investigated the spatio-temporal dynamics of the HIV-1B epidemic in The Caribbean and Central America using 1,610 HIV-1B partial pol sequences from 13 Caribbean and 5 Central American countries. Timing of HIV-1B introduction and virus evolutionary rates, as well as the spatial genetic structure of the HIV-1B populations and the virus migration patterns were inferred. Results revealed that in The Caribbean and Central America most of the HIV-1B variability was generated since the 80 s. At odds with previous data suggesting that Haiti was the origin of the epidemic in The Caribbean, our reconstruction indicated that the virus could have been disseminated from Puerto Rico and Antigua. These two countries connected two distinguishable migration areas corresponding to the (mainly Spanish-colonized Easter and (mainly British-colonized Western islands, which indicates that virus migration patterns are determined by geographical barriers and by the movement of human populations among culturally related countries. Similar factors shaped the migration of HIV-1B in Central America. The HIV-1B population was significantly structured according to the country of origin, and the genetic diversity in each country was associated with the virus prevalence in both regions, which suggests that virus populations evolve mainly through genetic drift. Thus, our work contributes to the understanding of HIV-1B evolution and dispersion pattern in the Americas, and its relationship with the geography of the area and the movements of

  15. Modelling the Spread of HIV/AIDS Epidemic

    Institute of Scientific and Technical Information of China (English)

    Huang Qing-dao

    2013-01-01

    In this paper, a deterministic mathematical model for the spread of HIV/AIDS in a variable size population through horizontal transmission is considered. The existence of a threshold parameter, the basic reproduction number, is established, and the stability of both the disease-free equilibrium and the endemic equilibrium is discussed in terms of R0.

  16. Spatial and temporal dynamics of infected populations: the Mexican epidemic

    CERN Document Server

    Rodriguez-Meza, Mario A

    2012-01-01

    Recently the A/H1N1-2009 virus pandemic appeared in Mexico and in other nations. We present a study of this pandemic in the Mexican case using the SIR model to describe epidemics. This model is one of the simplest models but it has been a successful description of some epidemics of closed populations. We consider the data for the Mexican case and use the SIR model to make some predictions. Then, we generalize the SIR model in order to describe the spatial dynamics of the disease. We make a study of the spatial and temporal spread of the infected population with model parameters that are consistent with temporal SIR model parameters obtained by fitting to the Mexican case.

  17. Recombinant viruses initiated the early HIV-1 epidemic in Burkina Faso.

    Directory of Open Access Journals (Sweden)

    Peter N Fonjungo

    Full Text Available We analyzed genetic diversity and phylogenetic relationships among 124 HIV-1 and 19 HIV-2 strains in sera collected in 1986 from patients of the state hospital in Ouagadougou, Burkina Faso. Phylogenetic analysis of the HIV-1 env gp41 region of 65 sequences characterized 37 (56.9% as CRF06_cpx strains, 25 (38.5% as CRF02_AG, 2 (3.1% as CRF09_cpx, and 1 (1.5% as subtype A. Similarly, phylogenetic analysis of the protease (PR gene region of 73 sequences identified 52 (71.2% as CRF06_cpx, 15 (20.5% as CRF02_AG, 5 (6.8% as subtype A, and 1 (1.4% was a unique strain that clustered along the B/D lineage but basal to the node connecting the two lineages. HIV-2 PR or integrase (INT groups A (n = 17 [89.5%] and B (n = 2 [10.5%] were found in both monotypic (n = 11 and heterotypic HIV-1/HIV-2 (n = 8 infections, with few HIV-2 group B infections. Based on limited available sampling, evidence suggests two recombinant viruses, CRF06_cpx and CRF02_AG, appear to have driven the beginning of the mid-1980s HIV-1 epidemic in Burkina Faso.

  18. Optima: A Model for HIV Epidemic Analysis, Program Prioritization, and Resource Optimization.

    Science.gov (United States)

    Kerr, Cliff C; Stuart, Robyn M; Gray, Richard T; Shattock, Andrew J; Fraser-Hurt, Nicole; Benedikt, Clemens; Haacker, Markus; Berdnikov, Maxim; Mahmood, Ahmed Mohamed; Jaber, Seham Abdalla; Gorgens, Marelize; Wilson, David P

    2015-07-01

    Optima is a software package for modeling HIV epidemics and interventions that we developed to address practical policy and program problems encountered by funders, governments, health planners, and program implementers. Optima's key feature is its ability to perform resource optimization to meet strategic HIV objectives, including HIV-related financial commitment projections and health economic assessments. Specifically, Optima allows users to choose a set of objectives (such as minimizing new infections, minimizing HIV-related deaths, and/or minimizing long-term financial commitments) and then determine the optimal resource allocation (and thus program coverage levels) for meeting those objectives. These optimizations are based on the following: calibrations to epidemiological data; assumptions about the costs of program implementation and the corresponding coverage levels; and the effects of these programs on clinical, behavioral, and other epidemiological outcomes. Optima is flexible for which population groups (specified by behavioral, epidemiological, and/or geographical factors) and which HIV programs are modeled, the amount of input data used, and the types of outputs generated. Here, we introduce this model and compare it with existing HIV models that have been used previously to inform decisions about HIV program funding and coverage targets. Optima has already been used in more than 20 countries, and there is increasing demand from stakeholders to have a tool that can perform evidence-based HIV epidemic analyses, revise and prioritize national strategies based on available resources, set program coverage targets, amend subnational program implementation plans, and inform the investment strategies of governments and their funding partners.

  19. Adolescent girls and young women: key populations for HIV epidemic control.

    Science.gov (United States)

    Dellar, Rachael C; Dlamini, Sarah; Karim, Quarraisha Abdool

    2015-01-01

    At the epicentre of the HIV epidemic in southern Africa, adolescent girls and young women aged 15-24 contribute a disproportionate ~30% of all new infections and seroconvert 5-7 years earlier than their male peers. This age-sex disparity in HIV acquisition continues to sustain unprecedentedly high incidence rates, and preventing HIV infection in this age group is a pre-requisite for achieving an AIDS-free generation and attaining epidemic control. Adolescent girls and young women in southern Africa are uniquely vulnerable to HIV and have up to eight times more infection than their male peers. While the cause of this vulnerability has not been fully elucidated, it is compounded by structural, social and biological factors. These factors include but are not limited to: engagement in age-disparate and/or transactional relationships, few years of schooling, experience of food insecurity, experience of gender-based violence, increased genital inflammation, and amplification of effects of transmission co-factors. Despite the large and immediate HIV prevention need of adolescent girls and young women, there is a dearth of evidence-based interventions to reduce their risk. The exclusion of adolescents in biomedical research is a huge barrier. School and community-based education programmes are commonplace in many settings, yet few have been evaluated and none have demonstrated efficacy in preventing HIV infection. Promising data are emerging on prophylactic use of anti-retrovirals and conditional cash transfers for HIV prevention in these populations. There is an urgent need to meet the HIV prevention needs of adolescent girls and young women, particularly those who are unable to negotiate monogamy, condom use and/or male circumcision. Concerted efforts to expand the prevention options available to these young women in terms of the development of novel HIV-specific biomedical, structural and behavioural interventions are urgently needed for epidemic control. In the interim

  20. Adolescent girls and young women: key populations for HIV epidemic control

    Directory of Open Access Journals (Sweden)

    Rachael C Dellar

    2015-02-01

    Full Text Available Introduction: At the epicentre of the HIV epidemic in southern Africa, adolescent girls and young women aged 15–24 contribute a disproportionate ~30% of all new infections and seroconvert 5–7 years earlier than their male peers. This age–sex disparity in HIV acquisition continues to sustain unprecedentedly high incidence rates, and preventing HIV infection in this age group is a pre-requisite for achieving an AIDS-free generation and attaining epidemic control. Discussion: Adolescent girls and young women in southern Africa are uniquely vulnerable to HIV and have up to eight times more infection than their male peers. While the cause of this vulnerability has not been fully elucidated, it is compounded by structural, social and biological factors. These factors include but are not limited to: engagement in age-disparate and/or transactional relationships, few years of schooling, experience of food insecurity, experience of gender-based violence, increased genital inflammation, and amplification of effects of transmission co-factors. Despite the large and immediate HIV prevention need of adolescent girls and young women, there is a dearth of evidence-based interventions to reduce their risk. The exclusion of adolescents in biomedical research is a huge barrier. School and community-based education programmes are commonplace in many settings, yet few have been evaluated and none have demonstrated efficacy in preventing HIV infection. Promising data are emerging on prophylactic use of anti-retrovirals and conditional cash transfers for HIV prevention in these populations. Conclusions: There is an urgent need to meet the HIV prevention needs of adolescent girls and young women, particularly those who are unable to negotiate monogamy, condom use and/or male circumcision. Concerted efforts to expand the prevention options available to these young women in terms of the development of novel HIV-specific biomedical, structural and behavioural

  1. Planning horizon affects prophylactic decision-making and epidemic dynamics.

    Science.gov (United States)

    Nardin, Luis G; Miller, Craig R; Ridenhour, Benjamin J; Krone, Stephen M; Joyce, Paul; Baumgaertner, Bert O

    2016-01-01

    The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon-the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals' payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.

  2. Interplay Between Hiv/aids Epidemics and Demographic Structures Based on Sexual Contact Networks

    Science.gov (United States)

    Bai, Wen-Jie; Zhou, Tao; Wang, Bing-Hong

    In this article, we propose a network spreading model for HIV epidemics, wherein each individual is represented by a node of the transmission network and the edges are the connections between individuals along which the infection may spread. The sexual activity of each individual, measured by its degree, is not homogeneous but obeys a power-law distribution. Due to the heterogeneity of activity, the infection can persistently exist at a very low prevalence, which has been observed in the real data but cannot be illuminated by previous models with homogeneous mixing hypothesis. The model displays a clear picture of hierarchical spread: In the early stage the infection is adhered to these high-risk persons, and then, diffuses toward low-risk population. Furthermore, we find that to reduce the risky behaviors is much more effective in the fight against HIV/AIDS rather than the antiretroviral drug therapies. The prediction results show that the development of epidemics can be roughly categorized into three patterns for different countries, and the pattern of a given country is mainly determined by the average sex-activity and transmission probability per sexual partner. In most cases, the effect of HIV epidemics on demographic structure is very small. However, for some extremely countries, like Botswana, the number of sex-active people can be depressed to nearly a half by AIDS.

  3. HIV/AIDS epidemic in the State of Amazonas: characteristics and trends from 2001 to 2012.

    Science.gov (United States)

    Oliveira, Romina do Socorro Marques de; Benzaken, Adele Schwartz; Saraceni, Valeria; Sabidó, Meritxell

    2015-01-01

    A scoping review was conducted to describe the epidemiological characteristics of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in the State of Amazonas, Brazil, from 2001 to 2012, and temporary patterns were estimated from surveillance data. The results suggest that in its third decade, the Amazon HIV/AIDS epidemic is far from being stabilized and displays rising AIDS incidence and mortality rates and late diagnoses. The data suggest that AIDS cases are hitting mostly young adults and have recently shifted toward men, both homosexual and heterosexual. AIDS cases among the indigenous people have remained stable and low. However, the epidemic has disseminated to the interior of the state, which adds difficulties to its control, given the geographical isolation, logistical barriers, and culturally and ethnically diverse population. Antiretroviral (ARV) therapy has been decentralized, but peripheral ARV services are still insufficient and too distant from people who need them. Recently, the expansion of point-of-care (POC) rapid HIV testing has been contributing to overcoming logistical barriers. Other new POC devices, such as the PIMA CD4 analyzer, will bring the laboratory to the patient. AIDS uniquely coexists with other tropical infections, sharing their epidemiological profiles. The increased demand for HIV/AIDS care services can only be satisfied through increased decentralization to peripheral health units, which can also naturally integrate care with other tropical infections and can promote a shift from vertical to integrated programming. Future challenges involve building surveillance data on HIV case notification and covering the spectrum of engagement in care, including adherence to treatment and follow-up loss.

  4. HIV/AIDS epidemic in the State of Amazonas: characteristics and trends from 2001 to 2012

    Directory of Open Access Journals (Sweden)

    Romina do Socorro Marques de Oliveira

    2015-06-01

    Full Text Available A scoping review was conducted to describe the epidemiological characteristics of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS epidemic in the State of Amazonas, Brazil, from 2001 to 2012, and temporary patterns were estimated from surveillance data. The results suggest that in its third decade, the Amazon HIV/AIDS epidemic is far from being stabilized and displays rising AIDS incidence and mortality rates and late diagnoses. The data suggest that AIDS cases are hitting mostly young adults and have recently shifted toward men, both homosexual and heterosexual. AIDS cases among the indigenous people have remained stable and low. However, the epidemic has disseminated to the interior of the state, which adds difficulties to its control, given the geographical isolation, logistical barriers, and culturally and ethnically diverse population. Antiretroviral (ARV therapy has been decentralized, but peripheral ARV services are still insufficient and too distant from people who need them. Recently, the expansion of point-of-care (POC rapid HIV testing has been contributing to overcoming logistical barriers. Other new POC devices, such as the PIMA CD4 analyzer, will bring the laboratory to the patient. AIDS uniquely coexists with other tropical infections, sharing their epidemiological profiles. The increased demand for HIV/AIDS care services can only be satisfied through increased decentralization to peripheral health units, which can also naturally integrate care with other tropical infections and can promote a shift from vertical to integrated programming. Future challenges involve building surveillance data on HIV case notification and covering the spectrum of engagement in care, including adherence to treatment and follow-up loss.

  5. Dynamical Monte Carlo method for stochastic epidemic models

    CERN Document Server

    Aiello, O E

    2002-01-01

    A new approach to Dynamical Monte Carlo Methods is introduced to simulate markovian processes. We apply this approach to formulate and study an epidemic Generalized SIRS model. The results are in excellent agreement with the forth order Runge-Kutta method in a region of deterministic solution. Introducing local stochastic interactions, the Runge-Kutta method is not applicable, and we solve and check it self-consistently with a stochastic version of the Euler Method. The results are also analyzed under the herd-immunity concept.

  6. Matrix expression and vaccination control for epidemic dynamics over dynamic networks

    Institute of Scientific and Technical Information of China (English)

    Peilian GUO; Yuzhen WANG

    2016-01-01

    This paper investigates epidemic dynamics over dynamic networks via the approach of semi-tensor product of matrices. First, a formal susceptible-infected-susceptible epidemic dynamic model over dynamic networks (SISED-DN) is given. Second, based on a class of determinate co-evolutionary rule, the matrix expressions are established for the dynamics of individual states and network topologies, respectively. Then, all possible final spreading equilibria are obtained for any given initial epidemic state and network topology by the matrix expression. Third, a sufficient and necessary condition of the existence of state feedback vaccination control is presented to make every individual susceptible. The study of illustrative examples shows the effectiveness of our new results.

  7. Dynamic properties of epidemic spreading on finite size complex networks

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Liu Yang; Shan Xiu-Ming; Ren Yong; Jiao Jian; Qiu Ben

    2005-01-01

    The Internet presents a complex topological structure, on which computer viruses can easily spread. By using theoretical analysis and computer simulation methods, the dynamic process of disease spreading on finite size networks with complex topological structure is investigated. On the finite size networks, the spreading process of SIS (susceptibleinfected-susceptible) model is a finite Markov chain with an absorbing state. Two parameters, the survival probability and the conditional infecting probability, are introduced to describe the dynamic properties of disease spreading on finite size networks. Our results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks. Also, knowledge about the dynamic character of virus spreading is helpful for adopting immunity policy.

  8. Shift in HIV/AIDS Epidemic in Southeastern China: A Longitudinal Study from 1987 to 2015

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    Yansheng Yan

    2016-08-01

    subtypes were genotyped in the province during the study period, and CRF01-AE and CRF07-BC intersubtype recombinant forms were predominant; however, a declining trend in the proportion of HIV-1 CRF01-AE recombinant virus and a significant rise in the proportion of HIV-1 CRF07-BC recombinant virus were observed. Over 90% HIV inhibition was found in all cases receiving antiretroviral therapy during the period from 2011 to 2015, indicating a low prevalence of HIV drug resistance. Conclusions: An increasing trend is still observed in the HIV/AIDS epidemics in Fujian Province, southeastern China. However, the epidemiological pattern of HIV/AIDS has recently changed in the province, and effective control interventions targeting the shift in the epidemiological features of HIV/AIDS should therefore be implemented to control the spread of the epidemic.

  9. Shift in HIV/AIDS Epidemic in Southeastern China: A Longitudinal Study from 1987 to 2015

    Science.gov (United States)

    Yan, Yansheng; Wu, Shouli; Chen, Liang; Yan, Pingping; Qiu, Yuefeng; Xie, Meirong; Wang, Zhenghua; Lin, Xun

    2016-01-01

    the province during the study period, and CRF01-AE and CRF07-BC intersubtype recombinant forms were predominant; however, a declining trend in the proportion of HIV-1 CRF01-AE recombinant virus and a significant rise in the proportion of HIV-1 CRF07-BC recombinant virus were observed. Over 90% HIV inhibition was found in all cases receiving antiretroviral therapy during the period from 2011 to 2015, indicating a low prevalence of HIV drug resistance. Conclusions: An increasing trend is still observed in the HIV/AIDS epidemics in Fujian Province, southeastern China. However, the epidemiological pattern of HIV/AIDS has recently changed in the province, and effective control interventions targeting the shift in the epidemiological features of HIV/AIDS should therefore be implemented to control the spread of the epidemic. PMID:27509511

  10. Global discourses and experiential speculation: Secondary and tertiary graduate Malawians dissect the HIV/AIDS epidemic

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    Myroniuk Tyler W

    2011-10-01

    Full Text Available Abstract Background Since the beginning of the HIV/AIDS epidemic, the perspectives of secondary and tertiary school graduates in sub-Saharan Africa regarding the effectiveness of government and international HIV/AIDS policies and programmes have not been thoroughly examined. When extensive monetary aid is directed toward "development" in a country like Malawi, it is the educated elites - secondary and tertiary graduates who are heavily involved and influential in the domestic re-distribution and implementation of millions of dollars worth of aid - on whom international expectations fall to decrease the transmission of HIV. Many Malawian jobs related to public health and HIV/AIDS are created as a direct result of this funding and are occupied by the few secondary and tertiary graduates. Thus, it is a practical venture to understand their perspectives on highly contentious and heavily funded HIV/AIDS issues that affect their nation. Methods Qualitative data was collected in this study in efforts to discover in-depth perspectives on the HIV/AIDS epidemic. Thirty-eight secondary and tertiary graduate Malawians took part in semi-structured interviews. Data was analysed using an early grounded theory approach and subsequent themes of "global discourses" and "experiential knowledge of HIV/AIDS" emerged. Results This group of Malawians frequently responded to questions regarding healthcare and access to medicine, sexual behaviours and methods of reducing the spread of HIV/AIDS by citing and explaining the widespread, international and "proper" responses. The secondary and tertiary graduate Malawians also discussed these same topics in terms of what they perceive or have experienced. Experiential responses, such as the counter-productivity of circumcision and condoms, the overestimation of HIV/AIDS prevalence, and calls for more authoritarian policing of commercial sex work, were remarkably divergent from the HIV/AIDS discourse. Conclusions The opinions

  11. Global discourses and experiential speculation: Secondary and tertiary graduate Malawians dissect the HIV/AIDS epidemic.

    Science.gov (United States)

    Myroniuk, Tyler W

    2011-10-04

    Since the beginning of the HIV/AIDS epidemic, the perspectives of secondary and tertiary school graduates in sub-Saharan Africa regarding the effectiveness of government and international HIV/AIDS policies and programmes have not been thoroughly examined. When extensive monetary aid is directed toward "development" in a country like Malawi, it is the educated elites - secondary and tertiary graduates who are heavily involved and influential in the domestic re-distribution and implementation of millions of dollars worth of aid - on whom international expectations fall to decrease the transmission of HIV. Many Malawian jobs related to public health and HIV/AIDS are created as a direct result of this funding and are occupied by the few secondary and tertiary graduates. Thus, it is a practical venture to understand their perspectives on highly contentious and heavily funded HIV/AIDS issues that affect their nation. Qualitative data was collected in this study in efforts to discover in-depth perspectives on the HIV/AIDS epidemic. Thirty-eight secondary and tertiary graduate Malawians took part in semi-structured interviews. Data was analysed using an early grounded theory approach and subsequent themes of "global discourses" and "experiential knowledge of HIV/AIDS" emerged. This group of Malawians frequently responded to questions regarding healthcare and access to medicine, sexual behaviours and methods of reducing the spread of HIV/AIDS by citing and explaining the widespread, international and "proper" responses. The secondary and tertiary graduate Malawians also discussed these same topics in terms of what they perceive or have experienced. Experiential responses, such as the counter-productivity of circumcision and condoms, the overestimation of HIV/AIDS prevalence, and calls for more authoritarian policing of commercial sex work, were remarkably divergent from the HIV/AIDS discourse. The opinions of this group of secondary and tertiary graduate Malawians do not

  12. Characteristics of the HIV/AIDS Epidemic in Women Aged 15-49 Years from 2005 to 2012 in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xia Yan; HUANG Tao; FENG Yi Bing; LI Meng; CHEN Fang Fang; LI Yin Ge; JIN Shan Shan; BU Kai; WANG Lu

    2015-01-01

    Objective To describe the characteristics of the HIV/AIDS epidemic in women aged 15-49 years in China. Methods HIV/AIDS cases from 2005 to 2012 that fulfilled the inclusion and exclusion criteria were identified on the Chinese HIV/AIDS case reporting system. Descriptive and spatial analyses were performed. Results A total of 103,559 female HIV/AIDS cases were included in our study. Based on the descriptive analysis, between 2005 and 2012, the proportion of heterosexually acquired HIV infection among women (15-49 years) increased rapidly from 35.8% to 87.4%. Approximately 60% of these cases were infected through non-marital heterosexual contact. Among older women (40-49 years), a slightly increasing trend was identified. The spatial analysis detected ‘hot spots’ in the Xinjiang, Yunnan, Sichuan, Guangxi, and Chongqing provinces. The epidemic trends in these areas were predominately driven by heterosexual transmission. Conclusion Non-marital heterosexual contact is a very important factor in the HIV/AIDS epidemic in women aged 15-49 years, and the HIV infection rate in older women is increasing. Several epidemic hot spots were detected in northwestern and southwestern China. Efficient interventions are needed to control the spread of HIV/AIDS among women living in these areas.

  13. When Statistical Literacy Really Matters: Understanding Published Information about the HIV/AIDS Epidemic in South Africa

    Science.gov (United States)

    Hobden, Sally

    2014-01-01

    Information on the HIV/AIDS epidemic in Southern Africa is often interpreted through a veil of secrecy and shame and, I argue, with flawed understanding of basic statistics. This research determined the levels of statistical literacy evident in 316 future Mathematical Literacy teachers' explanations of the median in the context of HIV/AIDS…

  14. Effectiveness and cost effectiveness of expanding harm reduction and antiretroviral therapy in a mixed HIV epidemic: a modeling analysis for Ukraine.

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    Sabina S Alistar

    2011-03-01

    Full Text Available Injection drug use (IDU and heterosexual virus transmission both contribute to the growing mixed HIV epidemics in Eastern Europe and Central Asia. In Ukraine-chosen in this study as a representative country-IDU-related risk behaviors cause half of new infections, but few injection drug users (IDUs receive methadone substitution therapy. Only 10% of eligible individuals receive antiretroviral therapy (ART. The appropriate resource allocation between these programs has not been studied. We estimated the effectiveness and cost-effectiveness of strategies for expanding methadone substitution therapy programs and ART in mixed HIV epidemics, using Ukraine as a case study.We developed a dynamic compartmental model of the HIV epidemic in a population of non-IDUs, IDUs using opiates, and IDUs on methadone substitution therapy, stratified by HIV status, and populated it with data from the Ukraine. We considered interventions expanding methadone substitution therapy, increasing access to ART, or both. We measured health care costs, quality-adjusted life years (QALYs, HIV prevalence, infections averted, and incremental cost-effectiveness. Without incremental interventions, HIV prevalence reached 67.2% (IDUs and 0.88% (non-IDUs after 20 years. Offering methadone substitution therapy to 25% of IDUs reduced prevalence most effectively (to 53.1% IDUs, 0.80% non-IDUs, and was most cost-effective, averting 4,700 infections and adding 76,000 QALYs compared with no intervention at US$530/QALY gained. Expanding both ART (80% coverage of those eligible for ART according to WHO criteria and methadone substitution therapy (25% coverage was the next most cost-effective strategy, adding 105,000 QALYs at US$1,120/QALY gained versus the methadone substitution therapy-only strategy and averting 8,300 infections versus no intervention. Expanding only ART (80% coverage added 38,000 QALYs at US$2,240/QALY gained versus the methadone substitution therapy-only strategy, and

  15. Changing trends and the impact of alcohol on the HIV/AIDS epidemic in South Africa: review.

    Science.gov (United States)

    Setshedi, Mashiko; de la Monte, Suzanne M

    2011-01-01

    The association between increased HIV infection and alcohol use has been extensively studied and is established. South Africa is among one of the sub-Saharan African countries with the highest prevalence and number of people living with HIV/AIDS in the world. Although recent evidence suggests that the epidemic has stabilised, infection rates remain unacceptably high. Alcohol use is on the increase, particularly in the groups most susceptible to HIV infection, namely women and young adults, and informs poor choices with respect to safer sexual practices. This paper reviews the association between alcohol and HIV. More specifically, however, it aims to explore the potential socio-politico-biological and cultural explanations as to the factors that intersect to drive these two epidemic diseases: alcoholism and HIV/AIDS in South Africa. Understanding some of the underlying factors will provide a framework to implement public health measures to curb HIV.

  16. 90-90-90 – Charting a steady course to end the paediatric HIV epidemic

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    Elaine J Abrams

    2015-12-01

    Full Text Available Introduction: The new “90-90-90” UNAIDS agenda proposes that 90% of all people living with HIV will know their HIV status, 90% of all people with diagnosed HIV infection will receive sustained antiretroviral therapy and 90% of all people receiving antiretroviral therapy will have viral suppression by 2020. By focusing on children, the global community is in the unique position of realizing an end to the paediatric HIV epidemic. Discussion: Despite vast scientific advances in the prevention and treatment of paediatric HIV infection over the last two decades, in 2014 there were an estimated 220,000 new paediatric infections attributed to mother-to-child HIV transmission (MTCT and 150,000 HIV-related paediatric deaths. Furthermore, adolescents remain at particularly high risk for acquisition of new HIV infections, and HIV/AIDS remains the second leading cause of death in this age group. Among the estimated 2.6 million children less than 15 years of age living with HIV infection, only 32% were receiving life-saving antiretroviral treatment. After decades of languishing, good progress is now being made to prevent MTCT. Unfortunately, efforts to scale up HIV treatment services have been less robust for children and adolescents compared with adult populations. These discrepancies reflect substantial gaps in essential services and numerous missed opportunities to prevent HIV transmission and provide effective life-saving antiretroviral treatment to children, adolescents and families. The road to an AIDS-free generation will require bridging the gaps in HIV services and addressing the particular needs of children across the developmental spectrum from infancy through adolescence. To reach the ambitious new targets, innovations and service improvements will need to be rapidly escalated at each step along the prevention-treatment cascade. Conclusions: Charting a successful course to reach the 90-90-90 targets will require sustained political and

  17. Research Notes ~ Combating HIV/AIDS Epidemic in Nigeria: Responses from National Open University of Nigeria (NOUN

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    Terhemba Nom Ambe-Uva

    2007-11-01

    Full Text Available Universities have come under serious attack because of their lackluster response to HIV/AIDS. This article examines the response of National Open University of Nigeria (NOUN and its strategic responses in combating HIV/AIDS epidemic. This is achieved by examining NOUN’s basic structures that position the University to respond to the epidemic; and second, by assessing HIV/AIDS strategies and policy framework the University has put in place. An interpretative epistemological stance was used for this study, and a qualitative research involving focus group discussion (FGD and analysis of secondary data was carried out. Results showed that NOUN has identified the impact the epidemic has on the university, although it has yet to institutionalize an HIV/AIDS policy. NOUN’s Draft Service Charter, however, has identified the fight against HIV/AIDS as a core mandate of the University, and the introduction of HIV/AIDS certification programs can be viewed as proactive policies in response to the epidemic. Results of this study are discussed in terms of their relevance to future research and the impact such policy frameworks may have on combating the epidemic, both within the University and the wider community.

  18. Dynamics of public opinion under the influence of epidemic spreading

    Science.gov (United States)

    Wu, Junhui; Ni, Shunjiang; Shen, Shifei

    2016-02-01

    In this paper, we propose a novel model with dynamically adjusted confidence level of others to investigate the propagation of public opinion on whether to buy chicken in the case of avian influenza infection in humans. We study how people adjust their confidence level in other people’s opinions according to their perceived infection risk and how the opinion evolution and epidemic spreading affect each other on different complex networks by taking into account the spreading feature of avian influenza, that is, only people who buy chicken are possible to be infected. The simulation results show that in a closed system, people who support buying chicken and people who are infected can achieve a dynamic balance after a few time-steps, and the final stable state is mainly dependent on the level of people’s risk perception, rather than the initial distribution of the different opinions. Our results imply that in the course of the epidemic spread, transparent and timely announcement of the number of infections and the risk of infection can help people take the right self-protection actions, and thus help control the spread of avian influenza.

  19. Dynamic Forecasting of Zika Epidemics Using Google Trends.

    Science.gov (United States)

    Teng, Yue; Bi, Dehua; Xie, Guigang; Jin, Yuan; Huang, Yong; Lin, Baihan; An, Xiaoping; Feng, Dan; Tong, Yigang

    2017-01-01

    We developed a dynamic forecasting model for Zika virus (ZIKV), based on real-time online search data from Google Trends (GTs). It was designed to provide Zika virus disease (ZVD) surveillance and detection for Health Departments, and predictive numbers of infection cases, which would allow them sufficient time to implement interventions. In this study, we found a strong correlation between Zika-related GTs and the cumulative numbers of reported cases (confirmed, suspected and total cases; pforecasting results indicated that the predicted data by ARIMA model, which used the online search data as the external regressor to enhance the forecasting model and assist the historical epidemic data in improving the quality of the predictions, are quite similar to the actual data during ZIKV epidemic early November 2016. Integer-valued autoregression provides a useful base predictive model for ZVD cases. This is enhanced by the incorporation of GTs data, confirming the prognostic utility of search query based surveillance. This accessible and flexible dynamic forecast model could be used in the monitoring of ZVD to provide advanced warning of future ZIKV outbreaks.

  20. What happened to the HIV epidemic among non-injecting drug users in New York City?

    Science.gov (United States)

    Des Jarlais, Don C; Arasteh, Kamyar; McKnight, Courtney; Feelemyer, Jonathan; Campbell, Aimee N C; Tross, Susan; Cooper, Hannah L F; Hagan, Holly; Perlman, David C

    2017-02-01

    HIV has reached high prevalence in many non-injecting drug user (NIDU) populations. The aims of this study were to (1) examine the trend in HIV prevalence among non-injecting cocaine and heroin NIDUs in New York City, (2) identify factors potentially associated with the trend and (3) estimate HIV incidence among NIDUs. Serial-cross sectional surveys of people entering drug treatment programs. People were permitted to participate only once per year, but could participate in multiple years. Mount Sinai Beth Israel drug treatment programs in New York City, USA. We recruited 3298 non-injecting cocaine and heroin users from 2005 to 2014. Participants were 78.7% male, 6.1% white, 25.7% Hispanic and 65.8% African American. Smoking crack cocaine was the most common non-injecting drug practice. Trend tests were used to examine HIV prevalence, demographics, drug use, sexual behavior and use of antiretroviral treatment (ART) by calendar year; χ(2) and multivariable logistic regression were used to compare 2005-10 versus 2011-14. HIV prevalence declined approximately 1% per year (P New York City. These results can be considered a proof of concept that it is possible to control non-injecting drug use related sexual transmission HIV epidemics. © 2016 Society for the Study of Addiction.

  1. The HIV / AIDS epidemic in Thailand: addressing the impact on children.

    Science.gov (United States)

    Brown, T; Sittitrai, W

    1995-01-01

    Within the space of a decade, the level of HIV infection in Thailand has grown to epidemic proportions. With regard to children, 16,000 had been born with HIV by the end of 1994, while tens of thousands of child prostitutes and street children are at risk of infection. By the year 2000, more than one million Thai children will have at least one HIV-infected parent. Many of these children will therefore become either orphans or abandoned by their infected parents. The magnitude of these problems over the course of the lives of HIV-affected children depends heavily upon actions taken now. This paper summarizes the joint report of the Thai Red Cross Society and the East-West Center's Program on Population on the impact of HIV on children in Thailand. The current situation, projected impacts, and policy recommendations are described. No other country has had as complete a monitoring system or as early a warning of the problems ahead. Some recommended approaches are familiar and simply need to be strengthened and expanded to the regional or national level, while others require field testing. The authors stress the need for shared commitment, ideas, resources, and efforts of all sectors of society to plan for the future needs of children affected by HIV, to protect them from infection, and to provide them with the social and economic support, medical treatment, and legal protection they need.

  2. Knowledge epidemics and population dynamics models for describing idea diffusion

    CERN Document Server

    Vitanov, Nikolay K

    2012-01-01

    The diffusion of ideas is often closely connected to the creation and diffusion of knowledge and to the technological evolution of society. Because of this, knowledge creation, exchange and its subsequent transformation into innovations for improved welfare and economic growth is briefly described from a historical point of view. Next, three approaches are discussed for modeling the diffusion of ideas in the areas of science and technology, through (i) deterministic, (ii) stochastic, and (iii) statistical approaches. These are illustrated through their corresponding population dynamics and epidemic models relative to the spreading of ideas, knowledge and innovations. The deterministic dynamical models are considered to be appropriate for analyzing the evolution of large and small societal, scientific and technological systems when the influence of fluctuations is insignificant. Stochastic models are appropriate when the system of interest is small but when the fluctuations become significant for its evolution...

  3. Increasing rates of obesity among HIV-infected persons during the HIV epidemic.

    Directory of Open Access Journals (Sweden)

    Nancy Crum-Cianflone

    Full Text Available BACKGROUND: The prevalence and factors associated with overweight/obesity among human immunodeficiency virus (HIV-infected persons are unknown. METHODS: We evaluated prospective data from a U.S. Military HIV Natural History Study (1985-2004 consisting of early diagnosed patients. Statistics included multivariate linear regression and longitudinal linear mixed effects models. RESULTS: Of 1682 patients, 2% were underweight, 37% were overweight, and 9% were obese at HIV diagnosis. Multivariate predictors of a higher body mass index (BMI at diagnosis included more recent year of HIV diagnosis, older age, African American race, and earlier HIV stage (all p<0.05. The majority of patients (62% gained weight during HIV infection. Multivariate factors associated with a greater increase in BMI during HIV infection included more recent year of diagnosis, lower BMI at diagnosis, higher CD4 count, lower HIV RNA level, lack of AIDS diagnosis, and longer HIV duration (all p<0.05. Nucleoside agents were associated with less weight gain; other drug classes had no significant impact on weight change in the HAART era. CONCLUSIONS: HIV-infected patients are increasingly overweight/obese at diagnosis and during HIV infection. Weight gain appears to reflect improved health status and mirror trends in the general population. Weight management programs may be important components of HIV care.

  4. Women's rights and women's health during HIV/AIDS epidemics: the experience of women in sub-Saharan Africa.

    Science.gov (United States)

    Dugassa, Begna F

    2009-08-01

    Twenty-five years have passed since HIV/AIDS was recognized as a major public health problem. Although billions of dollars are spent in research and development, we still have no medical cure or vaccination. In the early days of the epidemic, public health slogans suggested that HIV/AIDS does not discriminate. Now it is becoming clear that HIV/AIDS spreads most rapidly among poor, marginalized, women, colonized, and disempowered groups of people more than others. The HIV/AIDS epidemic is exacerbated by the social, economic, political, and cultural conditions of societies such as gender, racial, class, and other forms of inequalities. Sub-Saharan African countries are severely hit by HIV/AIDS. For these countries the pandemic of HIV/AIDS demands the need to travel extra miles. My objective in this article is to promote the need to go beyond the biomedical model of "technical fixes" and the traditional public health education tools, and come up with innovative ideas and strategic thinking to contain the epidemic. In this article, I argue that containing the HIV/AIDS epidemic and improving family and community health requires giving appropriate attention to the social illnesses that are responsible for exacerbating biological disorders.

  5. The changing epidemiology of the global paediatric HIV epidemic: keeping track of perinatally HIV-infected adolescents

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    Annette H Sohn

    2013-06-01

    Full Text Available The global paediatric HIV epidemic is shifting into a new phase as children on antiretroviral therapy (ART move into adolescence and adulthood, and face new challenges of living with HIV. UNAIDS reports that 3.4 million children aged below 15 years and 2 million adolescents aged between 10 and 19 years have HIV. Although the vast majority of children were perinatally infected, older children are combined with behaviourally infected adolescents and youth in global reporting, making it difficult to keep track of their outcomes. Perinatally HIV-infected adolescents (PHIVA are a highly unique patient sub-population, having been infected before development of their immune systems, been subject to suboptimal ART options and formulations, and now face transition from complete dependence on adult caregivers to becoming their own caregivers. As we are unable to track long-term complications and survival of PHIVA through national and global reporting systems, local and regional cohorts are the main sources for surveillance and research among PHIVA. This global review will utilize those data to highlight the epidemiology of PHIVA infection, treatment challenges and chronic disease risks. Unless mechanisms are created to count and separate out PHIVA outcomes, we will have few opportunities to characterize the negative consequences of life-long HIV infection in order to find ways to prevent them.

  6. Heterosexual HIV transmission dynamics: implications for prevention and control.

    Science.gov (United States)

    Chin, James; Bennett, Anthony

    2007-08-01

    Understanding the epidemiologic definition of epidemic versus non-epidemic spread of an infectious disease agent and the different patterns of heterosexual HIV transmission are needed to fully understand the low potential for heterosexual HIV epidemics in most heterosexual populations. Epidemic sexual HIV transmission can occur only in populations where there are large numbers of persons who have unprotected sex with multiple and concurrent sex partners. How high HIV prevalence may reach in these populations depends on the size and overlap of sex networks, and the prevalence of facilitating and protective factors that can greatly increase or limit the amount of infected blood and sexual fluids exchanged during intercourse. The wide difference in potentials for heterosexual HIV epidemics that exists within and between countries must be recognized, accepted and monitored in order to design and focus prevention strategies where they are most needed and most effective.

  7. Phylodynamic and Phylogeographic Profiles of Subtype B HIV-1 Epidemics in South Spain

    Science.gov (United States)

    Pérez-Parra, Santiago; Chueca, Natalia; Álvarez, Marta; Pasquau, Juan; Omar, Mohamed; Collado, Antonio; Vinuesa, David; Lozano, Ana B.; Yebra, Gonzalo; García, Federico

    2016-01-01

    Background Since 1982, HIV-1 epidemics have evolved to different scenarios in terms of transmission routes, subtype distribution and characteristics of transmission clusters. We investigated the evolutionary history of HIV-1 subtype B in south Spain. Patients & Methods We studied all newly diagnosed HIV-1 subtype B patients in East Andalusia during the 2005–2012 period. For the analysis, we used the reverse transcriptase and protease sequences from baseline resistance, and the Trugene® HIV Genotyping kit (Siemens, Barcelona, Spain). Subtyping was done with REGA v3.0. The maximum likelihood trees constructed with RAxML were used to study HIV-1 clustering. Phylogeographic and phylodynamic profiles were studied by Bayesian inference methods with BEAST v1.7.5 and SPREAD v1.0.6. Results Of the 493 patients infected with HIV-1 subtype B, 234 grouped into 55 clusters, most of which were small (44 clusters ≤ 5 patients, 31 with 2 patients, 13 with 3). The rest (133/234) were grouped into 11 clusters with ≥ 5 patients, and most (82%, 109/133) were men who have sex with men (MSM) grouped into 8 clusters. The association with clusters was more frequent in Spanish (p = 0.02) men (p< 0.001), MSM (p<0.001) younger than 35 years (p = 0.001) and with a CD4+ T-cell count above 350 cells/ul (p<0.001). We estimated the date of HIV-1 subtype B regional epidemic diversification around 1970 (95% CI: 1965–1987), with an evolutionary rate of 2.4 (95%CI: 1.7–3.1) x 10−3 substitutions/site/year. Most clusters originated in the 1990s in MSMs. We observed exponential subtype B HIV-1 growth in 1980–1990 and 2005–2008. The most significant migration routes for subtype B went from inland cities to seaside locations. Conclusions We provide the first data on the phylodynamic and phylogeographic profiles of HIV-1 subtype B in south Spain. Our findings of transmission clustering among MSMs should alert healthcare managers to enhance preventive measures in this risk group in order to

  8. Testing the hypothesis that treatment can eliminate HIV: a nationwide, population-based study of the Danish HIV epidemic in men who have sex with men

    Science.gov (United States)

    Okano, Justin T.; Robbins, Danielle; Palk, Laurence; Gerstoft, Jan; Obel, Niels; Blower, Sally

    2017-01-01

    Summary Background Worldwide, ~35 million individuals are infected with HIV; ~25 million in sub-Saharan Africa (SSA). The WHO proposes using “treatment as prevention” (TasP) to eliminate HIV. Treatment suppresses viral load, decreasing the probability an individual transmits HIV. The elimination threshold is one new HIV infection per 1,000 individuals. Here, we test the hypothesis that TasP can substantially reduce epidemics and eliminate HIV. We estimate the impact of TasP, between 1996–2013, on the Danish HIV epidemic in Men-who-have-Sex-with-Men (MSM), an epidemic UNAIDS has identified as a priority for elimination. Methods We use a CD4-staged Bayesian back-calculation approach to estimate incidence, and the “hidden epidemic” (the number of HIV-infected undiagnosed MSM). We use data from an ongoing nationwide population-based study: the Danish HIV Cohort Study. Findings Incidence, and the hidden epidemic, decreased substantially after treatment was introduced in 1996. By 2013, incidence was close to the elimination threshold: 1·4 (median, 95% Bayesian Credible Interval (BCI): 0·4–2·1) new HIV infections per 1,000 MSM. There were only 617 (median, 95% BCI: 264–858) undiagnosed MSM. Decreasing incidence and increasing treatment coverage are highly correlated; a threshold effect is apparent. Interpretation Our study is the first to show that TasP can substantially reduce a country’s HIV epidemic, and bring it close to elimination. However, we have shown the effectiveness of TasP under optimal conditions: very high treatment coverage, and exceptionally high (98%) viral suppression rate. Unless these extremely challenging conditions can be met in SSA, the WHO’s global elimination strategy is unlikely to succeed. Funding NIAID/NIH PMID:27174504

  9. Population-Level Immune-Mediated Adaptation in HIV-1 Polymerase during the North American Epidemic.

    Science.gov (United States)

    Kinloch, Natalie N; MacMillan, Daniel R; Le, Anh Q; Cotton, Laura A; Bangsberg, David R; Buchbinder, Susan; Carrington, Mary; Fuchs, Jonathan; Harrigan, P Richard; Koblin, Beryl; Kushel, Margot; Markowitz, Martin; Mayer, Kenneth; Milloy, M J; Schechter, Martin T; Wagner, Theresa; Walker, Bruce D; Carlson, Jonathan M; Poon, Art F Y; Brumme, Zabrina L

    2015-11-11

    Human leukocyte antigen (HLA) class I-associated polymorphisms in HIV-1 that persist upon transmission to HLA-mismatched hosts may spread in the population as the epidemic progresses. Transmission of HIV-1 sequences containing such adaptations may undermine cellular immune responses to the incoming virus in future hosts. Building upon previous work, we investigated the extent of HLA-associated polymorphism accumulation in HIV-1 polymerase (Pol) through comparative analysis of linked HIV-1/HLA class I genotypes sampled during historic (1979 to 1989; n = 338) and modern (2001 to 2011; n = 278) eras from across North America (Vancouver, BC, Canada; Boston, MA; New York, NY; and San Francisco, CA). Phylogenies inferred from historic and modern HIV-1 Pol sequences were star-like in shape, with an inferred most recent common ancestor (epidemic founder virus) sequence nearly identical to the modern North American subtype B consensus sequence. Nevertheless, modern HIV-1 Pol sequences exhibited roughly 2-fold-higher patristic (tip-to-tip) genetic distances than historic sequences, with HLA pressures likely driving ongoing diversification. Moreover, the frequencies of published HLA-associated polymorphisms in individuals lacking the selecting HLA class I allele was on average ∼2.5-fold higher in the modern than in the historic era, supporting their spread in circulation, though some remained stable in frequency during this time. Notably, polymorphisms restricted by protective HLA alleles appear to be spreading to a greater relative extent than others, though these increases are generally of modest absolute magnitude. However, despite evidence of polymorphism spread, North American hosts generally remain at relatively low risk of acquiring an HIV-1 polymerase sequence substantially preadapted to their HLA profiles, even in the present era. HLA class I-restricted cytotoxic T-lymphocyte (CTL) escape mutations in HIV-1 that persist upon transmission may accumulate in

  10. Orphans of the HIV epidemic: the challenges from toddlerhood to adolescence and beyond.

    Science.gov (United States)

    Lala, Mamatha M

    2014-01-01

    This presentation focuses on the challenges and practical issues faced each day by orphans of the HIV epidemic and the holistic care that can be provided, as they continue to grow from toddlerhood to adolescence and beyond. An HIV Research Trust Scholarship enabled me to spend quality time in a sub-Saharan African province worst hit by the HIV epidemic and to interact with local experts and learn from mutual clinical experience. It was an immensely useful exercise as the clinical spectra of the diseases are very similar to ours and they have ongoing active research programs very relevant to our setting. India is arguably home to the largest number of orphans of the HIV epidemic. The responsibility of caring for orphaned children overwhelms and pushes many extended families beyond their ability to cope. Many countries are experiencing large increases in the number of families headed by women and grandparents, or even young children. These households are often unable to meet basic needs, and so the number of children living on the streets is rising. Orphaned children are disadvantaged in many devastating ways. In addition to the trauma of witnessing the sickness and death of one or both parents and perhaps siblings, they lack the necessary parental guidance through crucial life-stages of identity formation and transition into adulthood. They are more likely to suffer damage to their cognitive and emotional development and be subjected to; exploitation in terms of labour, social exclusion, extreme economic uncertainty, physical and sexual abuse, illiteracy, malnutrition and illness. Education remains a distant dream. With stigma and discrimination, they lack legal protection, lose inheritance rights, access to essential services available to other community members and professional help from doctors, teachers and lawyers. The implications for these unfortunate children are extraordinarily grave but governments, international agencies, non-governmental organizations

  11. Orphans of the HIV epidemic: the challenges from toddlerhood to adolescence and beyond

    Directory of Open Access Journals (Sweden)

    Mamatha M Lala

    2014-11-01

    Full Text Available This presentation focuses on the challenges and practical issues faced each day by orphans of the HIV epidemic and the holistic care that can be provided, as they continue to grow from toddlerhood to adolescence and beyond. An HIV Research Trust Scholarship enabled me to spend quality time in a sub-Saharan African province worst hit by the HIV epidemic and to interact with local experts and learn from mutual clinical experience. It was an immensely useful exercise as the clinical spectra of the diseases are very similar to ours and they have ongoing active research programs very relevant to our setting. India is arguably home to the largest number of orphans of the HIV epidemic. The responsibility of caring for orphaned children overwhelms and pushes many extended families beyond their ability to cope. Many countries are experiencing large increases in the number of families headed by women and grandparents, or even young children. These households are often unable to meet basic needs, and so the number of children living on the streets is rising. Orphaned children are disadvantaged in many devastating ways. In addition to the trauma of witnessing the sickness and death of one or both parents and perhaps siblings, they lack the necessary parental guidance through crucial life-stages of identity formation and transition into adulthood. They are more likely to suffer damage to their cognitive and emotional development and be subjected to; exploitation in terms of labour, social exclusion, extreme economic uncertainty, physical and sexual abuse, illiteracy, malnutrition and illness. Education remains a distant dream. With stigma and discrimination, they lack legal protection, lose inheritance rights, access to essential services available to other community members and professional help from doctors, teachers and lawyers. The implications for these unfortunate children are extraordinarily grave but governments, international agencies, non

  12. What's to be done? Report on a bosberaad to discuss the HIV epidemic in South Africa

    CSIR Research Space (South Africa)

    Williams, BG

    2000-06-01

    Full Text Available -related deaths are predicted, up from 100 000 this year. If anything, these models have underestimated the course of the epidemic so far. There is a need for better models to understand the dynamics of AIDS as well as to measure the effects of co...

  13. Global dynamics of an SIRS epidemic model with saturation incidence.

    Science.gov (United States)

    Hao, Lijie; Jiang, Guirong; Liu, Suyu; Ling, Lin

    2013-10-01

    In this paper, the dynamical behavior of an SIRS epidemic model with birth pulse, pulse vaccination, and saturation incidence is studied. By using a discrete map, the existence and stability of the infection-free periodic solution and the endemic periodic solution are investigated. The conditions required for the existence of supercritical bifurcation are derived. A threshold for a disease to be extinct or endemic is established. The Poincaré map and center manifold theorem are used to discuss flip bifurcation of the endemic periodic solution. Moreover, numerical simulations for bifurcation diagrams, phase portraits and periodic solutions, which are illustrated with an example, are in good agreement with the theoretical analysis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  14. Effectiveness and cost effectiveness of oral pre-exposure prophylaxis in a portfolio of prevention programs for injection drug users in mixed HIV epidemics.

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    Sabina S Alistar

    Full Text Available BACKGROUND: Pre-exposure prophylaxis with oral antiretroviral treatment (oral PrEP for HIV-uninfected injection drug users (IDUs is potentially useful in controlling HIV epidemics with a significant injection drug use component. We estimated the effectiveness and cost effectiveness of strategies for using oral PrEP in various combinations with methadone maintenance treatment (MMT and antiretroviral treatment (ART in Ukraine, a representative case for mixed HIV epidemics. METHODS AND FINDINGS: We developed a dynamic compartmental model of the HIV epidemic in a population of non-IDUs, IDUs who inject opiates, and IDUs in MMT, adding an oral PrEP program (tenofovir/emtricitabine, 49% susceptibility reduction for uninfected IDUs. We analyzed intervention portfolios consisting of oral PrEP (25% or 50% of uninfected IDUs, MMT (25% of IDUs, and ART (80% of all eligible patients. We measured health care costs, quality-adjusted life years (QALYs, HIV prevalence, HIV infections averted, and incremental cost effectiveness. A combination of PrEP for 50% of IDUs and MMT lowered HIV prevalence the most in both IDUs and the general population. ART combined with MMT and PrEP (50% access averted the most infections (14,267. For a PrEP cost of $950, the most cost-effective strategy was MMT, at $520/QALY gained versus no intervention. The next most cost-effective strategy consisted of MMT and ART, costing $1,000/QALY gained compared to MMT alone. Further adding PrEP (25% access was also cost effective by World Health Organization standards, at $1,700/QALY gained. PrEP alone became as cost effective as MMT at a cost of $650, and cost saving at $370 or less. CONCLUSIONS: Oral PrEP for IDUs can be part of an effective and cost-effective strategy to control HIV in regions where injection drug use is a significant driver of the epidemic. Where budgets are limited, focusing on MMT and ART access should be the priority, unless PrEP has low cost.

  15. Male Circumcision and the Epidemic Emergence of HIV-2 in West Africa

    Science.gov (United States)

    Hewlett, Barry Stephen; Camacho, Ricardo Jorge

    2016-01-01

    Background Epidemic HIV-2 (groups A and B) emerged in humans circa 1930–40. Its closest ancestors are SIVsmm infecting sooty mangabeys from southwestern Côte d'Ivoire. The earliest large-scale serological surveys of HIV-2 in West Africa (1985–91) show a patchy spread. Côte d'Ivoire and Guinea-Bissau had the highest prevalence rates by then, and phylogeographical analysis suggests they were the earliest epicenters. Wars and parenteral transmission have been hypothesized to have promoted HIV-2 spread. Male circumcision (MC) is known to correlate negatively with HIV-1 prevalence in Africa, but studies examining this issue for HIV-2 are lacking. Methods We reviewed published HIV-2 serosurveys for 30 cities of all West African countries and obtained credible estimates of real prevalence through Bayesian estimation. We estimated past MC rates of 218 West African ethnic groups, based on ethnographic literature and fieldwork. We collected demographic tables specifying the ethnic partition in cities. Uncertainty was incorporated by defining plausible ranges of parameters (e.g. timing of introduction, proportion circumcised). We generated 1,000 sets of past MC rates per city using Latin Hypercube Sampling with different parameter combinations, and explored the correlation between HIV-2 prevalence and estimated MC rate (both logit-transformed) in the 1,000 replicates. Results and Conclusions Our survey reveals that, in the early 20th century, MC was far less common and geographically more variable than nowadays. HIV-2 prevalence in 1985–91 and MC rates in 1950 were negatively correlated (Spearman rho = -0.546, IQR: -0.553–-0.546, p≤0.0021). Guinea-Bissau and Côte d'Ivoire cities had markedly lower MC rates. In addition, MC was uncommon in rural southwestern Côte d'Ivoire in 1930.The differential HIV-2 spread in West Africa correlates with different historical MC rates. We suggest HIV-2 only formed early substantial foci in cities with substantial uncircumcised

  16. Increasing Rates of Obesity Among HIV-Infected Persons During the HIV Epidemic

    Science.gov (United States)

    2010-04-01

    overweight /obese at diagnosis and during HIV infection. Weight gain appears to reflect improved health status and mirror trends in the general...study results may be related to differences in timing of HIV diagnosis and treatment, socioeconomic status , and access to medical care. Of note, our...America Abstract Background: The prevalence and factors associated with overweight /obesity among human immunodeficiency virus (HIV)- infected persons are

  17. The HIV/AIDS epidemic in sub-Saharan Africa: thinking ahead on programmatic tasks and related operational research

    Directory of Open Access Journals (Sweden)

    Zachariah Rony

    2011-07-01

    Full Text Available Abstract Until now, we have all been desperately trying to run behind the HIV/AIDS epidemic and catch up with it, but despite all our efforts, the epidemic remains well ahead of us. In 2010, the antiretroviral treatment (ART gap was about 60%, AIDS-related deaths were almost two million a year, and on top of these figures, for every one person started on ART, there were two new HIV infections. What is needed to change this situation is to think ahead of the epidemic in terms of the programmatic tasks we will be faced with and try to act boldly in trying to implement those tasks. From a programmatic perspective, we: a highlight what needs to fundamentally change in our thinking and overall approach to the epidemic; and b outline a number of key task areas for implementation and related operational research.

  18. Impact and Cost-Effectiveness of Point-Of-Care CD4 Testing on the HIV Epidemic in South Africa.

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    Alastair Heffernan

    Full Text Available Rapid diagnostic tools have been shown to improve linkage of patients to care. In the context of infectious diseases, assessing the impact and cost-effectiveness of such tools at the population level, accounting for both direct and indirect effects, is key to informing adoption of these tools. Point-of-care (POC CD4 testing has been shown to be highly effective in increasing the proportion of HIV positive patients who initiate ART. We assess the impact and cost-effectiveness of introducing POC CD4 testing at the population level in South Africa in a range of care contexts, using a dynamic compartmental model of HIV transmission, calibrated to the South African HIV epidemic. We performed a meta-analysis to quantify the differences between POC and laboratory CD4 testing on the proportion linking to care following CD4 testing. Cumulative infections averted and incremental cost-effectiveness ratios (ICERs were estimated over one and three years. We estimated that POC CD4 testing introduced in the current South African care context can prevent 1.7% (95% CI: 0.4% - 4.3% of new HIV infections over 1 year. In that context, POC CD4 testing was cost-effective 99.8% of the time after 1 year with a median estimated ICER of US$4,468/DALY averted. In healthcare contexts with expanded HIV testing and improved retention in care, POC CD4 testing only became cost-effective after 3 years. The results were similar when, in addition, ART was offered irrespective of CD4 count, and CD4 testing was used for clinical assessment. Our findings suggest that even if ART is expanded to all HIV positive individuals and HIV testing efforts are increased in the near future, POC CD4 testing is a cost-effective tool, even within a short time horizon. Our study also illustrates the importance of evaluating the potential impact of such diagnostic technologies at the population level, so that indirect benefits and costs can be incorporated into estimations of cost-effectiveness.

  19. Impact and Cost-Effectiveness of Point-Of-Care CD4 Testing on the HIV Epidemic in South Africa.

    Science.gov (United States)

    Heffernan, Alastair; Barber, Ella; Thomas, Ranjeeta; Fraser, Christophe; Pickles, Michael; Cori, Anne

    2016-01-01

    Rapid diagnostic tools have been shown to improve linkage of patients to care. In the context of infectious diseases, assessing the impact and cost-effectiveness of such tools at the population level, accounting for both direct and indirect effects, is key to informing adoption of these tools. Point-of-care (POC) CD4 testing has been shown to be highly effective in increasing the proportion of HIV positive patients who initiate ART. We assess the impact and cost-effectiveness of introducing POC CD4 testing at the population level in South Africa in a range of care contexts, using a dynamic compartmental model of HIV transmission, calibrated to the South African HIV epidemic. We performed a meta-analysis to quantify the differences between POC and laboratory CD4 testing on the proportion linking to care following CD4 testing. Cumulative infections averted and incremental cost-effectiveness ratios (ICERs) were estimated over one and three years. We estimated that POC CD4 testing introduced in the current South African care context can prevent 1.7% (95% CI: 0.4% - 4.3%) of new HIV infections over 1 year. In that context, POC CD4 testing was cost-effective 99.8% of the time after 1 year with a median estimated ICER of US$4,468/DALY averted. In healthcare contexts with expanded HIV testing and improved retention in care, POC CD4 testing only became cost-effective after 3 years. The results were similar when, in addition, ART was offered irrespective of CD4 count, and CD4 testing was used for clinical assessment. Our findings suggest that even if ART is expanded to all HIV positive individuals and HIV testing efforts are increased in the near future, POC CD4 testing is a cost-effective tool, even within a short time horizon. Our study also illustrates the importance of evaluating the potential impact of such diagnostic technologies at the population level, so that indirect benefits and costs can be incorporated into estimations of cost-effectiveness.

  20. Evolution of primary HIV drug resistance in a subtype C dominated epidemic in Mozambique.

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    Dulce Celina Adolfo Bila

    Full Text Available OBJECTIVE: In Mozambique, highly active antiretroviral treatment (HAART was introduced in 2004 followed by decentralization and expansion, resulting in a more than 20-fold increase in coverage by 2009. Implementation of HIV drug resistance threshold surveys (HIVDR-TS is crucial in order to monitor the emergence of transmitted viral resistance, and to produce evidence-based recommendations to support antiretroviral (ARV policy in Mozambique. METHODS: World Health Organization (WHO methodology was used to evaluate transmitted drug resistance (TDR in newly diagnosed HIV-1 infected pregnant women attending ante-natal clinics in Maputo and Beira to non-nucleoside reverse transcriptase inhibitors (NNRTI, nucleoside reverse transcriptase inhibitors (NRTI and protease inhibitors (PI. Subtypes were assigned using REGA HIV-1 subtyping tool and phylogenetic trees constructed using MEGA version 5. RESULTS: Although mutations associated with resistance to all three drug were detected in these surveys, transmitted resistance was analyzed and classified as <5% in Maputo in both surveys for all three drug classes. Transmitted resistance to NNRTI in Beira in 2009 was classified between 5-15%, an increase from 2007 when no NNRTI mutations were found. All sequences clustered with subtype C. CONCLUSIONS: Our results show that the epidemic is dominated by subtype C, where the first-line option based on two NRTI and one NNRTI is still effective for treatment of HIV infection, but intermediate levels of TDR found in Beira reinforce the need for constant evaluation with continuing treatment expansion in Mozambique.

  1. Conceptual Framework and Research Methods for Migration and HIV Transmission Dynamics

    Science.gov (United States)

    Cassels, Susan; Jenness, Samuel M.; Khanna, Aditya

    2014-01-01

    Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic. PMID:24257897

  2. Epidemic Dynamics with Feedback Mechanism in Exponential Networks

    Institute of Scientific and Technical Information of China (English)

    LIU Zi-Ran; YAN Jia-Ren; ZHANG Jian-Guo; WANG Li

    2006-01-01

    @@ We introduce a feedback mechanism to study the spreading of an epidemic by analytical methods and large scale simulations in exponential networks. It is found that introducing the feedback mechanism can reduce the density of infected individuals. Furthermore, it does not change the epidemic threshold (critical point) λc. These results can help us to understand epidemic spreading phenomena on social networks more practically and design appropriate strategies to control social infections.

  3. Accelerating harm reduction interventions to confront the HIV epidemic in the Western Pacific and Asia: the role of WHO (WPRO

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    Yifei Hu

    2008-08-01

    Full Text Available Abstract The epidemic of HIV/AIDS linked to injecting drug usage is one of the most explosive in recent years. After a historical epicentre in Europe, South and North America, at present it is clearly the main cause of dissemination of the epidemic in Eastern Europe and some key Asian countries. Recently, 10 African countries reported the spread of HIV through people who inject drugs (PWID, breaking one of the final geographical barriers to the globalization of the epidemic of HIV among and from PWID. Several countries of the Asia and Pacific Region have HIV epidemics that are driven by injecting drug usage. Harm reduction interventions have been implemented in many countries and potential barriers to implementation are being overcome. Harm reduction is no longer a marginal approach in the Region; instead, it is the core tool for responding to the HIV/AIDS epidemic among PWID. The development of a comprehensive response in the Region has been remarkable, including scaling up of needle and syringe programmes (NSPs, methadone maintenance treatment (MMT, and care, support and treatment for PWID. This development is being followed up by strong ongoing changes in policies and legislations. The main issue now is to enhance interventions to a level that can impact the epidemic. The World Health Organization (WHO is one of the leading UN agencies promoting harm reduction. Since the establishment of the Global Programme on AIDS, WHO has been working towards an effective response to the HIV epidemic among PWID. WHO's work is organized into a number of components: establishing an evidence base; advocacy; development of normative standards, tools and guidelines; providing technical support to countries; ensuring access to essential medicines, diagnostics and commodities; and mobilizing resources. In this paper, we trace the course of development of the HIV/AIDS epidemic among and from PWID in the Western Pacific and Asia Region (WPRO as well as WHO's role

  4. Selecting HIV infection prevention interventions in the mature HIV epidemic in Malawi using the mode of transmission model

    Directory of Open Access Journals (Sweden)

    Maleta Kenneth

    2010-08-01

    Full Text Available Abstract Background Malawi is reassessing its HIV prevention strategy in the light of a limited reduction in the epidemic. No community based incidence studies have been carried out in Malawi, so estimates of where new infections are occurring require the use of mathematical models and knowledge of the size and sexual behaviour of different groups. The results can help to choose where HIV prevention interventions are most needed. Methods The UNAIDS Mode of Transmission model was populated with Malawi data and estimates of incident cases calculated for each exposure group. Scenarios of single and multiple interventions of varying success were used to identify those interventions most likely to reduce incident cases. Results The groups accounting for most new infections were the low-risk heterosexual group - the discordant couples (37% and those who had casual sex and their partners (a further 16% and 27% respectively of new cases. Circumcision, condoms with casual sex and bar girls and improved STI treatment had limited effect in reducing incident cases, while condom use with discordant couples, abstinence and a zero-grazing campaign had major effects. The combination of a successful strategy to eliminate multiple concurrent partners and a successful strategy to eliminate all infections between discordant couples would reduce incident cases by 99%. Conclusions A revitalised HIV prevention strategy will need to include interventions which tackle the two modes of transmission now found to be so important in Malawi - concurrency and discordancy.

  5. Contribution of hidden modes to nonlinear epidemic dynamics in urban human proximity networks

    CERN Document Server

    Fujiwara, Naoya; Iwayama, Koji; Aihara, Kazuyuki

    2015-01-01

    Recently developed techniques to acquire high-quality human mobility data allow large-scale simulations of the spread of infectious diseases with high spatial and temporal resolution.Analysis of such data has revealed the oversimplification of existing theoretical frameworks to infer the final epidemic size or influential nodes from the network topology. Here we propose a spectral decomposition-based framework for the quantitative analysis of epidemic processes on realistic networks of human proximity derived from urban mobility data. Common wisdom suggests that modes with larger eigenvalues contribute more to the epidemic dynamics. However, we show that hidden dominant structures, namely modes with smaller eigenvalues but a greater contribution to the epidemic dynamics, exist in the proximity network. This framework provides a basic understanding of the relationship between urban human motion and epidemic dynamics, and will contribute to strategic mitigation policy decisions.

  6. An overview of the history of epidemic of and response to HIV/AIDS in China: achievements and challenges

    Institute of Scientific and Technical Information of China (English)

    CUI Yan; Adrian Liau; WU Zun-you

    2009-01-01

    @@ Since the first case of acquired immunodeficiency syndrome (AIDS) in China was identified and reported in 1985, the country has experienced dramatic changes in the course of its human immunodeficiency virus (HIV)/AIDS epidemic along with the government's response to it in the past 24 years.

  7. Estimation and prediction of the HIV-AIDS-epidemic under conditions of HAART using mixtures of incubation time distributions

    NARCIS (Netherlands)

    Heisterkamp, S. H.; de Vries, R.; Sprenger, H. G.; Hubben, G. A. A.; Postma, M. J.

    2008-01-01

    The estimation of the HIV-AIDS epidemic by means of back-calculation (BC) has been difficult since the introduction of highly active anti-retroviral therapy (HAART) because the incubation time distributions needed for BC were poorly known. Moreover, it has been assumed that if the general public is

  8. Genotypic and functional impact of HIV-1 adaptation to its host population during the North American epidemic.

    Directory of Open Access Journals (Sweden)

    Laura A Cotton

    2014-04-01

    Full Text Available HLA-restricted immune escape mutations that persist following HIV transmission could gradually spread through the viral population, thereby compromising host antiviral immunity as the epidemic progresses. To assess the extent and phenotypic impact of this phenomenon in an immunogenetically diverse population, we genotypically and functionally compared linked HLA and HIV (Gag/Nef sequences from 358 historic (1979-1989 and 382 modern (2000-2011 specimens from four key cities in the North American epidemic (New York, Boston, San Francisco, Vancouver. Inferred HIV phylogenies were star-like, with approximately two-fold greater mean pairwise distances in modern versus historic sequences. The reconstructed epidemic ancestral (founder HIV sequence was essentially identical to the North American subtype B consensus. Consistent with gradual diversification of a "consensus-like" founder virus, the median "background" frequencies of individual HLA-associated polymorphisms in HIV (in individuals lacking the restricting HLA[s] were ∼ 2-fold higher in modern versus historic HIV sequences, though these remained notably low overall (e.g. in Gag, medians were 3.7% in the 2000s versus 2.0% in the 1980s. HIV polymorphisms exhibiting the greatest relative spread were those restricted by protective HLAs. Despite these increases, when HIV sequences were analyzed as a whole, their total average burden of polymorphisms that were "pre-adapted" to the average host HLA profile was only ∼ 2% greater in modern versus historic eras. Furthermore, HLA-associated polymorphisms identified in historic HIV sequences were consistent with those detectable today, with none identified that could explain the few HIV codons where the inferred epidemic ancestor differed from the modern consensus. Results are therefore consistent with slow HIV adaptation to HLA, but at a rate unlikely to yield imminent negative implications for cellular immunity, at least in North America

  9. Spatiotemporal dynamics of the epidemic transmission in a predator-prey system.

    Science.gov (United States)

    Su, Min; Hui, Cang; Zhang, Yanyu; Li, Zizhen

    2008-11-01

    Epidemic transmission is one of the critical density-dependent mechanisms that affect species viability and dynamics. In a predator-prey system, epidemic transmission can strongly affect the success probability of hunting, especially for social animals. Predators, therefore, will suffer from the positive density-dependence, i.e., Allee effect, due to epidemic transmission in the population. The rate of species contacting the epidemic, especially for those endangered or invasive, has largely increased due to the habitat destruction caused by anthropogenic disturbance. Using ordinary differential equations and cellular automata, we here explored the epidemic transmission in a predator-prey system. Results show that a moderate Allee effect will destabilize the dynamics, but it is not true for the extreme Allee effect (weak or strong). The predator-prey dynamics amazingly stabilize by the extreme Allee effect. Predators suffer the most from the epidemic disease at moderate transmission probability. Counter-intuitively, habitat destruction will benefit the control of the epidemic disease. The demographic stochasticity dramatically influences the spatial distribution of the system. The spatial distribution changes from oil-bubble-like (due to local interaction) to aggregated spatially scattered points (due to local interaction and demographic stochasticity). It indicates the possibility of using human disturbance in habitat as a potential epidemic-control method in conservation.

  10. Ending the HIV/AIDS epidemic in low- and middle-income countries by 2030: is it possible? [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Anthony D. Harries

    2016-09-01

    Full Text Available The international community has committed to ending the epidemics of HIV/AIDS, tuberculosis, malaria, and neglected tropical infections by 2030, and this bold stance deserves universal support. In this paper, we discuss whether this ambitious goal is achievable for HIV/AIDS and what is needed to further accelerate progress. The joint United Nations Program on HIV/AIDS (UNAIDS 90-90-90 targets and the related strategy are built upon currently available health technologies that can diagnose HIV infection and suppress viral replication in all people with HIV. Nonetheless, there is much work to be done in ensuring equitable access to these HIV services for key populations and those who remain outside the rims of the traditional health services. Identifying a cure and a preventive vaccine would further help accelerate progress in ending the epidemic. Other disease control programmes could learn from the response to the HIV/AIDS epidemic.

  11. Reconstituting the epidemic history of mono lineage of HIV-1 CRF01_AE in Guizhou province, Southern China.

    Science.gov (United States)

    Zeng, Haiyan; Sun, Binlian; Li, Lingnuo; Li, Yanpeng; Liu, Yong; Xiao, Yao; Jiang, Yan; Yang, Rongge

    2014-08-01

    Guizhou province, located between border provinces and Central province of China, plays a crucial role in the transmission of HIV-1, implying it is important to monitor the epidemic of HIV-1 in this region. Available HIV-1 infected patients' plasma (n=78) were collected from Tongren city, Eastern Guizhou. Full-length gag, partial pol and env gene sequences were amplified and analyzed using phylogenetic, recombinant and Bayesian molecular clock approaches. Phylogenetic and recombinant analyses showed that CRF01_AE predominated among injecting drug users and heterosexuals in Tongren city with 85.9% proportion, it was followed by B' (5.1%), CRF07_BC (3.8%), CRF08_BC (3.8%), and B (1.3%). Moreover, 98.5% of CRF01_AE strains belonged to the distinct lineage CRF01_AE-v previously found in Guangxi province. To infer the most probable origin of CRF01_AE-v in Guizhou province, we download all available full length of CRF01_AE gag, pol and env gene region sequences from China in Los Alamos HIV sequence database. Phylodynamic and phylogeographic analyses revealed that the expanding CRF01_AE-v epidemic in Guizhou province was the result of local epidemic driven by multiple independent introductions of CRF01_AE-v strains from Guangxi province in early 2000s. High prevalence of CRF01_AE in Guizhou province may bridge the epidemic to Central China. It provides a new insight for the understanding of HIV-1 epidemic in Guizhou province and makes the evolutionary history of CRF01_AE in China more intact. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. HIV incidence among injection drug users in New York City, 1992-1997: evidence for a declining epidemic.

    Science.gov (United States)

    Des Jarlais, D C; Marmor, M; Friedmann, P; Titus, S; Aviles, E; Deren, S; Torian, L; Glebatis, D; Murrill, C; Monterroso, E; Friedman, S R

    2000-01-01

    OBJECTIVES: We assessed recent (1992-1997) HIV incidence in the large HIV epidemic among injection drug users in New York City. METHODS: Data were compiled from 10 separate studies (N = 4979), including 6 cohort studies, 2 "repeat service user" studies, and 2 analyses of voluntary HIV testing and counseling services within drug treatment programs. RESULTS: In the 10 studies, 52 seroconversions were found in 6344 person-years at risk. The observed incidence rates among the 10 studies were all within a narrow range, from 0 per 100 person-years at risk to 2.96 per 100 person-years at risk. In 9 of the 10 studies, the observed incidence rate was less than 2 per 100 person-years at risk. The weighted average incidence rate was 0.7 per 100 person-years at risk. CONCLUSIONS: The recent incidence rate in New York City is quite low for a high-seroprevalence population of injection drug users. The very large HIV epidemic among injection drug users in New York City appears to have entered a "declining phase," characterized by low incidence and declining prevalence. The data suggest that very large high-seroprevalence HIV epidemics may be "reversed." PMID:10705851

  13. Rationale for an HIV / AIDS prevention and mitigation strategy for Africa: combatting the multisectoral impact of the epidemic.

    Science.gov (United States)

    Lyerly, W H

    1996-01-01

    Unlike most infectious diseases in Africa, HIV/AIDS affects the urban elite as well as the rural poor, and generally during their most economically productive years. An increase in deaths among young adults of the magnitude predicted is likely to have substantial adverse effects on economic, political, and military/security stability throughout Africa. AIDS is causing increased stress on fragile African economic infrastructures as labor productivity declines, particularly in agricultural, labor-dependent economies. AIDS is causing obstacles to trade, foreign investment and tourism. Health systems and social coping mechanisms already are overburdened. High rates of HIV infection among police and military personnel threaten internal security. Furthermore, the demobilization of military forces in Africa may exacerbate the epidemic when HIV-infected soldiers return home and spread the virus. This presentation will illustrate why African AIDS Programs must be expanded to mitigate the multisectoral impact of the epidemic while preserving its spread.

  14. Interplay between HIV/AIDS Epidemics and Demographic Structures Based on Sexual Contact Networks

    CERN Document Server

    Bai, W J; Zhou, T; Bai, Wen-Jie; Wang, Bing-Hong; Zhou, Tao

    2006-01-01

    In this article, we propose a network spread model for HIV epidemics, wherein each individual is represented by a node of the transmission network and the edges are the connections between individuals along which the infection may spread. The sexual activity of each individual, measured by its degree, is not homogeneous but obeys a power-law distribution. Due to the heterogeneity of activity, the infection can persistently exist at a very low prevalence, which has been observed in real data but can not be illuminated by previous models with homogeneous mixing hypothesis. Furthermore, the model displays a clear picture of hierarchical spread: In the early stage the infection is adhered to these high-risk persons, and then, diffuses toward low-risk population. The prediction results show that the development of epidemics can be roughly categorized into three patterns for different countries, and the pattern of a given country is mainly determined by the average sex-activity and transmission probability per sexu...

  15. Prevention of Parent to Child Transmission (PPTCT program data in India: an emerging data set for appraising the HIV epidemic.

    Directory of Open Access Journals (Sweden)

    Sema K Sgaier

    Full Text Available BACKGROUND: Evidence based resource allocation and decentralized planning of an effective HIV/AIDS response requires reliable information on levels and trends of HIV at national and sub-national geographic levels. HIV sentinel surveillance data from antenatal clinics (HSS-ANC has been an important data source to assess the HIV/AIDS epidemic in India, but has a number of limitations. We assess the value of Prevention of Parent to Child Transmission (PPTCT programme data to appraise the HIV epidemic in India. METHODS/FINDINGS: HIV data from PPTCT sites were compared to HSS-ANC and general population level surveys at various geographic levels in the states of Karnataka, Maharashtra and Andhra Pradesh. Chi-square tests were used to ascertain statistical significance. PPTCT HIV prevalence was significantly lower than HSS-ANC HIV prevalence (0.92% vs. 1.22% in Andhra Pradesh, 0.65% vs. 0.89% in Karnataka, 0.52% vs. 0.60% in Maharashtra, p<0.001 for all three states. In all three states, HIV prevalence from PPTCT centres that were part of the sentinel surveillance was comparable to HSS-ANC prevalence but significantly higher than PPTCT centres that were not part of the sentinel surveillance. HIV prevalence from PPTCT data was comparable to that from general population surveys. In all three states, significant declines in HIV prevalence between 2007 and 2010 were observed with the PPTCT data set. District level analyses of HIV trends and sub-district level analysis of HIV prevalence were possible using the PPTCT and not the HSS-ANC data sets. CONCLUSION: HIV prevalence from PPTCT may be a better proxy for general population prevalence than HSS-ANC. PPTCT data allow for analysis of HIV prevalence and trends at smaller geographic units, which is important for decentralized planning of HIV/AIDS programming. With further improvements to the system, India could replace its HSS-ANC with PPTCT programme data for surveillance.

  16. ANALYSIS HIV/AIDS EPIDEMIC CHARACTERISTICS IN YINGTAN%鹰潭市HIV/AIDS的流行特征分析

    Institute of Scientific and Technical Information of China (English)

    王复选

    2011-01-01

    [Objective]To understand the AIDS epidemic characteristics in Yingtan City during 2002-2009, to provide scientific basis for AIDS prevention.[Methods]Analyzed all HIV/AIDS case data, the constitution and so on targets in the city.[Results]HIV/AIDS65 cases were reported, it mainly distributes in A county, accounting for 78.46%, next to accounting for 13.85% in the C area; infected persons over the age of 60 were most, accounting for 43.08%, this was followed by 30-39 years old accounting for 20.00%; the main population were farmers, retirees, accounting for 29.23%, 24.62%; the more e-ducational levels were illiterate and primary school, accounting for 38.46%, 30.77%; the way that non-marital heterosexual sexual contact was 86.15%.[Conclusion]The number of infected population with HIV shows an upward trend in the city each year.Infection in older age groups is relatively serious.AIDS prevention and control work should lie strengthened in future, especially among older people.%[目的]了解鹰潭市2002~2009年艾滋病的流行特征,为今后的艾滋病防治工作提供科学依据.[方法]对该市所有的HIV/AIDS个案资料进行率、构成比等指标分析.[结果]共报告HIV/AIDS 65例,其主要分布在A县占78.46%、其次在C区占13.85%;感染者60岁以上居多占43.08%、其次为30~39岁占20.00%;以农民、离退人员为主分别占29.23%、24.62%:以文盲、小学为主分别占38.46%、30.77%;以非婚异性性接触为主占86.15%.[结论]该市感染HIV人数呈逐年上升趋势,老年人群感染相对严重,日后应加强高危人群,特别是老年重点人群艾滋病的防控工作.

  17. Confronting the HIV epidemic in Asia and the Pacific: developing successful strategies to minimize the spread of HIV infection.

    Science.gov (United States)

    Moodie, R; Aboagye-Kwarteng, T

    1993-12-01

    In Asia, the cumulative total of HIV-infected adults will reach 1.22 million by 1995, and, by 2000, the number is estimated to reach 11-45 million. The modes of transmission vary from country to country and include injecting drug users, commercial sex workers and their clients, commercial blood donors, hemophiliacs, and homosexuals. Social, cultural, and health factors also affect transmission, such as rites of passage to adulthood, lack of female autonomy, multiple sex partners, wars and civil unrest, and availability of drugs. The HIV epidemic has economic ramifications and causes, e.g., migrant worker camps, the sex industry, and rapid urbanization luring Burmese girls to Thailand. Governments must create an environment for behavior-change through financial, political, and legislative measures. Community organizations also play a role in prevention, as in programs initiated by a squatter settlement in Bangkok, where 36% of IV drug users were found to be HIV-positive. In Maharashtra State, India, peer-based prevention programs were developed for sex workers. Successful behavior change of individuals is based on redefinition of peer norms, understanding the danger and vulnerability to infection, and building confidence to change behavior. Successful programs require placing priority on HIV issues on the political agenda, negotiation and consensus-building skills, and competent program management. For instance, in Zimbabwe a project enlisted 380,000 people in 4500 education sessions within 2 years, and distributed 2.5 million condoms. Among sex workers, condom use increased from 5% to 50%. Implementation strategies include the provision of information and interpersonal education. In Zaire, mass media and social marketing efforts boosted condom sales from less than half a million in 1987 to over 20 million in 1991. The means to change behavior requires the availability of good quality condoms, disinfectants, and syringes. Furthermore, clinical management of

  18. The Interaction of Risk Network Structures and Virus Natural History in the Non-spreading of HIV Among People Who Inject Drugs in the Early Stages of the Epidemic.

    Science.gov (United States)

    Dombrowski, Kirk; Khan, Bilal; Habecker, Patrick; Hagan, Holly; Friedman, Samuel R; Saad, Mohamed

    2017-04-01

    This article explores how social network dynamics may have reduced the spread of HIV-1 infection among people who inject drugs during the early years of the epidemic. Stochastic, discrete event, agent-based simulations are used to test whether a "firewall effect" can arise out of self-organizing processes at the actor level, and whether such an effect can account for stable HIV prevalence rates below population saturation. Repeated simulation experiments show that, in the presence of recurring, acute, and highly infectious outbreaks, micro-network structures combine with the HIV virus's natural history to reduce the spread of the disease. These results indicate that network factors likely played a significant role in the prevention of HIV infection within injection risk networks during periods of peak prevalence. They also suggest that social forces that disturb network connections may diminish the natural firewall effect and result in higher rates of HIV.

  19. Accounting for nonsampling error in estimates of HIV epidemic trends from antenatal clinic sentinel surveillance.

    Science.gov (United States)

    Eaton, Jeffrey W; Bao, Le

    2017-04-01

    The aim of the study was to propose and demonstrate an approach to allow additional nonsampling uncertainty about HIV prevalence measured at antenatal clinic sentinel surveillance (ANC-SS) in model-based inferences about trends in HIV incidence and prevalence. Mathematical model fitted to surveillance data with Bayesian inference. We introduce a variance inflation parameter (Equation is included in full-text article.)that accounts for the uncertainty of nonsampling errors in ANC-SS prevalence. It is additive to the sampling error variance. Three approaches are tested for estimating (Equation is included in full-text article.)using ANC-SS and household survey data from 40 subnational regions in nine countries in sub-Saharan, as defined in UNAIDS 2016 estimates. Methods were compared using in-sample fit and out-of-sample prediction of ANC-SS data, fit to household survey prevalence data, and the computational implications. Introducing the additional variance parameter (Equation is included in full-text article.)increased the error variance around ANC-SS prevalence observations by a median of 2.7 times (interquartile range 1.9-3.8). Using only sampling error in ANC-SS prevalence (Equation is included in full-text article.), coverage of 95% prediction intervals was 69% in out-of-sample prediction tests. This increased to 90% after introducing the additional variance parameter (Equation is included in full-text article.). The revised probabilistic model improved model fit to household survey prevalence and increased epidemic uncertainty intervals most during the early epidemic period before 2005. Estimating (Equation is included in full-text article.)did not increase the computational cost of model fitting. We recommend estimating nonsampling error in ANC-SS as an additional parameter in Bayesian inference using the Estimation and Projection Package model. This approach may prove useful for incorporating other data sources such as routine prevalence from Prevention of

  20. Origin and dynamics of HIV-1 subtype C infection in India.

    Directory of Open Access Journals (Sweden)

    Chengli Shen

    Full Text Available OBJECTIVE: To investigate the geographical origin and evolution dynamics of HIV-1 subtype C infection in India. DESIGN: Ninety HIV-1 subtype C env gp120 subtype C sequences from India were compared with 312 env gp120 reference subtype C sequences from 27 different countries obtained from Los Alamos HIV database. All the HIV-1 subtype C env gp120 sequences from India were used for the geographical origin analysis and 61 subtype C env gp120 sequences with known sampling year (from 1991 to 2008 were employed to determine the origin of HIV infection in India. METHODS: Phylogenetic analysis of HIV-1 env sequences was used to investigate the geographical origin and tMRCA of Indian HIV-1 subtype C. Evolutionary parameters including origin date and demographic growth patterns of Indian subtype C were estimated using a Bayesian coalescent-based approach under relaxed molecular clock models. FINDINGS: The majority of the analyzed Indian and South African HIV-1 subtype C sequences formed a single monophyletic cluster. The most recent common ancestor date was calculated to be 1975.56 (95% HPD, 1968.78-1981.52. Reconstruction of the effective population size revealed three phases of epidemic growth: an initial slow growth, followed by exponential growth, and then a plateau phase approaching present time. Stabilization of the epidemic growth phase correlated with the foundation of National AIDS Control Organization in India. INTERPRETATION: Indian subtype C originated from a single South African lineage in the middle of 1970s. The current study emphasizes not only the utility of HIV-1 sequence data for epidemiological studies but more notably highlights the effectiveness of community or government intervention strategies in controlling the trend of the epidemic.

  1. Estimating and Projecting Trends in HIV/AIDS Generalized Epidemics Using Incremental Mixture Importance Sampling.

    Science.gov (United States)

    Raftery, Adrian E; Bao, Le

    2010-12-01

    The Joint United Nations Programme on HIV/AIDS (UNAIDS) has decided to use Bayesian melding as the basis for its probabilistic projections of HIV prevalence in countries with generalized epidemics. This combines a mechanistic epidemiological model, prevalence data, and expert opinion. Initially, the posterior distribution was approximated by sampling-importance-resampling, which is simple to implement, easy to interpret, transparent to users, and gave acceptable results for most countries. For some countries, however, this is not computationally efficient because the posterior distribution tends to be concentrated around nonlinear ridges and can also be multimodal. We propose instead incremental mixture importance sampling (IMIS), which iteratively builds up a better importance sampling function. This retains the simplicity and transparency of sampling importance resampling, but is much more efficient computationally. It also leads to a simple estimator of the integrated likelihood that is the basis for Bayesian model comparison and model averaging. In simulation experiments and on real data, it outperformed both sampling importance resampling and three publicly available generic Markov chain Monte Carlo algorithms for this kind of problem.

  2. A decade of investments in monitoring the HIV epidemic: how far have we come? A descriptive analysis.

    Science.gov (United States)

    Alfven, Tobias; McDougal, Lotus; Frescura, Luisa; Aran, Christian; Amler, Paul; Gill, Wayne

    2014-10-16

    The 2001 Declaration of Commitment (DoC) adopted by the General Assembly Special Session on HIV/AIDS (UNGASS) included a call to monitor national responses to the HIV epidemic. Since the DoC, efforts and investments have been made globally to strengthen countries' HIV monitoring and evaluation (M&E) capacity. This analysis aims to quantify HIV M&E investments, commitments, capacity, and performance during the last decade in order to assess the success and challenges of national and global HIV M&E systems. M&E spending and performance was assessed using data from UNGASS country progress reports. The National Composite Policy Index (NCPI) was used to measure government commitment, government engagement, partner/civil society engagement, and data generation, as well as to generate a composite HIV M&E System Capacity Index (MESCI) score. Analyses were restricted to low and middle income countries (LMICs) who submitted NCPI reports in 2006, 2008, and 2010 (n = 78). Government commitment to HIV M&E increased considerably between 2006 and 2008 but decreased between 2008 and 2010. The percentage of total AIDS spending allocated to HIV M&E increased from 1.1% to 1.4%, between 2007 and 2010, in high-burden LMICs. Partner/civil society engagement and data generation capacity improved between 2006 and 2010 in the high-burden countries. The HIV MESCI increased from 2006 to 2008 in high-burden countries (78% to 94%), as well as in other LMICs (70% to 77%), and remained relatively stable in 2010 (91% in high-burden countries, 79% in other LMICs). Among high-burden countries, M&E system performance increased from 52% in 2006 to 89% in 2010. The last decade has seen increased commitments and spending on HIV M&E, as well as improved M&E capacity and more available data on the HIV epidemic in both high-burden and other LMICs. However, challenges remain in the global M&E of the AIDS epidemic as we approach the 2015 Millennium Development Goal targets.

  3. Racial/Ethnic Disparities at the End of an HIV Epidemic: Persons Who Inject Drugs in New York City, 2011-2015.

    Science.gov (United States)

    Des Jarlais, Don C; Arasteh, Kamyar; McKnight, Courtney; Feelemyer, Jonathan; Tross, Susan; Perlman, David; Friedman, Samuel; Campbell, Aimee

    2017-07-01

    To examine whether racial/ethnic disparities persist at the "end of the HIV epidemic" (prevalence of untreated HIV infection New York City. We recruited 2404 PWID entering New York City substance use treatment in 2001 to 2005 and 2011 to 2015. We conducted a structured interview, and testing for HIV and herpes simplex virus 2 (HSV-2; a biomarker for high sexual risk). We estimated incidence by using newly diagnosed cases of HIV. Disparity analyses compared HIV, untreated HIV, HIV-HSV-2 coinfection, HIV monoinfection, and estimated HIV incidence among Whites, African Americans, and Latinos. By 2011 to 2015, Whites, African Americans, and Latino/as met both criteria of our operational "end-of-the-epidemic" definition. All comparisons that included HIV-HSV-2-coinfected persons had statistically significant higher rates of HIV among racial/ethnic minorities. No comparisons limited to HIV monoinfected persons were significant. "End-of-the-epidemic" criteria were met among White, African American, and Latino/a PWID in New York City, but elimination of disparities may require a greater focus on PWID with high sexual risk.

  4. Effects of human dynamics on epidemic spreading in C\\^{o}te d'Ivoire

    CERN Document Server

    Li, Ruiqi; Di, Zengru

    2016-01-01

    Understanding and predicting outbreaks of contagious diseases are crucial to the development of society and public health, especially for underdeveloped countries. However, challenging problems are encountered because of complex epidemic spreading dynamics influenced by spatial structure and human dynamics (including both human mobility and human interaction intensity). We propose a systematical model to depict nationwide epidemic spreading in C\\^{o}te d'Ivoire, which integrates multiple factors, such as human mobility, human interaction intensity, and demographic features. We provide insights to aid in modeling and predicting the epidemic spreading process by data-driven simulation and theoretical analysis, which is otherwise beyond the scope of local evaluation and geometrical views. We show that the requirement that the average local basic reproductive number to be greater than unity is not necessary for outbreaks of epidemics. The observed spreading phenomenon can be roughly explained as a heterogeneous d...

  5. ANALYSIS ON STABILITY OF AN AUTONOMOUS DYNAMICS SYSTEM FOR SARS EPIDEMIC

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuang-de; HAO Hai

    2005-01-01

    An extended dynamic model for SARS epidemic was deduced on the basis of the K-M infection model with taking the density constraint of susceptible population and the cure and death rates of patients into consideration. It is shown that the infectionfree equilibrium is the global asymptotic stability under given conditions, and endemic equilibrium is not the asymptotic stability. It comes to the conclusion that the epidemic system is the permanent persistence existence under appropriate conditions.

  6. Declining seroprevalence in a very large HIV epidemic: injecting drug users in New York City, 1991 to 1996.

    Science.gov (United States)

    Des Jarlais, D C; Perlis, T; Friedman, S R; Deren, S; Chapman, T; Sotheran, J L; Tortu, S; Beardsley, M; Paone, D; Torian, L V; Beatrice, S T; DeBernardo, E; Monterroso, E; Marmor, M

    1998-01-01

    OBJECTIVES: This study assessed recent trends in HIV seroprevalence among injecting drug users in New York City. METHODS: We analyzed temporal trends in HIV seroprevalence from 1991 through 1996 in 5 studies of injecting drug users recruited from a detoxification program, a methadone maintenance program, research storefronts in the Lower East Side and Harlem areas, and a citywide network of sexually transmitted disease clinics. A total of 11,334 serum samples were tested. RESULTS: From 1991 through 1996, HIV seroprevalence declined substantially among subjects in all 5 studies: from 53% to 36% in the detoxification program, from 45% to 29% in the methadone program, from 44% to 22% at the Lower East Side storefront, from 48% to 21% at the Harlem storefront, and from 30% to 21% in the sexually transmitted disease clinics (all P < .002 by chi 2 tests for trend). CONCLUSIONS: The reductions in HIV seroprevalence seen among injecting drug users in New York City from 1991 through 1996 indicate a new phase in this large HIV epidemic. Potential explanatory factors include the loss of HIV-seropositive individuals through disability and death and lower rates of risk behavior leading to low HIV incidence. PMID:9842377

  7. From the Millennium Development Goals to Sustainable Development Goals.: The response to the HIV epidemic in Indonesia: challenges and opportunities.

    Science.gov (United States)

    Wijayanti, Fetty; Tarmizi, Siti Nadia; Tobing, Viny; Nisa, Tiara; Akhtar, Muhammad; Trihandini, Indang; Djuwita, Ratna

    2016-11-28

    Since the first case was reported in 1981, the Indonesian government and civil society have implemented many initiatives to respond to the HIV/AIDS epidemic. From an historical perspective, the country now has the means to rapidly diagnose cases of HIV infection and provide antiretroviral therapy. The concern expressed by international health agencies about a potential major HIV epidemic in the country has not been confirmed, as evidenced by a slowing down of the number cases. The threat from non-sterile needle sharing has been relatively well controlled through harm-reduction programmes; however, drug trafficking remains a challenge. It has reached worrying levels and involves law enforcement units at the forefront of the battle. In parallel, the level of condom use in high-risk behaviour groups seems unsuccessful in reducing infection rates, especially among heterosexuals. The lack of information and the high mobility of the groups at risk of acquiring HIV infection have created tremendous challenges for outreach programmes. Heterosexual transmission represents the most important route of transmission in the country. When reflecting on the country's 2014 Millennium Development Goals, condom use during high-risk sex only reaches 43.5%, and only 21.3% of young people have a comprehensive knowledge about HIV/AIDS. The 2030 Millennium Development Goal Agenda offers an opportunity to catch up on goals that still need to be achieved. Therefore, efforts are underway to try to halt the epidemic by 2030 and also to ensure that all high-risk populations are included in this effort.

  8. Sexual learning among East African adolescents in the context of generalized HIV epidemics: A systematic qualitative meta-synthesis.

    Science.gov (United States)

    Knopf, Amelia S; McNealy, Kim R; Al-Khattab, Halima; Carter-Harris, Lisa; Oruche, Ukamaka Marian; Naanyu, Violet; Draucker, Claire Burke

    2017-01-01

    AIDS-related illness is the leading cause of mortality for adolescents in sub-Saharan Africa. Together, Kenya, Tanzania, and Uganda account for 21% of HIV-infected adolescents in sub-Saharan Africa. The United Nations framework for addressing the epidemic among adolescents calls for comprehensive sexual and reproductive health education. These HIV prevention efforts could be informed by a synthesis of existing research about the formal and informal sexual education of adolescents in countries experiencing generalized epidemics. The purpose of this study was to describe the process of sexual learning among East African adolescents living in the context of generalized HIV epidemics. Qualitative metasynthesis, a systematic procedure for integrating the results of multiple qualitative studies addressing a similar phenomenon, was used. Thirty-two research reports met study inclusion criteria. The reports were assessed in a four-step analytic process: appraisal, classification of findings, synthesis of findings, and construction of a framework depicting the process of sexual learning in this population. The framework includes three phases of sexual learning: 1) being primed for sex, 2) making sense of sex, and 3) having sexual experiences. Adolescents were primed for sex through gender norms, cultural practices, and economic structures as well as through conversations and formal instruction. They made sense of sex by acquiring information about sexual intercourse, reproduction and pregnancy, sexually transmitted infections, and relationships and by developing a variety of beliefs and attitudes about these topics. Some adolescents described having sexual experiences that met wants or needs, but many experienced sex that was coerced or violent. Whether sex was wanted, coerced, or violent, adolescents experienced worry about sexually transmitted infections or premarital pregnancy. The three phases of sexual learning interact to shape adolescents' sexual lives and their risk

  9. Sexual learning among East African adolescents in the context of generalized HIV epidemics: A systematic qualitative meta-synthesis

    Science.gov (United States)

    McNealy, Kim R.; Al-Khattab, Halima; Carter-Harris, Lisa; Oruche, Ukamaka Marian; Naanyu, Violet; Draucker, Claire Burke

    2017-01-01

    Background AIDS-related illness is the leading cause of mortality for adolescents in sub-Saharan Africa. Together, Kenya, Tanzania, and Uganda account for 21% of HIV-infected adolescents in sub-Saharan Africa. The United Nations framework for addressing the epidemic among adolescents calls for comprehensive sexual and reproductive health education. These HIV prevention efforts could be informed by a synthesis of existing research about the formal and informal sexual education of adolescents in countries experiencing generalized epidemics. The purpose of this study was to describe the process of sexual learning among East African adolescents living in the context of generalized HIV epidemics. Methods Qualitative metasynthesis, a systematic procedure for integrating the results of multiple qualitative studies addressing a similar phenomenon, was used. Thirty-two research reports met study inclusion criteria. The reports were assessed in a four-step analytic process: appraisal, classification of findings, synthesis of findings, and construction of a framework depicting the process of sexual learning in this population. Results The framework includes three phases of sexual learning: 1) being primed for sex, 2) making sense of sex, and 3) having sexual experiences. Adolescents were primed for sex through gender norms, cultural practices, and economic structures as well as through conversations and formal instruction. They made sense of sex by acquiring information about sexual intercourse, reproduction and pregnancy, sexually transmitted infections, and relationships and by developing a variety of beliefs and attitudes about these topics. Some adolescents described having sexual experiences that met wants or needs, but many experienced sex that was coerced or violent. Whether sex was wanted, coerced, or violent, adolescents experienced worry about sexually transmitted infections or premarital pregnancy. Conclusions The three phases of sexual learning interact to shape

  10. Strain-specific estimation of epidemic success provides insights into the transmission dynamics of tuberculosis

    Science.gov (United States)

    Rasigade, Jean-Philippe; Barbier, Maxime; Dumitrescu, Oana; Pichat, Catherine; Carret, Gérard; Ronnaux-Baron, Anne-Sophie; Blasquez, Ghislaine; Godin-Benhaim, Christine; Boisset, Sandrine; Carricajo, Anne; Jacomo, Véronique; Fredenucci, Isabelle; Pérouse de Montclos, Michèle; Flandrois, Jean-Pierre; Ader, Florence; Supply, Philip; Lina, Gérard; Wirth, Thierry

    2017-01-01

    The transmission dynamics of tuberculosis involves complex interactions of socio-economic and, possibly, microbiological factors. We describe an analytical framework to infer factors of epidemic success based on the joint analysis of epidemiological, clinical and pathogen genetic data. We derive isolate-specific, genetic distance-based estimates of epidemic success, and we represent success-related time-dependent concepts, namely epidemicity and endemicity, by restricting analysis to specific time scales. The method is applied to analyze a surveillance-based cohort of 1,641 tuberculosis patients with minisatellite-based isolate genotypes. Known predictors of isolate endemicity (older age, native status) and epidemicity (younger age, sputum smear positivity) were identified with high confidence (P tuberculosis can be gained from active surveillance data. PMID:28349973

  11. IMPACT OF MIGRATION ON TUBERCULOSIS AND HIV EPIDEMIC SITUATION IN RUSSIA

    Directory of Open Access Journals (Sweden)

    O. B. Nechaeva

    2015-01-01

    Full Text Available The growing changes in migration and mobility of the population in Russia require additional study of the epidemic situation related to infectious diseases and evaluation of preparedness of specialized medical services and existing resources of the health care system. Assessment of the incidence rates shows the higher figures among foreign citizens compared to native population as regards tuberculosis (2013: 163.2 versus 61.6 per 100,000 population and lower figures for HIV-infection (107.5 versus 315.1 respectively.The study of behavioral risks of acquiring infectious diseases (HIV-infection, sexually transmitted diseases, tuberculosis and socio-economic living conditions and factors influencing on the self-referral to the Russian medical units conducted among labor migrants in St. Petersburg, showed fairly low level of awareness of socially important diseases and protection from infections in migrants. Due to the fear of deportation in case of detection of infectious diseases, high price of medical services and lack of motivation of the employer to pay for medical insurance, migrants often practice self-treatment. Very few migrants (10% present themselves for mandatory annual fluorography screening.A significant flow of refugees from Ukraine especially from the regions with high risk of infectious diseases require special attention from the Russian Ministry of Health and the relevant financial support.There is also a lack of cooperation between bodies of Rospotrebnadzor and medical units submitting data on notifications of HIV-infection and tuberculosis in foreign citizens. Coordination mechanisms have to be improved to overcome the found deficiencies. 

  12. Who is epidemiologically fathomable in the HIV/AIDS epidemic? Gender, sexuality, and intersectionality in public health.

    Science.gov (United States)

    Dworkin, Shari L

    2005-01-01

    This paper examines the shifting nature of contemporary epidemiological classifications in the HIV/AIDS epidemic. It first looks at assumptions that guide a discourse of vulnerability and circulate around risk categories. It then examines the underlying emphasis in public health on the popular frame of "vulnerable women" who acquire HIV through heterosexual transmission. Drawing on work on gender, sexuality, and intersectionality, the paper asks why a discourse of vulnerability is infused into discussions of heterosexually-active women's HIV risks but not those pertaining to heterosexually-active men's. The paper then moves to current surveillance categories that are hierarchically and differentially applied to women's and men's risks in the HIV epidemic. Here, the focus is on the way in which contemporary classifications allow for the emergence of the vulnerable heterosexually-active woman while simultaneously constituting lack of fathomability concerning bisexual and lesbian transmission risk. Lastly, theories of intersectionality, are used to examine current research on woman-to-woman transmission, and to suggest future more productive options.

  13. Spatio-temporal dynamics of cholera during the first year of the epidemic in Haiti.

    Directory of Open Access Journals (Sweden)

    Jean Gaudart

    Full Text Available BACKGROUND: In October 2010, cholera importation in Haiti triggered an epidemic that rapidly proved to be the world's largest epidemic of the seventh cholera pandemic. To establish effective control and elimination policies, strategies rely on the analysis of cholera dynamics. In this report, we describe the spatio-temporal dynamics of cholera and the associated environmental factors. METHODOLOGY/PRINCIPAL FINDINGS: Cholera-associated morbidity and mortality data were prospectively collected at the commune level according to the World Health Organization standard definition. Attack and mortality rates were estimated and mapped to assess epidemic clusters and trends. The relationships between environmental factors were assessed at the commune level using multivariate analysis. The global attack and mortality rates were 488.9 cases/10,000 inhabitants and 6.24 deaths/10,000 inhabitants, respectively. Attack rates displayed a significantly high level of spatial heterogeneity (varying from 64.7 to 3070.9 per 10,000 inhabitants, thereby suggesting disparate outbreak processes. The epidemic course exhibited two principal outbreaks. The first outbreak (October 16, 2010-January 30, 2011 displayed a centrifugal spread of a damping wave that suddenly emerged from Mirebalais. The second outbreak began at the end of May 2011, concomitant with the onset of the rainy season, and displayed a highly fragmented epidemic pattern. Environmental factors (river and rice fields: p<0.003 played a role in disease dynamics exclusively during the early phases of the epidemic. CONCLUSION: Our findings demonstrate that the epidemic is still evolving, with a changing transmission pattern as time passes. Such an evolution could have hardly been anticipated, especially in a country struck by cholera for the first time. These results argue for the need for control measures involving intense efforts in rapid and exhaustive case tracking.

  14. Spatio-Temporal Dynamics of Cholera during the First Year of the Epidemic in Haiti

    Science.gov (United States)

    Gaudart, Jean; Rebaudet, Stanislas; Barrais, Robert; Boncy, Jacques; Faucher, Benoit; Piarroux, Martine; Magloire, Roc; Thimothe, Gabriel; Piarroux, Renaud

    2013-01-01

    Background In October 2010, cholera importation in Haiti triggered an epidemic that rapidly proved to be the world's largest epidemic of the seventh cholera pandemic. To establish effective control and elimination policies, strategies rely on the analysis of cholera dynamics. In this report, we describe the spatio-temporal dynamics of cholera and the associated environmental factors. Methodology/Principal findings Cholera-associated morbidity and mortality data were prospectively collected at the commune level according to the World Health Organization standard definition. Attack and mortality rates were estimated and mapped to assess epidemic clusters and trends. The relationships between environmental factors were assessed at the commune level using multivariate analysis. The global attack and mortality rates were 488.9 cases/10,000 inhabitants and 6.24 deaths/10,000 inhabitants, respectively. Attack rates displayed a significantly high level of spatial heterogeneity (varying from 64.7 to 3070.9 per 10,000 inhabitants), thereby suggesting disparate outbreak processes. The epidemic course exhibited two principal outbreaks. The first outbreak (October 16, 2010–January 30, 2011) displayed a centrifugal spread of a damping wave that suddenly emerged from Mirebalais. The second outbreak began at the end of May 2011, concomitant with the onset of the rainy season, and displayed a highly fragmented epidemic pattern. Environmental factors (river and rice fields: p<0.003) played a role in disease dynamics exclusively during the early phases of the epidemic. Conclusion Our findings demonstrate that the epidemic is still evolving, with a changing transmission pattern as time passes. Such an evolution could have hardly been anticipated, especially in a country struck by cholera for the first time. These results argue for the need for control measures involving intense efforts in rapid and exhaustive case tracking. PMID:23593516

  15. Dynamic Variation in Sexual Contact Rates in a Cohort of HIV-Negative Gay Men.

    Science.gov (United States)

    Romero-Severson, E O; Volz, E; Koopman, J S; Leitner, T; Ionides, E L

    2015-08-01

    Human immunodeficiency virus (HIV) transmission models that include variability in sexual behavior over time have shown increased incidence, prevalence, and acute-state transmission rates for a given population risk profile. This raises the question of whether dynamic variation in individual sexual behavior is a real phenomenon that can be observed and measured. To study this dynamic variation, we developed a model incorporating heterogeneity in both between-person and within-person sexual contact patterns. Using novel methodology that we call iterated filtering for longitudinal data, we fitted this model by maximum likelihood to longitudinal survey data from the Centers for Disease Control and Prevention's Collaborative HIV Seroincidence Study (1992-1995). We found evidence for individual heterogeneity in sexual behavior over time. We simulated an epidemic process and found that inclusion of empirically measured levels of dynamic variation in individual-level sexual behavior brought the theoretical predictions of HIV incidence into closer alignment with reality given the measured per-act probabilities of transmission. The methods developed here provide a framework for quantifying variation in sexual behaviors that helps in understanding the HIV epidemic among gay men.

  16. Trends in the HIV and AIDS epidemic in a Puerto Rican cohort of patients: 1992-2005.

    Science.gov (United States)

    Báez-Feliciano, Doris V; Quintana, Rafael; Gómez, María A; Fernández, Diana M; Velázquez, Miriam; Olivares, Eddy; León Valiente, Carlos; Mayor, Angel M; Hunter-Mellado, Robert F

    2006-01-01

    The HIV epidemic is a significant global health care issue. With increasing knowledge and improved therapeutics the natural history of the infection has been modified. In this paper we aim to present the general socio-demographic profile and the clinical and therapeutic spectrum of patients with HIV infection who have visited the Bayamón Health Care facilities over the last 12 years and who are part of the Retrovirus Research Center (RRC). The objectives of the study are: 1) describe changes in the demographic, risk factors and clinical stage of patients with HIV infection initially seen in our center; 2) assess changing trends from the clinical and immunological perspective across time; 3) describe mortality risk of patients particularly after the introduction of antiretroviral therapy (ART). This is a cross-sectional study of 3,569 patients admitted to the RRC at the Universidad Central del Caribe between years 1992 through 2005. The variables studied were demographic, risk factors exposure, HIV status at baseline, clinical and immunological parameters, ART and the mortality risk. Chi square with Cramer's coefficient, Kaplan Meier and Cox proportional hazard ratio analysis were performed. The study revealed that individuals presenting at our health care facilities are older and that the proportion of females has increased. The risk factor profile shows increase in heterosexual contact with the disease. The study found that patients treated with ART had significantly lower mortality risk than those without ART. Patients who arrive to RRC with AIDS and Intravenous Drug Users (IDU) had a higher mortality risk than participants with HIV. The analysis of the trends showed changes in the demographic and clinical profile of patients across the years. HIV/AIDS prevention programs and policies need to be continued in Puerto Rico in order to better control the spread of the epidemic.

  17. Political and socio-economic instability: does it have a role in the HIV/AIDS epidemic in sub-Saharan Africa?

    Science.gov (United States)

    Premkumar, Ramaswamy; Tebandeke, Achilles

    2011-01-01

    Many sub-Saharan African countries are confronted by the HIV/AIDS epidemic. This article reviews academic literature in the social sciences and health to discover why HIV/AIDS has become an epidemic in sub-Saharan Africa and not in other parts of the world. This was studied by examining the social determinants of diminishment of tradition and social cohesion in terms of political, social and economic problems. Four countries in this region were selected for this case study, namely South Africa, Botswana, Uganda and Zimbabwe. The findings showed that instability in socio-economic and political aspects in these nations was responsible for creating a suitable environment for the spread of HIV/AIDS infection. This paper concludes by using the theories of collective action/responsibility and social cohesion to hypothesise that the breakdown of social ties due to various kinds of conflicts and unrest is one of the main contributors to the HIV/AIDS epidemic.

  18. Evolution of HIV/AIDS in Southern Africa

    NARCIS (Netherlands)

    Lauwers, L.; Pruyt, E.; Hens, L.; Brans, J.p.

    2008-01-01

    This paper presents a system dynamics model to study the spread of HIV/AIDS in Southern Africa. The HIV/AIDS model includes important feedback mechanisms of the spread of HIV/AIDS, and partly explains the dynamics of the epidemic in a representative Southern African country. The HIV/AIDS model indic

  19. Evolution of HIV/AIDS in Southern Africa

    NARCIS (Netherlands)

    Lauwers, L.; Pruyt, E.; Hens, L.; Brans, J.p.

    2008-01-01

    This paper presents a system dynamics model to study the spread of HIV/AIDS in Southern Africa. The HIV/AIDS model includes important feedback mechanisms of the spread of HIV/AIDS, and partly explains the dynamics of the epidemic in a representative Southern African country. The HIV/AIDS model indic

  20. Global dynamics of a dengue epidemic mathematical model

    Energy Technology Data Exchange (ETDEWEB)

    Cai Liming [Department of Mathematics, Xinyang Normal University, Xinyang 464000 (China); Academy of Mathematics and Systems Science, Academia Sinica, Beijing 100080 (China)], E-mail: lmcai06@yahoo.com.cn; Guo Shumin [Beijing Institute of Information Control, Beijing 100037 (China); Li, XueZhi [Department of Mathematics, Xinyang Normal University, Xinyang 464000 (China); Ghosh, Mini [School of Mathematics and Computer Application, Thapar University, Patiala 147004 (India)

    2009-11-30

    The paper investigates the global stability of a dengue epidemic model with saturation and bilinear incidence. The constant human recruitment rate and exponential natural death, as well as vector population with asymptotically constant population, are incorporated into the model. The model exhibits two equilibria, namely, the disease-free equilibrium and the endemic equilibrium. The stability of these two equilibria is controlled by the threshold number R{sub 0}. It is shown that if R{sub 0} is less than one, the disease-free equilibrium is globally asymptotically stable and in such a case the endemic equilibrium does not exist; if R{sub 0} is greater than one, then the disease persists and the unique endemic equilibrium is globally asymptotically stable.

  1. Dynamics of tax evasion through an epidemic-like model

    CERN Document Server

    Brum, Rafael M

    2016-01-01

    In this work we study a model of tax evasion. We considered a fixed population divided in three compartments, namely honest tax payers, tax evaders and a third class between the mentioned two, which we call \\textit{susceptibles} to become evaders. The transitions among those compartments are ruled by probabilities, similarly to a model of epidemic spreading. These probabilities model social interactions among the individuals, as well as the government's fiscalization. We simulate the model on fully-connected graphs, as well as on scale-free and random complex networks. For the fully-connected and random graph cases we observe that the emergence of tax evaders in the population is associated with an active-absorbing nonequilibrium phase transition, that is absent in scale-free networks.

  2. Impact and Cost-Effectiveness of Point-Of-Care CD4 Testing on the HIV Epidemic in South Africa

    National Research Council Canada - National Science Library

    Heffernan, Alastair; Barber, Ella; Thomas, Ranjeeta; Fraser, Christophe; Pickles, Michael; Cori, Anne

    2016-01-01

    .... We assess the impact and cost-effectiveness of introducing POC CD4 testing at the population level in South Africa in a range of care contexts, using a dynamic compartmental model of HIV transmission...

  3. The Dynamics of Epidemic Model with Two Types of Infectious Diseases and Vertical Transmission

    Directory of Open Access Journals (Sweden)

    Raid Kamel Naji

    2016-01-01

    Full Text Available An epidemic model that describes the dynamics of the spread of infectious diseases is proposed. Two different types of infectious diseases that spread through both horizontal and vertical transmission in the host population are considered. The basic reproduction number R0 is determined. The local and the global stability of all possible equilibrium points are achieved. The local bifurcation analysis and Hopf bifurcation analysis for the four-dimensional epidemic model are studied. Numerical simulations are used to confirm our obtained analytical results.

  4. Dynamical behaviour of an epidemic on complex networks with population mobility

    Institute of Scientific and Technical Information of China (English)

    Zhang Hai-Feng; Small Michael; Fu Xin-Chu; Wang Bing-Hong

    2009-01-01

    In this paper,we study the dynamical behaviour of an epidemic on complex networks with population mobility.In our model,the number of people on each node is unrestricted as the nodes of the network are considered as cities,communities,and so on. Because people can travel between different cities,we study the effect of a population's mobility on the epidemic spreading. In view of the population's mobility,we suppose that the usceptible individual can be infected by an infected individual in the same city or other connected cities. Simulations are presented to verify our analysis.

  5. Periodic and aperiodic traveling pulses in population dynamics: An example from the occurrence of epidemic infections

    Science.gov (United States)

    Vecchio, A.; Primavera, L.; Carbone, V.

    2006-03-01

    The dynamics of the occurrence of the dengue hemorrhagic fever in the 72 provinces of Thailand is investigated by performing a proper orthogonal decomposition (POD) on spatiotemporal data. Using this technique, we are able to identify and select the contribution of different modes, selected according to the energy content, to the evolution of the epidemic during 14 years. We found that the phenomenon is characterized by periodic cycles of yearly occurrence characterized by spatial scales of about 420 km. Superimposed on this basic mode, POD analysis is able to reveal the presence of high-energetic aperiodic traveling pulses of the epidemic, which extend spatially for about 510 km from Bangkok.

  6. Dynamics of epidemic spreading with vaccination: Impact of social pressure and engagement

    Science.gov (United States)

    Pires, Marcelo A.; Crokidakis, Nuno

    2017-02-01

    In this work we consider a model of epidemic spreading coupled with an opinion dynamics in a fully-connected population. Regarding the opinion dynamics, the individuals may be in two distinct states, namely in favor or against a vaccination campaign. Individuals against the vaccination follow a standard SIS model, whereas the pro-vaccine individuals can also be in a third compartment, namely Vaccinated. In addition, the opinions change according to the majority-rule dynamics in groups with three individuals. We also consider that the vaccine can give permanent or temporary immunization to the individuals. By means of analytical calculations and computer simulations, we show that the opinion dynamics can drastically affect the disease propagation, and that the engagement of the pro-vaccine individuals can be crucial for stopping the epidemic spreading. The full numerical code for simulating the model is available from the authors' webpage.

  7. Dynamics of epidemic spreading with vaccination: impact of social pressure and engagement

    CERN Document Server

    Pires, Marcelo A

    2016-01-01

    In this work we consider a model of epidemic spreading coupled with an opinion dynamics in a fully-connected population. Regarding the opinion dynamics, the individuals may be in two distinct states, namely in favor or against a vaccination campaign. Individuals against the vaccination follow a standard SIS model, whereas the pro-vaccine individuals can also be in a third compartment, namely Vaccinated. In addition, the opinions change according to the majority-rule dynamics in groups with three individuals. We also consider that the vaccine can give permanent or temporary immunization to the individuals. By means of analytical calculations and computer simulations, we show that the opinion dynamics can drastically affect the disease propagation, and that the engagement of the pro-vaccine individuals can be crucial for stopping the epidemic spreading.

  8. The Securization of the HIV/AIDS Epidemic as a Norm: A Contribution to Construtivist Scholarship on the Emergence and Diffusion of International Norms

    Directory of Open Access Journals (Sweden)

    Marco Antonio Vieira

    2007-03-01

    Full Text Available This article discusses the emergence in the late 1990s of an innovative conceptualization of security that proclaims the global HIV/AIDS epidemic a threat to international peace and stability. The study provides a framework for understanding the securitization of the HIV/AIDS epidemic as an international norm defined and promoted mainly by multilateral bodies, powerful states in the North and transnational HIV/AIDS advocacy networks. The HIV/AIDS securitization norm (HASN is an attempt of the present analysis to synthesize under a single analytical concept the myriad of ideas and international prescriptions about HIV/AIDS interventions. The article identifies the actors who developed the main strategic prescriptions of the HASN and the transnational mechanisms that promoted the diffusion of its concepts throughout the state system.

  9. What drives the US and Peruvian HIV epidemics in men who have sex with men (MSM?

    Directory of Open Access Journals (Sweden)

    Steven M Goodreau

    Full Text Available In this work, we estimate the proportions of transmissions occurring in main vs. casual partnerships, and by the sexual role, infection stage, and testing and treatment history of the infected partner, for men who have sex with men (MSM in the US and Peru. We use dynamic, stochastic models based in exponential random graph models (ERGMs, obtaining inputs from multiple large-scale MSM surveys. Parallel main partnership and casual sexual networks are simulated. Each man is characterized by age, race, circumcision status, sexual role behavior, and propensity for unprotected anal intercourse (UAI; his history is modeled from entry into the adult population, with potential transitions including HIV infection, detection, treatment, AIDS diagnosis, and death. We implemented two model variants differing in assumptions about acute infectiousness, and assessed sensitivity to other key inputs. Our two models suggested that only 4-5% (Model 1 or 22-29% (Model 2 of HIV transmission results from contacts with acute-stage partners; the plurality (80-81% and 49%, respectively stem from chronic-stage partners and the remainder (14-16% and 27-35%, respectively from AIDS-stage partners. Similar proportions of infections stem from partners whose infection is undiagnosed (24-31%, diagnosed but untreated (36-46%, and currently being treated (30-36%. Roughly one-third of infections (32-39% occur within main partnerships. Results by country were qualitatively similar, despite key behavioral differences; one exception was that transmission from the receptive to insertive partner appears more important in Peru (34% than the US (21%. The broad balance in transmission contexts suggests that education about risk, careful assessment, pre-exposure prophylaxis, more frequent testing, earlier treatment, and risk-reduction, disclosure, and adherence counseling may all contribute substantially to reducing the HIV incidence among MSM in the US and Peru.

  10. The EuroSIDA study: Regional differences in the HIV-1 epidemic and treatment response to antiretroviral therapy among HIV-infected patients across Europe--a review of published results

    DEFF Research Database (Denmark)

    Podlekareva, Daria; Bannister, Wendy; Mocroft, Amanda

    2008-01-01

    EuroSIDA is a pan-European observational study that follows 14,265 HIV-infected patients from 31 European countries, Israel and Argentina, of which 2,560 are patients from eastern Europe (EE). The study group has performed several analyses addressing regional differences in the HIV-epidemic across...

  11. The EuroSIDA study: Regional differences in the HIV-1 epidemic and treatment response to antiretroviral therapy among HIV-infected patients across Europe--a review of published results

    DEFF Research Database (Denmark)

    Podlekareva, Daria; Bannister, Wendy; Mocroft, Amanda;

    2008-01-01

    EuroSIDA is a pan-European observational study that follows 14,265 HIV-infected patients from 31 European countries, Israel and Argentina, of which 2,560 are patients from eastern Europe (EE). The study group has performed several analyses addressing regional differences in the HIV-epidemic across...

  12. Effects of human dynamics on epidemic spreading in Côte d'Ivoire

    Science.gov (United States)

    Li, Ruiqi; Wang, Wenxu; Di, Zengru

    2017-02-01

    Understanding and predicting outbreaks of contagious diseases are crucial to the development of society and public health, especially for underdeveloped countries. However, challenging problems are encountered because of complex epidemic spreading dynamics influenced by spatial structure and human dynamics (including both human mobility and human interaction intensity). We propose a systematical model to depict nationwide epidemic spreading in Côte d'Ivoire, which integrates multiple factors, such as human mobility, human interaction intensity, and demographic features. We provide insights to aid in modeling and predicting the epidemic spreading process by data-driven simulation and theoretical analysis, which is otherwise beyond the scope of local evaluation and geometrical views. We show that the requirement that the average local basic reproductive number to be greater than unity is not necessary for outbreaks of epidemics. The observed spreading phenomenon can be roughly explained as a heterogeneous diffusion-reaction process by redefining mobility distance according to the human mobility volume between nodes, which is beyond the geometrical viewpoint. However, the heterogeneity of human dynamics still poses challenges to precise prediction.

  13. Exact mean field dynamics for epidemic-like processes on heterogeneous networks

    CERN Document Server

    Lucas, Andrew

    2012-01-01

    We show that the mean field equations for the SIR epidemic can be exactly solved for a network with arbitrary degree distribution. Our exact solution consists of reducing the dynamics to a lone first order differential equation, which has a solution in terms of an integral over functions dependent on the degree distribution of the network, and reconstructing all mean field functions of interest from this integral. Irreversibility of the SIR epidemic is crucial for the solution. We also find exact solutions to the sexually transmitted disease SI epidemic on bipartite graphs, to a simplified rumor spreading model, and to a new model for recommendation spreading, via similar techniques. Numerical simulations of these processes on scale free networks demonstrate the qualitative validity of mean field theory in most regimes.

  14. A Universal Model for Predicting Dynamics of the Epidemics Caused by Special Pathogens

    Directory of Open Access Journals (Sweden)

    Alexander G. Bachinsky

    2013-01-01

    Full Text Available A universal model intended primarily for predicting dynamics of the mass epidemics (outbreaks caused by special pathogens is being developed at the State Research Center of Virology and Biotechnology Vector. The model includes the range of major countermeasures: preventive and emergency mass vaccination, vaccination of risk groups as well as search for and isolation/observation of infected cases, contacts, and suspects, and quarantine. The intensity of interventions depends on the availability of the relevant resources. The effect of resource limitations on the development of a putative epidemic of Ebola hemorrhagic fever is demonstrated. The modeling results allow for estimation of the material and human resources necessary for eradication of an epidemic.

  15. On the oscillatory dynamical behaviour of epidemic spreading in fractal media

    Energy Technology Data Exchange (ETDEWEB)

    Bab, M A; Albano, E V [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CONICET, Casilla de Correo 16, Sucursal 4 (1900) La Plata (Argentina)

    2008-02-01

    We present numerical evidence that dynamical physical processes that develop a time-dependent characteristic length, and take place in fractal media exhibiting spatial discrete scale invariance (DSI) with fundamental scaling ratio b, may become coupled to the topology of the fractal leading to the observation of time DSI. The hallmark of time DSI is the observation of a log-periodic modulation of the dynamic or kinetic observables, which is characterized by a well-defined fundamental time scaling ratio ({tau}). Both fundamental scaling ratios are linked according to b = {tau}{sup 1/z}, where z is the dynamic exponent characteristic of the physical process. Specifically, we have studied the epidemic behaviour of the contact process (CP) in Sierpinski Carpets. The CP exhibits second-order irreversible phase transitions between an active regime and an absorbing state where the system is trapped without any escape possibility. We observed that relevant dynamic observables, such as the number of active sites, the survival probability of the epidemics and the mean square displacement of the epidemic from the origin (R{sup 2}(t)), exhibit log-periodic modulations. By fitting the data we evaluate the fundamental time scaling ratio for various fractals and the corresponding dynamic exponents. Since, at criticality, one has that R{sup 2}(t) {approx} t{sup 2/z}, an independent estimation of the dynamic exponent can be performed, in excellent agreement with results obtained by using the conjectured relationship for the fundamental scaling ratios b and {tau}.

  16. Modeling dual-scale epidemic dynamics on complex networks with reaction diffusion processes

    Institute of Scientific and Technical Information of China (English)

    Xiao-gang JIN; Yong MIN

    2014-01-01

    The frequent outbreak of severe foodborne diseases (e.g., haemolytic uraemic syndrome and Listeriosis) in 2011 warns of a potential threat that world trade could spread fatal pathogens (e.g., enterohemorrhagic Escherichia coli). The epidemic potential from trade involves both intra-proliferation and inter-diffusion. Here, we present a worldwide vegetable trade network and a stochastic computational model to simulate global trade-mediated epidemics by considering the weighted nodes and edges of the network and the dual-scale dynamics of epidemics. We address two basic issues of network structural impact in global epi-demic patterns:(1) in contrast to the prediction of heterogeneous network models, the broad variability of node degree and edge weights of the vegetable trade network do not determine the threshold of global epidemics;(2) a‘penetration effect’, by which community structures do not restrict propagation at the global scale, quickly facilitates bridging the edges between communities, and leads to synchronized diffusion throughout the entire network. We have also defined an appropriate metric that combines dual-scale behavior and enables quantification of the critical role of bridging edges in disease diffusion from widespread trading. The unusual structure mechanisms of the trade network model may be useful in producing strategies for adaptive immunity and reducing international trade frictions.

  17. Review on the epidemiology and dynamics of BSE epidemics.

    Science.gov (United States)

    Ducrot, Christian; Arnold, Mark; de Koeijer, Aline; Heim, Dagmar; Calavas, Didier

    2008-01-01

    The paper describes how the comprehensive surveillance of bovine spongiform encephalopathy (BSE) and studies carried out on these data has enhanced our knowledge of the epidemiology of BSE. Around 7, 000 BSE cases were detected through the screening of about 50 million cattle with rapid tests in Europe. It confirmed that the clinical surveillance had a poor capacity to detect cases, and also showed the discrepancy of this passive surveillance efficiency between regions and production types (dairy/beef). Other risk factors for BSE were being in a dairy herd (three times more than beef), having a young age at first calving (for dairy cattle), being autumn-born (dairy and beef), and being in a herd with a very high milk yield. These findings focus the risk on the feeding regimen of calves/heifers. Several epidemiological studies across countries suggest that the feedborne source related to meat and bone meal (MBM) is the only substantiated route of infection - even after the feed ban -, while it is not possible to exclude maternal transmission or milk replacers as a source of some infections. In most European countries, the average age of the cases is increasing over time and the prevalence decreasing, which reflects the effectiveness of control measures. Consistent results on the trend of the epidemic were obtained using back-calculation modelling, the R(0) approach and Age-Period-Cohort models. Furthermore, active surveillance also resulted in the finding of atypical cases. These are distinct from previously found BSE and classified in two different forms based on biochemical characteristics; their prevalence is very low (36 cases up to 1st September 2007), affected animals were old and some of them displayed clinical signs. The origin and possibility of natural transmission is unknown.

  18. What do young adults know about the HIV/AIDS epidemic? Findings from a population based study in Karachi, Pakistan

    Directory of Open Access Journals (Sweden)

    Johansson Eva

    2009-03-01

    Full Text Available Abstract Background HIVAIDS is spreading globally, hitting the younger generations. In Pakistan, the prevalence of HIV in high-risk subpopulations is five per cent or higher. This poses a serious threat of a generalised epidemic especially among the younger population. In the wake of HIVAIDS epidemic this is worrying as a well informed younger generation is crucial in restricting the spread of this epidemic. This study investigated Pakistani young adults' (male and female knowledge and awareness of the HIV/AIDS disease. Methods A population-based, cross-sectional study of 1,650 male and female adults aged 17–21 years living in Karachi was conducted using a structured questionnaire. A multi-stage cluster sampling design was used to collect data representative of the general population in an urban area. Bivariate and multivariate analyses were performed separately for males and females. Results Of 1,650 subjects, 24 per cent (n = 390 reported that they had not heard of HIV/AIDS. Among the males, those with a poor knowledge were younger (AOR = 2.20; 95 per cent CI, 1.38, 3.49, with less than six years of schooling (AOR = 2.46; 1.29 4.68 and no computer at home (AOR = 1.88; 1.06 3.34. Among the females, the risk factors for poor knowledge were young age (AOR = 1.74; 1.22, 2.50, low socio-economic status (AOR = 1.54; 1.06, 2.22, lack of enrolment at school/college (AOR = 1.61; 1.09, 2.39 and being unmarried (AOR = 1.85; 1.05, 3.26. Conclusion Alarming gaps in knowledge relating to HIV/AIDS were detected. The study emphasises the need to educate young adults and equip them with the appropriate information and skills to enable them to protect themselves from HIV/AIDS. However, taboos surrounding public discussions of sexuality remain a key constraint to preventive activities.

  19. What do young adults know about the HIV/AIDS epidemic? Findings from a population based study in Karachi, Pakistan.

    Science.gov (United States)

    Farid-ul-Hasnain, Syed; Johansson, Eva; Krantz, Gunilla

    2009-03-26

    HIVAIDS is spreading globally, hitting the younger generations. In Pakistan, the prevalence of HIV in high-risk subpopulations is five per cent or higher. This poses a serious threat of a generalised epidemic especially among the younger population. In the wake of HIVAIDS epidemic this is worrying as a well informed younger generation is crucial in restricting the spread of this epidemic. This study investigated Pakistani young adults' (male and female) knowledge and awareness of the HIV/AIDS disease. A population-based, cross-sectional study of 1,650 male and female adults aged 17-21 years living in Karachi was conducted using a structured questionnaire. A multi-stage cluster sampling design was used to collect data representative of the general population in an urban area. Bivariate and multivariate analyses were performed separately for males and females. Of 1,650 subjects, 24 per cent (n = 390) reported that they had not heard of HIV/AIDS. Among the males, those with a poor knowledge were younger (AOR = 2.20; 95 per cent CI, 1.38, 3.49), with less than six years of schooling (AOR = 2.46; 1.29 4.68) and no computer at home (AOR = 1.88; 1.06 3.34). Among the females, the risk factors for poor knowledge were young age (AOR = 1.74; 1.22, 2.50), low socio-economic status (AOR = 1.54; 1.06, 2.22), lack of enrolment at school/college (AOR = 1.61; 1.09, 2.39) and being unmarried (AOR = 1.85; 1.05, 3.26). Alarming gaps in knowledge relating to HIV/AIDS were detected. The study emphasises the need to educate young adults and equip them with the appropriate information and skills to enable them to protect themselves from HIV/AIDS. However, taboos surrounding public discussions of sexuality remain a key constraint to preventive activities.

  20. HIV Prevalence Trends, Risky Behaviours, and Governmental and Community Responses to the Epidemic among Men Who Have Sex with Men in China

    Directory of Open Access Journals (Sweden)

    Eric P. F. Chow

    2014-01-01

    Full Text Available Purpose of Review. Numerous studies reported the rapid spread of HIV/AIDS epidemic among men who have sex with men (MSM in China. This paper aims to investigate the overall epidemic trend and associated high-risk behaviours among Chinese MSM and to explore the governmental and community responses to the epidemic. Recent Findings. HIV prevalence among Chinese MSM increased rapidly in all Chinese regions in the past decade and disproportionally affected the Southwest China. In addition to the high-risk homosexual behaviours, overlapping bisexual, commercial, and drug use behaviours are commonly observed among Chinese MSM. The Chinese government has significantly expanded the surveillance efforts among MSM over the past decade. Community responses against HIV have been substantially strengthened with the support of international aid. However, lack of enabling legal and financial environment undermines the role of community-based organisations (CBOs in HIV surveillance and prevention. Conclusion. HIV continues to spread rapidly among MSM in China. The hidden nature of MSM and the overlapping homosexual, bisexual, and commercial behaviours remain a challenge for HIV prevention among MSM. Strong collaboration between the government and CBOs and innovative intervention approaches are essential for effective HIV surveillance and prevention among MSM in China.

  1. Dynamical Epidemic Suppression Using Stochastic Prediction and Control

    Science.gov (United States)

    2004-10-28

    reduce the rate of input of susceptibles. By using the PDF flux, we are able to distinguish regions used in other chaos control schemes that are...use this information in a control algo- stochastic chaos control methods that account specifically for rithm to prevent bursting dynamics (that is, to

  2. Global dynamics behaviors for new delay SEIR epidemic disease model with vertical transmission and pulse vaccination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A robust SEIR epidemic disease model with a profitless delay and vertical transmission is formulated, and the dynamics behaviors of the model under pulse vaccination are analyzed.By use of the discrete dynamical system determined by the the model are under appropriate conditions.Using the theory on delay functional and impulsive differential equation, the sufficient condition with time delay for the permanence of the system is obtained, and it is proved that time delays, pulse vaccination and vertical transmission can bring obvious effects on the dynamics behaviors of the model.

  3. Dynamical behavior of a stochastic SVIR epidemic model with vaccination

    Science.gov (United States)

    Zhang, Xinhong; Jiang, Daqing; Hayat, Tasawar; Ahmad, Bashir

    2017-10-01

    In this paper, we investigate the dynamical behavior of SVIR models in random environments. Firstly, we show that if R0s model will die out exponentially; if R˜0s > 1, the disease will be prevail. Moreover, this system admits a unique stationary distribution and it is ergodic when R˜0s > 1. Results show that environmental white noise is helpful for disease control. Secondly, we give sufficient conditions for the existence of nontrivial periodic solutions to stochastic SVIR model with periodic parameters. Finally, numerical simulations validate the analytical results.

  4. Strong ties promote the epidemic prevalence in susceptible-infected-susceptible spreading dynamics

    CERN Document Server

    Cui, Ai-Xiang; Zhou, Tao

    2013-01-01

    Understanding spreading dynamics will benefit society as a whole in better preventing and controlling diseases, as well as facilitating the socially responsible information while depressing destructive rumors. In network-based spreading dynamics, edges with different weights may play far different roles: a friend from afar usually brings novel stories, and an intimate relationship is highly risky for a flu epidemic. In this article, we propose a weighted susceptible-infected-susceptible model on complex networks, where the weight of an edge is defined by the topological proximity of the two associated nodes. Each infected individual is allowed to select limited number of neighbors to contact, and a tunable parameter is introduced to control the preference to contact through high-weight or low-weight edges. Experimental results on six real networks show that the epidemic prevalence can be largely promoted when strong ties are favored in the spreading process. By comparing with two statistical null models respe...

  5. Global dynamics of a network-based SIQRS epidemic model with demographics and vaccination

    Science.gov (United States)

    Huang, Shouying; Chen, Fengde; Chen, Lijuan

    2017-02-01

    This paper investigates a new SIQRS epidemic model with demographics and vaccination on complex heterogeneous networks. We analytically derive the basic reproduction number R0, which determines not only the existence of endemic equilibrium but also the global dynamics of the model. The permanence of the disease and the globally asymptotical stability of disease-free equilibrium are proved in detail. By using a monotone iterative technique, we show that the unique endemic equilibrium is globally attractive under certain conditions. Our results really improve and enrich the results in Li et al (2014) [14]. Interestingly, the basic reproduction number R0 bears no relation to the degree-dependent birth, but our simulations indicate that the degree-dependent birth does affect the epidemic dynamics. Furthermore, we find that quarantine plays a more active role than vaccination in controlling the disease.

  6. HIV among African-born persons in the United States: a hidden epidemic?

    Science.gov (United States)

    Kerani, Roxanne P; Kent, James B; Sides, Tracy; Dennis, Greg; Ibrahim, Abdel R; Cross, Helene; Wiewel, Ellen W; Wood, Robert W; Golden, Matthew R

    2008-09-01

    Although a large proportion of HIV diagnoses in Western Europe occur in African-born persons, analyses of US HIV surveillance data do not routinely assess the proportion of diagnoses occurring in African-born US residents. To determine the percentage of newly reported HIV diagnoses occurring in African-born persons in selected areas of the United States with large African-born immigrant populations. We collated and analyzed aggregate data on persons diagnosed with HIV in 2003-2004 and reported to HIV surveillance units in the states of California, Georgia, Massachusetts, Minnesota, and New Jersey and in King County, Washington; New York City; and the portion of Virginia included in the Washington, DC, metropolitan area. African-born persons accounted for 0.6% of the population and 3.8% of HIV diagnoses in participating areas (HIV diagnoses range: 1%-20%). Across all areas, up to 41% of diagnoses in women (mean: 8.4%, range: 4%-41%) and up to 50% of diagnoses in blacks (mean: 8.0%, range: 2%-50%) occurred among African-born individuals. In some areas, classifying HIV cases among foreign-born blacks as occurring in African Americans dramatically alters the epidemiological picture of HIV. Country of birth should be consistently included in local and national analyses of HIV surveillance data.

  7. Higher-order structure and epidemic dynamics in clustered networks

    CERN Document Server

    Ritchie, Martin; House, Thomas; Kiss, Istvan Z

    2013-01-01

    Clustering is typically measured by the ratio of triangles to all triples, open or closed. Generating clustered networks, and how clustering affects dynamics on networks, is reasonably well understood for certain classes of networks \\cite{vmclust, karrerclust2010}, e.g., networks composed of lines and non-overlapping triangles. In this paper we show that it is possible to generate networks which, despite having the same degree distribution and equal clustering, exhibit different higher-order structure, specifically, overlapping triangles and other order-four (a closed network motif composed of four nodes) structures. To distinguish and quantify these additional structural features, we develop a new network metric capable of measuring order-four structure which, when used alongside traditional network metrics, allows us to more accurately describe a network's topology. Three network generation algorithms are considered: a modified configuration model and two rewiring algorithms. By generating homogeneous netwo...

  8. Dynamics of co-infection with M. Tuberculosis and HIV-1.

    Science.gov (United States)

    Kirschner, D

    1999-02-01

    Since 1985, there has been a renewed epidemic of tuberculosis (TB) that was previously thought to be in check. There is evidence to believe the main factor for this resurgence has been the human immunodeficiency virus (HIV). Co-infection with HIV and M. Tuberculosis has profound implications for the course of both diseases. This study represents a first attempt to understand how the introduction of an opportunistic infection, namely Mycobacterium tuberculosis, the bacteria that causes TB, affects the dynamic interaction of HIV-1 and the immune system. We create a mathematical model using ordinary differential equations to describe the interaction of HIV and TB with the immune system. It is known that infection with TB can decrease the CD4(+) T cell counts-a key marker of AIDS progression; thus, it shortens survival in HIV infected individuals. Another main marker for HIV progression is the viral load. If this load is increased due to the presence of opportunistic infections, the disease progression is much more rapid. We also explore the effects of drug treatment on the TB infection in the doubly-infected patient. Copyright 1999 Academic Press.

  9. Analysis on the Trends of HIV/AIDS Epidemic in Shenzhen

    Institute of Scientific and Technical Information of China (English)

    CHEN Lin(陈琳); FENG Tiejian(冯铁建); LI Liangcheng(李良成); HE Jianfan(何建凡)

    2002-01-01

    Objectives: To make a summary of the trends of HIV/AIDSepidemic and route of transmission in Shenzhen from 1992 to2000 to provide scientific evidence for the policy-maker toformulate strategies of HIV/AIDS prevention and control inShenzhen.Method: To analyze HIV/AIDS surveillance data inShenzhen from 1992 to 2000 by software Epi-Info.Results: One hundred and two HIV positive cases including18 AIDS cases (three cases deceased) were identified inShenzhen from 1992 to 2000. Among the 102 cases, thoseinfected via sex were 46.0%, intravenous drug use 42.9%.Blood donation 7.8%, blood transfusion recipient 3.9%, andindeterminate 2 %.Conclusion: In Shenzhen, HIV/AIDS infection is spreadingand increasing rapidly. Effective prevention measures must betaken to reduce the HIV prevalence as soon as possible.

  10. Is HIV/AIDS epidemic outcome of poverty in sub-saharan Africa?

    Science.gov (United States)

    Mbirimtengerenji, Noel Dzimnenani

    2007-10-01

    Undisputable fact is that 14000 people in Sub-Saharan Africa are being infected daily with HIV and 11000 are dying every day due to HIV/AIDS related illnesses. In this region more than 60% of the people live below UN poverty line of US$ 1 per day. Some studies have shown that poverty and HIV infection are in correlation, but none has shown whether HIV/AIDS in Sub-Saharan Africa is an outcome of poverty. This article, therefore, shows that HIV is an important outcome of poverty, with sexual trade, migration, polygamy, and teenage marriages as its predictors in the Sub Saharan region. I used the examples of 20 countries with the highest poverty level in the region to demonstrate the gravity of the HIV scourge, using the data from different international databases.

  11. Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence

    Directory of Open Access Journals (Sweden)

    Sawers Larry

    2010-09-01

    Full Text Available Abstract The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the region's high HIV prevalence is accepted by many as conventional wisdom. In this paper, we evaluate the quantitative and qualitative evidence offered by the principal proponents of the concurrency hypothesis and analyze the mathematical model they use to establish the plausibility of the hypothesis. We find that research seeking to establish a statistical correlation between concurrency and HIV prevalence either finds no correlation or has important limitations. Furthermore, in order to simulate rapid spread of HIV, mathematical models require unrealistic assumptions about frequency of sexual contact, gender symmetry, levels of concurrency, and per-act transmission rates. Moreover, quantitative evidence cited by proponents of the concurrency hypothesis is unconvincing since they exclude Demographic and Health Surveys and other data showing that concurrency in Africa is low, make broad statements about non-African concurrency based on very few surveys, report data incorrectly, report data from studies that have no information about concurrency as though they supported the hypothesis, report incomparable data and cite unpublished or unavailable studies. Qualitative evidence offered by proponents of the hypothesis is irrelevant since, among other reasons, there is no comparison of Africa with other regions. Promoters of the concurrency hypothesis have failed to establish that concurrency is unusually prevalent in Africa or that the kinds of concurrent partnerships found in Africa produce more rapid spread of HIV than other forms of sexual behaviour. Policy makers should turn attention to drivers of African HIV epidemics that are policy sensitive and for which there is substantial epidemiological evidence.

  12. Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence.

    Science.gov (United States)

    Sawers, Larry; Stillwaggon, Eileen

    2010-09-13

    The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the region's high HIV prevalence is accepted by many as conventional wisdom. In this paper, we evaluate the quantitative and qualitative evidence offered by the principal proponents of the concurrency hypothesis and analyze the mathematical model they use to establish the plausibility of the hypothesis.We find that research seeking to establish a statistical correlation between concurrency and HIV prevalence either finds no correlation or has important limitations. Furthermore, in order to simulate rapid spread of HIV, mathematical models require unrealistic assumptions about frequency of sexual contact, gender symmetry, levels of concurrency, and per-act transmission rates. Moreover, quantitative evidence cited by proponents of the concurrency hypothesis is unconvincing since they exclude Demographic and Health Surveys and other data showing that concurrency in Africa is low, make broad statements about non-African concurrency based on very few surveys, report data incorrectly, report data from studies that have no information about concurrency as though they supported the hypothesis, report incomparable data and cite unpublished or unavailable studies. Qualitative evidence offered by proponents of the hypothesis is irrelevant since, among other reasons, there is no comparison of Africa with other regions.Promoters of the concurrency hypothesis have failed to establish that concurrency is unusually prevalent in Africa or that the kinds of concurrent partnerships found in Africa produce more rapid spread of HIV than other forms of sexual behaviour. Policy makers should turn attention to drivers of African HIV epidemics that are policy sensitive and for which there is substantial epidemiological evidence.

  13. Assessing the HIV-1 Epidemic in Brazilian Drug Users: A Molecular Epidemiology Approach.

    Directory of Open Access Journals (Sweden)

    Monick Lindenmeyer Guimarães

    Full Text Available Person who inject illicit substances have an important role in HIV-1 blood and sexual transmission and together with person who uses heavy non-injecting drugs may have less than optimal adherence to anti-retroviral treatment and eventually could transmit resistant HIV variants. Unfortunately, molecular biology data on such key population remain fragmentary in most low and middle-income countries. The aim of the present study was to assess HIV infection rates, evaluate HIV-1 genetic diversity, drug resistance, and to identify HIV transmission clusters in heavy drug users (DUs. For this purpose, DUs were recruited in the context of a Respondent-Driven Sampling (RDS study in different Brazilian cities during 2009. Overall, 2,812 individuals were tested for HIV, and 168 (6% of them were positive, of which 19 (11.3% were classified as recent seroconverters, corresponding to an estimated incidence rate of 1.58%/year (95% CI 0.92-2.43%. Neighbor joining phylogenetic trees from env and pol regions and bootscan analyses were employed to subtype the virus from132 HIV-1-infected individuals. HIV-1 subtype B was prevalent in most of the cities under analysis, followed by BF recombinants (9%-35%. HIV-1 subtype C was the most prevalent in Curitiba (46% and Itajaí (86% and was also detected in Brasília (9% and Campo Grande (20%. Pure HIV-1F infections were detected in Rio de Janeiro (9%, Recife (6%, Salvador (6% and Brasília (9%. Clusters of HIV transmission were assessed by Maximum likelihood analyses and were cross-compared with the RDS network structure. Drug resistance mutations were verified in 12.2% of DUs. Our findings reinforce the importance of the permanent HIV-1 surveillance in distinct Brazilian cities due to viral resistance and increasing subtype heterogeneity all over Brazil, with relevant implications in terms of treatment monitoring, prophylaxis and vaccine development.

  14. Global Dynamics of Avian Influenza Epidemic Models with Psychological Effect

    Directory of Open Access Journals (Sweden)

    Sanhong Liu

    2015-01-01

    Full Text Available Cross-sectional surveys conducted in Thailand and China after the outbreaks of the avian influenza A H5N1 and H7N9 viruses show a high degree of awareness of human avian influenza in both urban and rural populations, a higher level of proper hygienic practice among urban residents, and in particular a dramatically reduced number of visits to live markets in urban population after the influenza A H7N9 outbreak in China in 2013. In this paper, taking into account the psychological effect toward avian influenza in the human population, a bird-to-human transmission model in which the avian population exhibits saturation effect is constructed. The dynamical behavior of the model is studied by using the basic reproduction number. The results demonstrate that the saturation effect within avian population and the psychological effect in human population cannot change the stability of equilibria but can affect the number of infected humans if the disease is prevalent. Numerical simulations are given to support the theoretical results and sensitivity analyses of the basic reproduction number in terms of model parameters that are performed to seek for effective control measures for avian influenza.

  15. Dispersion of the HIV-1 Epidemic in Men Who Have Sex with Men in the Netherlands: A Combined Mathematical Model and Phylogenetic Analysis

    NARCIS (Netherlands)

    Bezemer, D. (Daniela); A. Cori (Anne); Ratmann, O. (Oliver); A.I. van Sighem (Ard); Hermanides, H.S. (Hillegonda S.); B.E. Dutilh (Bas); L.A. Gras (Luuk); Rodrigues Faria, N. (Nuno); van den Hengel, R. (Rob); A.J. Duits (Ashley); P. Reiss (Peter); F. de Wolf (Frank); C. Fraser (Christophe); J.M. Prins (Jan); T.W. Kuijpers (Taco W.); H.J. Scherpbier; J.T.M. van der Meer (J. T M); F. Wit (Ferdinand); M.H. Godfried; P. Reiss; van der Poll, T.; F.J.B. Nellen (F. J B); S.E. Geerlings (Suzanne); M. Van Vugt; D. Pajkrt (Dasja); J.C. Bos (Jeannet); W.J. Wiersinga; M. van der Valk (Marc); A. Goorhuis (Abraham); J.W.R. Hovius (Joppe); J. Van Eden; A. Henderiks; A.M.H. Van Hes; M. Mutschelknauss; H.E. Nobel; F.J.J. Pijnappel; A.M. Westerman; S. Jurriaans (Suzanne); Back, N.K.T.; H.L. Zaaijer (Hans); B. Berkhout (Ben); M. Cornelissen (Marion); C.J. Schinkel; X.V. Thomas; M. Van Den Berge; A. Stegeman; S. Baas; Hage de Looff, L.; D. Versteeg; M.J.H. Pronk; H.S.M. Ammerlaan (Heidi); E.M.H.M. Korsten-Vorstermans; E.S. De Munnik; Jansz, A.R.; Tjhie, J.; M.C.A. Wegdam; Deiman, B.; V. Scharnhorst; A. van der Plas (A.); A.M. Weijsenfeld; M.E. van der Ende (Marchina); T.E.M.S. de Vriessluijs (Theodora); E.C.M. van Gorp (Eric); C.A.M. Schurink (Carolina); J.L. Nouwen (Jan); A. Verbon (Annelies); B.J.A. Rijnders (Bart); H.I. Bax (Hannelore); R.J. Hassing (Robert); M. van der Feltz; N. Bassant; J.E.A. Van Beek; M. Vriesde; L. van Zonneveld (Laura); A. De Oude-Lubbers; H.J. Van Den Berg-Cameron; F.B. Bruinsma-Broekman; J. De Groot; M. De Zeeuw-De Man; M. Schutten (Martin); A.D.M.E. Osterhaus (Albert); C.A. Boucher (Charles); G.J.A. Driessen (Gertjan); A.M.C. van Rossum (Annemarie); L. van der Knaap (Linda); E. Visser; J. Branger; C.J.H.M. Duijf-Van De Ven; E.F. Schippers (Emile F); C. van Nieuwkoop (C.); R.W. Brimicombe (R.); van IJperen, J.M.; G. Van Der Hut; P.F.H. Franck; A. van Eeden (A.); Brokking, W.; M. Groot; Elsenburg, L.J.M.; Damen, M.; I.S. Kwa; P.H.P. Groeneveld (Paul); J.W. Bouwhuis (Jolande); van den Berg, J.F.; A.G.W. Van Hulzen; van der Bliek, G.L.; P.C.J. Bor; P. Bloembergen; M.J.H.M. Wolfhagen; G. Ruijs (G.); F.P. Kroon; Arend, S.M.; M.G.J. de Boer (Mark); M.P. Bauer; A. Jolink (Albert); A. Vollaard (Albert); W. Dorama (Willemien); van Holten, N.; E.C.J. Claas (Eric); A.C.M. Kroes (Aloys C.M.); J.G. den Hollander (Jan); K. Pogány (Katalin); Kastelijns, M.; J.V. Smit; E. Smit; Bezemer, M.; T. Van Niekerk; O. Pontesilli (Oscar); S. Lowe (S.); A. Oude Lashof (A.); D. Posthouwer (Dirk); Ackens, R.P.; J. Schippers; R. Vergoossen; Weijenberg Maes, B.; Savelkoul, P.H.M.; I.H. Loo; Mulder, J.W.; B.C. Vrouenraets (Bart); Lauw, F.N.; van Broekhuizen, M.C.; H. Paap; D.J. Vlasblom; Oudmaijer Sanders, E.; P. Smits (Peter); A.W. Rosingh; Weijer, S.; R. El Moussaoui; Bosma, A.S.; B. Kortmann; G. van Twillert (Gitte); J.W.T. Cohen Stuart (James); B.M.W. Diederen (Bram); Pronk, D.; F.A. Van Truijen-Oud; van der Reijden, W.A.; R.J. Jansen (Roel); E.M.S. Leyten (Eliane M. S.); L.B.S. Gelinck (Luc); van Hartingsveld, A.; C. Meerkerk; G.S. Wildenbeest; Mutsaers, J.A.E.M.; C.L. Jansen; M.G.A. van Vonderen; D.P.F. Van Houte; Kampschreur, L.M.; Dijkstra, K.; S. Faber; Weel, J.; J.G. Kootstra (Jille); C.E. Delsing; van der Burg-van de Plas, M.; H. Heins; Lucas, E.; K. Brinkman; P.H.J. Frissen; W.L. Blok (Willem); W.E.M. Schouten; G.E.L. van den Berk (Guido); C.J. Brouwer; G.F. Geerders; K. Hoeksema; M.J. Kleene; I.B. Van Der Meché; A.J.M. Toonen; Wijnands, S.; van Ogtrop, M.L.; R. Jansen; P.P. Koopmans (Peter); M. Keuter (Monique); A.D. van Ven; ter Hofstede, H.J.M.; A.S.M. Dofferhoff; R. van Crevel (Reinout); Albers, M.; M.E.W. Bosch; K.J.T. Grintjes-Huisman; Zomer, B.J.; Stelma, F.F.; D.M. Burger (David); C. Richter (Clemens); J.P. van der Berg; E.H. Gisolf (Elisabeth); ter Beest, G.; P.H.M. Van Bentum; N. Langebeek (Nienke); Tiemessen, R.; Swanink, C.M.A.; Veenstra, J.; K.D. Lettinga; Spelbrink, M.; H. Sulman; Spelbrink, M.; E. Witte; Damen, M.; P.G. Peerbooms; S.F.L. van Lelyveld; R. Soetekouw (R.); Hulshoff, N.; L.M.M. Van Der Prijt; van der Swaluw, J.; Bermon, N.; W. van der Reijden (Wil); R. Jansen; Herpers, B.L.; D. Veenendaal (Dick); D.W.M. Verhagen (D. W M); Geilings, J.; M.E.E. van Kasteren (Marjo); A.E. Brouwer; de Kruijfvan de Wiel, B.A.F.M.; M. Kuipers; R.M.W.J. Santegoets (R. M W J); B. Van Der Ven; Marcelis, J.H.; A.G.M. Buiting (Anton); P.J. Kabel; W.F.W. Bierman; H.G. Sprenger (Herman); E.H. Schölvinck; S. van Assen; K.R. Wilting; Y. Stienstra; de Groot-de Jonge, H.; P.A. Van Der Meulen; D.A. De Weerd; Niesters, H.G.M.; A. Riezebos-Brilman (Annelies); C. Van Leer-Buter (Coretta); I.M. Hoepelman (Ilja Mohandas); M.M.E. Schneider (Margriet M.); T. Mudrikova (Tania Tania); P.M. Ellerbroek (P.); J.J. Oosterheert (Jan Jelrik); J.E. Arends (Joop); Barth, R.E.; M.W.M. Wassenberg; van Elst, D.H.M.; van Oers-Hazelzet-Laurijssen, E.E.B.; J. Patist; S.C.J.M. Vervoort (Sigrid C. J. M.); Nieuwenhuis, H.E.; R. Frauenfelder; R. Schuurman; F. Verduyn-Lunel; A. Wensing (Amj); E.J.G. Peters; M.A. Agtmael (Michiel); M. Bomers; J. De Vocht; Heitmuller, M.; L.M. Laan; Pettersson, A.M.; C.M.J.E. Vandenbroucke-Grauls (Christina); C.W. Ang (Wim); S. Geelen (S.); T.F.W. Wolfs (Tom); L.J. Bont; Nauta, N.; Winkel, C.; Durand, A.; F.A.J. Muskiet (Frits); Voigt, R.; van der Meer, I.; P. Reiss (Peter); D.O. Bezemer (Daniela); L. Gras; van Sighem, A.I.; C. Smit (Colette); Zaheri, S.; M.M.J. Hillebregt (Mariska); A. De Jong; D. Bergsma; P. Hoekstra; A. De Lang; M. Berkhout; S. Grivell; A. Jansen; M.J. Rademaker; M. Raethke; de Groot, L.; M. van den Akker (Marjan); Y. Bakker; M. Broekhoven; E. Claessen; El Berkaoui, A.; E. Kruijne; C. Lodewijk; R. Meijering; L. Munjishvili; B. Peeck; C. Ree; R. Regtop; Y. Ruijs; M. Schoorl; Schnörr, S.; E. Tuijn; L. Veenenberg; van der Vliet, S.; T. Woudstra; Tuk, B.

    2015-01-01

    textabstractBackground: The HIV-1 subtype B epidemic amongst men who have sex with men (MSM) is resurgent in many countries despite the widespread use of effective combination antiretroviral therapy (cART). In this combined mathematical and phylogenetic study of observational data, we aimed to find

  16. 2009-2011年深圳市HIV/AIDS疫情分析%Epidemic Analysis of HIV/AIDS from 2009 to 2011 in Shenzhen

    Institute of Scientific and Technical Information of China (English)

    谭唯; 陈琳; 谭京广; 孔东锋

    2013-01-01

    目的 了解深圳市2009-2011年艾滋病流行特点,为制定切实有效的预防和控制策略提供依据.方法 对深圳市2009-2011年艾滋病疫情资料进行流行病学分析.结果 2009-2011年深圳市累计报告HIV/AIDS病例2 982例,其中HIV感染者2 139例,AIDS病人843例.男女性别比为4.8∶1;年龄主要集中在20~岁组,占77.7%,平均年龄(32.9±0.6)岁;初中、高中或中专文化程度人群占68.9%;流动和暂住人口占86.5%;性传播为主要传播途径,占76.6%,其中同性性传播的占31.9%,且异性性接触传播和同性性接触传播的感染比重均逐年上升(P<0.01).结论 深圳市HIV/AIDS人群以流动和暂住人口占绝大多数,传播途径以性传播为主,且呈逐年上升趋势,同性性传播应给予关注.近期的控制策略为遏制经性途径传播的速度,预防二代传播,加强对男同性恋人群和流动人口的防治力度.%Objective To understand the characteristics of AIDS epidemic from 2009 to 2011 in Shenzhen and provide basis for HIV/AIDS prevention and control strategies. Method The epidemic data of HIV/AIDS from 2009 to 2011 ir Shenzhen were analyzed by epidemiological method. Results There were 2 982 HIV positive cases reported from 2009 tc 2011 in Shenzhen,in which 2 139 cases were HIV positive,843 cases were diagnosed as AIDS. The ratio of male tc female was 4.8:1,most of cases were people aged 20~39 years old (77.7% ), with an average age of (32.9±0.6)years. 68.9% of them had the education level on junior high school and senior high school.86.5% of them were floating population. The major route of transmission was sexual contact, accounting for 76.6% of all HIV positive cases, in which the same-sex transmission was 31.9% .In addition, the infection ratio caused by both heterosexual and homosexual transmission increased year by year (P<0.01). Conclusions Most of HIV cases were floating population in Shenzhen. The major route of transmission was

  17. Modelling HIV/AIDS Epidemic among Men Who Have Sex with Men in China

    Directory of Open Access Journals (Sweden)

    Xiaodan Sun

    2013-01-01

    a higher transmission rate and a lower diagnose rate among MSM than those for another high-risk population. We compared the current treatment policy and immediate therapy once people are diagnosed with HIV, and numerical studies indicated that immediate antiviral therapy would lead to few HIV new infections conditional upon relatively low infectiousness; otherwise the current treatment policy would result in low HIV new infection. Further, increasing treatment coverage rate may lead to decline in HIV new infections and be beneficial to disease control, depending on the infectiousness of the infected individuals with antiviral therapy. The finding suggested that treatment efficacy (directly affecting infectiousness, behavior changes, and interventions greatly affect HIV new infection; strengthening intensity will contribute to the disease control.

  18. HIV/AIDS epidemic features and trends in Iran, 1986-2006.

    Science.gov (United States)

    Fallahzadeh, H; Morowatisharifabad, M; Ehrampoosh, M H

    2009-04-01

    This study describes the reported HIV/AIDS data for all verified cases in Iran between 1986 and 2006. The cumulative number of the reported cases of HIV/AIDS among Iranians, up to the end of September 2006 was 13,702. Over the 20-year surveillance period, the rate of HIV/AIDS infections diagnosed annually among Iranian citizens gradually increased and, over the period 1997-2004, it reached from 1.38 to 4.6 cases per 100,000 populations per year. Our findings highlight the need for intensified HIV prevention efforts with men who use drugs via injection and strengthened efforts to encourage the individual at risk to get tested for HIV.

  19. The epidemic of HIV infection and AIDS, promotion of testing, and innovative strategies

    Directory of Open Access Journals (Sweden)

    Barbara Suligoi

    2010-03-01

    Full Text Available In Europe, the incidence of new diagnoses of HIV infection in 2008 was 86.7 cases per one million population, and most cases were attributable to sexual transmission. In Italy, in 2007, the incidence was 60.0 cases per one million population (in the areas in which surveillance exists, and 73.7% of the cases were attributable to sexual transmission. At present, there are an estimated 170 000-180 000 persons living with HIV/AIDS in Italy, some of whom are unaware of being infected. Based on available epidemiological data and taking into consideration the level of risk of exposure to HIV, we describe several proposals for promoting access to HIV testing in diverse population groups and contexts, including some innovative approaches. The promotion of HIV testing is fundamental for public health and human rights and must be associated with treatment, care and prevention activities, which must be guaranteed for the entire population.

  20. Stochastic lattice gas model describing the dynamics of the SIRS epidemic process

    Science.gov (United States)

    de Souza, David R.; Tomé, Tânia

    2010-03-01

    We study a stochastic process describing the onset of spreading dynamics of an epidemic in a population composed of individuals of three classes: susceptible (S), infected (I), and recovered (R). The stochastic process is defined by local rules and involves the following cyclic process: S → I → R → S (SIRS). The open process S → I → R (SIR) is studied as a particular case of the SIRS process. The epidemic process is analyzed at different levels of description: by a stochastic lattice gas model and by a birth and death process. By means of Monte Carlo simulations and dynamical mean-field approximations we show that the SIRS stochastic lattice gas model exhibit a line of critical points separating the two phases: an absorbing phase where the lattice is completely full of S individuals and an active phase where S, I and R individuals coexist, which may or may not present population cycles. The critical line, that corresponds to the onset of epidemic spreading, is shown to belong in the directed percolation universality class. By considering the birth and death process we analyze the role of noise in stabilizing the oscillations.

  1. Bursty communication patterns facilitate spreading in a threshold-based epidemic dynamics

    CERN Document Server

    Takaguchi, Taro; Holme, Petter

    2015-01-01

    Records of social interactions provide us with new sources of data for understanding how interaction patterns affect collective dynamics. Such human activity patterns are often bursty, i.e., they consist of short periods of intense activity followed by long periods of silence. This burstiness has been shown to affect spreading phenomena; it accelerates epidemic spreading in some cases and slows it down in other cases. We investigate a model of history-dependent contagion. In our model, repeated interactions between susceptible and infected individuals in a short period of time is needed for a susceptible individual to contract infection. We carry out numerical simulations on real temporal network data to find that bursty activity patterns facilitate epidemic spreading in our model.

  2. Bursty communication patterns facilitate spreading in a threshold-based epidemic dynamics.

    Directory of Open Access Journals (Sweden)

    Taro Takaguchi

    Full Text Available Records of social interactions provide us with new sources of data for understanding how interaction patterns affect collective dynamics. Such human activity patterns are often bursty, i.e., they consist of short periods of intense activity followed by long periods of silence. This burstiness has been shown to affect spreading phenomena; it accelerates epidemic spreading in some cases and slows it down in other cases. We investigate a model of history-dependent contagion. In our model, repeated interactions between susceptible and infected individuals in a short period of time is needed for a susceptible individual to contract infection. We carry out numerical simulations on real temporal network data to find that bursty activity patterns facilitate epidemic spreading in our model.

  3. Crystal methamphetamine, its analogues, and HIV infection: medical and psychiatric aspects of a new epidemic.

    Science.gov (United States)

    Urbina, Antonio; Jones, Kristina

    2004-03-15

    The use of the recreational drug crystal methamphetamine among younger homosexual men is expanding, and with it, unsafe sex behaviors that increase the transmission of human immunodeficiency virus (HIV). This article reviews available literature on the medical and psychiatric morbidities associated with methamphetamine abuse in HIV-infected patients. Medical complications include hypertension, hyperthermia, rhabdoymyolysis, and stroke. One fatal case of ingestion of methamphetamine with HIV medication has been documented. Two fatal cases of ingestion of HIV medication with the amphetamine analogue n-methyl-3,4 methylenedioxymethamphetamine (MDMA, or "ecstasy") have also been reported. Some molecular researchers suggest that dopaminergic systems are vulnerable to the combined neurotoxicity of HIV infection and methamphetamine. Population surveys indicate high rates of HIV infection among methamphetamine abusers and high rates of unprotected anal intercourse during drug intoxication. Intoxication can sometimes produce paranoia, auditory hallucinations, and, occasionally, violent behavior. Amphetamine withdrawal commonly results in symptoms of depression. Methamphetamine is a new challenge related to treatment and prevention of HIV infection.

  4. Religion, spirituality, and older adults with HIV: critical personal and social resources for an aging epidemic

    Directory of Open Access Journals (Sweden)

    Vance D

    2011-05-01

    Full Text Available David E Vance1, Mark Brennan2, Comfort Enah1, Glenda L Smith1, Jaspreet Kaur31School of Nursing, University of Alabama at Birmingham (UAB, Birmingham, AL, USA; 2New York University College of Nursing, AIDS Community Research Initiative of America, New York, NY, USA; 3Department of Psychology and Edward R. Roybal Center for Translational Research in Aging and Mobility, University of Alabama at Birmingham (UAB, Birmingham, AL, USAAbstract: By 2015, approximately half of adults with HIV in the United States will be 50 and older. The demographic changes in this population due to successful treatment represent a unique challenge, not only in assisting these individuals to cope with their illness, but also in helping them to age successfully with this disease. Religious involvement and spirituality have been observed to promote successful aging in the general population and help those with HIV cope with their disease, yet little is known about how these resources may affect aging with HIV. Also, inherent barriers such as HIV stigma and ageism may prevent people from benefitting from religious and spiritual sources of solace as they age with HIV. In this paper, we present a model of barriers to successful aging with HIV, along with a discussion of how spirituality and religiousness may help people overcome these barriers. From this synthesis, implications for practice and research to improve the quality of life of this aging population are provided.Keywords: HIV, aging, spirituality, religion, stigma, coping, successful aging

  5. Public health triangulation: approach and application to synthesizing data to understand national and local HIV epidemics.

    Science.gov (United States)

    Rutherford, George W; McFarland, William; Spindler, Hilary; White, Karen; Patel, Sadhna V; Aberle-Grasse, John; Sabin, Keith; Smith, Nathan; Taché, Stephanie; Calleja-Garcia, Jesus M; Stoneburner, Rand L

    2010-07-29

    Public health triangulation is a process for reviewing, synthesising and interpreting secondary data from multiple sources that bear on the same question to make public health decisions. It can be used to understand the dynamics of HIV transmission and to measure the impact of public health programs. While traditional intervention research and meta-analysis would be ideal sources of information for public health decision making, they are infrequently available, and often decisions can be based only on surveillance and survey data. The process involves examination of a wide variety of data sources and both biological, behavioral and program data and seeks input from stakeholders to formulate meaningful public health questions. Finally and most importantly, it uses the results to inform public health decision-making. There are 12 discrete steps in the triangulation process, which included identification and assessment of key questions, identification of data sources, refining questions, gathering data and reports, assessing the quality of those data and reports, formulating hypotheses to explain trends in the data, corroborating or refining working hypotheses, drawing conclusions, communicating results and recommendations and taking public health action. Triangulation can be limited by the quality of the original data, the potentials for ecological fallacy and "data dredging" and reproducibility of results. Nonetheless, we believe that public health triangulation allows for the interpretation of data sets that cannot be analyzed using meta-analysis and can be a helpful adjunct to surveillance, to formal public health intervention research and to monitoring and evaluation, which in turn lead to improved national strategic planning and resource allocation.

  6. Public health triangulation: approach and application to synthesizing data to understand national and local HIV epidemics

    Directory of Open Access Journals (Sweden)

    Aberle-Grasse John

    2010-07-01

    Full Text Available Abstract Background Public health triangulation is a process for reviewing, synthesising and interpreting secondary data from multiple sources that bear on the same question to make public health decisions. It can be used to understand the dynamics of HIV transmission and to measure the impact of public health programs. While traditional intervention research and metaanalysis would be ideal sources of information for public health decision making, they are infrequently available, and often decisions can be based only on surveillance and survey data. Methods The process involves examination of a wide variety of data sources and both biological, behavioral and program data and seeks input from stakeholders to formulate meaningful public health questions. Finally and most importantly, it uses the results to inform public health decision-making. There are 12 discrete steps in the triangulation process, which included identification and assessment of key questions, identification of data sources, refining questions, gathering data and reports, assessing the quality of those data and reports, formulating hypotheses to explain trends in the data, corroborating or refining working hypotheses, drawing conclusions, communicating results and recommendations and taking public health action. Results Triangulation can be limited by the quality of the original data, the potentials for ecological fallacy and "data dredging" and reproducibility of results. Conclusions Nonetheless, we believe that public health triangulation allows for the interpretation of data sets that cannot be analyzed using meta-analysis and can be a helpful adjunct to surveillance, to formal public health intervention research and to monitoring and evaluation, which in turn lead to improved national strategic planning and resource allocation.

  7. Investigating the interface between health system reform and HIV/AIDS in sub-Saharan Africa: an approach for improving the fight against the epidemic.

    Science.gov (United States)

    Dawes, Rasmus C

    2003-01-01

    During the period in which the HIV/AIDS epidemic has taken hold in sub-Saharan Africa, health system reforms have and continue to be introduced throughout the region. In spite of the multidisciplinary research undertaken, it can be questioned whether the relationships between processes of reform and some of the critical issues of HIV/AIDS response have been fully appreciated. This is particularly worrying since many countries in sub-Saharan Africa have already embarked on reform whilst concurrently and independently attempting to develop and manage effective responses to the overwhelming challenges posed by the HIV/AIDS epidemic. This paper explores the relationship between health system reform and HIV/AIDS, and argues that an interface approach is crucial for understanding the complexity of combating the epidemic whilst reforming health systems. The interface refers to the interacting processes between reform and the effects of the disease and attempts to respond to it. It includes the ways in which reforms, and such features as decentralisation and user fees, affect the capacity to fight HIV/AIDS, and conversely how the implications of the disease affect the performance of reformed health systems. Two sets of constraints in the interface are defined: internal and delivery constraints. The former are illustrated by deteriorating levels of human resources, poor integration of HIV/AIDS activities and problems faced by tiered health systems. The latter are illustrated by issues of access to relevant health services and rural-urban disparities. Issues in the interface need to be addressed by researchers and implementers in order to move forward in containing the epidemic.

  8. Profile of the HIV epidemic in Cape Verde: molecular epidemiology and drug resistance mutations among HIV-1 and HIV-2 infected patients from distinct islands of the archipelago.

    Science.gov (United States)

    de Pina-Araujo, Isabel Inês M; Guimarães, Monick L; Bello, Gonzalo; Vicente, Ana Carolina P; Morgado, Mariza G

    2014-01-01

    HIV-1 and HIV-2 have been detected in Cape Verde since 1987, but little is known regarding the genetic diversity of these viruses in this archipelago, located near the West African coast. In this study, we characterized the molecular epidemiology of HIV-1 and HIV-2 and described the occurrence of drug resistance mutations (DRM) among antiretroviral therapy naïve (ARTn) patients and patients under treatment (ARTexp) from different Cape Verde islands. Blood samples, socio-demographic and clinical-laboratory data were obtained from 221 HIV-positive individuals during 2010-2011. Phylogenetic and bootscan analyses of the pol region (1300 bp) were performed for viral subtyping. HIV-1 and HIV-2 DRM were evaluated for ARTn and ARTexp patients using the Stanford HIV Database and HIV-GRADE e.V. Algorithm Homepage, respectively. Among the 221 patients (169 [76.5%] HIV-1, 43 [19.5%] HIV-2 and 9 [4.1%] HIV-1/HIV-2 co-infections), 67% were female. The median ages were 34 (IQR = 1-75) and 47 (IQR = 12-84) for HIV-1 and HIV-2, respectively. HIV-1 infections were due to subtypes G (36.6%), CRF02_AG (30.6%), F1 (9.7%), URFs (10.4%), B (5.2%), CRF05_DF (3.0%), C (2.2%), CRF06_cpx (0.7%), CRF25_cpx (0.7%) and CRF49_cpx (0.7%), whereas all HIV-2 infections belonged to group A. Transmitted DRM (TDRM) was observed in 3.4% (2/58) of ARTn HIV-1-infected patients (1.7% NRTI, 1.7% NNRTI), but not among those with HIV-2. Among ARTexp patients, DRM was observed in 47.8% (33/69) of HIV-1 (37.7% NRTI, 37.7% NNRTI, 7.4% PI, 33.3% for two classes) and 17.6% (3/17) of HIV-2-infections (17.6% NRTI, 11.8% PI, 11.8% both). This study indicates that Cape Verde has a complex and unique HIV-1 molecular epidemiological scenario dominated by HIV-1 subtypes G, CRF02_AG and F1 and HIV-2 subtype A. The occurrence of TDRM and the relatively high level of DRM among treated patients are of concern. Continuous monitoring of patients on ART, including genotyping, are public policies to be implemented.

  9. Engineering behaviour change in an epidemic: the epistemology of NIH-funded HIV prevention science.

    Science.gov (United States)

    Green, Adam; Kolar, Kat

    2015-05-01

    Social scientific and public health literature on National Institutes of Health-funded HIV behavioural prevention science often assumes that this body of work has a strong biomedical epistemological orientation. We explore this assumption by conducting a systematic content analysis of all NIH-funded HIV behavioural prevention grants for men who have sex with men between 1989 and 2012. We find that while intervention research strongly favours a biomedical orientation, research into the antecedents of HIV risk practices favours a sociological, interpretive and structural orientation. Thus, with respect to NIH-funded HIV prevention science, there exists a major disjunct in the guiding epistemological orientations of how scientists understand HIV risk, on the one hand, and how they engineer behaviour change in behavioural interventions, on the other. Building on the extant literature, we suggest that the cause of this disjunct is probably attributable not to an NIH-wide positivist orientation, but to the specific standards of evidence used to adjudicate HIV intervention grant awards, including randomised controlled trials and other quantitative measures of intervention efficacy.

  10. Religion, spirituality, and older adults with HIV: critical personal and social resources for an aging epidemic.

    Science.gov (United States)

    Vance, David E; Brennan, Mark; Enah, Comfort; Smith, Glenda L; Kaur, Jaspreet

    2011-01-01

    By 2015, approximately half of adults with HIV in the United States will be 50 and older. The demographic changes in this population due to successful treatment represent a unique challenge, not only in assisting these individuals to cope with their illness, but also in helping them to age successfully with this disease. Religious involvement and spirituality have been observed to promote successful aging in the general population and help those with HIV cope with their disease, yet little is known about how these resources may affect aging with HIV. Also, inherent barriers such as HIV stigma and ageism may prevent people from benefitting from religious and spiritual sources of solace as they age with HIV. In this paper, we present a model of barriers to successful aging with HIV, along with a discussion of how spirituality and religiousness may help people overcome these barriers. From this synthesis, implications for practice and research to improve the quality of life of this aging population are provided.

  11. High GUD incidence in the early 20 century created a particularly permissive time window for the origin and initial spread of epidemic HIV strains.

    Directory of Open Access Journals (Sweden)

    João Dinis de Sousa

    Full Text Available The processes that permitted a few SIV strains to emerge epidemically as HIV groups remain elusive. Paradigmatic theories propose factors that may have facilitated adaptation to the human host (e.g., unsafe injections, none of which provide a coherent explanation for the timing, geographical origin, and scarcity of epidemic HIV strains. Our updated molecular clock analyses established relatively narrow time intervals (roughly 1880-1940 for major SIV transfers to humans. Factors that could favor HIV emergence in this time frame may have been genital ulcer disease (GUD, resulting in high HIV-1 transmissibility (4-43%, largely exceeding parenteral transmissibility; lack of male circumcision increasing male HIV infection risk; and gender-skewed city growth increasing sexual promiscuity. We surveyed colonial medical literature reporting incidences of GUD for the relevant regions, concentrating on cities, suffering less reporting biases than rural areas. Coinciding in time with the origin of the major HIV groups, colonial cities showed intense GUD outbreaks with incidences 1.5-2.5 orders of magnitude higher than in mid 20(th century. We surveyed ethnographic literature, and concluded that male circumcision frequencies were lower in early 20(th century than nowadays, with low rates correlating spatially with the emergence of HIV groups. We developed computer simulations to model the early spread of HIV-1 group M in Kinshasa before, during and after the estimated origin of the virus, using parameters derived from the colonial literature. These confirmed that the early 20(th century was particularly permissive for the emergence of HIV by heterosexual transmission. The strongest potential facilitating factor was high GUD levels. Remarkably, the direct effects of city population size and circumcision frequency seemed relatively small. Our results suggest that intense GUD in promiscuous urban communities was the main factor driving HIV emergence. Low

  12. Looking upstream to prevent HIV transmission: can interventions with sex workers alter the course of HIV epidemics in Africa as they did in Asia?

    NARCIS (Netherlands)

    Steen, R. van der; Hontelez, J.A.; Veraart, A.; White, R.G.; Vlas, S.J. de

    2014-01-01

    BACKGROUND: High rates of partner change in 'upstream' sex work networks have long been recognized to drive 'downstream' transmission of sexually transmitted infections (STIs). We used a stochastic microsimulation model (STDSIM) to explore such transmission dynamics in a generalized African HIV epid

  13. Agent-based financial dynamics model from stochastic interacting epidemic system and complexity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yunfan, E-mail: yunfanlu@yeah.net; Wang, Jun; Niu, Hongli

    2015-06-12

    An agent-based financial stock price model is developed and investigated by a stochastic interacting epidemic system, which is one of the statistical physics systems and has been used to model the spread of an epidemic or a forest fire. Numerical and statistical analysis are performed on the simulated returns of the proposed financial model. Complexity properties of the financial time series are explored by calculating the correlation dimension and using the modified multiscale entropy method. In order to verify the rationality of the financial model, the real stock market indexes, Shanghai Composite Index and Shenzhen Component Index, are studied in comparison with the simulation data of the proposed model for the different infectiousness parameters. The empirical research reveals that this financial model can reproduce some important features of the real stock markets. - Highlights: • A new agent-based financial price model is developed by stochastic interacting epidemic system. • The structure of the proposed model allows to simulate the financial dynamics. • Correlation dimension and MMSE are applied to complexity analysis of financial time series. • Empirical results show the rationality of the proposed financial model.

  14. Re-thinking global health sector efforts for HIV and tuberculosis epidemic control: promoting integration of programme activities within a strengthened health system

    Directory of Open Access Journals (Sweden)

    Maher Dermot

    2010-07-01

    Full Text Available Abstract Background The global financial crisis threatens global health, particularly exacerbating diseases of inequality, e.g. HIV/AIDS, and diseases of poverty, e.g. tuberculosis. The aim of this paper is to reconsider established practices and policies for HIV and tuberculosis epidemic control, aiming at delivering better results and value for money. This may be achieved by promoting greater integration of HIV and tuberculosis control programme activities within a strengthened health system. Discussion HIV and tuberculosis share many similarities in terms of their disease burden and the recommended stratagems for their control. HIV and tuberculosis programmes implement similar sorts of control activities, e.g. case finding and treatment, which depend for success on generic health system issues, including vital registration, drug procurement and supply, laboratory network, human resources, and financing. However, the current health system approach to HIV and tuberculosis control often involves separate specialised services. Despite some recent progress, collaboration between the programmes remains inadequate, progress in obtaining synergies has been slow, and results remain far below those needed to achieve universal access to key interventions. A fundamental re-think of the current strategic approach involves promoting integrated delivery of HIV and tuberculosis programme activities as part of strengthened general health services: epidemiological surveillance, programme monitoring and evaluation, community awareness of health-seeking behavior, risk behaviour modification, infection control, treatment scale-up (first-line treatment regimens, drug-resistance surveillance, containing and countering drug-resistance (second-line treatment regimens, research and development, global advocacy and global partnership. Health agencies should review policies and progress in HIV and tuberculosis epidemic control, learn mutual lessons for policy

  15. Reconstructing the Timing and Dispersion Routes of HIV-1 Subtype B Epidemics in The Caribbean and Central America: A Phylogenetic Story.

    OpenAIRE

    Israel Pagán; Africa Holguín

    2013-01-01

    The Caribbean and Central America are among the regions with highest HIV-1B prevalence worldwide. Despite of this high virus burden, little is known about the timing and the migration patterns of HIV-1B in these regions. Migration is one of the major processes shaping the genetic structure of virus populations. Thus, reconstruction of epidemiological network may contribute to understand HIV-1B evolution and reduce virus prevalence. We have investigated the spatio-temporal dynamics of the HIV-...

  16. HIV-1 subtype distribution and its demographic determinants in newly diagnosed patients in Europe suggest highly compartmentalized epidemics

    Directory of Open Access Journals (Sweden)

    Abecasis Ana B

    2013-01-01

    Full Text Available Abstract Background Understanding HIV-1 subtype distribution and epidemiology can assist preventive measures and clinical decisions. Sequence variation may affect antiviral drug resistance development, disease progression, evolutionary rates and transmission routes. Results We investigated the subtype distribution of HIV-1 in Europe and Israel in a representative sample of patients diagnosed between 2002 and 2005 and related it to the demographic data available. 2793 PRO-RT sequences were subtyped either with the REGA Subtyping tool or by a manual procedure that included phylogenetic tree and recombination analysis. The most prevalent subtypes/CRFs in our dataset were subtype B (66.1%, followed by sub-subtype A1 (6.9%, subtype C (6.8% and CRF02_AG (4.7%. Substantial differences in the proportion of new diagnoses with distinct subtypes were found between European countries: the lowest proportion of subtype B was found in Israel (27.9% and Portugal (39.2%, while the highest was observed in Poland (96.2% and Slovenia (93.6%. Other subtypes were significantly more diagnosed in immigrant populations. Subtype B was significantly more diagnosed in men than in women and in MSM > IDUs > heterosexuals. Furthermore, the subtype distribution according to continent of origin of the patients suggests they acquired their infection there or in Europe from compatriots. Conclusions The association of subtype with demographic parameters suggests highly compartmentalized epidemics, determined by social and behavioural characteristics of the patients.

  17. Threshold Dynamics in Stochastic SIRS Epidemic Models with Nonlinear Incidence and Vaccination.

    Science.gov (United States)

    Wang, Lei; Teng, Zhidong; Tang, Tingting; Li, Zhiming

    2017-01-01

    In this paper, the dynamical behaviors for a stochastic SIRS epidemic model with nonlinear incidence and vaccination are investigated. In the models, the disease transmission coefficient and the removal rates are all affected by noise. Some new basic properties of the models are found. Applying these properties, we establish a series of new threshold conditions on the stochastically exponential extinction, stochastic persistence, and permanence in the mean of the disease with probability one for the models. Furthermore, we obtain a sufficient condition on the existence of unique stationary distribution for the model. Finally, a series of numerical examples are introduced to illustrate our main theoretical results and some conjectures are further proposed.

  18. An SIRS Epidemic Model with Vital Dynamics and a Ratio-Dependent Saturation Incidence Rate

    Directory of Open Access Journals (Sweden)

    Xinli Wang

    2015-01-01

    Full Text Available This paper presents an investigation on the dynamics of an epidemic model with vital dynamics and a nonlinear incidence rate of saturated mass action as a function of the ratio of the number of the infectives to that of the susceptibles. The stabilities of the disease-free equilibrium and the endemic equilibrium are first studied. Under the assumption of nonexistence of periodic solution, the global dynamics of the model is established: either the number of infective individuals tends to zero as time evolves or it produces bistability in which there is a region such that the disease will persist if the initial position lies in the region and disappears if the initial position lies outside this region. Computer simulation shows such results.

  19. Evolution of Primary HIV Drug Resistance in a Subtype C Dominated Epidemic in Mozambique

    Science.gov (United States)

    Bila, Dulce Celina Adolfo; Young, Peter; Merks, Harriet; Vubil, Adolfo Salvador; Mahomed, Mussagy; Augusto, Angelo; Abreu, Celina Monteiro; Mabunda, Nédio Jonas; Brooks, James I.; Tanuri, Amilcar; Jani, Ilesh Vinodrai

    2013-01-01

    Objective In Mozambique, highly active antiretroviral treatment (HAART) was introduced in 2004 followed by decentralization and expansion, resulting in a more than 20-fold increase in coverage by 2009. Implementation of HIV drug resistance threshold surveys (HIVDR-TS) is crucial in order to monitor the emergence of transmitted viral resistance, and to produce evidence-based recommendations to support antiretroviral (ARV) policy in Mozambique. Methods World Health Organization (WHO) methodology was used to evaluate transmitted drug resistance (TDR) in newly diagnosed HIV-1 infected pregnant women attending ante-natal clinics in Maputo and Beira to non-nucleoside reverse transcriptase inhibitors (NNRTI), nucleoside reverse transcriptase inhibitors (NRTI) and protease inhibitors (PI). Subtypes were assigned using REGA HIV-1 subtyping tool and phylogenetic trees constructed using MEGA version 5. Results Although mutations associated with resistance to all three drug were detected in these surveys, transmitted resistance was analyzed and classified as Mozambique. PMID:23935858

  20. Controlling the HIV/AIDS epidemic: current status and global challenges

    Directory of Open Access Journals (Sweden)

    Thorsten eDemberg

    2012-08-01

    Full Text Available This review provides an overview of the current status of the global HIV pandemic and strategies to bring it under control. It updates numerous preventive approaches including behavioral interventions, male circumcision, pre- and post-exposure prophylaxis, vaccines, and microbicides. The manuscript summarizes current anti-retroviral treatment options, their impact in the western world, and difficulties faced by emerging and resource-limited nations in providing and maintaining appropriate treatment regimens. Current clinical and pre-clinical approaches towards a cure for HIV are described, including new drug compounds that target viral reservoirs and gene therapy approaches aimed at altering susceptibility to HIV infection. Recent progress in vaccine development is summarized, including novel approaches and new discoveries.

  1. Effect of the HIV epidemic on infant feeding in South Africa: "When they see me coming with the tins they laugh at me".

    Science.gov (United States)

    Doherty, Tanya; Chopra, Mickey; Nkonki, Lungiswa; Jackson, Debra; Greiner, Ted

    2006-01-01

    OBJECTIVE: To explore how the human immunodeficiency virus (HIV) epidemic has affected the infant-feeding experiences of HIV-positive mothers in South Africa. METHODS: This was a qualitative interview study within a prospective cohort study. We purposively selected a subsample of 40 women from a larger cohort of 650 HIV-positive mothers for in-depth interviews. FINDINGS: The HIV epidemic has changed the context in which infant-feeding choices are made and implemented. HIV-positive mothers in this study -- who were predominantly young, single and unemployed -- were struggling to protect their decision-making autonomy. Uncertainty about the safety of breastfeeding has increased the power and influence of health workers, who now act as gatekeepers to not only this new knowledge but also to essential resources such as formula milk. Fear of disclosure of HIV status and stigma has also weakened the ability of mothers to resist entrenched family and community norms that encourage early introduction of fluids and foods and that question non-breastfeeding. Women who chose to exclusively formula feed had difficulties accessing formula milk because of inflexible policies and a lack of supplies at clinics. Limited postpartum support led to social isolation and mothers doubting their ability to care for their children. CONCLUSION: The infant-feeding experiences of HIV-positive mothers have serious implications for the operational effectiveness of programmes that aim to prevent HIV transmission from mother to child. A better understanding of how HIV is changing infant-feeding practices can inform the development of interventions to improve infant-feeding counselling and postpartum support. PMID:16501725

  2. Highly divergent subtypes and new recombinant forms prevail in the HIV/AIDS epidemic in Angola: new insights into the origins of the AIDS pandemic.

    Science.gov (United States)

    Bártolo, Inês; Rocha, Cheila; Bartolomeu, José; Gama, António; Marcelino, Rute; Fonseca, Marlene; Mendes, Ana; Epalanga, Marta; Silva, Patrícia Cavaco; Taveira, Nuno

    2009-07-01

    Angola, located in South-Western Africa, has a remarkably low HIV/AIDS prevalence in the adult population (3.7%). It is bordered in the North by the Democratic Republic of Congo (DRC) and Republic of Congo that are at the origin of human HIV-1 infections. It is, therefore, likely that HIV-1 strains circulating in Angola are genetically diverse and representative of the origin of the HIV/AIDS epidemic. The aim of this work was to investigate in detail the genetic diversity and molecular epidemiology of HIV-1 in Angola. Almost 400 sequences were obtained from the gag (p17), pol (PR and RT) and/or env (C2C3) genes of 159 HIV-1 infected patients living in eight provinces of Angola (Benguela, Cabinda, Cuanza Norte, Luanda, Lunda Norte, Malange, Uíge, and Zaire) and their genotype was determined by phylogenetic analyses. Gene regions representing all HIV-1 group M clades were found as well as unclassifiable sequences. In env and pol (RT), two groups of sequences forming distinct sub-clusters within the subtype A radiation were found and may define new A5 and A6 sub-subtypes. Recombinant forms were found in almost half (47.1%) of the patients of which 36.0% were second-generation recombinants. Fifty-eight different patterns of recombination were found. The A subtype, including CRF02_AG, was represented in most recombinant viruses. Epidemiological data suggests that the AIDS epidemic in Angola has probably started as early as 1961, the major cause being the independence war, and spread to Portugal soon thereafter. The extraordinary degree of HIV-1 group M genetic diversity and evolution in Angola may pose unprecedented challenges to diagnostic, treatment and prevention of HIV-1 infection.

  3. HIV/AIDS counseling skills and strategies: Can testing and counseling curb the epidemic?

    Directory of Open Access Journals (Sweden)

    Amar Shireesh Kanekar

    2011-01-01

    Conclusions: Multiple approaches are used by counselors in providing education and prevention counseling to ′at risk′ individuals and also individuals who have been infected with the virus. No one method is superior to another and some gamut of techniques are practiced by HIV/AIDS counselors.

  4. Appraisal of the inherent socio-demographic dynamics of HIV/AIDS ...

    African Journals Online (AJOL)

    E. Agwu a agwuezera@yahoo.comagwuezera@gmail.com, V. Pazos a , J. C. Ihongbe b & J. Ssengendo c

    Most countries in the world have concentrated HIV-1 epidemics, in which .... logistic linear regression was used to test the strength of association between ..... methods for second-stage sampling in urban cluster surveys Emerging Themes.

  5. Optimal control of HIV/AIDS dynamic: Education and treatment

    Science.gov (United States)

    Sule, Amiru; Abdullah, Farah Aini

    2014-07-01

    A mathematical model which describes the transmission dynamics of HIV/AIDS is developed. The optimal control representing education and treatment for this model is explored. The existence of optimal Control is established analytically by the use of optimal control theory. Numerical simulations suggest that education and treatment for the infected has a positive impact on HIV/AIDS control.

  6. Stochastic simulation of HIV population dynamics through complex network modelling

    NARCIS (Netherlands)

    Sloot, P.M.A.; Ivanov, S.V.; Boukhanovsky, A.V.; van de Vijver, D.A.M.C.; Boucher, C.A.B.

    2008-01-01

    We propose a new way to model HIV infection spreading through the use of dynamic complex networks. The heterogeneous population of HIV exposure groups is described through a unique network degree probability distribution. The time evolution of the network nodes is modelled by a Markov process and

  7. Stochastic simulation of HIV population dynamics through complex network modelling

    NARCIS (Netherlands)

    Sloot, P. M. A.; Ivanov, S. V.; Boukhanovsky, A. V.; van de Vijver, D. A. M. C.; Boucher, C. A. B.

    We propose a new way to model HIV infection spreading through the use of dynamic complex networks. The heterogeneous population of HIV exposure groups is described through a unique network degree probability distribution. The time evolution of the network nodes is modelled by a Markov process and

  8. Dispersion of the HIV-1 Epidemic in Men Who Have Sex with Men in the Netherlands: A Combined Mathematical Model and Phylogenetic Analysis.

    Directory of Open Access Journals (Sweden)

    Daniela Bezemer

    2015-11-01

    Full Text Available The HIV-1 subtype B epidemic amongst men who have sex with men (MSM is resurgent in many countries despite the widespread use of effective combination antiretroviral therapy (cART. In this combined mathematical and phylogenetic study of observational data, we aimed to find out the extent to which the resurgent epidemic is the result of newly introduced strains or of growth of already circulating strains.As of November 2011, the ATHENA observational HIV cohort of all patients in care in the Netherlands since 1996 included HIV-1 subtype B polymerase sequences from 5,852 patients. Patients who were diagnosed between 1981 and 1995 were included in the cohort if they were still alive in 1996. The ten most similar sequences to each ATHENA sequence were selected from the Los Alamos HIV Sequence Database, and a phylogenetic tree was created of a total of 8,320 sequences. Large transmission clusters that included ≥10 ATHENA sequences were selected, with a local support value ≥ 0.9 and median pairwise patristic distance below the fifth percentile of distances in the whole tree. Time-varying reproduction numbers of the large MSM-majority clusters were estimated through mathematical modeling. We identified 106 large transmission clusters, including 3,061 (52% ATHENA and 652 Los Alamos sequences. Half of the HIV sequences from MSM registered in the cohort in the Netherlands (2,128 of 4,288 were included in 91 large MSM-majority clusters. Strikingly, at least 54 (59% of these 91 MSM-majority clusters were already circulating before 1996, when cART was introduced, and have persisted to the present. Overall, 1,226 (35% of the 3,460 diagnoses among MSM since 1996 were found in these 54 long-standing clusters. The reproduction numbers of all large MSM-majority clusters were around the epidemic threshold value of one over the whole study period. A tendency towards higher numbers was visible in recent years, especially in the more recently introduced clusters

  9. Are HIV Epidemics among Men Who Have Sex with Men Emerging in the Middle East and North Africa?: A Systematic Review and Data Synthesis

    Science.gov (United States)

    Mumtaz, Ghina; Hilmi, Nahla; McFarland, Willi; Kaplan, Rachel L.; Akala, Francisca Ayodeji; Semini, Iris; Riedner, Gabriele; Tawil, Oussama; Wilson, David; Abu-Raddad, Laith J.

    2011-01-01

    Background Men who have sex with men (MSM) bear a disproportionately higher burden of HIV infection than the general population. MSM in the Middle East and North Africa (MENA) are a largely hidden population because of a prevailing stigma towards this type of sexual behavior, thereby limiting the ability to assess infection transmission patterns among them. It is widely perceived that data are virtually nonexistent on MSM and HIV in this region. The objective of this review was to delineate, for the first time, the evidence on the epidemiology of HIV among MSM in MENA. Methods and Findings This was a systematic review of all biological, behavioral, and other related data on HIV and MSM in MENA. Sources of data included PubMed (Medline), international organizations' reports and databases, country-level reports and databases including governmental and nongovernmental organization publications, and various other institutional documents. This review showed that onsiderable data are available on MSM and HIV in MENA. While HIV prevalence continues at low levels among different MSM groups, HIV epidemics appear to be emerging in at least few countries, with a prevalence reaching up to 28% among certain MSM groups. By 2008, the contribution of MSM transmission to the total HIV notified cases increased and exceeded 25% in several countries. The high levels of risk behavior (4–14 partners on average in the last six months among different MSM populations) and of biomarkers of risks (such as herpes simplex virus type 2 at 3%–54%), the overall low rate of consistent condom use (generally below 25%), the relative frequency of male sex work (20%–76%), and the substantial overlap with heterosexual risk behavior and injecting drug use suggest potential for further spread. Conclusions This systematic review and data synthesis indicate that HIV epidemics appear to be emerging among MSM in at least a few MENA countries and could already be in a concentrated state among several

  10. Are HIV epidemics among men who have sex with men emerging in the Middle East and North Africa?: a systematic review and data synthesis.

    Directory of Open Access Journals (Sweden)

    Ghina Mumtaz

    2010-08-01

    Full Text Available BACKGROUND: Men who have sex with men (MSM bear a disproportionately higher burden of HIV infection than the general population. MSM in the Middle East and North Africa (MENA are a largely hidden population because of a prevailing stigma towards this type of sexual behavior, thereby limiting the ability to assess infection transmission patterns among them. It is widely perceived that data are virtually nonexistent on MSM and HIV in this region. The objective of this review was to delineate, for the first time, the evidence on the epidemiology of HIV among MSM in MENA. METHODS AND FINDINGS: This was a systematic review of all biological, behavioral, and other related data on HIV and MSM in MENA. Sources of data included PubMed (Medline, international organizations' reports and databases, country-level reports and databases including governmental and nongovernmental organization publications, and various other institutional documents. This review showed that onsiderable data are available on MSM and HIV in MENA. While HIV prevalence continues at low levels among different MSM groups, HIV epidemics appear to be emerging in at least few countries, with a prevalence reaching up to 28% among certain MSM groups. By 2008, the contribution of MSM transmission to the total HIV notified cases increased and exceeded 25% in several countries. The high levels of risk behavior (4-14 partners on average in the last six months among different MSM populations and of biomarkers of risks (such as herpes simplex virus type 2 at 3%-54%, the overall low rate of consistent condom use (generally below 25%, the relative frequency of male sex work (20%-76%, and the substantial overlap with heterosexual risk behavior and injecting drug use suggest potential for further spread. CONCLUSIONS: This systematic review and data synthesis indicate that HIV epidemics appear to be emerging among MSM in at least a few MENA countries and could already be in a concentrated state among

  11. Spatial and temporal dynamics of superspreading events in the 2014–2015 West Africa Ebola epidemic

    Science.gov (United States)

    Lau, Max S. Y.; Dalziel, Benjamin Douglas; Funk, Sebastian; McClelland, Amanda; Tiffany, Amanda; Riley, Steven; Metcalf, C. Jessica E.; Grenfell, Bryan T.

    2017-01-01

    The unprecedented scale of the Ebola outbreak in Western Africa (2014–2015) has prompted an explosion of efforts to understand the transmission dynamics of the virus and to analyze the performance of possible containment strategies. Models have focused primarily on the reproductive numbers of the disease that represent the average number of secondary infections produced by a random infectious individual. However, these population-level estimates may conflate important systematic variation in the number of cases generated by infected individuals, particularly found in spatially localized transmission and superspreading events. Although superspreading features prominently in first-hand narratives of Ebola transmission, its dynamics have not been systematically characterized, hindering refinements of future epidemic predictions and explorations of targeted interventions. We used Bayesian model inference to integrate individual-level spatial information with other epidemiological data of community-based (undetected within clinical-care systems) cases and to explicitly infer distribution of the cases generated by each infected individual. Our results show that superspreaders play a key role in sustaining onward transmission of the epidemic, and they are responsible for a significant proportion (∼61%) of the infections. Our results also suggest age as a key demographic predictor for superspreading. We also show that community-based cases may have progressed more rapidly than those notified within clinical-care systems, and most transmission events occurred in a relatively short distance (with median value of 2.51 km). Our results stress the importance of characterizing superspreading of Ebola, enhance our current understanding of its spatiotemporal dynamics, and highlight the potential importance of targeted control measures. PMID:28193880

  12. Deciphering Dynamics of Recent Epidemic Spread and Outbreak in West Africa: The Case of Ebola Virus

    Science.gov (United States)

    Upadhyay, Ranjit Kumar; Roy, Parimita

    Recently, the 2014 Ebola virus (EBOV) outbreak in West Africa was the largest outbreak to date. In this paper, an attempt has been made for modeling the virus dynamics using an SEIR model to better understand and characterize the transmission trajectories of the Ebola outbreak. We compare the simulated results with the most recent reported data of Ebola infected cases in the three most affected countries Guinea, Liberia and Sierra Leone. The epidemic model exhibits two equilibria, namely, the disease-free and unique endemic equilibria. Existence and local stability of these equilibria are explored. Using central manifold theory, it is established that the transcritical bifurcation occurs when basic reproduction number passes through unity. The proposed Ebola epidemic model provides an estimate to the potential number of future cases. The model indicates that the disease will decline after peaking if multisectorial and multinational efforts to control the spread of infection are maintained. Possible implication of the results for disease eradication and its control are discussed which suggests that proper control strategies like: (i) transmission precautions, (ii) isolation and care of infectious Ebola patients, (iii) safe burial, (iv) contact tracing with follow-up and quarantine, and (v) early diagnosis are needed to stop the recurrent outbreak.

  13. HIV/Aids epidemic trend in Liwan%荔湾区HIV/AIDS流行趋势

    Institute of Scientific and Technical Information of China (English)

    张瑞丹

    2005-01-01

    目的:通过对荔湾区历年报告病例的流行趋势分析,为制定HIV/AIDS防制措施提供科学依据.方法:通过疫情报告网收集自1997年到2004年居住在本区、经艾滋病病毒抗体确认的报告病例.结果:截止2004年,全区HIV/AIDS总报告病例数203例,历年居全市的报告病例排位第一位,总死亡数52例,死亡数是HIV/AIDS报告病例的25.62%,其中HIV感染者173例,死亡35例,死亡数占报告数20.231%,艾滋病病人30人,死亡18例,病死率60%.性别比:男性170例,女性33例,男:女为5.15:1,女性病例每年持续增加.年龄分布以20-40年龄段为主,占总报告病例数的93.59%,最小年龄为1天,最大年龄为73岁.13个行政街其中12个行政街有病例报告,全区病例报告覆盖率为92.31%.人群特征:吸毒180例,性19例,母婴传播3例,不明原因1例.结论:病例以青壮年为主,母婴传播已出现,性传播的病例不容忽视,同性恋病例开始报告,男女报告病例的比例正在缩小,今后的预防方向由吸毒为主的重点人群向一般人群转移.

  14. Threshold Dynamics in Stochastic SIRS Epidemic Models with Nonlinear Incidence and Vaccination

    Science.gov (United States)

    Wang, Lei; Tang, Tingting

    2017-01-01

    In this paper, the dynamical behaviors for a stochastic SIRS epidemic model with nonlinear incidence and vaccination are investigated. In the models, the disease transmission coefficient and the removal rates are all affected by noise. Some new basic properties of the models are found. Applying these properties, we establish a series of new threshold conditions on the stochastically exponential extinction, stochastic persistence, and permanence in the mean of the disease with probability one for the models. Furthermore, we obtain a sufficient condition on the existence of unique stationary distribution for the model. Finally, a series of numerical examples are introduced to illustrate our main theoretical results and some conjectures are further proposed. PMID:28194223

  15. Nonlinear multi-analysis of agent-based financial market dynamics by epidemic system

    Science.gov (United States)

    Lu, Yunfan; Wang, Jun; Niu, Hongli

    2015-10-01

    Based on the epidemic dynamical system, we construct a new agent-based financial time series model. In order to check and testify its rationality, we compare the statistical properties of the time series model with the real stock market indices, Shanghai Stock Exchange Composite Index and Shenzhen Stock Exchange Component Index. For analyzing the statistical properties, we combine the multi-parameter analysis with the tail distribution analysis, the modified rescaled range analysis, and the multifractal detrended fluctuation analysis. For a better perspective, the three-dimensional diagrams are used to present the analysis results. The empirical research in this paper indicates that the long-range dependence property and the multifractal phenomenon exist in the real returns and the proposed model. Therefore, the new agent-based financial model can recurrence some important features of real stock markets.

  16. Nonlinear multi-analysis of agent-based financial market dynamics by epidemic system.

    Science.gov (United States)

    Lu, Yunfan; Wang, Jun; Niu, Hongli

    2015-10-01

    Based on the epidemic dynamical system, we construct a new agent-based financial time series model. In order to check and testify its rationality, we compare the statistical properties of the time series model with the real stock market indices, Shanghai Stock Exchange Composite Index and Shenzhen Stock Exchange Component Index. For analyzing the statistical properties, we combine the multi-parameter analysis with the tail distribution analysis, the modified rescaled range analysis, and the multifractal detrended fluctuation analysis. For a better perspective, the three-dimensional diagrams are used to present the analysis results. The empirical research in this paper indicates that the long-range dependence property and the multifractal phenomenon exist in the real returns and the proposed model. Therefore, the new agent-based financial model can recurrence some important features of real stock markets.

  17. Transmission Dynamics and Final Epidemic Size of Ebola Virus Disease Outbreaks with Varying Interventions.

    Science.gov (United States)

    Barbarossa, Maria Vittoria; Dénes, Attila; Kiss, Gábor; Nakata, Yukihiko; Röst, Gergely; Vizi, Zsolt

    2015-01-01

    The 2014 Ebola Virus Disease (EVD) outbreak in West Africa was the largest and longest ever reported since the first identification of this disease. We propose a compartmental model for EVD dynamics, including virus transmission in the community, at hospitals, and at funerals. Using time-dependent parameters, we incorporate the increasing intensity of intervention efforts. Fitting the system to the early phase of the 2014 West Africa Ebola outbreak, we estimate the basic reproduction number as 1.44. We derive a final size relation which allows us to forecast the total number of cases during the outbreak when effective interventions are in place. Our model predictions show that, as long as cases are reported in any country, intervention strategies cannot be dismissed. Since the main driver in the current slowdown of the epidemic is not the depletion of susceptibles, future waves of infection might be possible, if control measures or population behavior are relaxed.

  18. [Decentralization of the HIV/AIDS epidemic and inter-municipal flow of hospital admissions in the Zona da Mata, Minas Gerais State, Brazil: a spatial analysis].

    Science.gov (United States)

    Reis, Cláudia Tartaglia; Czeresnia, Dina; Barcellos, Christovam; Tassinari, Wagner Souza

    2008-06-01

    The aim of this article was to analyze the decentralization of the HIV/AIDS epidemic (a shift towards rural areas or away from the coast) and to investigate access to HIV/AIDS services from 1988 to 2002 in the Zona da Mata, Minas Gerais State, Brazil. An ecological study was performed using temporal and spatial approaches. A hospital admissions flow between municipalities developed, and the reference group was AIDS patients over 15 years of age admitted in 1996 and 2004, residing in municipalities in the Zona da Mata. There were 2,469 reported AIDS cases in individuals over 15 during the period. Mean incidence and mortality rates were calculated and recalculated by a local empirical Bayesian method in order to more clearly represent the municipalities with the highest concentration of cases and deaths. Decentralization of the epidemic was observed. Juiz de Fora was the municipality with the most cases and may have acted as a hub for spread of HIV in the region. Hospital care for AIDS cases in the Zona da Mata was concentrated in that municipality. There is a strong need to further investigate why referral hospitals in other municipalities in the region have not participated in providing management and care for HIV/AIDS patients.

  19. The HIV Protein gp120 Alters Mitochondrial Dynamics in Neurons

    Science.gov (United States)

    Castellano, Paul; Dedoni, Simona; Palchik, Guillermo; Trejo, Margarita; Adame, Anthony; Rockenstein, Edward; Eugenin, Eliseo; Masliah, Eliezer; Mocchetti, Italo

    2016-01-01

    Neurotoxicity of human immunodeficiency virus-1 (HIV) includes synaptic simplification and neuronal apoptosis. However, the mechanisms of HIV-associated neurotoxicity remain unclear, thus precluding an effective treatment of the neurological complications. The present study was undertaken to characterize novel mechanisms of HIV neurotoxicity that may explain how HIV subjects develop neuronal degeneration. Several neurodegenerative disorders are characterized by mitochondrial dysfunction; therefore, we hypothesized that HIV promotes mitochondrial damage. We first analyzed brains from HIV encephalitis (HIVE) by electron microscopy. Several sections of HIVE subjects contained enlarged and damaged mitochondria compared to brains from HIV subjects with no neurological complications. Similar pathologies were observed in mice overexpressing the HIV protein gp120, suggesting that this viral protein may be responsible for mitochondrial pathology found in HIVE. To gain more information about the cellular mechanisms of gp120 neurotoxicity, we exposed rat cortical neurons to gp120 and we determined cellular oxygen consumption rate, mitochondrial distribution, and trafficking. Our data show that gp120 evokes impairment in mitochondrial function and distribution. These data suggest that one of the mechanisms of HIV neurotoxicity includes altered mitochondrial dynamics in neurons. PMID:26936603

  20. Multi-Sector Participation In The National Response To Prevent And Address The Hiv/Aids Epidemic In The Republic Of Cuba, 2007-2008

    Directory of Open Access Journals (Sweden)

    Isora Ramos Valle

    2010-12-01

    Full Text Available The development of a strong national response involving multiple sectors—including civil society—is an essential aspect of the social management of the HIV/AIDS epidemic. The goals of this response are to control the epidemic and improve the quality of life for people living with HIV/AIDS; this includes combating stigma and discrimination, as well as ensuring due compliance with the law. Cuba has a national program to prevent and control HIV/AIDS. Since 2003 Cuba’s national program has received material and financial support from the Global Fund to Fight AIDS, Tuberculosis and Malaria. Program evaluation is carried out by an independent team at ENSAP (National School of Public Health. This paper reports on results of one part of that evaluation: an assessment of the agencies and sectors who made up the organized social and national response to the HIV/AIDS epidemic. The evaluation primarily used qualitative analyses of the activities and tasks proposed by sectors in their 2006-2008 work plans. Visits were made to the provinces of Ciudad de la Habana, Matanzas, and Holguín. Qualitative techniques included in-depth interviews, semi-structured interviews, observation, and review of documentary evidence of all kinds (videos, reports, minutes, protocols, results of social research, and radio broadcast messages and varied depending on the particular features of each sector. We noted improvements in multi-sector participation in the prevention and response to the national HIV/AIDS epidemic. Conscious of their role, sectors generally carried out their programmed activities and had improved their organization, planning, and systematization; integration among the sectors was also better. These local initiatives provided evidence of a multi-sector response characterized by autonomy, emotional involvement, and an identification with the goals of the project; this went beyond simply meeting targets. Cross-sector work showed a marked increase and a

  1. Dynamic communicability and epidemic spread: a case study on an empirical dynamic contact network

    CERN Document Server

    Chen, Isabel; Chang, Howard H; Hertzberg, Vicki S

    2016-01-01

    We analyze a recently proposed temporal centrality measure applied to an empirical network based on person-to-person contacts in an emergency department of a busy urban hospital. We show that temporal centrality identifies a distinct set of top-spreaders than centrality based on the time-aggregated binarized contact matrix, so that taken together, the accuracy of capturing top-spreaders improves significantly. However, with respect to predicting epidemic outcome, the temporal measure does not necessarily outperform less complex measures. Our results also show that other temporal markers such as duration observed and the time of first appearance in the the network can be used in a simple predictive model to generate predictions that capture the trend of the observed data remarkably well.

  2. Increased HIV incidence in men who have sex with men despite high levels of ART-induced viral suppression: analysis of an extensively documented epidemic.

    Directory of Open Access Journals (Sweden)

    Andrew N Phillips

    Full Text Available BACKGROUND: There is interest in expanding ART to prevent HIV transmission, but in the group with the highest levels of ART use, men-who-have-sex-with-men (MSM, numbers of new infections diagnosed each year have not decreased as ARTcoverage has increased for reasons which remain unclear. METHODS: We analysed data on the HIV-epidemic in MSM in the UK from a range of sources using an individual-based simulation model. Model runs using parameter sets found to result in good model fit were used to infer changes in HIV-incidence and risk behaviour. RESULTS: HIV-incidence has increased (estimated mean incidence 0.30/100 person-years 1990-1997, 0.45/100 py 1998-2010, associated with a modest (26% rise in condomless sex. We also explored counter-factual scenarios: had ART not been introduced, but the rise in condomless sex had still occurred, then incidence 2006-2010 was 68% higher; a policy of ART initiation in all diagnosed with HIV from 2001 resulted in 32% lower incidence; had levels of HIV testing been higher (68% tested/year instead of 25% incidence was 25% lower; a combination of higher testing and ART at diagnosis resulted in 62% lower incidence; cessation of all condom use in 2000 resulted in a 424% increase in incidence. In 2010, we estimate that undiagnosed men, the majority in primary infection, accounted for 82% of new infections. CONCLUSION: A rise in HIV-incidence has occurred in MSM in the UK despite an only modest increase in levels of condomless sex and high coverage of ART. ART has almost certainly exerted a limiting effect on incidence. Much higher rates of HIV testing combined with initiation of ART at diagnosis would be likely to lead to substantial reductions in HIV incidence. Increased condom use should be promoted to avoid the erosion of the benefits of ART and to prevent other serious sexually transmitted infections.

  3. Look into the HIV Epidemic of Gay Community with a Socio-Cultural Perspective: A Qualitative Study in China, 2015-2016

    Science.gov (United States)

    He, Huijing; Lv, Fan; Zhang, Nanci Nanyi; Wu, Zunyou; Liao, Qinghua; Chang, Zhanjun; Li, Yi; Xu, Huifang; OuYang, Lin; Huan, Xiping; Yang, Juan

    2017-01-01

    Background Current Chinese studies continue to view male homosexuality through a disease focused lens which pays limited attention to socio-cultural aspects of sexual behavior and HIV transmission. This qualitative study aimed to investigate how socio-cultural factors influence gay men’s sexual beliefs and behaviors in contemporary China, and their implications for HIV epidemic. Methods and Findings Qualitative methodology was used in this study. During 2015–2016, in-depth interviews were conducted with 61 self identified gay men in Jiangxi, Henan, Heilongjiang, Guangdong, Jiangsu provinces and Chongqing municipality of China. Our study revealed that: 1) influenced by Chinese traditional culture, gay men have conflicts on self-identity, which led to low self-acceptance and negative attitude on sex, and huge socio-psychological stress; 2) a generational differences within gay community was observed, reflected in varied sexual attitudes and practices as well as way for approaching new friends, both of which have implications and challenges on HIV control and prevention; 3) socio-cultural barriers, including open minds towards casual sex and nonmonogamous relationship, and low priority of health demands were widely observed and led to negative coping with AIDS among gay community. Conclusions It is essential to take a holistic view into gay men’s HIV epidemic in China. Socio-cultural barriers for HIV control and prevention found in this study call for serious and imperative consideration on integrated measures, including targeted efforts towards effective sex education and further inclusion of socio-cultural perspectives in HIV/AIDS interventions for gay men. PMID:28107523

  4. Solution of deterministic-stochastic epidemic models by dynamical Monte Carlo method

    Science.gov (United States)

    Aièllo, O. E.; Haas, V. J.; daSilva, M. A. A.; Caliri, A.

    2000-07-01

    This work is concerned with dynamical Monte Carlo (MC) method and its application to models originally formulated in a continuous-deterministic approach. Specifically, a susceptible-infected-removed-susceptible (SIRS) model is used in order to analyze aspects of the dynamical MC algorithm and achieve its applications in epidemic contexts. We first examine two known approaches to the dynamical interpretation of the MC method and follow with the application of one of them in the SIRS model. The working method chosen is based on the Poisson process where hierarchy of events, properly calculated waiting time between events, and independence of the events simulated, are the basic requirements. To verify the consistence of the method, some preliminary MC results are compared against exact steady-state solutions and other general numerical results (provided by Runge-Kutta method): good agreement is found. Finally, a space-dependent extension of the SIRS model is introduced and treated by MC. The results are interpreted under and in accordance with aspects of the herd-immunity concept.

  5. Impact of time delay on the dynamics of SEIR epidemic model using cellular automata

    Science.gov (United States)

    Sharma, Natasha; Gupta, Arvind Kumar

    2017-04-01

    The delay of an infectious disease is significant when aiming to predict its strength and spreading patterns. In this paper the SEIR ​(susceptible-exposed-infected-recovered) epidemic spread with time delay is analyzed through a two-dimensional cellular automata model. The time delay corresponding to the infectious span, predominantly, includes death during the latency period in due course of infection. The advancement of whole system is described by SEIR transition function complemented with crucial factors like inhomogeneous population distribution, birth and disease independent mortality. Moreover, to reflect more realistic population dynamics some stochastic parameters like population movement and connections at local level are also considered. The existence and stability of disease free equilibrium is investigated. Two prime behavioral patterns of disease dynamics is found depending on delay. The critical value of delay, beyond which there are notable variations in spread patterns, is computed. The influence of important parameters affecting the disease dynamics on basic reproduction number is also examined. The results obtained show that delay plays an affirmative role to control disease progression in an infected host.

  6. Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting.

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    Clement N Mweya

    Full Text Available Rift Valley Fever (RVF is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics.Time-varying distributed delays (TVDD and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district.Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.

  7. Can male circumcision have an impact on the HIV epidemic in men who have sex with men?

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    Steven M Goodreau

    Full Text Available Three trials have demonstrated the prophylactic effect of male circumcision (MC for HIV acquisition among heterosexuals, and MC interventions are underway throughout sub-Saharan Africa. Similar efforts for men who have sex with men (MSM are stymied by the potential for circumcised MSM to acquire HIV easily through receptive sex and transmit easily through insertive sex. Existing work suggests that MC for MSM should reach its maximum potential in settings where sexual role segregation is historically high and relatively stable across the lifecourse; HIV incidence among MSM is high; reported willingness for prophylactic circumcision is high; and pre-existing circumcision rates are low. We aim to identify the likely public health impact that MC interventions among MSM would have in one setting that fulfills these conditions-Peru-as a theoretical upper bound for their effectiveness among MSM generally.We use a dynamic, stochastic sexual network model based in exponential-family random graph modeling and parameterized from multiple behavioral surveys of Peruvian MSM. We consider three enrollment criteria (insertive during 100%, >80% or >60% of UAI and two levels of uptake (25% and 50% of eligible men; we explore sexual role proportions from two studies and different frequencies of switching among role categories. Each scenario is simulated 10 times. We estimate that efficiency could reach one case averted per 6 circumcisions. However, the population-level impact of an optimistic MSM-MC intervention in this setting would likely be at most ∼5-10% incidence and prevalence reductions over 25 years.Roll-out of MC for MSM in Peru would not result in a substantial reduction in new HIV infections, despite characteristics in this population that could maximize such effects. Additional studies are needed to confirm these results for other MSM populations, and providers may consider the individual health benefits of offering MC to their MSM patients.

  8. Corporate social responsibility in public health: A case-study on HIV/AIDS epidemic by Johnson & Johnson company in Africa.

    Science.gov (United States)

    Chattu, Vijay Kumar

    2015-01-01

    HIV/AIDS has claimed millions of lives in the global workforce and continues to remain a threat to many businesses. An estimated 36.5 million of working people are living with HIV; the global workforce has lost 28 million people from AIDS since the beginning of the epidemic. In the absence of access to treatment, this number could grow to 74 million by 2015. The epidemic continues to affect the working population through absenteeism, sickness and death. Corporate Social Responsibility (CSR) is an obligation that corporates have toward their employees, community and society. A review and documentation of one such CSR by Johnson & Johnson (a multinational company) for HIV/AIDS in Africa is presented here. Johnson & Johnson Company is involved in numerous projects around the world to combat the HIV/AIDS epidemic. The company is working to fight the spread of the disease and improve the quality of life for those living with the illness through various donations of its products and sponsorship of local programs. This case study also highlights different categories of CSR activities such as Cause Promotion, Cause related Marketing, Corporate Philanthropy, Corporate Social Marketing, Corporate Volunteering and Socially responsible business practices, which are discussed with specific examples from different countries in Africa. CSR of any business encompasses the economic, legal, ethical & discretionary expectation placed on the organization by society at a given point of time. CSR is therefore the obligation that corporations have toward their stakeholders and society in general which horizons beyond what is prescribed by law or union contracts. Johnson & Johnson has a proved history of being committed to caring for people and a good example of a company with a long history of citizenship and sustainability.

  9. Estimation and Short-Term Prediction of the Course of the HIV Epidemic Using Demographic and Health Survey Methodology-Like Data.

    Directory of Open Access Journals (Sweden)

    Stéphanie Blaizot

    Full Text Available Mathematical models have played important roles in the understanding of epidemics and in the study of the impacts of various behavioral or medical measures. However, modeling accurately the future spread of an epidemic requires context-specific parameters that are difficult to estimate because of lack of data. Our objective is to propose a methodology to estimate context-specific parameters using Demographic and Health Survey (DHS-like data that can be used in mathematical modeling of short-term HIV spreading.The model splits the population according to sex, age, HIV status, and antiretroviral treatment status. To estimate context-specific parameters, we used individuals' histories included in DHS-like data and a statistical analysis that used decomposition of the Poisson likelihood. To predict the course of the HIV epidemic, sex- and age-specific differential equations were used. This approach was applied to recent data from Kenya. The approach allowed the estimation of several key epidemiological parameters. Women had a higher infection rate than men and the highest infection rate in the youngest age groups (15-24 and 25-34 years whereas men had the highest infection rate in age group 25-34 years. The immunosuppression rates were similar between age groups. The treatment rate was the highest in age group 35-59 years in both sexes. The results showed that, within the 15-24 year age group, increasing male circumcision coverage and antiretroviral therapy coverage at CD4 ≤ 350/mm3 over the current 70% could have short-term impacts.The study succeeded in estimating the model parameters using DHS-like data rather than literature data. The analysis provides a framework for using the same data for estimation and prediction, which can improve the validity of context-specific predictions and help designing HIV prevention campaigns.

  10. Distribution and dynamics of epidemic and pandemic Vibrio parahaemolyticus virulence factors

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    Daniela eCeccarelli

    2013-12-01

    Full Text Available Vibrio parahaemolyticus, autochthonous to estuarine, marine, and coastal environments throughout the world, is the causative agent of food-borne gastroenteritis. More than 80 serotypes have been described worldwide, based on antigenic properties of the somatic (O and capsular (K antigens. Serovar O3:K6 emerged in India in 1996 and subsequently was isolated worldwide, leading to the conclusion that the first V. parahaemolyticus pandemic had taken place. Most strains of V. parahaemolyticus isolated from the environment or seafood, in contrast to clinical strains, do not produce a thermostable direct hemolysin (TDH and/or a TDH-related hemolysin (TRH. Type 3 secretion systems (T3SSs, needle-like apparatuses able to deliver bacterial effectors into host cytoplasm, were identified as triggering cytotoxicity and enterotoxicity. Type 6 secretion systems (T6SS predicted to be involved in intracellular trafficking and vesicular transport appear to play a role in V. parahaemolyticus virulence. Recent advances in V. parahaemolyticus genomics identified several pathogenicity islands (VpaIs located on either chromosome in both epidemic and pandemic strains and comprising additional colonization factors, such as restriction-modification complexes, chemotaxis proteins, classical bacterial surface virulence factors, and putative colicins. Furthermore, studies indicate strains lacking toxins and genomic regions associated with pathogenicity may also be pathogenic, suggesting other important virulence factors remain to be identified. The unique repertoire of virulence factors identified to date, their occurrence and distribution in both epidemic and pandemic strains worldwide are described, with the aim of highlighting the complexity of V. parahaemolyticus pathogenicity as well as its dynamic genome.

  11. The epidemiology of HIV infection in Morocco: systematic review and data synthesis

    Science.gov (United States)

    Kouyoumjian, S P; Mumtaz, G R; Hilmi, N; Zidouh, A; El Rhilani, H; Alami, K; Bennani, A; Gouws, E; Ghys, P D; Abu-Raddad, L J

    2013-01-01

    Summary Morocco has made significant strides in building its HIV research capacity. Based on a wealth of empirical data, the objective of this study was to conduct a comprehensive and systematic literature review and analytical synthesis of HIV epidemiological evidence in this country. Data were retrieved using three major sources of literature and data. HIV transmission dynamics were found to be focused in high-risk populations, with female sex workers (FSWs) and clients contributing the largest share of new HIV infections. There is a pattern of emerging epidemics among some high-risk populations, and some epidemics, particularly among FSWs, appear to be established and stable. The scale of the local HIV epidemics and populations affected show highly heterogeneous geographical distribution. To optimize the national HIV response, surveillance and prevention efforts need to be expanded among high-risk populations and in geographic settings where low intensity and possibly concentrated HIV epidemics are emerging or are already endemic. PMID:23970764

  12. Dominance of HIV-1 subtype CRF01_AE in sexually acquired cases leads to a new epidemic in Yunnan province of China.

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    Yong Zhang

    2006-11-01

    Full Text Available BACKGROUND: Dating back to the first epidemic among injection drug users in 1989, the Yunnan province has had the highest number of human immunodeficiency virus type 1 (HIV-1 infections in China. However, the molecular epidemiology of HIV-1 in Yunnan has not been fully characterized. METHODS AND FINDINGS: Using immunoassays, we identified 103,015 accumulated cases of HIV-1 infections in Yunnan between 1989 and 2004. We studied 321 patients representing Yunnan's 16 prefectures from four risk groups, 11 ethnic populations, and ten occupations. We identified three major circulating subtypes: C/CRF07_BC/CRF08_BC (53%, CRF01_AE (40.5%, and B (6.5% by analyzing the sequence of p17, which is part of the gag gene. For patients with known risk factors, 90.9% of injection drug users had C/CRF07_BC/CRF08_BC viruses, whereas 85.4% of CRF01_AE infections were acquired through sexual transmission. No distinct segregation of CRF01_AE viruses was found among the Dai ethnic group. Geographically, C/CRF07_BC/CRF08_BC was found throughout the province, while CRF01_AE was largely confined to the prefectures bordering Myanmar. Furthermore, C/CRF07_BC/CRF08_BC viruses were found to consist of a group of viruses, including C, CRF08_BC, CRF07_BC, and new BC recombinants, based on the characterization of their reverse transcriptase genes. CONCLUSIONS: This is the first report of a province-wide HIV-1 molecular epidemiological study in Yunnan. While C/CRF07_BC/CRF08_BC and CRF01_AE are codominant, the discovery of many sexually transmitted CRF01_AE cases is new and suggests that this subtype may lead to a new epidemic in the general Chinese population. We discuss implications of our results for understanding the evolution of the HIV-1 pandemic and for vaccine development.

  13. Concerns and Recommendations of Internal Medicine Residents in HIV Patient Care in the Second Decade of the AIDS Epidemic in Taiwan

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    Ping-Chuan Hsiung

    2004-10-01

    Full Text Available Internal medicine residents are usually on the front line of caring for HIV-infected patients. In the second decade of the AIDS epidemic in Taiwan, a qualitative study was conducted to recognize the concerns of internal medicine residents in caring for HIV/AIDS patients and to identify possible strategies to promote HIV patient care that have not been addressed in previous research. Individual in-depth interviews were conducted with 47 internal medicine residents at a university hospital in Taiwan. Seven factors (stereotypes of AIDS; fear of transmission; concerns of families, friends, and colleagues; lack of clinical expertise; lack of collegial support; lack of a sense of accomplishment; and lack of worker's compensation if infected were found to be the chief concerns of participants in providing HIV/AIDS care. Four strategies (education, clinical experience, safe working environment, and employee benefits were voiced as those that could promote health care professionals' well-being and willingness to provide HIV/AIDS care. The results of this study are explained in light of the historical, social, and medical contexts in Taiwan.

  14. Proportion of long-term injection drug users as an indicator to characterize the state and prognosis of HIV-epidemic within a certain territory

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    Andreeva, Tatiana

    2012-07-01

    Full Text Available BACKGROUND: Epidemics of drug use and thus the spread of HIV have different duration in different regions, and, therefore, the prognosis of these epidemics may differ. We aimed to assess indicators measuring the peculiarities of injection drug use epidemics by region, informative for prevention activities among vulnerable to HIV groups. METHODS: Data from cross-sectional survey of 4026 injection drug users (IDUs conducted in 2007 in Ukraine were analyzed. The outcome measure was a binary variable depicting whether a respondent injects drugs for 20 years and over. Binary Logistic Regression in SPSS software was used to test associations with socio-demographic characteristics. RESULTS: More respondents from Odessa, Mykolayiv, Dnipropetrovsk, Cherkassy, Poltava, and Crimea regions inject over 20 years. Older respondents were more likely to belong to the group of long-term users. Men were more likely to inject over 20 years than women. Those respondents who were married, but did not live with their spouse or other sexual partner were more likely to inject longer than 20 years compared to those single or in a stable marriage. Those respondents who use opiates or combine them with stimulants were more likely to inject over 20 years and those who use only stimulants were more likely to inject less than 20 years. CONCLUSION: Injection drug use in Ukraine started earlier among men, on certain territories and was associated with opiate use. Percentage of IDUs who inject for more than 20 years was found to be a good indicator to distinguish territories with long-lasting epidemics.

  15. Effects of behavioral response and vaccination policy on epidemic spreading - an approach based on evolutionary-game dynamics

    Science.gov (United States)

    Zhang, Hai-Feng; Wu, Zhi-Xi; Tang, Ming; Lai, Ying-Cheng

    2014-07-01

    How effective are governmental incentives to achieve widespread vaccination coverage so as to prevent epidemic outbreak? The answer largely depends on the complex interplay among the type of incentive, individual behavioral responses, and the intrinsic epidemic dynamics. By incorporating evolutionary games into epidemic dynamics, we investigate the effects of two types of incentives strategies: partial-subsidy policy in which certain fraction of the cost of vaccination is offset, and free-subsidy policy in which donees are randomly selected and vaccinated at no cost. Through mean-field analysis and computations, we find that, under the partial-subsidy policy, the vaccination coverage depends monotonically on the sensitivity of individuals to payoff difference, but the dependence is non-monotonous for the free-subsidy policy. Due to the role models of the donees for relatively irrational individuals and the unchanged strategies of the donees for rational individuals, the free-subsidy policy can in general lead to higher vaccination coverage. Our findings indicate that any disease-control policy should be exercised with extreme care: its success depends on the complex interplay among the intrinsic mathematical rules of epidemic spreading, governmental policies, and behavioral responses of individuals.

  16. Utilization of dental health care services in context of the HIV epidemic- a cross-sectional study of dental patients in the Sudan

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    Åstrøm Anne

    2009-11-01

    Full Text Available Abstract Background HIV infected patients should be expected in the Sudanese dental health care services with an increasing frequency. Dental care utilization in the context of the HIV epidemic is generally poorly understood. Focusing on Sudanese dental patients with reported unknown HIV status, this study assessed the extent to which Andersen's model in terms of predisposing (socio-demographics, enabling (knowledge, attitudes and perceived risk related to HIV and need related factors (oral health status predict dental care utilization. It was hypothesized that enabling factors would add to the explanation of dental care utilization beyond that of predisposing and need related factors. Methods Dental patients were recruited from Khartoum Dental Teaching Hospital (KDTH and University of Science and Technology (UST during March-July 2008. A total of 1262 patients (mean age 30.7, 56.5% females and 61% from KDTH were examined clinically (DMFT and participated in an interview. Results A total of 53.9% confirmed having attended a dental clinic for treatment at least once in the past 2 years. Logistic regression analysis revealed that predisposing factors; travelling inside Sudan (OR = 0.5 were associated with lower odds and females were associated with higher odds (OR = 2.0 for dental service utilization. Enabling factors; higher knowledge of HIV transmission (OR = 0.6 and higher HIV related experience (OR = 0.7 were associated with lower odds, whereas positive attitudes towards infected people and high perceived risk of contagion (OR = 1.3 were associated with higher odds for dental care utilization. Among need related factors dental caries experience was strongly associated with dental care utilization (OR = 4.8. Conclusion Disparity in the history of dental care utilization goes beyond socio-demographic position and need for dental care. Public awareness of HIV infection control and confidence on the competence of dentists should be improved to

  17. The effect of HIV, behavioural change, and STD syndromic management on STD epidemiology in sub-Saharan Africa: simulations of Uganda

    NARCIS (Netherlands)

    E.L. Korenromp (Eline); R. Bakker (Roel); R. Gray; M.J. Wawer; D. Serwadda; J.D.F. Habbema (Dik)

    2002-01-01

    textabstractAn assessment was made of how the HIV epidemic may have influenced sexually transmitted disease (STD) epidemiology in Uganda, and how HIV would affect the effectiveness of syndromic STD treatment programmes during different stages of the epidemic. The dynamic

  18. The effect of HIV, behavioural change, and STD syndromic management on STD epidemiology in sub-Saharan Africa: simulations of Uganda

    NARCIS (Netherlands)

    E.L. Korenromp (Eline); R. Bakker (Roel); R. Gray; M.J. Wawer; D. Serwadda; J.D.F. Habbema (Dik)

    2002-01-01

    textabstractAn assessment was made of how the HIV epidemic may have influenced sexually transmitted disease (STD) epidemiology in Uganda, and how HIV would affect the effectiveness of syndromic STD treatment programmes during different stages of the epidemic. The dynamic transmissi

  19. The effect of HIV, behavioural change, and STD syndromic management on STD epidemiology in sub-Saharan Africa: simulations of Uganda

    NARCIS (Netherlands)

    E.L. Korenromp (Eline); R. Bakker (Roel); R. Gray; M.J. Wawer; D. Serwadda; J.D.F. Habbema (Dik)

    2002-01-01

    textabstractAn assessment was made of how the HIV epidemic may have influenced sexually transmitted disease (STD) epidemiology in Uganda, and how HIV would affect the effectiveness of syndromic STD treatment programmes during different stages of the epidemic. The dynamic transmissi

  20. Analysis of Infectious-Recovery Epidemic Models for Membership Dynamics of Online Social Networks

    CERN Document Server

    Cooney, Daniel; Bar-Yam, Yaneer

    2016-01-01

    The recent rapid growth of social media and online social networks (OSNs) has raised interesting questions about the spread of ideas and fads within our society. In the past year, several papers have drawn analogies between the rise and fall in popularity of OSNs and mathematical models used to study infectious disease. One such model, the irSIR model, made use of the idea of "infectious recovery" to outperform the traditional SIR model in replicating the rise and fall of MySpace and to predict a rapid drop in the popularity of Facebook. Here we explore the irSIR model and two of its logical extensions and we mathematically characterize the initial and long-run behavior of these dynamical systems. In particular, while the original irSIR model always predicts extinction of a social epidemic, we construct an extension of the model that matches the exponential growth phase of the irSIR model while allowing for the possibility of an arbitrary proportion of infections in the long run.

  1. Evolutionary dynamics of recent peste des petits ruminants virus epidemic in China during 2013-2014.

    Science.gov (United States)

    Bao, Jingyue; Wang, Qinghua; Li, Lin; Liu, Chunju; Zhang, Zhicheng; Li, Jinming; Wang, Shujuan; Wu, Xiaodong; Wang, Zhiliang

    2017-10-01

    Peste des petits ruminants virus (PPRV) causes a highly contagious disease, peste des petits ruminants (PPR), in sheep and goats which has been considered as a serious threat to the local economy in Africa and Asia. However, the in-depth evolutionary dynamics of PPRV during an epidemic is not well understood. We conducted phylogenetic analysis on genomic sequences of 25 PPRV strains from China 2013-2014 outbreaks. All these strains clustered into a novel clade in lineage 4. An evolutionary rate of 2.61 × 10(-6) nucleotide substitutions per site per day was estimated, dating the most recent common ancestor of PPRV China 2013-2014 strains to early August 2013. Transmission network analysis revealed that all the virus sequences could be grouped into five clusters of infection, suggesting long-distance animal transmission play an important role in the spread of PPRV in China. These results expanded our knowledge for PPRV evolution to achieve effective control measures. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. HIV/AIDS epidemic in Nanshan District in Shenzhen from 1998 to 2012%深圳市南山区1998-2012年HIV/AIDS流行情况分析

    Institute of Scientific and Technical Information of China (English)

    严燚; 姜世强; 温群文

    2013-01-01

    Objective To investigate the surveillance and epidemic trends of HIV/AIDS in Nanshan District,Shenzheng,Guangdong Province during the last 15 years,and analyze the epidemic factors,so as to provide evidences for developing measures for HIV/AIDS prevention and control.Methods Descriptive epidemiological method was used to analyze the surveillance data and the investigation data of HIV/AIDS in Nanshan District,Shenzhen,from 1998 to 2012.Results The number of reported HIV/AIDS patients was rising rapidly.There were 750 reported HIV/AIDS patients from 1998 to 2012,among whom those aged 20-40 and the immigrant population accounted for the major proportion.Sexual contact (74.80%) was the major route of transmission in the District,with the increasing proportion of homosexual transmission (38.27%).HIV/AIDS patients could get integrated management and free antiviral treatment.The mortality rate of HIV/AIDS patients decreased from 18.78% to 3.35% after free antiviral treatment.Conclusions The number of patients infected through sexual contact has been increasing in recent years,and the epidemic spreads in general population as well as in high-risk population.More and more newly found HIV-infected individuals have entered symptomatic phase.The number of older male HIV/AIDS patients and men who have sex with men is rising rapidly.Therefore,efforts should be made to enhance HIV/AIDS education,prevention and control,and improve self-protection consciousness.%目的 了解15年来深圳市南山区HIV/AIDS监测和流行情况的变化趋势,分析流行因素,为今后防控措施的制定提供理论依据.方法 采用描述性流行病学研究方法分析深圳市南山区1998-2012年HIV/AIDS监测资料和调查资料.结果 病例报告数呈快速增长趋势,累计报告750例HIV/AIDS患者,其中20~40岁占多数,以外地流动人口为主;性传播是区内目前最主要的感染途径,占全部病例的74.80%,男男同性传播感染比例为38.27%.HIV

  3. Molecular typing of the recently expanding subtype B HIV-1 epidemic in Romania: evidence for local spread among MSMs in Bucharest area.

    Science.gov (United States)

    Paraschiv, Simona; Otelea, Dan; Batan, Ionelia; Baicus, Cristian; Magiorkinis, Gkikas; Paraskevis, Dimitrios

    2012-07-01

    HIV-1 subtype B is predominant in Europe except in some countries from Eastern Europe which are characterized by a high prevalence of non-B subtypes and circulating recombinant forms (CRFs). Romania is a particular case: the HIV-1 epidemic started with subtype F1 which is still the most prevalent. Previous studies have shown an increasing prevalence of subtype B which is the second most frequent one among the newly diagnosed individuals, followed by subtype C and several CRFs as well as unique recombinant forms (URFs). Our objective was to analyze in detail the characteristics (way of dispersal, association with transmission risk groups) of the subtype B infections in Romania by means of phylogenetic analysis. Among all the individuals sampled during 2003-2010, 71 out of 1127 patients (6.3%) have been identified to be infected with subtype B strains. The most frequent route of infection identified in HIV-1 subtype B patients in Romania was MSM transmission (39.6%), followed by the heterosexual route (35.2%). Many of the patients acquired the infection abroad, mainly in Western European countries. Phylogenetic analysis indicated the existence of a local transmission network (monophyletic clade) including 14 patients, mainly MSM living in the Bucharest area. We estimate the origin of the local transmission network that dates at the beginning of the 90s; the introduction of the F1 and C subtypes occurred earlier. The rest of the sequences were intermixed with reference strains sampled across Europe suggesting that single infection were not followed by subsequent dispersal within the local population. Although HIV-1 subtype B epidemic in Romania is recent, there is evidence for local spread among the MSMs, in addition to multiple introductions.

  4. Molecular typing of the recently expanding subtype B HIV-1 epidemic in Romania: Evidence for local spread among MSMs in Bucharest area☆☆☆

    Science.gov (United States)

    Paraschiv, Simona; Otelea, Dan; Batan, Ionelia; Baicus, Cristian; Magiorkinis, Gkikas; Paraskevis, Dimitrios

    2012-01-01

    HIV-1 subtype B is predominant in Europe except in some countries from Eastern Europe which are characterized by a high prevalence of non-B subtypes and circulating recombinant forms (CRFs). Romania is a particular case: the HIV-1 epidemic started with subtype F1 which is still the most prevalent. Previous studies have shown an increasing prevalence of subtype B which is the second most frequent one among the newly diagnosed individuals, followed by subtype C and several CRFs as well as unique recombinant forms (URFs). Our objective was to analyze in detail the characteristics (way of dispersal, association with transmission risk groups) of the subtype B infections in Romania by means of phylogenetic analysis. Among all the individuals sampled during 2003–2010, 71 out of 1127 patients (6.3%) have been identified to be infected with subtype B strains. The most frequent route of infection identified in HIV-1 subtype B patients in Romania was MSM transmission (39.6%), followed by the heterosexual route (35.2%). Many of the patients acquired the infection abroad, mainly in Western European countries. Phylogenetic analysis indicated the existence of a local transmission network (monophyletic clade) including 14 patients, mainly MSM living in the Bucharest area. We estimate the origin of the local transmission network that dates at the beginning of the 90s; the introduction of the F1 and C subtypes occurred earlier. The rest of the sequences were intermixed with reference strains sampled across Europe suggesting that single infection were not followed by subsequent dispersal within the local population. Although HIV-1 subtype B epidemic in Romania is recent, there is evidence for local spread among the MSMs, in addition to multiple introductions. PMID:22430050

  5. Daphnia parasite dynamics across multiple Caullerya epidemics indicate selection against common parasite genotypes.

    Science.gov (United States)

    González-Tortuero, Enrique; Rusek, Jakub; Turko, Patrick; Petrusek, Adam; Maayan, Inbar; Piálek, Lubomír; Tellenbach, Christoph; Gießler, Sabine; Spaak, Piet; Wolinska, Justyna

    2016-08-01

    Studies of parasite population dynamics in natural systems are crucial for our understanding of host-parasite coevolutionary processes. Some field studies have reported that host genotype frequencies in natural populations change over time according to parasite-driven negative frequency-dependent selection. However, the temporal patterns of parasite genotypes have rarely been investigated. Moreover, parasite-driven negative frequency-dependent selection is contingent on the existence of genetic specificity between hosts and parasites. In the present study, the population dynamics and host-genotype specificity of the ichthyosporean Caullerya mesnili, a common endoparasite of Daphnia water fleas, were analysed based on the observed sequence variation in the first internal transcribed spacer (ITS1) of the ribosomal DNA. The Daphnia population of lake Greifensee (Switzerland) was sampled and subjected to parasite screening and host genotyping during C. mesnili epidemics of four consecutive years. The ITS1 of wild-caught C. mesnili-infected Daphnia was sequenced using the 454 pyrosequencing platform. The relative frequencies of C. mesnili ITS1 sequences differed significantly among years: the most abundant C. mesnili ITS1 sequence decreased and rare sequences increased over the course of the study, a pattern consistent with negative frequency-dependent selection. However, only a weak signal of host-genotype specificity between C. mesnili and Daphnia genotypes was detected. Use of cutting edge genomic techniques will allow further investigation of the underlying micro-evolutionary relationships within the Daphnia-C. mesnili system. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

  6. A Simulation Study Comparing Epidemic Dynamics on Exponential Random Graph and Edge-Triangle Configuration Type Contact Network Models.

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    David A Rolls

    Full Text Available We compare two broad types of empirically grounded random network models in terms of their abilities to capture both network features and simulated Susceptible-Infected-Recovered (SIR epidemic dynamics. The types of network models are exponential random graph models (ERGMs and extensions of the configuration model. We use three kinds of empirical contact networks, chosen to provide both variety and realistic patterns of human contact: a highly clustered network, a bipartite network and a snowball sampled network of a "hidden population". In the case of the snowball sampled network we present a novel method for fitting an edge-triangle model. In our results, ERGMs consistently capture clustering as well or better than configuration-type models, but the latter models better capture the node degree distribution. Despite the additional computational requirements to fit ERGMs to empirical networks, the use of ERGMs provides only a slight improvement in the ability of the models to recreate epidemic features of the empirical network in simulated SIR epidemics. Generally, SIR epidemic results from using configuration-type models fall between those from a random network model (i.e., an Erdős-Rényi model and an ERGM. The addition of subgraphs of size four to edge-triangle type models does improve agreement with the empirical network for smaller densities in clustered networks. Additional subgraphs do not make a noticeable difference in our example, although we would expect the ability to model cliques to be helpful for contact networks exhibiting household structure.

  7. Relative host body condition and food availability influence epidemic dynamics: a Poecilia reticulata-Gyrodactylus turnbulli host-parasite model.

    Science.gov (United States)

    Tadiri, Christina P; Dargent, Felipe; Scott, Marilyn E

    2013-03-01

    Understanding disease transmission is important to species management and human health. Host body condition, nutrition and disease susceptibility interact in a complex manner, and while the individual effects of these variables are well known, our understanding of how they interact and translate to population dynamics is limited. Our objective was to determine whether host relative body condition influences epidemic dynamics, and how this relationship is affected by food availability. Poecilia reticulata (guppies) of roughly similar size were selected and assembled randomly into populations of 10 guppies assigned to 3 different food availability treatments, and the relative condition index (Kn) of each fish was calculated. We infected 1 individual per group ('source' fish) with Gyrodactyus turnbulli and counted parasites on each fish every other day for 10 days. Epidemic parameters for each population were analysed using generalized linear models. High host Kn-particularly that of the 'source' fish-exerted a positive effect on incidence, peak parasite burden, and the degree of parasite aggregation. Low food availability increased the strength of the associations with peak burden and aggregation. Our findings suggest that host Kn and food availability interact to influence epidemic dynamics, and that the condition of the individual that brings the parasite into the host population has a profound impact on the spread of infection.

  8. HIV/AIDS epidemic in French Guiana: 1979-1997. Groupe d'Etude Clinique de l'Infection VIH en Guyane Française.

    Science.gov (United States)

    Sobesky, M; Dabis, F; Le Beux, P

    2000-06-01

    The incidence of AIDS in French Guiana remains one of the highest in Latin America and the Caribbean. The annual AIDS incidence rate increased continually from the start of the epidemic until 1995, when it reached 59.3/100,000 population declining thereafter to 26.6 in 1997. The prevalence of HIV in pregnant women was 0.9% in 1993, increasing to 1.3% in 1995, and that in individuals attending sexually transmitted disease (STD) clinics was 2.1% in 1996. We included 224 patients in a study of survival after AIDS diagnosis. The principal AIDS-defining diagnosis was tuberculosis in 20.5% of reported cases. The median duration of survival was 10.2 months. Multivariate analysis showed that, patients > or = 45 years at entry progressed more rapidly to AIDS than younger patients. HIV prevention and access to health care should be developed in the various ethnic communities and adapted to cultural status. The progressive implementation of multiple antiretroviral therapies since 1996 may further reduce progression of the disease but early HIV diagnosis is required to improve the overall prognosis of HIV-infected patients.

  9. 南岗区HIV/AIDS疫情流行情况分析%Analysis of HIV/AIDS Epidemic Situation in Nangang District

    Institute of Scientific and Technical Information of China (English)

    田育文; 马玲

    2014-01-01

    Objective To analyze the epidemiological characteristics and trends of HIV/AIDS in Nangang District, and to provide datafor formulating prevention and control strategies.Methods Collecting Nangang HIV /AIDS epidemic reporting data from 2002 to 2013,according to the routes of infection.Results 658 HIV/AIDS cases were reported from 2002 to 2013, including 409 homosexualtransmission cases and 175 heterosexual transmission cases.Transmission of infectious gay patients′rapid growth trend isobvious.Conclusion The Nangang District will face a critical period of AIDS prevention and control work.Intervention in high -riskgroups should be done, and the intervention of gay people should also be strengthened .%目的:分析南岗区HIV/AIDS流行病学特点及趋势,为制定防控策略提供数据支持。方法收集和整理2002~2013年南岗区HIV/AIDS疫情报告资料,针对感染途径进行整理和统计分析。结果2002~2013年南岗区共报告HIV/AIDS病例658例,其中同性传播409例,异性传播175例,经同性传播途径的患者呈逐年快速增长趋势明显。结论南岗区将面临防治艾滋病工作的关键期,应全面反思高危人群干预工作,加强同性恋人群干预工作刻不容缓。

  10. Modeling dynamics of HIV infected cells using stochastic cellular automaton

    Science.gov (United States)

    Precharattana, Monamorn; Triampo, Wannapong

    2014-08-01

    Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. Several cellular automata (CA) models have been introduced to gain insights into the dynamics of the disease progression but none of them has taken into account effects of certain immune cells such as the dendritic cells (DCs) and the CD8+ T lymphocytes (CD8+ T cells). In this work, we present a CA model, which incorporates effects of the HIV specific immune response focusing on the cell-mediated immunities, and investigate the interaction between the host immune response and the HIV infected cells in the lymph nodes. The aim of our work is to propose a model more realistic than the one in Precharattana et al. (2010) [10], by incorporating roles of the DCs, the CD4+ T cells, and the CD8+ T cells into the model so that it would reproduce the HIV infection dynamics during the primary phase of HIV infection.

  11. Molecular epidemiology is becoming complex under the dynamic HIV prevalence: The perspective from Harbin, China.

    Science.gov (United States)

    Shao, Bing; Song, Bo; Cao, Lijun; Du, Juan; Sun, Dongying; Lin, Yuanlong; Wang, Binyou; Wang, Fuxiang; Wang, Sunran

    2016-05-01

    Unlike most areas of China, HIV transmission via men who have sex with men (MSM) is increasing rapidly, and has become the main route of HIV transmission in Harbin city. The purpose of the current study was to elaborate the molecular epidemiologic characteristics of the new HIV epidemic. Eighty-one HIV-1 gag gene sequences (HXB2:806-1861) from local HIV infections were isolated; CRF01_AE predominated among HIV infections (71.6%), followed by subtype B (16.5%), CRF07_BC (6.2%), and unique recombinant strains (URFs; 6.2%). URFs were most often identified in the MSM population, which consisted of a recombination of CRF01_AE with subtype B or CRF07_BC. Six clusters were formed in this analysis; clusters I and II mainly circulated in southwest China. Clusters III and IV mainly circulated in southwest, southeast, and central China. Clusters V and VI mainly circulated in north and northeast China. Clusters III and IV may facilitate the transmission of the CRF01_AE strain from the southwest to the north and northeast regions of China. HIV subtypes are becoming diverse with the persistent epidemic in this geographic region. In brief, our results indicate that the molecular epidemiology of HIV is trending to be more complex. Thus, timely molecular epidemiologic supervision of HIV is necessary, especially for the MSM population.

  12. Dynamics of Ebola epidemics in West Africa 2014 [v2; ref status: indexed, http://f1000r.es/5fh

    Directory of Open Access Journals (Sweden)

    Robin J. Evans

    2015-05-01

    Full Text Available This paper investigates the dynamics of Ebola virus transmission in West Africa during 2014. The reproduction numbers for the total period of epidemic and for different consequent time intervals are estimated based on a simple linear model. It contains one major parameter - the average infectious period that defines the dynamics of epidemics. Numerical implementations are carried out on data collected from three countries Guinea, Sierra Leone and Liberia as well as the total data collected worldwide. Predictions are provided by considering different scenarios involving the average times of infectiousness for the next few months and the end of the current epidemic is estimated according to each scenario.

  13. Molecular epidemic of HCV quasispecies variability in HIV/HCV coinfection patients from Shanghai%上海地区HIV/HCV重叠感染者HCV准种的分子流行病学研究

    Institute of Scientific and Technical Information of China (English)

    胡越凯; 卢洪洲; 齐唐凯; 张云智; 张仁芳; 刘莉; 郑毓芳; 蒋卫民; 张继明; 潘孝彰

    2011-01-01

    Objective To observe the molecular epidemic effects of human immunodeficiency virus (HIV)/HCV coinfection and HAART on HCV quasispecies variability. Methods We detected quasispecies of HCV hypervariable region 1 (HVRl)by PCR, nucleotide sequencing and single-stranded conformation polymorphism method . We used the method in 48 subjects from Shanghai and observed the molecular epidemiology of HCV quasispecies variability in HIV-HCV coinfection of the region. Results This study shows that HIV-positive, HAART-naive subjects had significantly lower HCV quasispecies complexity and diversity than HIV-negative and HIV-positive HAART-treated subjects(P< 0. 05). Conclusion HIV coinfection is associated with decreased HCV quasispecies variability, which appears to be reversed by effective HAART.%目的 观察HIV/HCV重叠感染和高效抗反转录病毒治疗(HAART)对HCV准种的影响.方法 通过PCR、测序及单链构象多态性分析建立HCV高变1区(HVR1)准种变异率检测方法,运用该方法对我国上海地区48例HIV/HCV重叠感染者HCV准种变异的分子流行病学进行研究.结果 与单独HCV感染组和HIV/HCV重叠感染且已行HAART组相比较,HIV/HCV重叠感染但未行HAART组的HCV准种变异率较低,差异有统计学意义(P均<0.05).单独HCV感染组与HIV/HCV重叠感染且已行HAART组之间作比较,HCV准种的复杂性和多样性差异均无统计学意义.结论 HIV感染可降低HCV准种变异率.随着HAART长期应用,HIV/HCV重叠感染者的HCV准种率增加.

  14. Impacto da terapia anti-retroviral na magnitude da epidemia do HIV/AIDS no Brasil: diversos cenários Impact of antiretroviral therapy on the magnitude of the HIV/AIDS epidemic in Brazil: various scenarios

    Directory of Open Access Journals (Sweden)

    Maria Tereza S. Barbosa

    2003-04-01

    Full Text Available Neste trabalho, utilizaram-se os algoritmos EM e EMS aplicados ao método do Cálculo Retroativo para estimar a magnitude da epidemia do HIV no Brasil. Fazendo-se suposições a respeito do comportamento dos infectados, em relação à utilização da terapia combinada das drogas anti-retrovirais, construíram-se cinco cenários para a epidemia brasileira. O objetivo foi o de ilustrar os impactos que a utilização da terapia combinada das drogas anti-retrovirais possam estar tendo ou possam vir a ter na incubação do vírus e, por conseguinte, nas avaliações da epidemia realizadas a partir dos casos de Aids notificados.We applied the back-calculation method to estimate the magnitude of the HIV epidemic in Brazil, using the EM and EMS algorithms. Under certain assumptions regarding the behavior of infected patients towards combined antiretroviral therapy, we discuss five different scenarios applied to the Brazilian epidemic. Our objective was to illustrate the impact of combined antiretroviral treatment on the incubation period and thus on estimates of the size of the HIV-infected population, based on reported AIDS cases.

  15. The 2001-03 Famine and the Dynamics of HIV in Malawi: A Natural Experiment.

    Directory of Open Access Journals (Sweden)

    Michael Loevinsohn

    household survey confirmed that there was a surge of rural-to-urban migration during the famine, particularly by women under 25 years. Migration to less affected rural areas also increased.The Malawi famine appears to have had a substantial effect on HIV's dynamics and demography. Poverty and inequality, commonly considered structural determinants of HIV epidemics, can change rapidly, apparently transmitting their effects with little lag. Epidemic patterns risk being misread if such social and economic change is ignored. Many studies examining HIV prevalence declines have implicated sexual behaviour change but do not appear to have adequately considered the contribution of rural-urban migration. The evidence from Malawi, which links actions that undermined people's food security to changes in the prevalence and distribution of HIV infections, suggests new opportunities for prevention.

  16. Dynamic behaviors of a class of HIV compartmental models

    Science.gov (United States)

    Chen, Xiaoyan; Huang, Lihong; Yu, Pei

    2015-06-01

    Based on heterogeneities in drug efficacy (either spatial or phenotypic), two HIV compartmental models were proposed in Callaway and Perelson (2002) to study the HIV virus dynamics under drug treatment. In this paper, we provide a global analysis on the two models, including the positivity and boundedness of solutions and the global stability of equilibrium solutions. In particular, we show that when the basic reproduction number R0 ⩽ 1 (for which the infection equilibrium does not exist), the infection-free equilibrium is globally asymptotically stable; while when R0 > 1 (for which the infection equilibrium exists), the infection equilibrium is globally asymptotically stable.

  17. Quality of life of people living with HIV/AIDS under the new epidemic characteristics in China and the associated factors.

    Directory of Open Access Journals (Sweden)

    Wei Sun

    Full Text Available BACKGROUND: Improvement of quality of life has been one of goals in health care for people living with HIV/AIDS (PLWHA. In China, the epidemic characteristics have changed and transmission is now most commonly sexual contact. However, the assessment of quality of life of PLWHA under new characteristics has limited reporting. This study was designed to assess the quality of life among PLWHA who contracted disease mainly via sexual contact and to clarify the associated factors. METHODS: A cross-sectional study was performed in Liaoning Province. Sample size (800 was calculated based on the fatality rate and enlarged with consideration on the loss of response. Participants were sampled by tables of random numbers among all registered PLWHA. Questionnaires pertaining to quality of life (SF-36 and related factors (demographic characteristics, social support and network, HIV/AIDS awareness, and behavior factors were distributed during December 2010-April 2011. 783 effective responses were obtained. RESULTS: The average scores of physical component summary (PCS, mental component summary (MCS, and total score (TS were 66.8±21.9 (Mean±SD, 62.2±20.9, and 64.5±20.2. General linear model analysis revealed that, in standardized estimate (β sequence, PCS was significantly associated with monthly income, perceived social support, antiretroviral therapy, transmission, and ethnicity; MCS was associated with perceived social support, antiretroviral therapy, condom use, monthly income, transmission, ethnicity, and alcohol consumption; whereas TS was associated with perceived social support, antiretroviral therapy, monthly income, transmission, condom use, and ethnicity. CONCLUSIONS: Quality of life for PLWHA who contracted HIV mainly via sexual contact was worse and both physical conditions and social integration were impacted. Under current epidemic characteristics, efforts to increase social support and enhance the implementation of supporting policy are

  18. Quality of life of people living with HIV/AIDS under the new epidemic characteristics in China and the associated factors.

    Science.gov (United States)

    Sun, Wei; Wu, Ming; Qu, Peng; Lu, Chunming; Wang, Lie

    2013-01-01

    Improvement of quality of life has been one of goals in health care for people living with HIV/AIDS (PLWHA). In China, the epidemic characteristics have changed and transmission is now most commonly sexual contact. However, the assessment of quality of life of PLWHA under new characteristics has limited reporting. This study was designed to assess the quality of life among PLWHA who contracted disease mainly via sexual contact and to clarify the associated factors. A cross-sectional study was performed in Liaoning Province. Sample size (800) was calculated based on the fatality rate and enlarged with consideration on the loss of response. Participants were sampled by tables of random numbers among all registered PLWHA. Questionnaires pertaining to quality of life (SF-36) and related factors (demographic characteristics, social support and network, HIV/AIDS awareness, and behavior factors) were distributed during December 2010-April 2011. 783 effective responses were obtained. The average scores of physical component summary (PCS), mental component summary (MCS), and total score (TS) were 66.8±21.9 (Mean±SD), 62.2±20.9, and 64.5±20.2. General linear model analysis revealed that, in standardized estimate (β) sequence, PCS was significantly associated with monthly income, perceived social support, antiretroviral therapy, transmission, and ethnicity; MCS was associated with perceived social support, antiretroviral therapy, condom use, monthly income, transmission, ethnicity, and alcohol consumption; whereas TS was associated with perceived social support, antiretroviral therapy, monthly income, transmission, condom use, and ethnicity. Quality of life for PLWHA who contracted HIV mainly via sexual contact was worse and both physical conditions and social integration were impacted. Under current epidemic characteristics, efforts to increase social support and enhance the implementation of supporting policy are necessary to improve the quality of life of PLWHA.

  19. Phylogenetic analysis provides evidence of interactions between Italian heterosexual and South American homosexual males as the main source of national HIV-1 subtype C epidemics.

    Science.gov (United States)

    Lai, Alessia; Bozzi, Giorgio; Franzetti, Marco; Binda, Francesca; Simonetti, Francesco R; Micheli, Valeria; Meraviglia, Paola; Corsi, Paola; Bagnarelli, Patrizia; De Luca, Andrea; Ciccozzi, Massimo; Zehender, Gianguglielmo; Zazzi, Maurizio; Balotta, Claudia

    2014-05-01

    The HIV-1 clade C is prevalent worldwide and spread from Africa to South East Asia and South America early in the course of the epidemic. As a consequence of migration waves about 13% of the Italian HIV-1 epidemic is sustained by this clade. Two hundred fifty-four C pol sequences from the Italian ARCA database collected during 1997-2011 were analyzed. Epidemiological networks and geographical fluxes were identified through phylogeny using Bayesian approaches. Patients' country of origin was Italy, Africa, South America, and South East Asia for 44.9%, 23.6%, 4.7%, and 1.6%, respectively. Heterosexuals and men having sex with men accounted for 83.2% and 16.8%, respectively. Modality of infection was distributed differently: heterosexuals were largely prevalent among Italians (84.1%) and Africans (95.3%), while men having sex with men predominated among South Americans (66.7%). Eight significant clusters encompassing 111 patients (43.7%) were identified. Comparison between clustering and non-clustering patients indicated significant differences in country of origin, modality of infection and gender. Men having sex with men were associated to a higher probability to be included in networks (70% for men having sex with men vs. 30.3% for heterosexuals). Phylogeography highlighted two significant groups. One contained Indian strains and the second encompassed South Americans and almost all Italian strains. Phylogeography indicated that the spread of C subtype among Italians is related to South American variant. Although Italian patients mainly reported themselves as heterosexuals, homo-bisexual contacts were likely their source of infection. Phylogenetic monitoring is warranted to guide public health interventions aimed at controlling HIV infection.

  20. Common roots: a contextual review of HIV epidemics in black men who have sex with men across the African diaspora.

    Science.gov (United States)

    Millett, Gregorio A; Jeffries, William L; Peterson, John L; Malebranche, David J; Lane, Tim; Flores, Stephen A; Fenton, Kevin A; Wilson, Patrick A; Steiner, Riley; Heilig, Charles M

    2012-07-28

    Pooled estimates from across the African diaspora show that black men who have sex with men (MSM) are 15 times more likely to be HIV positive compared with general populations and 8·5 times more likely compared with black populations. Disparities in the prevalence of HIV infection are greater in African and Caribbean countries that criminalise homosexual activity than in those that do not criminalise such behaviour. With the exception of US and African epidemiological studies, most studies of black MSM mainly focus on outcomes associated with HIV behavioural risk rather than on prevalence, incidence, or undiagnosed infection. Nevertheless, black MSM across the African diaspora share common experiences such as discrimination, cultural norms valuing masculinity, concerns about confidentiality during HIV testing or treatment, low access to HIV drugs, threats of violence or incarceration, and few targeted HIV prevention resources.

  1. The Evolving HIV-1 Epidemic in Warao Amerindians Is Dominated by an Extremely High Frequency of CXCR4-Utilizing Strains.

    Science.gov (United States)

    Rangel, Héctor R; Bello, Gonzalo; Villalba, Julian A; Sulbaran, Yoneira F; Garzaro, Domingo; Maes, Mailis; Loureiro, Carmen L; de Waard, Jacobus H; Pujol, Flor H

    2015-12-01

    We previously reported a high prevalence of HIV-1 infection in Warao Amerindians from Venezuela due to the rapid spread of a single B subtype strain. In this study we evaluated the coreceptor use of the HIV-1 strains infecting this Amerindian community. Sequences of the HIV-1 V3 loop from 56 plasma samples were genotyped for coreceptor use. An extremely high frequency of CXCR4 strains was found among HIV-1-infecting Waraos (47/49, 96%), compared to HIV-1 strains infecting the non-Amerindian Venezuelan population (35/79, 44%, p HIV-1 transmissions occurred within the very early phase of infection (≤12 months). This is consistent with an initial infection dominated by an X4 strain or a very rapid selection of X4 variants after infection. This Amerindian population also exhibits the highest prevalence of tuberculosis in Venezuela, being synergistically bad prognostic factors for the evolution of morbidity and mortality in this vulnerable population.

  2. Analysis on HIV/AIDS Epidemic Situation in Shenyang City from 1991 to 2009%沈阳市1991-2009年艾滋病疫情分析

    Institute of Scientific and Technical Information of China (English)

    符文华; 白杉; 张吉慧; 苏孟

    2011-01-01

    [Objective]To analyze the epidemic characteristics of HIV/AIDS in Shenyang city, predict its trend, so as to provide scientific basis for making control countermeasures. [ Methods] Using data of HIV/AIDS epidemic report, HIV/AIDS epidemic situation in Shenyang city from 1991 to 2009 was analyzed. [Results]By the end of 2009, 1052 HIV/AIDS cases were reported, which included 933 male cases and 119 female cases. Most of cases were people aged 20 ~49 years old (82.7%). Population distribution: HIV was transmitted from exotic infected person to high-risk population before 1997, but HIV has spread to every population in the recent years. The major transmission ways was changed from blood transmission to sexual transmission, and the sexual transmission accounted for 59.9% in 2009. The same-sex transmission was two times more than blood transmission, and blood transmission accounted for 15.9%. [ Conclusion] The HIV/AIDS epidemic situation spreads rapidly in Shenyang city. More and more HIV/AIDS cases would occur by sexual transmission. It is necessary to carry out effective measures to control HIV/AIDS epidemic.%目的 分析沈阳市艾滋病流行特征并预测其流行趋势,为制定防治对策提供科学依据.方法 利用艾滋病疫情报告数据,分析沈阳市1991-2009年的艾滋病疫情.结果 至2009年底,共发现HIV/AIDS 1 052例,男933例,女119例;20~49岁年龄组报告的例数最多,占82.7%.人群分布:1997年前HIV传播是从外来输入到高危人群,近几年则扩展到各人群,并从以血液传播为主转变成以性传播为主,到2009年经性传播占59.9%,同性传播是异性传播的2倍,血液传播占15.9%.结论 沈阳市近年来艾滋病疫情发展迅速,经性传播引起的HIV/AIDS将越来越多,需采取有效措施,遏制艾滋病的蔓延.

  3. HIV/AIDS epidemic in Inner Mongolia, 1996-2010%1996-2010年内蒙古自治区艾滋病疫情分析

    Institute of Scientific and Technical Information of China (English)

    杨景元; 曲琳; 高永明; 涛波

    2011-01-01

    目的 通过分析内蒙古艾滋病疫情流行形势和特点,寻找有效的工作方式,为今后防治工作提供依据.方法 通过对内蒙古报告的所有艾滋病病毒感染者/艾滋病患者(HIV/AIDS)病例相关数据进行收集整理,采用Excel 2007、SPSS 15.0软件进行统计分析.结果 内蒙古HIV/AIDS病例报告呈上升趋势,地区分布以呼和浩特、包头市为主;经性接触传播为现在内蒙古主要传播途径;病例发现主要以术前检测、羁押人员筛查等方式为主.结论 内蒙古艾滋病疫情仍呈明显上升趋势,疫情特点较以前有一些变化,但仍处在低发阶段.要结合疫情变化的特点,继续加大力度,制定有效的措施,将疫情控制在最低范围.%Objective To analyze the epidemic pattern and characteristics of AIDS in Inner Mongolia, and provide evixdence for the future prevention and control of AIDS. Methods The incidence data of HIV/AIDS reported in Inner Mongolia from 1996 to 2010 were collected to conduct statictical analysis by using Excel 2007 and SPSS 15.0 software. Results The incidence of HIV/AIDS was in an upward trend in Inner Mongolia, The cases were mainly distributed in Hohhot and Baotou. The sexual transmission was the major route. The cases were mainly detected by pre-operation examination and the screening in detained people. Conclusion The incidence of HIV/AIDS continued to increase in Inner Mongolia. Although some change was observed in the disease incidence, the incidence was still low. It is important to develop effective measures according to new characteristics of AIDS epidemic and strengthen the prevention and control of the disease to minimize the spread of AIDS.

  4. How are countries in the Western Pacific Region tracking the HIV epidemic? Results from a 2011 survey of ministries of health

    Science.gov (United States)

    Wi, Teodora; Calleja, Jesus Garcia

    2012-01-01

    In 2011, as part of the World Health Organization global reporting tool to collect data on the progress of improving the health sector response to HIV/AIDS towards universal access, a questionnaire was sent to ministries of health of Western Pacific Region Member States on the scope and functioning of their HIV surveillance systems. Of the 17 countries that responded, 13 were low- to middle-income countries and four were high-income countries. Regular serosurveillance surveys are conducted with female sex workers in all lower- and middle-income countries that responded to the survey but less so with people who inject drugs and men who have sex with men. Furthermore, there are no surveillance activities of the key populations in most of the Pacific island countries. It is recommended that estimations of high-risk populations be conducted in priority Pacific island countries and tailored surveillance systems be designed. Efforts should also be made to gather and accumulate data from sufficient geographic coverage to allow the HIV epidemic to continue to be monitored. PMID:23971003

  5. Evidence for localised HIV related micro–epidemics associated with the decentralised provision of antiretroviral treatment in rural South Africa: a spatio–temporal analysis of changing mortality patterns (2007–2010

    Directory of Open Access Journals (Sweden)

    Paul Mee

    2014-06-01

    Full Text Available In this study we analysed the spatial and temporal changes in patterns of mortality over a period when antiretroviral therapy (ART was rolled out in a rural region of north–eastern South Africa. Previous studies have identified localised concentrated HIV related sub–epidemics and recommended that micro–level analyses be carried out in order to direct focused interventions.

  6. Mathematical model for HIV dynamics in HIV-specific helper cells

    Science.gov (United States)

    Pinto, Carla M. A.; Carvalho, Ana

    2014-03-01

    In this paper we study a delay mathematical model for the dynamics of HIV in HIV-specific CD4 + T helper cells. We modify the model presented by Roy and Wodarz in 2012, where the HIV dynamics is studied, considering a single CD4 + T cell population. Non-specific helper cells are included as alternative target cell population, to account for macrophages and dendritic cells. In this paper, we include two types of delay: (1) a latent period between the time target cells are contacted by the virus particles and the time the virions enter the cells and; (2) virus production period for new virions to be produced within and released from the infected cells. We compute the reproduction number of the model, R0, and the local stability of the disease free equilibrium and of the endemic equilibrium. We find that for values of R01, the model approximates asymptotically the endemic equilibrium. We observe numerically the phenomenon of backward bifurcation for values of R0⪅1. This statement will be proved in future work. We also vary the values of the latent period and the production period of infected cells and free virus. We conclude that increasing these values translates in a decrease of the reproduction number. Thus, a good strategy to control the HIV virus should focus on drugs to prolong the latent period and/or slow down the virus production. These results suggest that the model is mathematically and epidemiologically well-posed.

  7. Is it growing exponentially fast? -- Impact of assuming exponential growth for characterizing and forecasting epidemics with initial near-exponential growth dynamics.

    Science.gov (United States)

    Chowell, Gerardo; Viboud, Cécile

    2016-10-01

    The increasing use of mathematical models for epidemic forecasting has highlighted the importance of designing models that capture the baseline transmission characteristics in order to generate reliable epidemic forecasts. Improved models for epidemic forecasting could be achieved by identifying signature features of epidemic growth, which could inform the design of models of disease spread and reveal important characteristics of the transmission process. In particular, it is often taken for granted that the early growth phase of different growth processes in nature follow early exponential growth dynamics. In the context of infectious disease spread, this assumption is often convenient to describe a transmission process with mass action kinetics using differential equations and generate analytic expressions and estimates of the reproduction number. In this article, we carry out a simulation study to illustrate the impact of incorrectly assuming an exponential-growth model to characterize the early phase (e.g., 3-5 disease generation intervals) of an infectious disease outbreak that follows near-exponential growth dynamics. Specifically, we assess the impact on: 1) goodness of fit, 2) bias on the growth parameter, and 3) the impact on short-term epidemic forecasts. Designing transmission models and statistical approaches that more flexibly capture the profile of epidemic growth could lead to enhanced model fit, improved estimates of key transmission parameters, and more realistic epidemic forecasts.

  8. Recurrent dynamics in an epidemic model due to stimulated bifurcation crossovers

    Energy Technology Data Exchange (ETDEWEB)

    Juanico, Drandreb Earl [Department of Mathematics, Ateneo de Manila University, Loyola Heights, Quezon City, Philippines 1108 (Philippines); National Institute of Physics, University of the Philippines, Diliman, Quezon City, Philippines 1101 (Philippines)

    2015-05-15

    Epidemics are known to persist in the form of recurrence cycles. Despite intervention efforts through vaccination and targeted social distancing, peaks of activity for infectious diseases like influenza reappear over time. Analysis of a stochastic model is here undertaken to explore a proposed cycle-generating mechanism – the bifurcation crossover. Time series from simulations of the model exhibit oscillations similar to the temporal signature of influenza activity. Power-spectral density indicates a resonant frequency, which corresponds to the annual seasonality of influenza in temperate zones. The study finds that intervention actions influence the extinguishability of epidemic activity. Asymptotic solution to a backward Kolmogorov equation corresponds to a mean extinction time that is a function of both intervention efficacy and population size. Intervention efficacy must be greater than a certain threshold to increase the chances of extinguishing the epidemic. Agreement of the model with several phenomenological features of epidemic cycles lends to it a tractability that may serve as early warning of imminent outbreaks.

  9. Evolutionary Analysis of Inter-Farm Transmission Dynamics in a Highly Pathogenic Avian Influenza Epidemic

    NARCIS (Netherlands)

    Bataille, A.; Meer, van der F.; Stegeman, A.; Koch, G.

    2011-01-01

    Phylogenetic studies have largely contributed to better understand the emergence, spread and evolution of highly pathogenic avian influenza during epidemics, but sampling of genetic data has never been detailed enough to allow mapping of the spatiotemporal spread of avian influenza viruses during a

  10. 低流行地区HIV/AIDS发现及管理的策略研究%Study on strategies to find and manage the new-found HIV/AIDS in low-epidemic areas

    Institute of Scientific and Technical Information of China (English)

    郭燕; 王欣; 柏建芸; 柳忠泉; 夏建晖; 程绍辉

    2012-01-01

    Objective To analyse the human immunodeficiency virus(HIV)and acquired immunodeficiency syndrome (AIDS) survelliance data in 2009 and 2010, and to explore the strategy for finding and managing the new-found HIV/AIDS in low-epidemic areas. Methods The survelliance data in 2009 and 2010 were collected to calculate the rate of HIV-positive and the rate of testing primary CD4 T lymphocytes before limited time and the mean number of primary CDJ T lymphocytes, and to analyse the unit cost of HIV/AIDS reported in 2009 and 2010. Results The survelliance data showed that among different detection channels, clients of sexually transmitted disease, voluntary counseling testing ( VCT) , investigation of men who have sex with men ( MSM ) have the higher detection rates and the mean of primary CD4 T lymphocytes than others. Besides, the unit cost were lower than other detections. At the same time, the rate of testing primaryCDJ T lymphocytes was higher and the rate of management of HIV/AIDS new-found was higher. Conclusions The work on STD, VCT and investigation of MSM should be strengthened, and the fund for the three sureillances under the limited investment should be increased, so as to further improve the rate of HIV-positive, manage the new-found HIV/AIDS as early as possible, and effectively reduce the second-generation transmission.%目的 通过分析天津市2009-2010年艾滋病病毒(human immunodeficiency virus,HIV)感染者和艾滋病(acquired immunodeficiency syndrome,AIDS)病人相关的监测数据,探索低流行地区HIV/AIDS发现及管理的策略.方法 收集天津市2009-2010年相关监测数据,对不同检出途径的HIV/AIDS检出率、报告的HIV/AIDS在规定期限内开展首次CD+4T淋巴细胞检测的比例、首次CD+4T淋巴细胞的均值和发现1例HIV/AIDS的成本进行分析.结果 艾滋病自愿咨询检测(voluntary counseling and testing,VCT)、性病门诊就诊者和男男性接触人群(menwho have sex with men,MSM)专项调查HIV

  11. Inference in HIV dynamics models via hierarchical likelihood

    CERN Document Server

    Commenges, D; Putter, H; Thiebaut, R

    2010-01-01

    HIV dynamical models are often based on non-linear systems of ordinary differential equations (ODE), which do not have analytical solution. Introducing random effects in such models leads to very challenging non-linear mixed-effects models. To avoid the numerical computation of multiple integrals involved in the likelihood, we propose a hierarchical likelihood (h-likelihood) approach, treated in the spirit of a penalized likelihood. We give the asymptotic distribution of the maximum h-likelihood estimators (MHLE) for fixed effects, a result that may be relevant in a more general setting. The MHLE are slightly biased but the bias can be made negligible by using a parametric bootstrap procedure. We propose an efficient algorithm for maximizing the h-likelihood. A simulation study, based on a classical HIV dynamical model, confirms the good properties of the MHLE. We apply it to the analysis of a clinical trial.

  12. Inference in HIV dynamics models via hierarchical likelihood

    OpenAIRE

    2010-01-01

    HIV dynamical models are often based on non-linear systems of ordinary differential equations (ODE), which do not have analytical solution. Introducing random effects in such models leads to very challenging non-linear mixed-effects models. To avoid the numerical computation of multiple integrals involved in the likelihood, we propose a hierarchical likelihood (h-likelihood) approach, treated in the spirit of a penalized likelihood. We give the asymptotic distribution of the maximum h-likelih...

  13. Likely impact of pre-exposure prophylaxis on HIV epidemics among men who have sex with men.

    Science.gov (United States)

    Zablotska, Iryna B

    2016-11-25

    Rapid developments in the field of HIV pre-exposure prophylaxis (PrEP) with antiretrovirals offer a promise to bring HIV transmission among gay and other men who have sex with men (MSM) to zero by 2030. This review evaluates studies, which modelled the impact of PrEP on HIV diagnoses, and discusses the progress towards PrEP implementation. Studies in English, conducted after 2010 among MSM in countries of the Organization for Economic Cooperation and Development (OECD) were reviewed. Six modelling studies were included, three of which had been conducted outside the US. None of the published models showed that PrEP alone can reduce HIV diagnoses to zero and eliminate HIV transmission by 2030. However, PrEP in combination with other biomedical interventions can reduce HIV diagnoses on the population level by ~95%. Other upcoming biomedical prevention strategies may strengthen combination prevention. Access to PrEP remains limited, even in the OECD countries. Modelling studies can assist governments with decision-making about PrEP implementation and add urgency to the implementation of PrEP. More work is needed on modelling of the impact of PrEP on HIV diagnoses trends outside the US where PrEP implementation is in its early stages.

  14. Impact of male circumcision on the HIV epidemic in Papua New Guinea: a country with extensive foreskin cutting practices.

    Directory of Open Access Journals (Sweden)

    Richard T Gray

    Full Text Available The degree to which adult medical male circumcision (MC programs can reduce new HIV infections in a moderate HIV prevalence country like Papua New Guinea (PNG are uncertain especially given the widespread prevalence of longitudinal foreskin cuts among adult males. We estimated the likely impact of a medical MC intervention in PNG using a mathematical model of HIV transmission. The model was age-structured and incorporated separate components for sex, rural/urban, men who have sex with men and female sex workers. Country-specific data of the prevalence of foreskin cuts, sexually transmitted infections, condom usage, and the acceptability of MC were obtained by our group through related studies. If longitudinal foreskin cutting has a protective efficacy of 20% compared to 60% for MC, then providing MC to 20% of uncut males from 2012 would require 376,000 procedures, avert 7,900 HIV infections by 2032, and require 143 MC per averted infection. Targeting uncut urban youths would achieve the most cost effective returns of 54 MC per HIV infection averted. These numbers of MC required to avert an HIV infection change little even with coverage up to 80% of men. The greater the protective efficacy of longitudinal foreskin cuts against HIV acquisition, the less impact MC interventions will have. Dependent on this efficacy, increasing condom use could have a much greater impact with a 10 percentage point increase averting 18,400 infections over this same period. MC programs could be effective in reducing HIV infections in PNG, particularly in high prevalence populations. However the overall impact is highly dependent on the protective efficacy of existing longitudinal foreskin cutting in preventing HIV.

  15. Impact of male circumcision on the HIV epidemic in Papua New Guinea: a country with extensive foreskin cutting practices.

    Science.gov (United States)

    Gray, Richard T; Vallely, Andrew; Wilson, David P; Kaldor, John; MacLaren, David; Kelly-Hanku, Angela; Siba, Peter; Murray, John M

    2014-01-01

    The degree to which adult medical male circumcision (MC) programs can reduce new HIV infections in a moderate HIV prevalence country like Papua New Guinea (PNG) are uncertain especially given the widespread prevalence of longitudinal foreskin cuts among adult males. We estimated the likely impact of a medical MC intervention in PNG using a mathematical model of HIV transmission. The model was age-structured and incorporated separate components for sex, rural/urban, men who have sex with men and female sex workers. Country-specific data of the prevalence of foreskin cuts, sexually transmitted infections, condom usage, and the acceptability of MC were obtained by our group through related studies. If longitudinal foreskin cutting has a protective efficacy of 20% compared to 60% for MC, then providing MC to 20% of uncut males from 2012 would require 376,000 procedures, avert 7,900 HIV infections by 2032, and require 143 MC per averted infection. Targeting uncut urban youths would achieve the most cost effective returns of 54 MC per HIV infection averted. These numbers of MC required to avert an HIV infection change little even with coverage up to 80% of men. The greater the protective efficacy of longitudinal foreskin cuts against HIV acquisition, the less impact MC interventions will have. Dependent on this efficacy, increasing condom use could have a much greater impact with a 10 percentage point increase averting 18,400 infections over this same period. MC programs could be effective in reducing HIV infections in PNG, particularly in high prevalence populations. However the overall impact is highly dependent on the protective efficacy of existing longitudinal foreskin cutting in preventing HIV.

  16. Bayesian estimation of HIV-1 dynamics in vivo.

    Science.gov (United States)

    Ushakova, Anastasia; Pettersen, Frank Olav; Mæland, Arild; Lindqvist, Bo Henry; Kvale, Dag

    2015-03-01

    Statistical analysis of viral dynamics in HIV-1 infected patients undergoing structured treatment interruptions were performed using a novel model that accounts for treatment efficiency as well as total CD8+ T cell counts. A brief review of parameter estimates obtained in other studies is given, pointing to a considerable variation in the estimated values. A Bayesian approach to parameter estimation was used with longitudinal measurements of CD4+ and CD8+ T cell counts and HIV RNA. We describe an estimation procedure which uses spline approximations of CD8+ T cells dynamics. This approach reduces the number of parameters that must be estimated and is especially helpful when the CD8+ T cells growth function has a delayed dependence on the past. Seven important parameters related to HIV-1 in-host dynamics were estimated, most of them treated as global parameters across the group of patients. The estimated values were mainly in keeping with the estimates obtained in other reports, but our paper also introduces the estimates of some new parameters which supplement the current knowledge. The method was also tested on a simulated data set.

  17. Trends and predictors of transmitted drug resistance (TDR) and clusters with TDR in a local Belgian HIV-1 epidemic

    NARCIS (Netherlands)

    A.-C. Pineda-Peña (Andrea-Clemencia); J. Schrooten; L. Vinken (Lore); F. Ferreira (Fossie); G. Li (Guangdi); N.S. Trovão (Nídia Sequeira); R. Khouri (Ricardo); I. Derdelinck (Inge); P. de Munter (Paul); C. K̈ucherer (C.); L.G. Kostrikis (Leondios); C. Nielsen (Claus); K. Littsola (Kirsi); A.M.J. Wensing (Annemarie); M. Stanojevic (Maja); R. Paredes (Roger); C. Balotta (Claudia); J. Albert (Jan); C.A. Boucher (Charles); A. Gomez-Lopez (Arley); E. van Wijngaerden (Eric); M. van Ranst (Marc); J. Vercauteren (Jurgen); A.M. Vandamme (Anne Mieke); K. van Laethem (Kristel)

    2014-01-01

    textabstractWe aimed to study epidemic trends and predictors for transmitted drug resistance (TDR) in our region, its clinical impact and its association with transmission clusters. We included 778 patients from the AIDS Reference Center in Leuven (Belgium) diagnosed from 1998 to 2012. Resistance te

  18. Trends and predictors of transmitted drug resistance (TDR) and clusters with TDR in a local Belgian HIV-1 epidemic

    NARCIS (Netherlands)

    A.-C. Pineda-Peña (Andrea-Clemencia); J. Schrooten; L. Vinken (Lore); F. Ferreira (Fossie); G. Li (Guangdi); N.S. Trovão (Nídia Sequeira); R. Khouri (Ricardo); I. Derdelinck (Inge); P. de Munter (Paul); C. K̈ucherer (C.); L.G. Kostrikis (Leondios); C. Nielsen (Claus); K. Littsola (Kirsi); A.M.J. Wensing (Annemarie); M. Stanojevic (Maja); R. Paredes (Roger); C. Balotta (Claudia); J. Albert (Jan); C.A. Boucher (Charles); A. Gomez-Lopez (Arley); E. van Wijngaerden (Eric); M. van Ranst (Marc); J. Vercauteren (Jurgen); A.M. Vandamme (Anne Mieke); K. van Laethem (Kristel)

    2014-01-01

    textabstractWe aimed to study epidemic trends and predictors for transmitted drug resistance (TDR) in our region, its clinical impact and its association with transmission clusters. We included 778 patients from the AIDS Reference Center in Leuven (Belgium) diagnosed from 1998 to 2012. Resistance

  19. Trends and predictors of transmitted drug resistance (TDR) and clusters with TDR in a local Belgian HIV-1 epidemic

    NARCIS (Netherlands)

    A.-C. Pineda-Peña (Andrea-Clemencia); J. Schrooten; L. Vinken (Lore); F. Ferreira (Fossie); G. Li (Guangdi); N.S. Trovão (Nídia Sequeira); R. Khouri (Ricardo); I. Derdelinck (Inge); P. de Munter (Paul); C. K̈ucherer (C.); L.G. Kostrikis (Leondios); C. Nielsen (Claus); K. Littsola (Kirsi); A.M.J. Wensing (Annemarie); M. Stanojevic (Maja); R. Paredes (Roger); C. Balotta (Claudia); J. Albert (Jan); C.A. Boucher (Charles); A. Gomez-Lopez (Arley); E. van Wijngaerden (Eric); M. van Ranst (Marc); J. Vercauteren (Jurgen); A.M. Vandamme (Anne Mieke); K. van Laethem (Kristel)

    2014-01-01

    textabstractWe aimed to study epidemic trends and predictors for transmitted drug resistance (TDR) in our region, its clinical impact and its association with transmission clusters. We included 778 patients from the AIDS Reference Center in Leuven (Belgium) diagnosed from 1998 to 2012. Resistance te

  20. HIV-1 subtype distribution and its demographic determinants in newly diagnosed patients in Europe suggest highly compartmentalized epidemics

    NARCIS (Netherlands)

    A.B. Abecasis (Ana ); A.M.J. Wensing (Annemarie); D. Paraskevis (Dimitrios); J. Vercauteren (Jurgen); K. Theys (Kristof); D.A.M.C. van de Vijver (David); J. Albert (Jan); B. Asjö (Birgitta); C. Balotta (Claudia); D. Beshkov (Danail); R.J. Camacho (Ricardo Jorge); B. Clotet; C. de Gascun (Cillian); A. Griskevicius (Algis); Z. Grossman (Zehava); O. Hamouda (Osamah); A. Horban (Andrzej); T. Kolupajeva (Tatjana); K. Korn; L.G. Kostrikis (Leondios); C. Kücherer (Claudia); K. Liitsola (Kirsi); M. Linka (Marek); C. Nielsen (Claus); D. Otelea (Dan); R. Paredes (Roger); M. Poljak (Mario); E. Puchhammer-Stöckl (Elisabeth); J.-C. Schmit (Jean-Claude); A. Sonnerborg (Anders); D. Stanekova (Danica); M. Stanojevic (Maja); D. Struck (Daniel); C.A. Boucher (Charles); A.M. Vandamme (Anne Mieke)

    2013-01-01

    textabstractBackground: Understanding HIV-1 subtype distribution and epidemiology can assist preventive measures and clinical decisions. Sequence variation may affect antiviral drug resistance development, disease progression, evolutionary rates and transmission routes.Results: We investigated the s

  1. The IWG (Interagency Working Group) model for the heterosexual spread of HIV and the demographic impact of the AIDS epidemic

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, E.A. (Los Alamos National Lab., NM (USA)); Seitz, S.T. (Illinois Univ., Urbana, IL (USA)); Way, P.O.; Johnson, P.D. (Bureau of the Census, Washington, DC (USA)); Curry, T.F. (Air Force Academy, CO (USA))

    1990-01-01

    This paper presents the State Department's Interagency Working Group (IWG) model for the spread of HIV. The model is fully operational for Pattern 2 (heterosexual blood transmission) and Pattern 3 (heterosexual, homosexual, and IV drug transmission) countries. This model was developed for various uses, including technical research, policy analysis, and support for decision making. Research uses include studying patterns of HIV spread, assessing the relative effect of different processes on the spread of HIV, examining the demographic impact of HIV infections, and comparing the potential impact of behavioral versus medical intervention strategies. The model will be used in workshops where policy makers and health officials can do hands-on scenario analyses, gain qualitative insights into the possible long-term-epidemiological and demographic impact of HIV, gauge the uncertainties in predictions for the future, and study the impact of HIV, gauge the uncertainties in predictions for the future, and study the impact that intervention strategies are likely to have. The computational model uses a deterministic system of differential equations and runs on a 286- or a 386-based IBM-compatible machine under Microsoft Windows. The program requires an input ASCII (text) file to run; all parameters used by the model are input through this file and, therefore, are user-accessible. The software is user-friendly, mouse-driven, and allows for interactive manipulation of input data and visualization and processing of model outputs. 15 refs., 13 figs., 1 tab.

  2. HIV epidemic among men who have sex with men in India: national scenario of an unfinished agenda

    Directory of Open Access Journals (Sweden)

    Jha UM

    2014-11-01

    Full Text Available Ugra Mohan Jha,1 Yujwal Raj,1 Srinivas Venkatesh,1 Neeraj Dhingra,1 Ramesh S Paranjpe,2 Niranjan Saggurti3 1Department of AIDS Control, Ministry of Health and Family Welfare, Government of India, New Delhi, India; 2National AIDS Research Institute, Pune, India; 3Population Council, New Delhi, India Background: Although India has demonstrated success in the overall reduction of human immunodeficiency virus (HIV incidence by 57% in the past 10 years, its control among men who have sex with men (MSM remains a critical challenge. This paper describes the current status, geographic variability, and factors associated with HIV among MSM from the national perspective. Methods: Data on the levels and trends of HIV seropositivity and associated risk behaviors among MSM were analyzed and presented from the following data sources: 1 annual HIV Sentinel Surveillance (HSS conducted during 2003–10, 2 two rounds of the high-risk group size estimation conducted in 2005 and 2009, 3 two rounds of the Behavioral Surveillance Survey conducted in 2006 and 2009, and 4 the Integrated Bio-behavioral Assessment Round 2. Data were analyzed according to selected sociodemographic characteristics and sexual identities of MSM to understand the factors associated with high HIV prevalence. Results: HSS data indicate that at the national level, HIV prevalence among MSM overall is declining (from 12.3% in 2003 to 4.43% in 2010. However, marginal increasing trends were observed in Chandigarh (from 1.4% in 2004 to 2.8% in 2008 and Haryana (from 0% in 2006 to 3.2% in 2008. HSS data indicate high (>5% levels and increasing trends in HIV prevalence among MSM in eight states of India during 2003–10. Analysis of 2010 HSS data indicates that HIV prevalence was >10% in seven states. The factors associated with high HIV prevalence among MSM were being a kothi (the receptive partner in oral and anal sex, and typically with effeminate mannerisms or a double-decker (both penetrative and

  3. Low Prevalence of HIV Infection in Djibouti - Has the AIDS Epidemic Come to a Stop at the Horn of Africa?

    Science.gov (United States)

    1989-01-01

    the mean number of antibodies to specific HIV proteins . Western blot of injections was 17) positive sera were defined by the detection of anti...Vaccinations 64𔄁 bodies to at least the p24 and either gp41 or gpl20 Recent dental work 163 kilodalton molecular weight HIV proteins . All con- Recent...A41, AVOP Bulin ,Tower 12 ELEMENT NO N M61 NOCESSC N Bethesda, MD 20889-5044 631011A 052 4 AA . TLE (include Security Clasification ) Low Prevalence of

  4. The impact of spatial arrangements on epidemic disease dynamics and intervention strategies

    Science.gov (United States)

    Kelly, Michael R.; Tien, Joseph H.; Eisenberg, Marisa C.; Lenhart, Suzanne

    2017-01-01

    The role of spatial arrangements on the spread and management strategies of a cholera epidemic is investigated. We consider the effect of human and pathogen movement on optimal vaccination strategies. A metapopulation model is used, incorporating a susceptible–infected–recovered system of differential equations coupled with an equation modelling the concentration of Vibrio cholerae in an aquatic reservoir. The model compared spatial arrangements and varying scenarios to draw conclusions on how to effectively manage outbreaks. The work is motivated by the 2010 cholera outbreak in Haiti. Results give guidance for vaccination strategies in response to an outbreak. PMID:26981710

  5. Low HIV testing uptake following diagnosis of a sexually transmitted infection in Spain: implications for the implementation of efficient strategies to reduce the undiagnosed HIV epidemic.

    Science.gov (United States)

    Fernández-Balbuena, Sonia; Hoyos, Juan; Rosales-Statkus, María Elena; Nardone, Anthony; Vallejo, Fernando; Ruiz, Mónica; Sánchez, Romina; Belza, María José; Indave, Blanca Iciar; Gutiérrez, Jorge; Álvarez, Jorge; Sordo, Luis

    2016-01-01

    Sexually transmitted infections (STIs) are recognized as one of the conditions in which HIV testing is most clearly indicated. We analyse whether people diagnosed with an STI are being tested for HIV according to the experience of participants in an outreach rapid testing programme in Spain. Between 2008 and 2010, 6293 individuals underwent rapid testing and completed a self-administered questionnaire. We calculated the percentage of individuals that were diagnosed with an STI in the last 5 years and identified the setting where the last episode occurred. We then determined the percentage not receiving an HIV test after the last STI diagnosis and estimated the associated factors. Overall, 17.3% (N = 959) of participants reported an STI diagnosis in the last 5 years, of which 81.5% occurred in general medical settings. Sixty-one percent reported not undergoing HIV testing after their last STI diagnosis, 2.2% of whom reported they had refused the test. Not receiving an HIV test after the last STI diagnosis was independently associated with not being a man who has sex with men (MSM), having had fewer sexual partners, being diagnosed in general medical settings and having received a diagnosis other than syphilis. An unacceptably large percentage of people diagnosed with STI are not being tested for HIV because healthcare providers frequently fail to offer the test. Offering routine HIV testing at general medical settings, regardless of the type of STI diagnosed and population group, should be a high priority and is probably a more efficient strategy than universal screening in general healthcare settings.

  6. Three Medical School Responses to the HIV/AIDS Epidemic and the Effect on Students' Knowledge and Attitudes.

    Science.gov (United States)

    Anderson, Donna G.; And Others

    1997-01-01

    A survey of 1991 and 1994 graduating medical school students at medical schools (N=175) in Colorado, New Mexico and South Dakota found that differences in prevalence of AIDS/HIV cases in those states did not affect schools' training programs but indirectly affected students' knowledge and attitudes, which were related to the numbers of…

  7. Effectiveness of a school-based AIDS education program among rural students in HIV high epidemic area of China.

    Science.gov (United States)

    Cheng, Yan; Lou, Chao-Hua; Mueller, Lisa M; Zhao, Shuang-Ling; Yang, Jian-Hua; Tu, Xiao-Wen; Gao, Er-Sheng

    2008-02-01

    To evaluate the feasibility and effectiveness of a life-planning skills training program using participatory methods among rural senior high school students in Shangcai County, Henan Province, China. The study was a quasi-experimental study conducted in three Shangcai County senior high schools with comparable socioculture-economic and demographic characteristics (two interventions and one control). The intervention, a life-planning skills program that uses participatory training methods, combining information education with effective skills building, was provided to all first-grade students (14-18 years old; 87% of them are between 15 and 17 years old) in the intervention group from October 2003 to December 2003. In total, 717 students from the intervention group, and 457 from the control enrolled at baseline, and over 91% of these were followed up at posttest. Group x time interaction effects in ordinal logistic regression analysis were found on HIV/AIDS-related knowledge (p .05). Three months of short-term HIV/AIDS education through life-planning skills training was welcomed by students and positively influenced HIV/AIDS-related knowledge, attitudes, protection self-efficacy, and communication among senior high school students in a rural area with high HIV prevalence.

  8. Impact of High-Risk Sex and Focused Interventions in Heterosexual HIV Epidemics: A Systematic Review of Mathematical Models

    NARCIS (Netherlands)

    S. Mishra (Sharmistha); R. Steen (Richard); A. Gerbase (Antonio); Y-R. Lo (Ying-Ru); M-C. Boily (Marie-Claude)

    2012-01-01

    textabstractBackground: The core-group theory of sexually transmitted infections suggests that targeting prevention to high-risk groups (HRG) could be very effective. We aimed to quantify the contribution of heterosexual HRGs and the potential impact of focused interventions to HIV transmission in t

  9. Hepatitis C virus infections among HIV-infected men who have sex with men: an expanding epidemic

    NARCIS (Netherlands)

    A.T. Urbanus; T.J. van de Laar; I.G. Stolte; J. Schinkel; T. Heijman; R.A. Coutinho; M. Prins

    2009-01-01

    Background: Since 2000 outbreaks of sexually transmitted hepatitis C Virus (HCV) infections have been reported among HIV-infected men who have sex with men (MSM). We studied the prevalence and determinants of HCV-infection among MSM attending a large sexually transmitted infection (STI) clinic in th

  10. Structure and dynamics of the HIV-1 frameshift element RNA.

    Science.gov (United States)

    Low, Justin T; Garcia-Miranda, Pablo; Mouzakis, Kathryn D; Gorelick, Robert J; Butcher, Samuel E; Weeks, Kevin M

    2014-07-08

    The HIV-1 ribosomal frameshift element is highly structured, regulates translation of all virally encoded enzymes, and is a promising therapeutic target. The prior model for this motif contains two helices separated by a three-nucleotide bulge. Modifications to this model were suggested by SHAPE chemical probing of an entire HIV-1 RNA genome. Novel features of the SHAPE-directed model include alternate helical conformations and a larger, more complex structure. These structural elements also support the presence of a secondary frameshift site within the frameshift domain. Here, we use oligonucleotide-directed structure perturbation, probing in the presence of formamide, and in-virion experiments to examine these models. Our data support a model in which the frameshift domain is anchored by a stable helix outside the conventional domain. Less stable helices within the domain can switch from the SHAPE-predicted to the two-helix conformation. Translational frameshifting assays with frameshift domain mutants support a functional role for the interactions predicted by and specific to the SHAPE-directed model. These results reveal that the HIV-1 frameshift domain is a complex, dynamic structure and underscore the importance of analyzing folding in the context of full-length RNAs.

  11. 1995-2011年常德市HIV/AIDS流行情况分析%Analysis on Epidemic Situation of HIV/AIDS in Changde from 1995 to 2011

    Institute of Scientific and Technical Information of China (English)

    黎雅娟; 黄道平; 胡冬珍

    2012-01-01

    目的 分析常德市1995-2011年艾滋病流行状况. 方法 运用描述性流行病学方法对常德市1995-2011年间艾滋病疫情报告进行分析. 结果 常德市1995-2011年间累计发现HIV/AIDS714例;年龄较为集中在30~49岁,以中青年为主(67.34%);以男性为主(67.61%);多为农民、家政家务及待业者和民工(68.56%);以性接触感染途径为主(72.60%),其中异性传播469例(63.29%),同性(MSM)传播69例(9.31%). 结论 常德市HIV/AIDS流行呈快速增长趋势,MSM传播日趋增多,疫情从高危人群向一般人群蔓延.开展普通人群和重点人群的艾滋病防控工作刻不容缓.%Objective To analyze the epidemic situation of AIDS in Changde during the period of 1995 - 2011. Methods Information about the epidemic situation of AIDS in Changde from 1995 to 2011 was collected and analyzed by using descriptive epidemiological analysis method. Results Totally 741 HIV/AIDS cases were reported accumulatively from 1995 to 2011. The distribution features showed that the cases were found mostly in the young and middle - aged people aged between 30 and 49 years (67.34%), the males (67.61%), farmers, homemakers, the unemployed and migrant workers (68.56%). Most of the cases were transmitted through sexual intercourse (72.60%), in which 469 (63.29%) cases were from heterosexual transmission and 69 (9.31%) were from homosexual transmission. Conclusions Between 1995 and 2011, there were rapid increases in HIV/ AIDS prevalence in Changde. MSM transmission showed an increasing trend, and the disease tended to spread from high - risk groups to general population. It is urgent to scientifically develop the work about AIDS prevention and control in Changde.

  12. Predicting depression in mothers with and without HIV: the role of social support and family dynamics.

    Science.gov (United States)

    Dyer, Typhanye Penniman; Stein, Judith A; Rice, Eric; Rotheram-Borus, Mary Jane

    2012-11-01

    Many women with HIV are primary caregivers for their children. Social factors, including family dynamics, play a major role in women's depression. We hypothesized an impact of HIV seropositivity on greater depression mediated through poorer family functioning and social support. Participants include 332 Mothers Living with HIV (MLH) and 200 Neighborhood Control Mothers (NCM) recruited in Los Angeles County. The NCM were matched by neighborhood. All had children ages 6 through 20. Analyses using structural equation modeling (SEM) indicated HIV seropositivity was positively correlated with depression and negatively correlated with positive social support and effective family functioning. In a predictive path model, the relationship between having HIV and depressed mood was mediated by social support and family functioning. Findings offer explanation for increased depression resulting from HIV and social and family dynamics, and suggest innovative interventions to abate psychosocial health problems and lower risk for depression among women with HIV.

  13. Dynamic motions of the HIV-1 frameshift site RNA.

    Science.gov (United States)

    Mouzakis, Kathryn D; Dethoff, Elizabeth A; Tonelli, Marco; Al-Hashimi, Hashim; Butcher, Samuel E

    2015-02-03

    The HIV-1 frameshift site (FS) plays a critical role in viral replication. During translation, the HIV-1 FS transitions from a 3-helix to a 2-helix junction RNA secondary structure. The 2-helix junction structure contains a GGA bulge, and purine-rich bulges are common motifs in RNA secondary structure. Here, we investigate the dynamics of the HIV-1 FS 2-helix junction RNA. Interhelical motions were studied under different ionic conditions using NMR order tensor analysis of residual dipolar couplings. In 150 mM potassium, the RNA adopts a 43°(±4°) interhelical bend angle (β) and displays large amplitude, anisotropic interhelical motions characterized by a 0.52(±0.04) internal generalized degree of order (GDOint) and distinct order tensor asymmetries for its two helices (η = 0.26(±0.04) and 0.5(±0.1)). These motions are effectively quenched by addition of 2 mM magnesium (GDOint = 0.87(±0.06)), which promotes a near-coaxial conformation (β = 15°(±6°)) of the two helices. Base stacking in the bulge was investigated using the fluorescent purine analog 2-aminopurine. These results indicate that magnesium stabilizes extrahelical conformations of the bulge nucleotides, thereby promoting coaxial stacking of helices. These results are highly similar to previous studies of the HIV transactivation response RNA, despite a complete lack of sequence similarity between the two RNAs. Thus, the conformational space of these RNAs is largely determined by the topology of their interhelical junctions.

  14. The HIV-1 epidemic in Bolivia is dominated by subtype B and CRF12_BF "family" strains

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    Guimarães Monick L

    2012-01-01

    Full Text Available Abstract Background Molecular epidemiological studies of HIV-1 in South America have revealed the occurrence of subtypes B, F1 and BF1 recombinants. Even so, little information concerning the HIV-1 molecular epidemiology in Bolivia is available. In this study we performed phylogenetic analyses from samples collected in Bolivia at two different points in time over a 10 year span. We analyzed these samples to estimate the trends in the HIV subtype and recombinant forms over time. Materials and methods Fifty one HIV-1 positive samples were collected in Bolivia over two distinct periods (1996 and 2005. These samples were genetically characterized based on partial pol protease/reverse transcriptase (pr/rt and env regions. Alignment and neighbor-joining (NJ phylogenetic analyses were established from partial env (n = 37 and all pol sequences using Mega 4. The remaining 14 env sequences from 1996 were previously characterized based on HMA-env (Heteroduplex mobility assay. The Simplot v.3.5.1 program was used to verify intragenic recombination, and SplitsTree 4.0 was employed to confirm the phylogenetic relationship of the BF1 recombinant samples. Results Phylogenetic analysis of both env and pol regions confirmed the predominance of "pure" subtype B (72.5% samples circulating in Bolivia and revealed a high prevalence of BF1 genotypes (27.5%. Eleven out of 14 BF1 recombinants displayed a mosaic structure identical or similar to that described for the CRF12_BF variant, one sample was classified as CRF17_BF, and two others were F1pol/Benv. No "pure" HIV-1 subtype F1 or B" variant of subtype B was detected in the present study. Of note, samples characterized as CRF12_BF-related were depicted only in 2005. Conclusion HIV-1 genetic diversity in Bolivia is mostly driven by subtype B followed by BF1 recombinant strains from the CRF12_BF "family". No significant temporal changes were detected between the mid-1990s and the mid-2000s for subtype B (76.2% vs 70

  15. The HIV-1 epidemic in Bolivia is dominated by subtype B and CRF12_BF "family" strains.

    Science.gov (United States)

    Guimarães, Monick L; Velarde-Dunois, Ketty G; Segurondo, David; Morgado, Mariza G

    2012-01-16

    Molecular epidemiological studies of HIV-1 in South America have revealed the occurrence of subtypes B, F1 and BF1 recombinants. Even so, little information concerning the HIV-1 molecular epidemiology in Bolivia is available. In this study we performed phylogenetic analyses from samples collected in Bolivia at two different points in time over a 10 year span. We analyzed these samples to estimate the trends in the HIV subtype and recombinant forms over time. Fifty one HIV-1 positive samples were collected in Bolivia over two distinct periods (1996 and 2005). These samples were genetically characterized based on partial pol protease/reverse transcriptase (pr/rt) and env regions. Alignment and neighbor-joining (NJ) phylogenetic analyses were established from partial env (n = 37) and all pol sequences using Mega 4. The remaining 14 env sequences from 1996 were previously characterized based on HMA-env (Heteroduplex mobility assay). The Simplot v.3.5.1 program was used to verify intragenic recombination, and SplitsTree 4.0 was employed to confirm the phylogenetic relationship of the BF1 recombinant samples. Phylogenetic analysis of both env and pol regions confirmed the predominance of "pure" subtype B (72.5%) samples circulating in Bolivia and revealed a high prevalence of BF1 genotypes (27.5%). Eleven out of 14 BF1 recombinants displayed a mosaic structure identical or similar to that described for the CRF12_BF variant, one sample was classified as CRF17_BF, and two others were F1pol/Benv. No "pure" HIV-1 subtype F1 or B" variant of subtype B was detected in the present study. Of note, samples characterized as CRF12_BF-related were depicted only in 2005. HIV-1 genetic diversity in Bolivia is mostly driven by subtype B followed by BF1 recombinant strains from the CRF12_BF "family". No significant temporal changes were detected between the mid-1990s and the mid-2000s for subtype B (76.2% vs 70.0%) or BF1 recombinant (23.8% vs 30.0%) samples from Bolivia.

  16. Characterizing the reproduction number of epidemics with early subexponential growth dynamics

    DEFF Research Database (Denmark)

    Chowell, Gerardo; Viboud, Cécile; Simonsen, Lone

    2016-01-01

    Early estimates of the transmission potential of emerging and re-emerging infections are increasingly used to inform public health authorities on the level of risk posed by outbreaks. Existing methods to estimate the reproduction number generally assume exponential growth in case incidence...... in the first few disease generations, before susceptible depletion sets in. In reality, outbreaks can display subexponential (i.e. polynomial) growth in the first few disease generations, owing to clustering in contact patterns, spatial effects, inhomogeneous mixing, reactive behaviour changes or other...... mechanisms. Here, we introduce the generalized growth model to characterize the early growth profile of outbreaks and estimate the effective reproduction number, with no need for explicit assumptions about the shape of epidemic growth. We demonstrate this phenomenological approach using analytical results...

  17. Oscillating epidemics in a dynamic network model: stochastic and mean-field analysis.

    Science.gov (United States)

    Szabó-Solticzky, András; Berthouze, Luc; Kiss, Istvan Z; Simon, Péter L

    2016-04-01

    An adaptive network model using SIS epidemic propagation with link-type-dependent link activation and deletion is considered. Bifurcation analysis of the pairwise ODE approximation and the network-based stochastic simulation is carried out, showing that three typical behaviours may occur; namely, oscillations can be observed besides disease-free or endemic steady states. The oscillatory behaviour in the stochastic simulations is studied using Fourier analysis, as well as through analysing the exact master equations of the stochastic model. By going beyond simply comparing simulation results to mean-field models, our approach yields deeper insights into the observed phenomena and help better understand and map out the limitations of mean-field models.

  18. Characterizing HIV epidemiology in stable couples in Cambodia, the Dominican Republic, Haiti, and India.

    Science.gov (United States)

    Chemaitelly, H; Abu-Raddad, L J

    2016-01-01

    Using a set of statistical methods and HIV mathematical models applied on nationally representative Demographic and Health Survey data, we characterized HIV serodiscordancy patterns and HIV transmission dynamics in stable couples (SCs) in four countries: Cambodia, the Dominican Republic, Haiti, and India. The majority of SCs affected by HIV were serodiscordant, and about a third of HIV-infected persons had uninfected partners. Overall, nearly two-thirds of HIV infections occurred in individuals in SCs, but only about half of these infections were due to transmissions within serodiscordant couples. The majority of HIV incidence in the population occurred through extra-partner encounters in SCs. There is similarity in HIV epidemiology in SCs between these countries and countries in sub-Saharan Africa, despite the difference in scale of epidemics. It appears that HIV epidemiology in SCs may share similar patterns globally, possibly because it is a natural 'spillover' effect of HIV dynamics in high-risk populations.

  19. Assessment of epidemic projections using recent HIV survey data in South Africa: a validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era

    NARCIS (Netherlands)

    Eaton, J.W.; Bacaer, N.; Bershteyn, A.; Cambiano, V.; Cori, A.; Dorrington, R.E.; Fraser, C.; Gopalappa, C.; Hontelez, J.A.; Johnson, L.F.; Klein, D.J.; Phillips, A.N.; Pretorius, C.; Stover, J.; Rehle, T.M.; Hallett, T.B.

    2015-01-01

    BACKGROUND: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. METHODS: We co

  20. Assessment of epidemic projections using recent HIV survey data in South Africa: a validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era

    NARCIS (Netherlands)

    Eaton, J.W.; Bacaer, N.; Bershteyn, A.; Cambiano, V.; Cori, A.; Dorrington, R.E.; Fraser, C.; Gopalappa, C.; Hontelez, J.A.; Johnson, L.F.; Klein, D.J.; Phillips, A.N.; Pretorius, C.; Stover, J.; Rehle, T.M.; Hallett, T.B.

    2015-01-01

    BACKGROUND: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. METHODS: We

  1. Assessment of epidemic projections using recent HIV survey data in South Africa: a validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era

    NARCIS (Netherlands)

    Eaton, J.W.; Bacaer, N.; Bershteyn, A.; Cambiano, V.; Cori, A.; Dorrington, R.E.; Fraser, C.; Gopalappa, C.; Hontelez, J.A.; Johnson, L.F.; Klein, D.J.; Phillips, A.N.; Pretorius, C.; Stover, J.; Rehle, T.M.; Hallett, T.B.

    2015-01-01

    BACKGROUND: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. METHODS: We co

  2. New emerging recombinant HIV-1 strains and close transmission linkage of HIV-1 strains in the Chinese MSM population indicate a new epidemic risk.

    Directory of Open Access Journals (Sweden)

    Jianjun Wu

    Full Text Available In recent years, the population of men who have sex with men (MSM have become the most significant increasing group of HIV-1 transmission in China. To identify new recombinant strains and transmission patterns of HIV-1 in Chinese MSM population, a cross-sectional investigation of MSM in Anhui Province (in south-eastern China was performed in 2011. The diagnosed AIDS case rate, CD4 T-cell counts, HIV subtypes, and origin of the recombinant strains were investigated in 138 collected samples. The phylogenetic and bootscan analyses demonstrated that, apart from three previously reported circulating strains (CRF07_BC, CRF01_AE, subtype B, various recombinant strains among subtype B, subtype C, CRF01_AE, and CRF07_BC were simultaneously identified in Chinese MSM for the first time. The introducing time of B subtype in Chinese MSM populations was estimated in 1985, CRF01_AE in 2000, and CRF07_BC in 2003; the latter two account for more than 85% of MSM infections. Notably, in comparison with B subtype infections in Anhui MSM, CRF01_AE, with the highest prevalence rate, may accelerate AIDS progression. Over half of patients (56% infected with new recombinant strains infection are diagnosed as progression into AIDS. Both Bayes and phylogenetic analyses indicated that there was active HIV transmission among MSM nationwide, which may facilitate the transmission of the new 01B recombinant strains in MSM. In conclusion, new recombinant strains and active transmission were identified in the Chinese MSM population, which may lead to a new alarming HIV pandemic in this population due to the increased pathogenesis of the newly emerging strains.

  3. Inverse problem of HIV cell dynamics using Genetic Algorithms

    Science.gov (United States)

    González, J. A.; Guzmán, F. S.

    2017-01-01

    In order to describe the cell dynamics of T-cells in a patient infected with HIV, we use a flavour of Perelson's model. This is a non-linear system of Ordinary Differential Equations that describes the evolution of healthy, latently infected, infected T-cell concentrations and the free viral cells. Different parameters in the equations give different dynamics. Considering the concentration of these types of cells is known for a particular patient, the inverse problem consists in estimating the parameters in the model. We solve this inverse problem using a Genetic Algorithm (GA) that minimizes the error between the solutions of the model and the data from the patient. These errors depend on the parameters of the GA, like mutation rate and population, although a detailed analysis of this dependence will be described elsewhere.

  4. [Antiretroviral therapy in HIV-infected children and adolescents: lessons learned in 30 years of the epidemic].

    Science.gov (United States)

    Bazin, Gabriela Ricordi; Gaspar, Mariza Curto Saavedra; Silva, Nicole Carvalho Xavier Micheloni da; Mendes, Carolina da Costa; Oliveira, Cora Pichler de; Bastos, Leonardo Soares; Cardoso, Claudete Aparecida Araújo

    2014-04-01

    This study aims to evaluate antiretroviral therapy in children and adolescents with AIDS. We selected 247 abstracts published from 1983 to 2013, collected from the PubMed and LILACS databases. Sixty-nine articles were selected. Attention to research in the pediatric age bracket in 30 years of the epidemic is explained by the age group's immunological characteristics, since AIDS progresses faster in children than in adults. Recent studies focus on the initiation of highly active antiretroviral therapy before the onset of symptoms. Early introduction of combination antiretroviral therapy has been implemented effectively and safely in populations with limited resources, leading to significantly improved survival. The current challenge is to manage a chronic disease with acute complications. New studies should focus on population specificities and identify the individual needs of pediatric patients.

  5. HIV-infection in the South Ural region of Russia at the present stage: the analysis of the epidemiological situation and new approaches to evaluating the effectiveness of the response to the epidemic

    Directory of Open Access Journals (Sweden)

    A. B. Kon’kova-Rejdman

    2015-01-01

    Full Text Available The unsuccessful epidemiological situation on HIV infection with negative tendencies is observed in Chelyabinsk region (1034,1 on 100 thousand population. The big difference between estimated quantity of people living with HIV and the registered number of HIV-positive people increase (for 59,7% – in 2012, for 60,2% – in 2013, for 61,1% – in 2014. The cascade model of levels of medical care of people living with HIV of Chelyabinsk region is used in thearticle. Main «losses» of people living with HIV are noted at the following stages of the cascade in Chelyabinsk region: «HIV infection – Detection of HIV (-61,1% With»; «Detection of HIV – statement on the dispensary account (-22,4%»; «Medical examination – needs in the ART (-71,1%». The cascade of delivery of health care in Chelyabinsk region is distinguished from data on the Russian Federation with big percent of losses (-32,7% at the stage «receiving the ART-epidemiologically safe level of virus loading». Leaving of the patient from everyone «cascade steps» of delivery of health care reflect problems in the organization of medical care. Transition of epidemic from groups of risk in the general population, its feminization and generalization demands optimization of strategy of counteraction of epidemic of HIV infection. The cascade model reflecting «profile» of the organization of medical care in a period can be effectively used as an independent element of an information and analytical subsystem of epidemic supervision of HIV infection in regions of the Russian Federation.

  6. Effects of clustered transmission on epidemic growth Comment on "Mathematical models to characterize early epidemic growth: A review" by Gerardo Chowell et al.

    Science.gov (United States)

    Merler, Stefano

    2016-09-01

    Characterizing the early growth profile of an epidemic outbreak is key for predicting the likely trajectory of the number of cases and for designing adequate control measures. Epidemic profiles characterized by exponential growth have been widely observed in the past and a grounding theoretical framework for the analysis of infectious disease dynamics was provided by the pioneering work of Kermack and McKendrick [1]. In particular, exponential growth stems from the assumption that pathogens spread in homogeneous mixing populations; that is, individuals of the population mix uniformly and randomly with each other. However, this assumption was readily recognized as highly questionable [2], and sub-exponential profiles of epidemic growth have been observed in a number of epidemic outbreaks, including HIV/AIDS, foot-and-mouth disease, measles and, more recently, Ebola [3,4].

  7. 2006-2010年蒲江县HIV/AIDS流行趋势分析%Epidemic Trend of HIV/AIDS in Pujiang County, 2006-2009

    Institute of Scientific and Technical Information of China (English)

    岳红林; 赵鹏; 张燕

    2011-01-01

    目的 分析蒲江县2006-2010年HIV/AIDS流行趋势.方法 对2006-2010年HIV/AIDS疫情资料、监测资料进行描述性分析.结果 2006-2010年共监测8464人份,发现HIV感染者32例,阳性检出率为0.38%,其中艾滋病患者17例,死亡5例.32例感染者中通过性传播占93.75%,通过配偶或性伴传播占21.88%,50岁以上人群占34.38%,农民占81.25%,出现1例学生,全县12个乡镇中有8个发现感染者.结论 目前蒲江县HIV/AIDS处于低流行,主要以性传播为主,存在从高危人群转向一般人群趋势.目前应加强HIV/AIDS监测,提高自愿咨询检测比例以及早发现感染者,在对感染者加强管理的同时应加强50岁以上人群及农民和学生的艾滋病防治知识宣传,防止疫情进一步蔓延扩散.

  8. Dynamics of a stochastic multi-strain SIS epidemic model driven by Lévy noise

    Science.gov (United States)

    Chen, Can; Kang, Yanmei

    2017-01-01

    A stochastic multi-strain SIS epidemic model is formulated by introducing Lévy noise into the disease transmission rate of each strain. First, we prove that the stochastic model admits a unique global positive solution, and, by the comparison theorem, we show that the solution remains within a positively invariant set almost surely. Next we investigate stochastic stability of the disease-free equilibrium, including stability in probability and pth moment asymptotic stability. Then sufficient conditions for persistence in the mean of the disease are established. Finally, based on an Euler scheme for Lévy-driven stochastic differential equations, numerical simulations for a stochastic two-strain model are carried out to verify the theoretical results. Moreover, numerical comparison results of the stochastic two-strain model and the deterministic version are also given. Lévy noise can cause the two strains to become extinct almost surely, even though there is a dominant strain that persists in the deterministic model. It can be concluded that the introduction of Lévy noise reduces the disease extinction threshold, which indicates that Lévy noise may suppress the disease outbreak.

  9. Porcine Epidemic Diarrhea in Europe: In-Detail Analyses of Disease Dynamics and Molecular Epidemiology

    Directory of Open Access Journals (Sweden)

    Dennis Hanke

    2017-07-01

    Full Text Available Porcine epidemic diarrhea (PED is an acute and highly contagious enteric disease of swine caused by the eponymous virus (PEDV which belongs to the genus Alphacoronavirus within the Coronaviridae virus family. Following the disastrous outbreaks in Asia and the United States, PEDV has been detected also in Europe. In order to better understand the overall situation, the molecular epidemiology, and factors that might influence the most variable disease impact; 40 samples from swine feces were collected from different PED outbreaks in Germany and other European countries and sequenced by shot-gun next-generation sequencing. A total of 38 new PEDV complete coding sequences were generated. When compared on a global scale, all investigated sequences from Central and South-Eastern Europe formed a rather homogeneous PEDV S INDEL cluster, suggesting a recent re-introduction. However, in-detail analyses revealed two new clusters and putative ancestor strains. Based on the available background data, correlations between clusters and location, farm type or clinical presentation could not be established. Additionally, the impact of secondary infections was explored using the metagenomic data sets. While several coinfections were observed, no correlation was found with disease courses. However, in addition to the PEDV genomes, ten complete viral coding sequences from nine different data sets were reconstructed each representing new virus strains. In detail, three pasivirus A strains, two astroviruses, a porcine sapelovirus, a kobuvirus, a porcine torovirus, a posavirus, and an enterobacteria phage were almost fully sequenced.

  10. Analysis on HIV/AIDS Epidemic in Bao'an District of Shenzhen from 1999 to 2009%深圳市宝安区1999-2009年HIV/AIDS疫情分析

    Institute of Scientific and Technical Information of China (English)

    何晓燕; 刘碧清; 张强; 李苑

    2011-01-01

    [ Objective ] To understand the epidemic situation of HIV/AIDS in Bao'an district of Shenzhen. [ Methods ] The epidemiological characteristics of HIV/AIDS in Bao'an district from 1999 to 2009 were analyzed with descriptive epidemiolosy. [ Results] From 1999 to 2009, the incidence of HIV/AIDS showed an upward tendency, and it has been increased significantly since 2002. 876 HIV-infected patients ( including 20 death cases) were reported in Bso'an district, which included 180 cases of AIDS and 696 cases of HIV infection. There were 680 male patients and 196 female patients, and the ratio of male to female was13.259. 11% of patients were 21 ~ 30 years old, and 52.40% were 31 ~40 years old. The household management, the housework and job-waiting accounted for 30. 37%, migrant worker, worker and farmer accounted for 26. 83%. The patients with primary education accounted for 27.51%, and patients with middle education accounted for 48.40%. Among patients, floating population accounted for 89.5%,and local population accounted for 7.42%. The sexual transmission and injection transmission accounted for 37.56% and 51.59% respectively. 4.45% of patients were reported by detection of addicts in compulsory detoxification, 37.67% were reported by physical examination among other prisoners, 9.82% were reported by STD clinics, 8.22% were detected in test and consultation, and 6.62% were detected in pregnant examination. [ Conclusion ] The HIV/AIDS epidemic in Bao'an district became more and more severe and complex. It is necessary to improve the educations further enlarge the service for voluntary test and consultation, implement the policy of "Four Frees and One Care", as well as strengthen the treatment and care for patients with HIV/AIDS.%目的 了解深圳市宝安区HIV/AIDS的流行情况,为制定HIV/AIDS的防治措施提供科学依据.方法 用描述流行病学方法分析宝安区1999-2009年HIV/AIDS流行特征.结果 1999-2009年

  11. The Epidemics of Corruption

    CERN Document Server

    Blanchard, P; Krüger, T; Martin, P; Blanchard, Ph.

    2005-01-01

    We study corruption as a generalized epidemic process on the graph of social relationships. The main difference to classical epidemic processes is the strong nonlinear dependence of the transmission probability on the local density of corruption and the mean field influence of the overall corruption in the society. Network clustering and the degree-degree correlation play an essential role in corruption dynamics. We discuss phase transitions, the influence of the graph structure and the implications for epidemic control. Structural and dynamical arguments are given why strongly hierarchically organized societies like systems with dictatorial tendency are more vulnerable to corruption than democracies. A similar type of modelling can be applied to other social contagion spreading processes like opinion formation, doping usage, social disorders or innovation dynamics.

  12. Sexual abstinence behavior among never-married youths in a generalized HIV epidemic country: evidence from the 2005 Côte d'Ivoire AIDS indicator survey

    Directory of Open Access Journals (Sweden)

    Kawahara Kazuo

    2008-12-01

    Full Text Available Abstract Background Sexual abstinence is the best available option for preventing both pregnancy and sexually transmitted infections, including HIV/AIDS. Identifying the factors associated with sexual abstinence among youths would have meaningful implications in a generalized HIV epidemic country such as the Côte d'Ivoire. Thus, we explored sexual abstinence behavior among never-married individuals aged 15 to 24 in Côte d'Ivoire and assessed factors that predict sexual abstinence. Methods We obtained data from the nationally representative and population-based 2005 Côte d'Ivoire AIDS Indicator Survey, conducted from September 2004 to October 2005. Our sample included 3041 never-married people aged 15 to 24. Of these, 990 reported never having sexual intercourse (primary abstinence and 137 reported sexual experience but not in the 12 months prior to the survey (secondary abstinence. In all, 1127 youths reported sexual abstinence practice. Results Of the 3041 never-married youths, 54.4% were male and 45.6% were female. About 33.0%, 6.7%, and 37.1% of them were practicing primary, secondary, and sexual abstinence behavior, respectively. Females of higher education level were significantly 11.14 times as likely as those of no education to practice either primary or secondary abstinence. Males who were animists, had no religion, or were practicing religions other than Christianity or Muslim were significantly less likely than other male youths to practice sexual abstinence (OR = 0.53, 95% CI = 0.30–0.95. Living in the north-west region of the country significantly decreased the odds of sexual abstinence among female youths. Similarly, female youths living in rural areas were significantly 0.42 times as likely as those in the urban zones to practice sexual abstinence. Conclusion HIV/AIDS prevention program components could include media campaigns, educational intervention improvement, as well as promoting policies that shape female youth

  13. Dynamics of immune escape during HIV/SIV infection.

    Directory of Open Access Journals (Sweden)

    Christian L Althaus

    Full Text Available Several studies have shown that cytotoxic T lymphocytes (CTLs play an important role in controlling HIV/SIV infection. Notably, the observation of escape mutants suggests a selective pressure induced by the CTL response. However, it remains difficult to assess the definite role of the cellular immune response. We devise a computational model of HIV/SIV infection having a broad cellular immune response targeting different viral epitopes. The CTL clones are stimulated by viral antigen and interact with the virus population through cytotoxic killing of infected cells. Consequently, the virus population reacts through the acquisition of CTL escape mutations. Our model provides realistic virus dynamics and describes several experimental observations. We postulate that inter-clonal competition and immunodominance may be critical factors determining the sequential emergence of escapes. We show that even though the total killing induced by the CTL response can be high, escape rates against a single CTL clone are often slow and difficult to estimate from infrequent sequence measurements. Finally, our simulations show that a higher degree of immunodominance leads to more frequent escape with a reduced control of viral replication but a substantially impaired replicative capacity of the virus. This result suggests two strategies for vaccine design: Vaccines inducing a broad CTL response should decrease the viral load, whereas vaccines stimulating a narrow but dominant CTL response are likely to induce escape but may dramatically reduce the replicative capacity of the virus.

  14. Evolutionary dynamics of HBV-D1 genotype epidemic in Turkey.

    Science.gov (United States)

    Ciccozzi, Massimo; Ciccaglione, Anna Rita; Lo Presti, Alessandra; Equestre, Michele; Cella, Eleonora; Ebranati, Erika; Gabanelli, Elena; Villano, Umbertina; Bruni, Roberto; Yalcinkaya, Tulay; Tanzi, Elisabetta; Zehender, Gianguglielmo

    2014-01-01

    Hepatitis B virus (HBV), is the leading cause of liver diseases infecting an estimated 240 million persons worldwide. The HBV prevalence rates are variables between different countries, with an high level of endemicity in the south-eastern part of Europe. Seven main HBV-D subgenotypes have been described until now (D1-D7). Turkey, seems to have played an important role in the penetration of HBV-D1 in the Mediterranean area. The importance of Turkey in the European epidemiology of HBV is also suggested by the observation that the highest spread of HBV infection in the Continent are reported in Turkey with Romania, Bulgaria, Greece, Albania and some southern regions of Italy. In this paper the molecular epidemiology and the epidemiological history of HBV-D in Turkey was studied, by characterizing 34 new Turkish isolates and performing a phylogeographic reconstruction. By using a phylodynamic and phylogeographic Bayesian approach, the analysis suggested that HBV-D1 originated in Turkey about in the early 1940s. The large prevalence of D1 in comparison to the other subgenotypes in Turkey confirms the importance of this Country as epidemiological reservoir of HBV-D1 dispersion. The phylogeny suggests that after each initial introduction of the virus in a specific population, separate transmission clusters have been evolving along independent phylogenetic lineages. Better characterization and continuous monitoring of such groups are going to be crucial to understand in detail the epidemiology of HBV-D1 subgenotype in Turkey and to assess the efficacy of prevention, vaccination and therapy in controlling the epidemic.

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... to help us Send the Message . Get the Facts What are HIV and AIDS? HIV (human immunodeficiency ... risk/age/youth/index.html​ . Resources Publications Drug Facts: HIV/AIDS and Drug Abuse: Intertwined Epidemics : Describes ...

  16. HGV在HIV阳性人群的调查%Survey on hepatitis G virus in HIV epidemic region

    Institute of Scientific and Technical Information of China (English)

    骆嘉拉; 桂希恩; 庄柯

    2003-01-01

    目的调查HIV流行地区庚型肝炎(HGV)在HIV阳性人群的感染率,并探讨其对HIV疾病进展的影响.方法对某HIV流行地区人们作病史询问及血清实验室检测.结果 328名HIV-Ab阳性人群检测出210名(64%)合并感染HGV者;合并HGV的HIV感染人群艾滋病人或艾滋病死亡者所占比率较低(10.5%).结论合并感染庚型肝炎似乎能延缓HIV感染者疾病的进展.

  17. Dynamic Post-Transcriptional Regulation of HIV-1 Gene Expression

    Science.gov (United States)

    Kula, Anna; Marcello, Alessandro

    2012-01-01

    Gene expression of the human immunodeficiency virus type 1 (HIV-1) is a highly regulated process. Basal transcription of the integrated provirus generates early transcripts that encode for the viral products Tat and Rev. Tat promotes the elongation of RNA polymerase while Rev mediates the nuclear export of viral RNAs that contain the Rev-responsive RNA element (RRE). These RNAs are exported from the nucleus to allow expression of Gag-Pol and Env proteins and for the production of full-length genomic RNAs. A balance exists between completely processed mRNAs and RRE-containing RNAs. Rev functions as an adaptor that recruits cellular factors to re-direct singly spliced and unspliced viral RNAs to nuclear export. The aim of this review is to address the dynamic regulation of this post-transcriptional pathway in light of recent findings that implicate several novel cellular cofactors of Rev function. PMID:24832221

  18. Dynamic Post-Transcriptional Regulation of HIV-1 Gene Expression

    Directory of Open Access Journals (Sweden)

    Alessandro Marcello

    2012-07-01

    Full Text Available Gene expression of the human immunodeficiency virus type 1 (HIV-1 is a highly regulated process. Basal transcription of the integrated provirus generates early transcripts that encode for the viral products Tat and Rev. Tat promotes the elongation of RNA polymerase while Rev mediates the nuclear export of viral RNAs that contain the Rev-responsive RNA element (RRE. These RNAs are exported from the nucleus to allow expression of Gag-Pol and Env proteins and for the production of full-length genomic RNAs. A balance exists between completely processed mRNAs and RRE-containing RNAs. Rev functions as an adaptor that recruits cellular factors to re-direct singly spliced and unspliced viral RNAs to nuclear export. The aim of this review is to address the dynamic regulation of this post-transcriptional pathway in light of recent findings that implicate several novel cellular cofactors of Rev function.

  19. Dataset showing the impact of the protonation states on molecular dynamics of HIV protease

    Directory of Open Access Journals (Sweden)

    Rosemberg O. Soares

    2016-09-01

    Full Text Available The data described here supports the research article “Unraveling HIV Protease Flaps Dynamics by Constant pH Molecular Dynamics Simulations” (Soares et al., 2016 [1]. The data involves both standard Molecular Dynamics (MD and Constant pH Molecular Dynamics (CpHMD to elucidate the effect of protonation states of catalytic dyad on the HIV-PR conformation. The data obtained from MD simulation demonstrate that the protonation state of the two aspartic acids (Asp25/Asp25′ has a strong influence on the dynamics of the HIV-PR. Regarding the CpHMD simulation, we performed pka calculations for HIV-PR and the data indicate that only one catalytic aspartate should be protonated.

  20. Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination.

    Directory of Open Access Journals (Sweden)

    Saki Takahashi

    2016-02-01

    post-EV-A71-vaccination period remained either comparable to or only slightly increased from levels prior to vaccination. The duration and strength of cross-protection following infection with EV-A71 or CV-A16 was estimated to be 9.95 wk (95% confidence interval [CI]: 3.31, 23.40 in 68% of the population (95% CI: 37%, 96%. Our predictions are limited by the necessarily short and under-sampled time series and the possible circulation of unidentified serotypes, but, nonetheless, sensitivity analyses indicate that our results are robust in predicting that the vaccine should drastically reduce incidence of EV-A71 without a substantial competitive release of CV-A16.The ability of our models to capture the observed epidemic cycles suggests that herd immunity is driving the epidemic dynamics caused by the multiple serotypes of enterovirus. Our results predict that the EV-A71 and CV-A16 serotypes provide a temporary immunizing effect against each other. Achieving high coverage rates of EV-A71 vaccination would be necessary to eliminate the ongoing transmission of EV-A71, but serotype replacement by CV-A16 following EV-A71 vaccination is likely to be transient and minor compared to the corresponding reduction in the burden of EV-A71-associated HFMD. Therefore, a mass EV-A71 vaccination program of infants and young children should provide significant benefits in terms of a reduction in overall HFMD burden.

  1. Trends and predictors of transmitted drug resistance (TDR and clusters with TDR in a local Belgian HIV-1 epidemic.

    Directory of Open Access Journals (Sweden)

    Andrea-Clemencia Pineda-Peña

    Full Text Available We aimed to study epidemic trends and predictors for transmitted drug resistance (TDR in our region, its clinical impact and its association with transmission clusters. We included 778 patients from the AIDS Reference Center in Leuven (Belgium diagnosed from 1998 to 2012. Resistance testing was performed using population-based sequencing and TDR was estimated using the WHO-2009 surveillance list. Phylogenetic analysis was performed using maximum likelihood and Bayesian techniques. The cohort was predominantly Belgian (58.4%, men who have sex with men (MSM (42.8%, and chronically infected (86.5%. The overall TDR prevalence was 9.6% (95% confidence interval (CI: 7.7-11.9, 6.5% (CI: 5.0-8.5 for nucleoside reverse transcriptase inhibitors (NRTI, 2.2% (CI: 1.4-3.5 for non-NRTI (NNRTI, and 2.2% (CI: 1.4-3.5 for protease inhibitors. A significant parabolic trend of NNRTI-TDR was found (p = 0.019. Factors significantly associated with TDR in univariate analysis were male gender, Belgian origin, MSM, recent infection, transmission clusters and subtype B, while multivariate and Bayesian network analysis singled out subtype B as the most predictive factor of TDR. Subtype B was related with transmission clusters with TDR that included 42.6% of the TDR patients. Thanks to resistance testing, 83% of the patients with TDR who started therapy had undetectable viral load whereas half of the patients would likely have received a suboptimal therapy without this test. In conclusion, TDR remained stable and a NNRTI up-and-down trend was observed. While the presence of clusters with TDR is worrying, we could not identify an independent, non-sequence based predictor for TDR or transmission clusters with TDR that could help with guidelines or public health measures.

  2. Preventing mother to child transmission of HIV in Vietnam and Indonesia: diverging care dynamics

    NARCIS (Netherlands)

    A.P. Hardon; P. Oosterhoff; J.D. Imelda; N.T. Anh; I. Hidayana

    2009-01-01

    How do women and frontline health workers engage in preventing mother-to-child HIV transmission (PMTCT) in urban areas of Vietnam and Indonesia, where HIV is highly stigmatized and is associated with injecting drug use and sex work? This qualitative study explores local dynamics of care, using a mix

  3. T-cell dynamics in healthy and HIV-infected individuals

    NARCIS (Netherlands)

    Vrisekoop, N.

    2007-01-01

    This thesis focuses on T-cell dynamics in healthy and both treated and untreated HIV-infected individuals. Although the progressive decline in CD4+ T-cell numbers is the hallmark of HIV infection, the mechanisms behind this depletion remain controversial. Currently the most prevailing ideas include

  4. Dez anos de epidemia do HIV-AIDS em maiores de 60 anos no Distrito Federal - Brasil Ten years of HIV-AIDS epidemic in more than 60 years in Federal District - Brazil

    Directory of Open Access Journals (Sweden)

    Maria Liz Cunha de Oliveira

    2013-03-01

    Full Text Available INTRODUÇÃO: O aumento progressivo no número de casos de HIV/AIDS em idosos traz a necessidade de estudos sobre as especificidades deste fenômeno por região. OBJETIVO: Descrever as características dos casos de AIDS em indivíduos com idade > 60 anos ou mais no Distrito Federal - Brasil. MÉTODO: Realizou-se um estudo de série temporal, com dados secundários do SINAN/AIDS, no período de Janeiro de 1999 a dezembro 2009. RESULTADO: Neste período foram diagnosticados 4258 novos casos de AIDS; destes, 89 (2,0% são idosos. Embora seja uma porcentagem pequena, o crescimento anual foi contínuo. A categoria de exposição mais frequente foi a de heterossexual, a faixa etária mais acometida foi de 60 a 69 anos com 71 (79,8% casos, e a proporção de casos homem/mulher vem mudando ao longo dos anos, sendo que em 1999 era de 1:1 e, em 2006, de 0,7:1. CONCLUSÕES: A epidemia de HIV/AIDS pode ser considerada estável entre os idosos no Distrito Federal. INTRODUCTION: The progressive increase in number of HIV/AIDS cases in old age brings the necessity of studies about the specificities of this phenomenon by region. OBJECTIVE: To identify the epidemiology in AIDS cases diagnosed in Distrito Federal - Brasil, in individuals aged > 60 years old. METHODS: We conducted a time serie study with secondary data from SINAN/AIDS for the period January 1999 to December 2009. RESULTS: In this period, 4,258 new cases of AIDS were of whom 89 (2.0% are elderly. Although a small percentage, the annual growth was continuous. The most frequent exposure category was heterosexual, the age group most affected was 60 and 69 years, with 71 (79.8% cases; the proportion of cases man/woman has changed over the years, in 1999 was 1:1 and in 2006, 0,7:1. CONCLUSION: The HIV/AIDS epidemic among the elderly can be seen stable on the Distrito Federal.

  5. An integrated approach to care attracts people living with HIV who use illicit drugs in an urban centre with a concentrated HIV epidemic.

    Science.gov (United States)

    Fernando, S; McNeil, R; Closson, K; Samji, H; Kirkland, S; Strike, C; Turje, R Baltzer; Zhang, W; Hogg, R S; Parashar, S

    2016-11-22

    People living with HIV (PLHIV) who are also marginalized by social and structural inequities often face barriers to accessing and adhering to HIV treatment and care. The Dr. Peter Centre (DPC) is a non-profit integrated care facility with a supervised injection room that serves PLHIV experiencing multiple barriers to social and health services in Vancouver, Canada. This study examines whether the DPC is successful in drawing in PLHIV with complex health issues, including addiction. Using data collected by the Longitudinal Investigations into Supportive and Ancillary health services (LISA) study from July 2007 to January 2010, linked with clinical variables available through the British Columbia Centre for Excellence in HIV/AIDS Drug Treatment Program, we identified DPC and non-DPC clients with a history of injection drug use. Bivariable and multivariable logistic regression analyses compared socio-demographic and clinical characteristics of DPC clients (n = 76) and non-DPC clients (n = 482) with a history of injection drug use. Of the 917 LISA participants included within this analysis, 100 (10.9%) reported being a DPC client, of which 76 reported a history of injection drug use. Adjusted results found that compared to non-DPC clients with a history of injection drug use, DPC-clients were more likely to be male (AOR: 4.18, 95% CI = 2.09-8.37); use supportive services daily vs. less than daily (AOR: 3.16, 95% CI = 1.79-5.61); to have been diagnosed with a mental health disorder (AOR: 2.11; 95% CI: 1.12-3.99); to have a history of interpersonal violence (AOR: 2.76; 95% CI: 1.23-6.19); and to have ever experienced ART interruption longer than 1 year (AOR: 2.39; 95% CI: 1.38-4.15). Our analyses suggest that the DPC operating care model engages PLHIV with complex care needs, highlighting that integrated care facilities are needed to support the multiple intersecting vulnerabilities faced by PLHIV with a history of injection drug use living within urban

  6. Configuring the autism epidemic

    DEFF Research Database (Denmark)

    Christensen, Fie Lund Lindegaard; Seeberg, Jens

    2017-01-01

    Autism has been described as an epidemic, but this claim is contested and may point to an awareness epidemic, i.e. changes in the definition of what autism is and more attention being invested in diagnosis leading to a rise in registered cases. The sex ratio of children diagnosed with autism...... is skewed in favour of boys, and girls with autism tend to be diagnosed much later than boys. Building and further developing the notion of ‘configuration’ of epidemics, this article explores the configuration of autism in Denmark, with a particular focus on the health system and social support to families...... with children diagnosed with autism, seen from a parental perspective. The article points to diagnostic dynamics that contribute to explaining why girls with autism are not diagnosed as easily as boys. We unfold these dynamics through the analysis of a case of a Danish family with autism....

  7. Visual Mining of Epidemic Networks

    CERN Document Server

    Clémençon, Stéphan; Rossi, Fabrice; Tran, Viet Chi; 10.1007/978-3-642-21498-1_35

    2012-01-01

    We show how an interactive graph visualization method based on maximal modularity clustering can be used to explore a large epidemic network. The visual representation is used to display statistical tests results that expose the relations between the propagation of HIV in a sexual contact network and the sexual orientation of the patients.

  8. 咸阳市HIV/AIDS流行现状及趋势分析%An Analysis of Epidemic and Trend for HIV/AIDS in Xianyang City

    Institute of Scientific and Technical Information of China (English)

    茹山城

    2007-01-01

    目的 探讨咸阳市HIV/AIDS流行现状并预测其流行趋势,为制定有效预防控制艾滋病流行蔓延政策提供科学依据.方法 对咸阳市1999~2006年的艾滋病报告疫情和哨点疫情进行分析.结果 1999年咸阳市发现首例艾滋病病毒携带者,至2006年底全市共报告HIV/AIDS77例,2003年以后疫情上升较快,2005和2006两年报告55例,占首例报告以来总数的71.43%;职业分布以农民为多;年龄以25~45岁年龄段居多;初期报告多与采供血有关系,性传播和传播途径不详报告病例逐年增多.结论 成阳市艾滋病疫情虽然处在低流行区,但疫情上升较快,正在从高危人群向一般人群扩散,采取积极的预防措施、遏制疫情蔓延很重要.

  9. Proximity Networks and Epidemics

    CERN Document Server

    Toroczkai, Z

    2007-01-01

    Disease spread in most biological populations requires the proximity of agents. In populations where the individuals have spatial mobility, the contact graph is generated by the "collision dynamics" of the agents, and thus the evolution of epidemics couples directly to the spatial dynamics of the population. We first briefly review the properties and the methodology of an agent-based simulation (EPISIMS) to model disease spread in realistic urban dynamic contact networks. Using the data generated by this simulation, we introduce the notion of dynamic proximity networks which takes into account the relevant time scales for disease spread: contact duration, infectivity period and rate of contact creation. This approach promises to be a good candidate for a unified treatment of epidemic types that are driven by agent collision dynamics. In particular, using a simple model, we show that it can can account for the observed qualitative differences between the degree distributions of contact graphs of diseases with ...

  10. HIV-1 A1 Subtype Epidemic in Italy Originated from Africa and Eastern Europe and Shows a High Frequency of Transmission Chains Involving Intravenous Drug Users.

    Directory of Open Access Journals (Sweden)

    Alessia Lai

    Full Text Available Subtype A accounts for only 12% of HIV-1 infections worldwide but predominates in Russia and Former Soviet Union countries of Eastern Europe. After an early propagation via heterosexual contacts, this variant spread explosively among intravenous drug users. A distinct A1 variant predominates in Greece and Albania, which penetrated directly from Africa. Clade A1 accounts for 12.5% of non-B subtypes in Italy, being the most frequent after F1 subtype.Aim of this study was to investigate the circulation of A1 subtype in Italy and trace its origin and diffusion through phylogenetic and phylodynamic approaches.The phylogenetic analysis of 113 A1 pol sequences included in the Italian ARCA database, indicated that 71 patients (62.8% clustered within 5 clades. A higher probability to be detected in clusters was found for patients from Eastern Europe and Italy (88.9% and 60.4%, respectively compared to those from Africa (20% (p < .001. Higher proportions of clustering sequences were found in intravenous drug users with respect to heterosexuals (85.7% vs. 59.3%, p = .056 and in women with respect to men (81.4% vs. 53.2%, p < .006. Subtype A1 dated phylogeny indicated an East African origin around 1961. Phylogeographical reconstruction highlighted 3 significant groups. One involved East European and some Italian variants, the second encompassed some Italian and African strains, the latter included the majority of viruses carried by African and Italian subjects and all viral sequences from Albania and Greece.Subtype A1 originated in Central Africa and spread among East European countries in 1982. It entered Italy through three introduction events: directly from East Africa, from Albania and Greece, and from the area encompassing Moldavia and Ukraine. As in previously documented A1 epidemics of East European countries, HIV-1 A1 subtype spread in Italy in part through intravenous drug users. However, Eastern European women contributed to the penetration of

  11. A stochastic model of the dynamics of HIV under a combination therapeutic intervention

    Directory of Open Access Journals (Sweden)

    VSS Yadavalli

    2009-06-01

    Full Text Available Drug resistance to single therapeutic treatment in HIV infected individuals has promoted research into combined treatments. In this paper we propose a stochastic model under combined therapeutic treatment by extending the model of HIV pathogenesis under treatment by anti-viral drugs given in [Perelson AS, Neumann AU, Markowits M, Leonard JM & Ho DD, 1996, "HIV-1 dynamics in vivo virion clearance rate, infected cell life span, and viral generation time", Science New Series, 271, pp. 1582-1586]. Variance and co-variance structures of variables are obtainable via this approach in addition to the mean numbers of free HIV, infectious free HIV and non-infectious free HIV that were obtained by Perelson et al. Comparing simulated data for before and after treatment indicates the importance of combined treatment and its overall effect(s.

  12. Do support groups members disclose less to their partners? The dynamics of HIV disclosure in four African countries

    NARCIS (Netherlands)

    A. Hardon; G.B. Gomez; E. Vernooij; A. Desclaux; R.K. Wanyenze; O. Ky-Zerbo; E. Kageha; I. Namakhoma; J. Kinsman; C. Spronk; E. Meij; M. Neuman; C.M. Obermeyer

    2013-01-01

    Background Recent efforts to curtail the HIV epidemic in Africa have emphasised preventing sexual transmission to partners through antiretroviral therapy. A component of current strategies is disclosure to partners, thus understanding its motivations will help maximise results. This study examines t

  13. A generating function approach to HIV transmission with dynamic contact rates.

    Science.gov (United States)

    Romero-Severson, E O; Meadors, G D; Volz, E M

    2014-03-01

    The basic reproduction number, R0, is often defined as the average number of infections generated by a newly infected individual in a fully susceptible population. The interpretation, meaning, and derivation of R0 are controversial. However, in the context of mean field models, R0 demarcates the epidemic threshold below which the infected population approaches zero in the limit of time. In this manner, R0 has been proposed as a method for understanding the relative impact of public health interventions with respect to disease eliminations from a theoretical perspective. The use of R0 is made more complex by both the strong dependency of R0 on the model form and the stochastic nature of transmission. A common assumption in models of HIV transmission that have closed form expressions for R0 is that a single individual's behavior is constant over time. In this paper we derive expressions for both R0 and probability of an epidemic in a finite population under the assumption that people periodically change their sexual behavior over time. We illustrate the use of generating functions as a general framework to model the effects of potentially complex assumptions on the number of transmissions generated by a newly infected person in a susceptible population. We find that the relationship between the probability of an epidemic and R0 is not straightforward, but, that as the rate of change in sexual behavior increases both R0 and the probability of an epidemic also decrease.

  14. Epidemic history and evolutionary dynamics of hepatitis B virus infection in two remote communities in rural Nigeria.

    Directory of Open Access Journals (Sweden)

    Joseph C Forbi

    suggested rapid HBV/E population expansion. Additionally, skyline plot analysis showed an increase in the size of the HBV/E-infected population over the last approximately 30-40 years. CONCLUSIONS: Our data suggest a massive introduction and relatively recent HBV/E expansion in the human population in Africa. Collectively, these data show a significant shift in the HBV/E epidemic dynamics in Africa over the last century.

  15. Directed Dynamic Small-World Network Model for Worm Epidemics in Mobile ad hoc Networks

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen-Ping; WANG Li; LIU Xiao-Ting; YAN Zhi-Jun

    2012-01-01

    We investigate the worm spreading process in mobile ad hoc networks with a susceptible-infected-recovered model on a two-dimensional plane.A medium access control mechanism operates within it,inhibiting transmission and relaying a message by using other nodes inside the node's transmitting circle during speaking.We measure the rewiring probability p with the transmitting range r and the average relative velocity (v) of the moving nodes,and map the problem into a directed dynamic small-world network.A new scaling relation for the recovered portion of the nodes reveals the effect caused by geometric distance,which has been ignored by previous models.%We investigate the worm spreading process in mobile ad hoc networks with a susceptible-infected-recovered model on a two-dimensional plane. A medium access control mechanism operates within it, inhibiting transmission and relaying a message by using other nodes inside the node's transmitting circle during speaking. We measure the rewiring probability p with the transmitting range r and the average relative velocity (v) of the moving nodes, and map the problem into a directed dynamic small-world network. A new scaling relation for the recovered portion of the nodes reveals the effect caused by geometric distance, which has been ignored by previous models.

  16. Dynamics of breast milk HIV-1 RNA with unilateral mastitis or abscess

    Science.gov (United States)

    Semrau, Katherine; Kuhn, Louise; Brooks, Daniel R.; Cabral, Howard; Sinkala, Moses; Kankasa, Chipepo; Thea, Donald M.; Aldrovandi, Grace M.

    2013-01-01

    Background Mastitis and abscess in HIV-infected women increase risk of breastfeeding transmission of HIV. Guidelines encourage women to stop breastfeeding on the affected breast and feed on the contralateral breast. However, impact of breast pathology on breast milk HIV dynamics is unknown. Methods HIV RNA was quantified in 211 breast milk samples collected before, during and after a clinical mastitis or abscess diagnosis from 38 HIV-infected women participating in a Zambian breastfeeding study. HIV RNA quantity was compared between affected and unaffected breasts over time using generalized estimating equation models. A sample of 115 women without breast pathology was selected as a control group. Results In the affected breast, breast milk HIV RNA quantity increased from the pre- to during-pathology period by log10 0.45 copies/mL (95% CI: 0.16, 0.74) and after symptom resolution, HIV RNA levels were no different from pre-pathology levels (log10 -0.04 copies/mL 95%CI: -0.33, 0.25). In the contralateral unaffected breast, HIV RNA quantity did not significantly increase (log10 0.15 copies/mL, 95% CI: -0.41, 0.10). Increase was more marked in women with abscess or with a greater number of mastitis symptoms. HIV RNA was not significantly different between affected and unaffected women, except at the time of diagnosis. Conclusions Breast milk HIV RNA increased modestly in the affected breast with unilateral mastitis or abscess and returned to pre-pathology levels with symptom resolution. Contralateral HIV RNA was not affected. Results support guidelines encouraging feeding from the contralateral breast to minimize risk of HIV transmission associated with unilateral breast pathology. PMID:23202812

  17. A assistência de enfermagem aos portadores de HIV/Aids no vislumbrar da sua epidemia em Ribeirão Preto: relato de experiÊncia de uma equipe de enfermagem The nursing assistance of HIV/Aids messenger in the glimpse of the epidemic in Ribeirão Preto city: experience report of a nursing team

    Directory of Open Access Journals (Sweden)

    Therezinha J.O. Resuto

    2000-09-01

    Full Text Available Trata-se de um relato de experiência vivenciada por uma equipe de enfermagem de uma Unidade de Internação, de um hospi tal geral do interior paulista, ao planejar e prestar assistência de enfermagem ao portador do HIV/Aids, no início da epidemia, em 1985.This is a report about the experience faced by a nursing team from public hospital in São Paulo city, that took care of HIV/Aids patients in the beginning of the epidemic in 1985.

  18. Cholera Transmission in Ouest Department of Haiti: Dynamic Modeling and the Future of the Epidemic.

    Directory of Open Access Journals (Sweden)

    Alexander Kirpich

    Full Text Available In the current study, a comprehensive, data driven, mathematical model for cholera transmission in Haiti is presented. Along with the inclusion of short cycle human-to-human transmission and long cycle human-to-environment and environment-to-human transmission, this novel dynamic model incorporates both the reported cholera incidence and remote sensing data from the Ouest Department of Haiti between 2010 to 2014. The model has separate compartments for infectious individuals that include different levels of infectivity to reflect the distribution of symptomatic and asymptomatic cases in the population. The environmental compartment, which serves as a source of exposure to toxigenic V. cholerae, is also modeled separately based on the biology of causative bacterium, the shedding of V. cholerae O1 by humans into the environment, as well as the effects of precipitation and water temperature on the concentration and survival of V. cholerae in aquatic reservoirs. Although the number of reported cholera cases has declined compared to the initial outbreak in 2010, the increase in the number of susceptible population members and the presence of toxigenic V. cholerae in the environment estimated by the model indicate that without further improvements to drinking water and sanitation infrastructures, intermittent cholera outbreaks are likely to continue in Haiti.

  19. Cholera Transmission in Ouest Department of Haiti: Dynamic Modeling and the Future of the Epidemic

    Science.gov (United States)

    Kirpich, Alexander; Weppelmann, Thomas A.; Yang, Yang; Ali, Afsar; Morris, J. Glenn; Longini, Ira M.

    2015-01-01

    In the current study, a comprehensive, data driven, mathematical model for cholera transmission in Haiti is presented. Along with the inclusion of short cycle human-to-human transmission and long cycle human-to-environment and environment-to-human transmission, this novel dynamic model incorporates both the reported cholera incidence and remote sensing data from the Ouest Department of Haiti between 2010 to 2014. The model has separate compartments for infectious individuals that include different levels of infectivity to reflect the distribution of symptomatic and asymptomatic cases in the population. The environmental compartment, which serves as a source of exposure to toxigenic V. cholerae, is also modeled separately based on the biology of causative bacterium, the shedding of V. cholerae O1 by humans into the environment, as well as the effects of precipitation and water temperature on the concentration and survival of V. cholerae in aquatic reservoirs. Although the number of reported cholera cases has declined compared to the initial outbreak in 2010, the increase in the number of susceptible population members and the presence of toxigenic V. cholerae in the environment estimated by the model indicate that without further improvements to drinking water and sanitation infrastructures, intermittent cholera outbreaks are likely to continue in Haiti. PMID:26488620

  20. Dynamics Analysis and Simulation of a Modified HIV Infection Model with a Saturated Infection Rate

    Directory of Open Access Journals (Sweden)

    Qilin Sun

    2014-01-01

    Full Text Available This paper studies a modified human immunodeficiency virus (HIV infection differential equation model with a saturated infection rate. It is proved that if the basic virus reproductive number R0 of the model is less than one, then the infection-free equilibrium point of the model is globally asymptotically stable; if R0 of the model is more than one, then the endemic infection equilibrium point of the model is globally asymptotically stable. Based on the clinical data from HIV drug resistance database of Stanford University, using the proposed model simulates the dynamics of the two groups of patients’ anti-HIV infection treatment. The numerical simulation results are in agreement with the evolutions of the patients’ HIV RNA levels. It can be assumed that if an HIV infected individual’s basic virus reproductive number R0<1 then this person will recover automatically; if an antiretroviral therapy makes an HIV infected individual’s R0<1, this person will be cured eventually; if an antiretroviral therapy fails to suppress an HIV infected individual’s HIV RNA load to be of unpredictable level, the time that the patient’s HIV RNA level has achieved the minimum value may be the starting time that drug resistance has appeared.

  1. Reconstructing the origin and transmission dynamics of the 1967-68 foot-and-mouth disease epidemic in the United Kingdom.

    Science.gov (United States)

    Wright, Caroline F; Knowles, Nick J; Di Nardo, Antonello; Paton, David J; Haydon, Daniel T; King, Donald P

    2013-12-01

    A large epidemic of foot-and-mouth disease (FMD) occurred in the United Kingdom (UK) over a seven month period in Northwest England from late 1967 to the summer of 1968. This was preceded by a number of smaller FMD outbreaks in the country, two in 1967, in Hampshire and Warwickshire and one in Northumberland during 1966. The causative agent of all four events was identified as FMD virus (FMDV) serotype O and the source of the large epidemic was attributed to infected bone marrow in lamb products imported from Argentina. However, the diagnostic tools available at the time were unable to entirely rule out connections with the earlier UK FMD outbreaks, as well as other potential sources from Europe. The aim of this study was to apply molecular sequencing to investigate the likely source of this epidemic using VP1 region and full genome (FG) sequences determined directly from clinical epithelium samples (n=13) or cell culture isolates (n=6), from this and contemporary outbreaks in the UK, Europe and South America. Analysis of the VP1 sequences provided evidence for at least three separate incursions of FMDV into the UK including one independent introduction that was responsible for the main 1967/68 epidemic. Analysis of FG sequences from the main 1967/68 outbreak (n=10) revealed nucleotide substitutions at 94 genomic sites providing evidence for the linear accumulation of nucleotide substitutions (rate=2.42 × 10(-)(5)nt substitutions/site/day). However, there were five samples where this linear relationship was absent, indicating evolutional dormancy of the virus, presumably outside a host. These results help define the evolutionary dynamics of FMDV during an epidemic and contribute to the knowledge and understanding from which to base future outbreak control strategies.

  2. Understanding the HIV coreceptor switch from a dynamical perspective

    Directory of Open Access Journals (Sweden)

    Kamp Christel

    2009-11-01

    Full Text Available Abstract Background The entry of HIV into its target cells is facilitated by the prior binding to the cell surface molecule CD4 and a secondary coreceptor, mostly the chemokine receptors CCR5 or CXCR4. In early infection CCR5-using viruses (R5 viruses are mostly dominant while a receptor switch towards CXCR4 occurs in about 50% of the infected individuals (X4 viruses which is associated with a progression of the disease. There are many hypotheses regarding the underlying dynamics without yet a conclusive understanding. Results While it is difficult to isolate key factors in vivo we have developed a minimal in silico model based on the approaches of Nowak and May to investigate the conditions under which the receptor switch occurs. The model allows to investigate the evolution of viral strains within a probabilistic framework along the three stages of disease from primary and latent infection to the onset of AIDS with a a sudden increase in viral load which goes along with the impairment of the immune response. The model is specifically applied to investigate the evolution of the viral quasispecies in terms of R5 and X4 viruses which directly translates into the composition of viral load and consequently the question of the coreceptor switch. Conclusion The model can explain the coreceptor switch as a result of a dynamical change in the underlying environmental conditions in the host. The emergence of X4 strains does not necessarily result in the dominance of X4 viruses in viral load which is more likely to occur in the model after some time of chronic infection. A better understanding of the conditions leading to the coreceptor switch is especially of interest as CCR5 blockers have recently been licensed as drugs which suppress R5 viruses but do not seem to necessarily induce a coreceptor switch.

  3. 趋势面分析法在艾滋病地理分布研究中的应用%Application of trend surface analysis method in geographical distribution of HIV/AIDS epidemic research

    Institute of Scientific and Technical Information of China (English)

    王璐; 罗静; 邓丹; 杨书; 张强

    2014-01-01

    Objective To study the geographical distribution of the HIV/AIDS epidemic in C city .Methods Based on the theory of multiple regression analysis ,trend surface regression mathematical model was constructed .The latitude and longitude coordinates of different districts and data of HIV/AIDS were collected in the model and the results by ArcGIS software were got ,the trend sur-face analysis chart was drawed at last .Results HIV/AIDS infection rates trend surface regression mathematical model of C city was statistically significant difference(P< 0 .05) ,its goodness-of-fit was 53 .18% .Regions exsisted abnormal residual value and should be the paid attention to explore protective or risk factors in these regions .Conclusion The method can be used in the analy-sis of C city HIV/AIDS epidemic systematic variation in the geographic distribution and local district ,and provide some clues for the local epidemic prevention and controlling of HIV/AIDS .%目的:了解某市艾滋病疫情的地理分布特征。方法以多元回归分析理论为基础,构建趋势面回归数学模型,将不同区县的经纬度坐标及艾滋病感染数据代入模型,并根据模型方程计算结果,通过 A rcG IS软件,绘制趋势面分析图。结果某市艾滋病感染率趋势面回归数学模型有统计学意义( P<0.05),其拟合优度为53.18%。存在异常残差值的地区,应作为重点研究对象,探讨这些地区可能存在的某种保护因素或危险因素。结论该方法可用于分析某市艾滋病疫情的地理分布系统变异和局部变异情况,可为当地艾滋病的疫情防控提供一些线索。

  4. Exploring migratory dynamics on HIV transmission: the case of Mexicans in New York City and Puebla, Mexico.

    Science.gov (United States)

    Ruiz, Yumary; Guilamo-Ramos, Vincent; McCarthy, Katharine; Muñoz-Laboy, Miguel A; de Lourdes Rosas López, Maria

    2014-06-01

    Migration and population movement are increasingly viewed as important factors associated with HIV transmission risk. With growing awareness of the potential impact of migration on HIV transmission, several perspectives have emerged that posit differing dynamics of risk. We considered available data on the role of migration on HIV transmission among Mexican migrants in New York City and Puebla, Mexico. Specifically, we examined 3 distinct models of migratory dynamics of HIV transmission-namely, the structural model, the local contextual model, and the interplay model. In doing so, we reframed current public health perspectives on the role of migration on HIV transmission.

  5. (AJST) TRANSMISSION DYNAMICS OF HIV/AIDS WITH ...

    African Journals Online (AJOL)

    decrease in risky behaviour resulting from HIV counselling ... therapy (ART) can translate into a significant benefit from ... In reality, populations may not be homogeneously mixed and thus it is more realistic to take heterogeneities in population ...

  6. The dynamics of T and B cells in lymph node during chronic HIV infection: TFH and HIV, unhappy dance partners?

    Directory of Open Access Journals (Sweden)

    Jung Joo Hong

    2016-11-01

    Full Text Available Although the dynamics of germinal center (GC formation, TFH cell recruitment to B cell follicles within lymphoid organs and changes of lymphoid tissue architecture in HIV/SIV infection have been documented, the underlying immunopathology remains unclear. Here, we summarize what is known regarding the kinetics of TFH cells and GC B cells during the course of infection as well as the potential immunopathological features associated with structural changes in the lymphoid compartment. This review also explores the implications cell dynamics in the formation and maintenance of viral reservoirs in hyperplastic follicles of secondary lymphoid organs before and after viral suppressive antiretroviral therapy.

  7. 柳州市1996-2010年艾滋病流行病学特征分析%Analysis on the epidemic characteristics of HIV/AIDS in Liuzhou from 1996 to 2010

    Institute of Scientific and Technical Information of China (English)

    冯献湘; 黎明强; 潘洁; 刘金纪

    2011-01-01

    目的 了解柳州市1996-2010年人类免疫缺陷病毒感染者(human immunodeficiency virus,HIV)和获得性免疫缺陷综合征病人(acquired immuno deficiency syndrome,AIDS)流行病学特征,为制订防控措施提供科学依据.方法 对1996-2010年艾滋病疫情报告和流行病学调查资料进行统计分析.结果 柳州市艾滋病感染情况呈明显上升趋势,所辖区县均有病例出现,总体呈弥漫性扩散趋势,感染病例已进入发病和死亡高峰;男性高于女性,女性比例有所增加;20 ~39岁年龄组为主,约占50%;40 ~59岁及60岁以上人群所占比例逐年增大;以农民和家务待业人员为主,约占60%,农民所占比例逐年增大;以异性性传播为主,占80%以上;非婚异性性行为是异性性传播的重要影响因素,样本来源中临床医疗机构占了新报告病例的75.1%,是最主要的疫情报告来源.结论 柳州市HIV/AIDS流行情况愈趋严重和复杂,控制传染源,切断传播途径,保护易感人群是防止艾滋病向普通人群蔓延的重要策略.%Objective To study the HIV/AIDS epidemic characteristics of liuzhou from 1996 to 2010, and provide scientific basis for making strategy to control the AIDS. Method The AIDS epidemic reported and epidemiological study data of 19% to 2010 were collected and analyzed. Results The HIV/AIDS infection status in Liuzhou showed obviously rise trend, and the patients appeared in all the counties. The disease showed diffuse trend, infection cases had came to the peak time of disease develop and death. Male patients were more than female, but female proportion had increased. Most of the patients were at the age of 20 to 39, which accounted for 30% , the proportion of 40 to 59 years group and over 60 years group grown. Most of the patients were farmers and unemployed people, which accounted for 60% , and the proportion of farmer was growing. The route of transmission was heterosexual sexual transmission, it

  8. Geographical differences of HIV/AIDS epidemic characteristics in Guangxi from 1996 to 2012%1996-2012年广西艾滋病流行地理差异分析

    Institute of Scientific and Technical Information of China (English)

    朱秋映; 陈栏心; 董柏青; 唐振柱; 沈智勇; 刘伟; 李明丽; 吴兴华

    2015-01-01

    目的:探讨广西1996—2012年艾滋病流行的地理差异,为针对性防控策略和措施的制定提供科学依据。方法以县(市、区)为基本统计单位,通过地理信息系统(GIS)软件的自然断点分级法,划分艾滋病累积报告感染率(CRIR)和累积报告发病率(CRI)的高、中、低流行区,对比分析各县的差异。结果累积报告感染率为高、中、低流行区的县分别有19、40、50个,相应区间分别为302.91/10万~700.98/10万、124.90/10万~302.90/10万、18.42/10万~124.89/10万;累积报告发病率为高、中、低流行区的县分别有13、35、61个,相应区间为159.79/10万~428.09/10万、64.69/10万~159.78/10万、7.23/10万~64.68/10万。以CRI为参照,CRIR与CRI高、中、低流行区的分布一致率分别为100.00%、82.86%、93.44%。广西艾滋病CRIR和CRI高、中、低流行区的分布呈“同心圆”状辐射递减及“孤点”现象。结论广西艾滋病流行有明显的地理差异性,其流行强度是地理、经济、社会、资源等各方面因素相互作用的结果,今后艾滋病防控策略研究应该融合更多的经济社会因素,以使防控更有成效。%Objective To explore the geographical differences of HIV/AIDS epidemic characteristics in Guangxi from 1996 to 2012, and provide scientific evidence for the targeted prevention and control strategies and measures. Methods The infected persons were seleted and counted up by county (city/district) as the basic statistical unit. The total of 109 counties (cities/districts) of Guangxi were classified into high, middle and low epidemic areas of HIV/AIDS according to cumulative reported infection rate(CRIR)and cumulative reported of incidence (CRI) by natural breakout classification method of the geographic information system (GIS) ,and compared the differences among different epidemic areas. Results Nineteen, forty, and fifty counties were classified

  9. Effect of crop growth and canopy filtration on the dynamics of plant disease epidemics spread by aerially dispersed spores.

    Science.gov (United States)

    Ferrandino, F J

    2008-05-01

    Most mathematical models of plant disease epidemics ignore the growth and phenology of the host crop. Unfortunately, reports of disease development are often not accompanied by a simultaneous and commensurate evaluation of crop development. However, the time scale for increases in the leaf area of field crops is comparable to the time scale of epidemics. This simultaneous development of host and pathogen has many ramifications on the resulting plant disease epidemic. First, there is a simple dilution effect resulting from the introduction of new healthy leaf area with time. Often, measurements of disease levels are made pro rata (per unit of host leaf area or total root length or mass). Thus, host growth will reduce the apparent infection rate. A second, related effect, has to do with the so-called "correction factor," which accounts for inoculum falling on already infected tissue. This factor accounts for multiple infection and is given by the fraction of the host tissue that is susceptible to disease. As an epidemic develops, less and less tissue is open to infection and the initial exponential growth slows. Crop growth delays the impact of this limiting effect and, therefore, tends to increase the rate of disease progress. A third and often neglected effect arises when an increase in the density of susceptible host tissue results in a corresponding increase in the basic reproduction ratio, R(0), defined as the ratio of the total number of daughter lesions produced to the number of original mother lesions. This occurs when the transport efficiency of inoculum from infected to susceptible host is strongly dependent on the spatial density of plant tissue. Thus, crop growth may have a major impact on the development of plant disease epidemics occurring during the vegetative phase of crop growth. The effects that these crop growth-related factors have on plant disease epidemics spread by airborne spores are evaluated using mathematical models and their importance is

  10. Epidemic cholera spreads like wildfire

    Science.gov (United States)

    Roy, Manojit; Zinck, Richard D.; Bouma, Menno J.; Pascual, Mercedes

    2014-01-01

    Cholera is on the rise globally, especially epidemic cholera which is characterized by intermittent and unpredictable outbreaks that punctuate periods of regional disease fade-out. These epidemic dynamics remain however poorly understood. Here we examine records for epidemic cholera over both contemporary and historical timelines, from Africa (1990-2006) and former British India (1882-1939). We find that the frequency distribution of outbreak size is fat-tailed, scaling approximately as a power-law. This pattern which shows strong parallels with wildfires is incompatible with existing cholera models developed for endemic regions, as it implies a fundamental role for stochastic transmission and local depletion of susceptible hosts. Application of a recently developed forest-fire model indicates that epidemic cholera dynamics are located above a critical phase transition and propagate in similar ways to aggressive wildfires. These findings have implications for the effectiveness of control measures and the mechanisms that ultimately limit the size of outbreaks.

  11. The Role of Viral Introductions in Sustaining Community-Based HIV Epidemics in Rural Uganda: Evidence from Spatial Clustering, Phylogenetics, and Egocentric Transmission Models

    OpenAIRE

    Grabowski, Mary K.; Justin Lessler; Redd, Andrew D.; Joseph Kagaayi; Oliver Laeyendecker; Anthony Ndyanabo; Nelson, Martha I.; Cummings, Derek A. T.; John Baptiste Bwanika; Mueller, Amy C.; Reynolds, Steven J.; Supriya Munshaw; Ray, Stuart C.; Tom Lutalo; Jordyn Manucci

    2014-01-01

    Editors' Summary Background About 35 million people (25 million of whom live in sub-Saharan Africa) are currently infected with HIV, the virus that causes AIDS, and about 2.3 million people become newly infected every year. HIV destroys immune system cells, leaving infected individuals susceptible to other infections. HIV infection can be controlled by taking antiretroviral drugs (antiretroviral therapy, or ART) daily throughout life. Although originally available only to people living in wea...

  12. Irregularity in dengue fever epidemics: difference between first and secondary infections drives the rich dynamics more than the detailed number of strains

    CERN Document Server

    Aguiar, Maíra; Stollenwerk, Nico

    2011-01-01

    Different extensions of the classical single-strain SIR model for the host population, motivated by modeling dengue fever epidemiology, have reported a rich dynamic structure including deterministic chaos which was able to explain the large fluctuations of disease incidences. A comparison between the basic two-strain dengue model, which already captures differences between primary and secondary infections, with the four-strain dengue model, that introduces the idea of competition of multiple strains in dengue epidemics shows that the difference between first and secondary infections drives the rich dynamics more than the detailed number of strains to be considered in the model structure. Chaotic dynamics were found to happen at the same parameter region of interest, for both the two and the four-strain models, able to explain the fluctuations observed in empirical data and showing a qualitatively good agreement between empirical data and model simulation. Since the law of parsimony favors the simplest of two ...

  13. Tracing the origin and northward dissemination dynamics of HIV-1 subtype C in Brazil.

    Directory of Open Access Journals (Sweden)

    Edson Delatorre

    Full Text Available Previous studies indicate that the HIV-1 subtype C epidemic in southern Brazil was initiated by the introduction of a single founder strain probably originating from east Africa. However, the exact country of origin of such a founder strain as well as the origin of the subtype C viruses detected outside the Brazilian southern region remains unknown. HIV-1 subtype C pol sequences isolated in the southern, southeastern and central-western Brazilian regions (n = 209 were compared with a large number (n ~ 2,000 of subtype C pol sequences of African origin. Maximum-likelihood analyses revealed that most HIV-1 subtype C Brazilian sequences branched in a single monophyletic clade (CBR-I, nested within a larger monophyletic lineage characteristic of east Africa. Bayesian analyses indicate that the CBR-I clade most probably originated in Burundi and was introduced into the Paraná state (southern region around the middle 1970s, after which it rapidly disseminated to neighboring regions. The states of Paraná and Santa Catarina have been the most important hubs of subtype C dissemination, and routine travel and spatial accessibility seems to have been the major driving forces of this process. Five additional introductions of HIV-1 subtype C strains probably originated in eastern (n = 2, southern (n = 2 and central (n = 1 African countries were detected in the Rio de Janeiro state (southeastern region. These results indicate a continuous influx of HIV-1 subtype C strains of African origin into Brazil and also unveil the existence of unrecognized transmission networks linking this country to east Africa.

  14. Analysis on HIV/AIDS Epidemic Characteristics in Huarong County from 2004 to 2010%华容县2004-2010年艾滋病流行特征分析

    Institute of Scientific and Technical Information of China (English)

    熊诗泉; 张志华; 杨能斌

    2012-01-01

    目的 了解华容县艾滋病的流行特征,为制定艾滋病的防治措施提供一定的理论依据. 方法 采用描述性流行病学方法对艾滋病疫情资料进行分析. 结果 2004 - 2010年华容县共报告HIV感染者/艾滋病患者59例,其中艾滋病患者28例,死亡18例.年龄主要在25~44岁,占71.1%;男性31例,占52.54%;职业分布以农民和家政、家务及待业人员为主,占50.8%;以性接触传播为主,占76.3%. 结论 华容县艾滋病疫情呈快速上升趋势,疫情已从高危人群向普通人群蔓延,必须采取有效的防治措施控制艾滋病的流行和蔓延.%Objective To investigate the characteristics of HIV/AIDS epidemic in Huarong County, and to provide a theoretical basis for developing effective and feasible control measures. Methods Descriptive epidemiological method was used for analyzing AIDS situation in Huarong County during the period of 2004-2010. Results There were 59 cases of HIV/AIDS reported in Huarong County from 2004 to 2010, including 28 cases of AIDS and 18 death cases. The age distribution was mainly between 25 to 44 years old, accounting for 71.1 %. There were 31 male patients, accounting for 52.54%. The proportion of peasants, housekeeping employees, and unemployment was 50.8%. Most of the patients infected with HIV/AIDS were mainly through sexual contact, accounted for 76.3%. Conclusions The prevalence of AIDS in Huarong County showed rapidly increasing trends, and the epidemic spread of HIV/AIDS was from high-risk groups to general population. Therefore, the effective countermeasures are necessary in controlling the prevalence of HIV/AIDS.

  15. HIV Sexual Risk Behavior and Family Dynamics in a Dominican Tourism Town

    Science.gov (United States)

    Guilamo-Ramos, Vincent; Padilla, Mark; Cedar, Anna Lindberg; Lee, Jane; Robles, Gabriel

    2013-01-01

    Expansion of the tourism industry in the Dominican Republic has had far-reaching health consequences for the local population. Research suggests families with one or more members living in tourism areas experience heightened vulnerability to HIV/STIs due to exposure to tourism environments, which can promote behaviors such as commercial and transactional sex and elevated alcohol use. Nevertheless, little is known about how tourism contexts influence family dynamics, which, in turn, shape HIV risk. This qualitative study examined family relationships through in-depth interviews with 32 adults residing in Sosúa, an internationally known destination for sex tourism. Interviewees situated HIV risk within a context of limited employment opportunities, high rates of migration, heavy alcohol use, and separation from family. This study has implications for effective design of health interventions that make use of the role of the family to prevent HIV transmission in tourism environments. PMID:23436038

  16. HIV sexual risk behavior and family dynamics in a Dominican tourism town.

    Science.gov (United States)

    Guilamo-Ramos, Vincent; Padilla, Mark; Cedar, Anna Lindberg; Lee, Jane; Robles, Gabriel

    2013-10-01

    Expansion of the tourism industry in the Dominican Republic has had far-reaching health consequences for the local population. Research suggests families with one or more members living in tourism areas experience heightened vulnerability to HIV/STIs due to exposure to tourism environments, which can promote behaviors such as commercial and transactional sex and elevated alcohol use. Nevertheless, little is known about how tourism contexts influence family dynamics, which, in turn, shape HIV risk. This qualitative study examined family relationships through in-depth interviews with 32 adults residing in Sosúa, an internationally known destination for sex tourism. Interviewees situated HIV risk within a context of limited employment opportunities, high rates of migration, heavy alcohol use, and separation from family. This study has implications for effective design of health interventions that make use of the role of the family to prevent HIV transmission in tourism environments.

  17. The Role of Relationship Dynamics and Gender Inequalities As Barriers to HIV-Serostatus Disclosure: Qualitative Study among Women and Men Living with HIV in Durban, South Africa.

    Science.gov (United States)

    Bhatia, Divya S; Harrison, Abigail D; Kubeka, Muriel; Milford, Cecilia; Kaida, Angela; Bajunirwe, Francis; Wilson, Ira B; Psaros, Christina; Safren, Steven A; Bangsberg, David R; Smit, Jennifer A; Matthews, Lynn T

    2017-01-01

    This qualitative study investigated gender power inequalities as they contribute to relationship dynamics and HIV-serostatus disclosure among men and women living with HIV in Durban, South Africa. HIV serodiscordance among men and women within stable partnerships contributes to high HIV incidence in southern Africa, yet disclosure rates remain low. Given the emphasis on prevention for HIV-serodiscordant couples, this research supports the urgent need to explore how best to support couples to recognize that they are part of this priority population and to access appropriate prevention and treatment. Thirty-five in-depth individual interviews were conducted with 15 HIV-positive men and 20 HIV-positive women (not couples) receiving care at public-sector clinics near Durban. A structured coding scheme was developed to investigate men's and women's attitudes toward HIV-serostatus disclosure and behaviors of sharing (or not sharing) HIV serostatus with a partner. Narratives were analyzed for barriers and facilitators of disclosure through the lens of sociocultural gender inequality, focusing on reasons for non-disclosure. Among 35 participants: median age was 33 years (men) and 30 years (women); average years since HIV diagnosis was 1 (men) and 1.5 (women). Four themes related to gender inequality and HIV-serostatus disclosure emerged: (1) Men and women fear disclosing to partners due to concerns about stigma and relationship dissolution, (2) suspicions and mistrust between partners underlies decisions for non-disclosure, (3) unequal, gendered power in relationships causes differential likelihood and safety of disclosure among men and women, and (4) incomplete or implicit disclosure are strategies to navigate disclosure challenges. Findings illustrate HIV-serostatus disclosure as a complex process evolving over time, rather than a one-time event. Partner communication about HIV serostatus is infrequent and complicated, with gender inequalities contributing to fear

  18. The Role of Relationship Dynamics and Gender Inequalities As Barriers to HIV-Serostatus Disclosure: Qualitative Study among Women and Men Living with HIV in Durban, South Africa

    Directory of Open Access Journals (Sweden)

    Divya S. Bhatia

    2017-07-01

    Full Text Available BackgroundThis qualitative study investigated gender power inequalities as they contribute to relationship dynamics and HIV-serostatus disclosure among men and women living with HIV in Durban, South Africa. HIV serodiscordance among men and women within stable partnerships contributes to high HIV incidence in southern Africa, yet disclosure rates remain low. Given the emphasis on prevention for HIV-serodiscordant couples, this research supports the urgent need to explore how best to support couples to recognize that they are part of this priority population and to access appropriate prevention and treatment.MethodsThirty-five in-depth individual interviews were conducted with 15 HIV-positive men and 20 HIV-positive women (not couples receiving care at public-sector clinics near Durban. A structured coding scheme was developed to investigate men’s and women’s attitudes toward HIV-serostatus disclosure and behaviors of sharing (or not sharing HIV serostatus with a partner. Narratives were analyzed for barriers and facilitators of disclosure through the lens of sociocultural gender inequality, focusing on reasons for non-disclosure.ResultsAmong 35 participants: median age was 33 years (men and 30 years (women; average years since HIV diagnosis was 1 (men and 1.5 (women. Four themes related to gender inequality and HIV-serostatus disclosure emerged: (1 Men and women fear disclosing to partners due to concerns about stigma and relationship dissolution, (2 suspicions and mistrust between partners underlies decisions for non-disclosure, (3 unequal, gendered power in relationships causes differential likelihood and safety of disclosure among men and women, and (4 incomplete or implicit disclosure are strategies to navigate disclosure challenges. Findings illustrate HIV-serostatus disclosure as a complex process evolving over time, rather than a one-time event.ConclusionPartner communication about HIV serostatus is infrequent and complicated

  19. Epidemic centrality and the underestimated epidemic impact on network peripheral nodes

    CERN Document Server

    Sikic, Mile; Antulov-Fantulin, Nino; Stefancic, Hrvoje

    2011-01-01

    Studies of disease spreading on complex networks have provided a deep insight into the conditions of onset, dynamics and prevention of epidemics in human populations and malicious software propagation in computer networks. Identifying nodes which, when initially infected, infect the largest part of the network and ranking them according to their epidemic impact is a priority for public health policies. In simulations of the disease spreading in SIR model on studied empirical complex networks, it is shown that the ranking depends on the dynamical regime of the disease spreading. A possible mechanism leading to this dynamical dependence is illustrated in an analytically tractable example. A measure called epidemic centrality, averaging the epidemic impact over all possible disease spreading regimes, is introduced as a basis of epidemic ranking. Contrary to standard notion, the epidemic centrality of nodes with high degree, k-cores value or betweenness, which are structurally central, is comparable to epidemic c...

  20. The HIV-poverty thesis re-examined: poverty, wealth or inequality as a social determinant of HIV infection in sub-Saharan Africa?

    Science.gov (United States)

    Fox, Ashley M

    2012-07-01

    Although health is generally believed to improve with higher wealth, research on HIV in sub-Saharan Africa has shown otherwise. Whereas researchers and advocates have frequently advanced poverty as a social determinant that can help to explain sub-Saharan Africa's disproportionate burden of HIV infection, recent evidence from population surveys suggests that HIV infection is higher among wealthier individuals. Furthermore, wealthier countries in Africa have experienced the fastest growing epidemics. Some researchers have theorized that inequality in wealth may be more important than absolute wealth in explaining why some countries have higher rates of infection and rapidly increasing epidemics. Studies taking a longitudinal approach have further suggested a dynamic process whereby wealth initially increases risk for HIV acquisition and later becomes protective. Prior studies, conducted exclusively at either the individual or the country level, have neither attempted to disentangle the effects of absolute and relative wealth on HIV infection nor to look simultaneously at different levels of analysis within countries at different stages in their epidemics. The current study used micro-, meso- and macro-level data from Demographic and Health Surveys (DHS) across 170 regions within sixteen countries in sub-Saharan Africa to test the hypothesis that socioeconomic inequality, adjusted for absolute wealth, is associated with greater risk of HIV infection. These analyses reveal that inequality trumps wealth: living in a region with greater inequality in wealth was significantly associated with increased individual risk of HIV infection, net of absolute wealth. The findings also reveal a paradox that supports a dynamic interpretation of epidemic trends: in wealthier regions/countries, individuals with less wealth were more likely to be infected with HIV, whereas in poorer regions/countries, individuals with more wealth were more likely to be infected with HIV. These

  1. Hierarchical Bayesian methods for estimation of parameters in a longitudinal HIV dynamic system.

    Science.gov (United States)

    Huang, Yangxin; Liu, Dacheng; Wu, Hulin

    2006-06-01

    HIV dynamics studies have significantly contributed to the understanding of HIV infection and antiviral treatment strategies. But most studies are limited to short-term viral dynamics due to the difficulty of establishing a relationship of antiviral response with multiple treatment factors such as drug exposure and drug susceptibility during long-term treatment. In this article, a mechanism-based dynamic model is proposed for characterizing long-term viral dynamics with antiretroviral therapy, described by a set of nonlinear differential equations without closed-form solutions. In this model we directly incorporate drug concentration, adherence, and drug susceptibility into a function of treatment efficacy, defined as an inhibition rate of virus replication. We investigate a Bayesian approach under the framework of hierarchical Bayesian (mixed-effects) models for estimating unknown dynamic parameters. In particular, interest focuses on estimating individual dynamic parameters. The proposed methods not only help to alleviate the difficulty in parameter identifiability, but also flexibly deal with sparse and unbalanced longitudinal data from individual subjects. For illustration purposes, we present one simulation example to implement the proposed approach and apply the methodology to a data set from an AIDS clinical trial. The basic concept of the longitudinal HIV dynamic systems and the proposed methodologies are generally applicable to any other biomedical dynamic systems.

  2. Network Firewall Dynamics and the Subsaturation Stabilization of HIV

    Directory of Open Access Journals (Sweden)

    Bilal Khan

    2013-01-01

    individuals engaging in risk acts over a period of 15 years. The model’s parameters are based on analyses of data collected in prior studies of the real-world risk networks of people who inject drugs (PWID in New York City. Analysis of system trajectories reveals the structural mechanisms by which individuals with mature HIV infections tend to partition the network into homogeneous clusters (with respect to infection status and how uninfected clusters remain relatively stable (with respect to infection status over long stretches of time. We confirm the spontaneous emergence of network firewalls in the system and reveal their structural role in the nonspreading of HIV.

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... depict the devastating consequences of compromised judgment and critical thinking that can result from drug use. Young ... HIV epidemic. As we learn more about the critical connection between drug abuse and HIV/AIDS and ...

  4. Inferring epidemic contact structure from phylogenetic trees.

    Directory of Open Access Journals (Sweden)

    Gabriel E Leventhal

    Full Text Available Contact structure is believed to have a large impact on epidemic spreading and consequently using networks to model such contact structure continues to gain interest in epidemiology. However, detailed knowledge of the exact contact structure underlying real epidemics is limited. Here we address the question whether the structure of the contact network leaves a detectable genetic fingerprint in the pathogen population. To this end we compare phylogenies generated by disease outbreaks in simulated populations with different types of contact networks. We find that the shape of these phylogenies strongly depends on contact structure. In particular, measures of tree imbalance allow us to quantify to what extent the contact structure underlying an epidemic deviates from a null model contact network and illustrate this in the case of random mixing. Using a phylogeny from the Swiss HIV epidemic, we show that this epidemic has a significantly more unbalanced tree than would be expected from random mixing.

  5. HIV prevalence and gender differences among new injection-drug-users in Tallinn, Estonia: A persisting problem in a stable high prevalence epidemic

    Science.gov (United States)

    Uusküla, Anneli; Raag, Mait; Marsh, Kristina; Talu, Ave; Vorobjov, Sigrid; Des Jarlais, Don

    2017-01-01

    Introduction New injectors / younger drug users are an important population to target for intervention because they are often at especially high risk of HIV and HCV infection. We examined HIV prevalence and gender differences in HIV prevalence and risk behavior among new injection-drug-users in Tallinn, Estonia. Methods Respondent driven sampling (RDS) interview surveys and HIV testing were conducted in Tallinn in 2009, 2011 and 2013. We classified “new injectors” as persons who reported their first injection as occurring within three years of the study interview. Recruiting trees of the three individual RDS studies were joined to form one RDS dataset and RDS estimates for prevalence and means were derived. Bootstrap tests were used to compare data from men and women, HIV infected and uninfected. Results Among 110 new injectors (34 women and 76 men) the mean age was 24.5 (SD 7.5) years; 63% reported injecting mainly fentanyl, 34% injecting mainly amphetamine, 36% sharing syringes, 89% were sexually active, and, of these, 88% did not always use condoms in the last 6 months. HIV prevalence was 18% (95%CI 8–28%) (41% (95%CI 19–63%) among female and 7% (95%CI 2–12%) among male new injectors). Based on self-reports, 8.1% of all new injectors (and 22% of female new injectors) were HIV positive before starting to inject drugs. 40% of HIV infected reported receiving antiretroviral therapy. In multivariable analysis, gender (male: OR 0.12, 95% CI 0.03–0.45), main drug injected (fentanyl: OR 6.7, 95% CI 1.3–35.7) and syringe sharing (distributive: OR 0.11, 95% CI 0.02–0.55; and receptive: OR 3.7, 95% CI 1.0–13.5) were associated with the HIV seropositivity. Conclusions New injectors exhibit high-risk behavior and correspondingly high HIV prevalence. Sexual transmission of HIV infection, including before injection initiation, is likely to be a significant contributor to HIV risk among female new injectors. This highlights the need to identify and target new

  6. Origin of HIV type 1 in colonial French Equatorial Africa?

    Science.gov (United States)

    Chitnis, A; Rawls, D; Moore, J

    2000-01-01

    Sociocultural factors during the postcolonial period have been implicated as paramount in generating conditions that promoted both the origin and subsequent epidemic spread of HIV-1 in Africa. We suggest, however, that the origin of the disease may lie in the interaction between colonial practices (e.g., labor camps, nonsterile vaccination campaigns) and traditional bushmeat hunting in French Equatorial Africa. Both the epidemiology of HIV-2 and the colonial history of West Africa appear more complex, but similar conditions existed there and may have contributed to the origin of HIV-2. Focusing the search for the origins of HIV-1 and HIV-2 on this earlier time period may contribute to understanding the evolution of the HIV viruses and the dynamics of emerging diseases.

  7. Dynamics and regulation of nuclear import and nuclear movements of HIV-1 complexes

    Science.gov (United States)

    Burdick, Ryan C.; Chen, Jianbo; Sastri, Jaya; Hu, Wei-Shau

    2017-01-01

    The dynamics and regulation of HIV-1 nuclear import and its intranuclear movements after import have not been studied. To elucidate these essential HIV-1 post-entry events, we labeled viral complexes with two fluorescently tagged virion-incorporated proteins (APOBEC3F or integrase), and analyzed the HIV-1 dynamics of nuclear envelope (NE) docking, nuclear import, and intranuclear movements in living cells. We observed that HIV-1 complexes exhibit unusually long NE residence times (1.5±1.6 hrs) compared to most cellular cargos, which are imported into the nuclei within milliseconds. Furthermore, nuclear import requires HIV-1 capsid (CA) and nuclear pore protein Nup358, and results in significant loss of CA, indicating that one of the viral core uncoating steps occurs during nuclear import. Our results showed that the CA-Cyclophilin A interaction regulates the dynamics of nuclear import by delaying the time of NE docking as well as transport through the nuclear pore, but blocking reverse transcription has no effect on the kinetics of nuclear import. We also visualized the translocation of viral complexes docked at the NE into the nucleus and analyzed their nuclear movements and determined that viral complexes exhibited a brief fast phase (HIV-1 complexes quickly tether to chromatin at or near their sites of integration in both wild-type cells and cells in which LEDGF/p75 was deleted using CRISPR/cas9, indicating that the tethering interactions do not require LEDGF/p75. These studies provide novel insights into the dynamics of viral complex-NE association, regulation of nuclear import, viral core uncoating, and intranuclear movements that precede integration site selection. PMID:28827840

  8. Substance Abuse and HIV/AIDS in the Caribbean.

    Science.gov (United States)

    Angulo-Arreola, Iliana Alexandra; Bastos, Francisco I; Strathdee, Steffanie A

    The Caribbean and Central America represent a formidable challenge for researchers and policy makers in the HIV field, due to their pronounced heterogeneity in terms of social, economic, and cultural contexts and the different courses the HIV epidemic has followed in the region. Such contrasting contexts and epidemics can be exemplified by 2 countries that share the island of Hispaniola, the French Creole-speaking Haiti, and the Spanish-speaking Dominican Republic. Haiti has experienced the worst epidemics outside of sub-Saharan Africa. Following a protracted economic and social crisis, recently aggravated by a devastating earthquake, the local HIV epidemic could experience resurgence. The region, strategically located on the way between coca-producing countries and the profitable North American markets, has been a transshipment area for years. Notwithstanding, the impact of such routes on local drug scenes has been very heterogeneous and dynamic, depending on a combination of local mores, drug enforcement activities, and the broad social and political context. Injecting drug use remains rare in the region, but local drug scenes are dynamic under the influence of increasing mobility of people and goods to and from North and South America, growing tourism and commerce, and prostitution. The multiple impacts of the recent economic and social crisis, as well as the influence of drug-trafficking routes across the Caribbean and other Latin American countries require a sustained effort to track changes in the HIV risk environment to inform sound drug policies and initiatives to minimize drug-related harms in the region.

  9. Intimate Partner Violence and Correlates with Risk Behaviors and HIV/STI Diagnoses Among Men Who Have Sex With Men and Men Who Have Sex with Men and Women in China: A Hidden Epidemic

    Science.gov (United States)

    Davis, Alissa; Best, John; Wei, Chongyi; Luo, Juhua; Van Der Pol, Barbara; Meyerson, Beth; Dodge, Brian; Aalsma, Matthew; Tucker, Joseph

    2015-01-01

    Background Intimate partner violence (IPV) research has primarily focused on heterosexual couples, but has largely ignored IPV among men who have sex with men (MSM). We examined IPV prevalence among MSM and men who have sex with men and women (MSMW) in China. Methods MSM over the age of 16 were recruited through three MSM-focused websites in China. An online survey containing items on sociodemographics, risk behaviors, IPV, and self-reported HIV or STI diagnosis was completed. Multivariate regression was used to examine associations between IPV and risk behaviors and an HIV or STI diagnosis. Results Among 610 participants, 182 (29.8%) reported experiencing at least one type of IPV. MSMW were at significantly greater risk for IPV (adjusted odds ratio (AOR) 1.65, 95% CI [1.08–2.53]) compared to MSM. Men who had experienced IPV were more likely to have participated in group sex (AOR 1.86, 95% CI [1.08–3.21]), to have had sex in exchange for gifts or money (AOR 5.06, 95% CI [2.47–10.35]), and to report a positive HIV diagnosis (AOR 2.59, 95% CI [1.22–5.51]). Conclusions There is a hidden epidemic of IPV among MSM in China, especially among MSMW. The hidden nature of MSM and MSMW suggests the need for a clinical environment more conducive to disclosure. Research is needed to understand the pathways linking IPV and HIV risk among MSM in order to optimize the design of effective interventions. PMID:26222752

  10. Human mobility and epidemic invasion

    Science.gov (United States)

    Colizza, Vittoria

    2010-03-01

    The current H1N1 influenza pandemic is just the latest example of how human mobility helps drive infectious diseases. Travel has grown explosively in the last decades, contributing to an emerging complex pattern of traffic flows that unfolds at different scales, shaping the spread of epidemics. Restrictions on people's mobility are thus investigated to design possible containment measures. By considering a theoretical framework in terms of reaction-diffusion processes, it is possible to study the invasion dynamics of epidemics in a metapopulation system with heterogeneous mobility patterns. The system is found to exhibit a global invasion threshold that sets the critical mobility rate below which the epidemic is contained. The results provide a general framework for the understanding of the numerical evidence from detailed data-driven simulations that show the limited benefit provided by travel flows reduction in slowing down or containing an emerging epidemic.

  11. Competing activation mechanisms in epidemics on networks

    CERN Document Server

    Castellano, Claudio

    2011-01-01

    In stark contrast to previous common wisdom that epidemic activity and thresholds in heterogeneous networks are dominated by the elements with the largest number of connections (the hubs), recent research has pointed out the role of the most efficient spreaders, located at the innermost, dense core of the network, in sustaining epidemic processes. Here we show that the mechanism responsible of epidemic spreading depends on the dynamical pattern of the epidemic process. For epidemics with a transient state, activity is essentially boosted by the innermost core of the network. On the contrary, epidemics allowing a steady state present a dual scenario, where either the vertex with the largest connectivity independently sustains activity and propagates it to the rest of the system, or, alternatively, the innermost core of the network collectively turns into the active state, maintaining it on a global scale. Which one of these two mechanisms actually governs the dynamics depends on the network features. In uncorr...

  12. The Social and Cultural Motivity of the Dissemination of HIV/AIDS%艾滋病传播的社会文化动力

    Institute of Scientific and Technical Information of China (English)

    翁乃群

    2003-01-01

    The asymmetrical dissemination of HIV/AIDS and the various vectors of HIV transmission in different regions or countries in the World as well as different localities within China imply specific social inequalities and cultural institutions. The HIV/AIDS situation in the World and within China may not be fully understood without considering the socio-cultural conditions that have shaped the social processes of the epidemics.This article discusses the socio-cultural dynamics of HIV/AIDS distribution in accordance with ethnographies of HIV/AIDS and anthropological field researches in Yunnan China last year conducted by a research team led by the author.

  13. Reconstructing the dynamics of HIV evolution within hosts from serial deep sequence data.

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    Art F Y Poon

    Full Text Available At the early stage of infection, human immunodeficiency virus (HIV-1 predominantly uses the CCR5 coreceptor for host cell entry. The subsequent emergence of HIV variants that use the CXCR4 coreceptor in roughly half of all infections is associated with an accelerated decline of CD4+ T-cells and rate of progression to AIDS. The presence of a 'fitness valley' separating CCR5- and CXCR4-using genotypes is postulated to be a biological determinant of whether the HIV coreceptor switch occurs. Using phylogenetic methods to reconstruct the evolutionary dynamics of HIV within hosts enables us to discriminate between competing models of this process. We have developed a phylogenetic pipeline for the molecular clock analysis, ancestral reconstruction, and visualization of deep sequence data. These data were generated by next-generation sequencing of HIV RNA extracted from longitudinal serum samples (median 7 time points from 8 untreated subjects with chronic HIV infections (Amsterdam Cohort Studies on HIV-1 infection and AIDS. We used the known dates of sampling to directly estimate rates of evolution and to map ancestral mutations to a reconstructed timeline in units of days. HIV coreceptor usage was predicted from reconstructed ancestral sequences using the geno2pheno algorithm. We determined that the first mutations contributing to CXCR4 use emerged about 16 (per subject range 4 to 30 months before the earliest predicted CXCR4-using ancestor, which preceded the first positive cell-based assay of CXCR4 usage by 10 (range 5 to 25 months. CXCR4 usage arose in multiple lineages within 5 of 8 subjects, and ancestral lineages following alternate mutational pathways before going extinct were common. We observed highly patient-specific distributions and time-scales of mutation accumulation, implying that the role of a fitness valley is contingent on the genotype of the transmitted variant.

  14. Reconstructing the dynamics of HIV evolution within hosts from serial deep sequence data.

    Science.gov (United States)

    Poon, Art F Y; Swenson, Luke C; Bunnik, Evelien M; Edo-Matas, Diana; Schuitemaker, Hanneke; van 't Wout, Angélique B; Harrigan, P Richard

    2012-01-01

    At the early stage of infection, human immunodeficiency virus (HIV)-1 predominantly uses the CCR5 coreceptor for host cell entry. The subsequent emergence of HIV variants that use the CXCR4 coreceptor in roughly half of all infections is associated with an accelerated decline of CD4+ T-cells and rate of progression to AIDS. The presence of a 'fitness valley' separating CCR5- and CXCR4-using genotypes is postulated to be a biological determinant of whether the HIV coreceptor switch occurs. Using phylogenetic methods to reconstruct the evolutionary dynamics of HIV within hosts enables us to discriminate between competing models of this process. We have developed a phylogenetic pipeline for the molecular clock analysis, ancestral reconstruction, and visualization of deep sequence data. These data were generated by next-generation sequencing of HIV RNA extracted from longitudinal serum samples (median 7 time points) from 8 untreated subjects with chronic HIV infections (Amsterdam Cohort Studies on HIV-1 infection and AIDS). We used the known dates of sampling to directly estimate rates of evolution and to map ancestral mutations to a reconstructed timeline in units of days. HIV coreceptor usage was predicted from reconstructed ancestral sequences using the geno2pheno algorithm. We determined that the first mutations contributing to CXCR4 use emerged about 16 (per subject range 4 to 30) months before the earliest predicted CXCR4-using ancestor, which preceded the first positive cell-based assay of CXCR4 usage by 10 (range 5 to 25) months. CXCR4 usage arose in multiple lineages within 5 of 8 subjects, and ancestral lineages following alternate mutational pathways before going extinct were common. We observed highly patient-specific distributions and time-scales of mutation accumulation, implying that the role of a fitness valley is contingent on the genotype of the transmitted variant.

  15. Statistical behavior of time dynamics evolution of HIV infection

    Science.gov (United States)

    González, Ramón E. R.; Santos, Iury A. X.; Nunes, Marcos G. P.; de Oliveira, Viviane M.; Barbosa, Anderson L. R.

    2017-09-01

    We use the tools of the random matrix theory (RMT) to investigate the statistical behavior of the evolution of human immunodeficiency virus (HIV) infection. By means of the nearest-neighbor spacing distribution we have identified four distinct regimes of the evolution of HIV infection. We verified that at the beginning of the so-called clinical latency phase the concentration of infected cells grows slowly and evolves in a correlated way. This regime is followed by another one in which the correlation is lost and that in turn leads the system to a regime in which the increase of infected cells is faster and correlated. In the final phase, the one in which acquired immunodeficiency syndrome (AIDS) is stablished, the system presents maximum correlation as demonstrated by GOE distribution.

  16. Impulsive vaccination and dispersal on dynamics of an SIR epidemic model with restricting infected individuals boarding transports

    Science.gov (United States)

    Jiao, Jianjun; Cai, Shaohong; Li, Limei

    2016-05-01

    To understand the effect of impulsive vaccination and restricting infected individuals boarding transports on disease spread, we establish an SIR model with impulsive vaccination, impulsive dispersal and restricting infected individuals boarding transports. This SIR epidemic model for two regions, which are connected by transportation of non-infected individuals, portrays the evolvement of diseases. We prove that all solutions of the investigated system are uniformly ultimately bounded. We also prove that there exists globally asymptotically stable infection-free boundary periodic solution. The condition for permanence is discussed. It is concluded that the approach of impulsive vaccination and restricting infected individuals boarding transports provides reliable tactic basis for preventing disease spread.

  17. Dynamic correlation between intrahost HIV-1 quasispecies evolution and disease progression.

    Directory of Open Access Journals (Sweden)

    Ha Youn Lee

    2008-12-01

    Full Text Available Quantifying the dynamics of intrahost HIV-1 sequence evolution is one means of uncovering information about the interaction between HIV-1 and the host immune system. In the chronic phase of infection, common dynamics of sequence divergence and diversity have been reported. We developed an HIV-1 sequence evolution model that simulated the effects of mutation and fitness of sequence variants. The amount of evolution was described by the distance from the founder strain, and fitness was described by the number of offspring a parent sequence produces. Analysis of the model suggested that the previously observed saturation of divergence and decrease of diversity in later stages of infection can be explained by a decrease in the proportion of offspring that are mutants as the distance from the founder strain increases rather than due to an increase of viral fitness. The prediction of the model was examined by performing phylogenetic analysis to estimate the change in the rate of evolution during infection. In agreement with our modeling, in 13 out of 15 patients (followed for 3-12 years we found that the rate of intrahost HIV-1 evolution was not constant but rather slowed down at a rate correlated with the rate of CD4+ T-cell decline. The correlation between the dynamics of the evolutionary rate and the rate of CD4+ T-cell decline, coupled with our HIV-1 sequence evolution model, explains previously conflicting observations of the relationships between the rate of HIV-1 quasispecies evolution and disease progression.

  18. Global Dynamics of HIV Infection of CD4+ T Cells and Macrophages

    OpenAIRE

    A. M. Elaiw; A. S. Alsheri

    2013-01-01

    We study the global dynamics of an HIV infection model describing the interaction of the HIV with CD4+ T cells and macrophages. The incidence rate of virus infection and the growth rate of the uninfected CD4+ T cells and macrophages are given by general functions. We have incorporated two types of distributed delays into the model to account for the time delay between the time the uninfected cells are contacted by the virus particle and the time for the emission of infectious (matures) virus ...

  19. Aberrant Neuronal Dynamics during Working Memory Operations in the Aging HIV-Infected Brain

    Science.gov (United States)

    Wilson, Tony W.; Proskovec, Amy L.; Heinrichs-Graham, Elizabeth; O’Neill, Jennifer; Robertson, Kevin R.; Fox, Howard S.; Swindells, Susan

    2017-01-01

    Impairments in working memory are among the most prevalent features of HIV-associated neurocognitive disorders (HAND), yet their origins are unknown, with some studies arguing that encoding operations are disturbed and others supporting deficits in memory maintenance. The current investigation directly addresses this issue by using a dynamic mapping approach to identify when and where processing in working memory circuits degrades. HIV-infected older adults and a demographically-matched group of uninfected controls performed a verbal working memory task during magnetoencephalography (MEG). Significant oscillatory neural responses were imaged using a beamforming approach to illuminate the spatiotemporal dynamics of neuronal activity. HIV-infected patients were significantly less accurate on the working memory task and their neuronal dynamics indicated that encoding operations were preserved, while memory maintenance processes were abnormal. Specifically, no group differences were detected during the encoding period, yet dysfunction in occipital, fronto-temporal, hippocampal, and cerebellar cortices emerged during memory maintenance. In addition, task performance in the controls covaried with occipital alpha synchronization and activity in right prefrontal cortices. In conclusion, working memory impairments are common and significantly impact the daily functioning and independence of HIV-infected patients. These impairments likely reflect deficits in the maintenance of memory representations, not failures to adequately encode stimuli. PMID:28155864

  20. High HIV incidence in the postpartum period sustains vertical transmission in settings with generalized epidemics: a cohort study in Southern Mozambique

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    Caroline De Schacht

    2014-03-01

    Full Text Available Introduction: Acute infection with HIV in the postpartum period results in a high risk of vertical transmission through breastfeeding. A study was done to determine the HIV incidence rate and associated risk factors among postpartum women in Southern Mozambique, where HIV prevalence among pregnant women is 21%. Methods: A prospective cohort study was conducted in six rural health facilities in Gaza and Maputo provinces from March 2008 to July 2011. A total of 1221 women who were HIV-negative on testing at delivery or within two months postpartum were recruited and followed until 18 months postpartum. HIV testing, collection of dried blood spot samples and administration of a structured questionnaire to women were performed every three months. Infant testing by DNA-PCR was done as soon as possible after identification of a new infection in women. HIV incidence was estimated, and potential risk factors at baseline were compared using Poisson regression. Results: Data from 957 women were analyzed with follow-up after the enrolment visit, with a median follow-up of 18.2 months. The HIV incidence in postpartum women is estimated at 3.20/100 women-years (95% CI: 2.30–4.46, with the highest rate among 18- to 19-year-olds (4.92 per 100 women-years; 95% CI: 2.65–9.15. Of the new infections, 14 (34% were identified during the first six months postpartum, 11 (27% between 6 and 12 months and 16 (39% between 12 and 18 months postpartum. Risk factors for incident HIV infection include young age, low number of children, higher education level of the woman's partner and having had sex with someone other than one's partner. The vertical transmission was 21% (95% CI: 5–36 among newly infected women. Conclusions: Incidence of HIV is high among breastfeeding women in Southern Mozambique, contributing to increasing numbers of HIV-infected infants. Comprehensive primary prevention strategies targeting women of reproductive age, particularly pregnant and

  1. High HIV incidence in the postpartum period sustains vertical transmission in settings with generalized epidemics: a cohort study in Southern Mozambique.

    Science.gov (United States)

    De Schacht, Caroline; Mabunda, Nédio; Ferreira, Orlando C; Ismael, Nália; Calú, Nurbai; Santos, Iolanda; Hoffman, Heather J; Alons, Catharina; Guay, Laura; Jani, Ilesh V

    2014-01-01

    Acute infection with HIV in the postpartum period results in a high risk of vertical transmission through breastfeeding. A study was done to determine the HIV incidence rate and associated risk factors among postpartum women in Southern Mozambique, where HIV prevalence among pregnant women is 21%. A prospective cohort study was conducted in six rural health facilities in Gaza and Maputo provinces from March 2008 to July 2011. A total of 1221 women who were HIV-negative on testing at delivery or within two months postpartum were recruited and followed until 18 months postpartum. HIV testing, collection of dried blood spot samples and administration of a structured questionnaire to women were performed every three months. Infant testing by DNA-PCR was done as soon as possible after identification of a new infection in women. HIV incidence was estimated, and potential risk factors at baseline were compared using Poisson regression. Data from 957 women were analyzed with follow-up after the enrolment visit, with a median follow-up of 18.2 months. The HIV incidence in postpartum women is estimated at 3.20/100 women-years (95% CI: 2.30-4.46), with the highest rate among 18- to 19-year-olds (4.92 per 100 women-years; 95% CI: 2.65-9.15). Of the new infections, 14 (34%) were identified during the first six months postpartum, 11 (27%) between 6 and 12 months and 16 (39%) between 12 and 18 months postpartum. Risk factors for incident HIV infection include young age, low number of children, higher education level of the woman's partner and having had sex with someone other than one's partner. The vertical transmission was 21% (95% CI: 5-36) among newly infected women. Incidence of HIV is high among breastfeeding women in Southern Mozambique, contributing to increasing numbers of HIV-infected infants. Comprehensive primary prevention strategies targeting women of reproductive age, particularly pregnant and postpartum women and their partners, will be crucial for the elimination

  2. Phylodynamics of HIV-1 subtype B among the men-having-sex-with-men (MSM population in Hong Kong.

    Directory of Open Access Journals (Sweden)

    Jonathan Hon-Kwan Chen

    Full Text Available The men-having-sex-with-men (MSM population has become one of the major risk groups for HIV-1 infection in the Asia Pacific countries. Hong Kong is located in the centre of Asia and the transmission history of HIV-1 subtype B transmission among MSM remained unclear. The aim of this study was to investigate the transmission dynamics of HIV-1 subtype B virus in the Hong Kong MSM population. Samples of 125 HIV-1 subtype B infected MSM patients were recruited in this study. Through this study, the subtype B epidemic in the Hong Kong MSM population was identified spreading mainly among local Chinese who caught infection locally. On the other hand, HIV-1 subtype B infected Caucasian MSM caught infection mainly outside Hong Kong. The Bayesian phylogenetic analysis also indicated that 3 separate subtype B epidemics with divergence dates in the 1990s had occurred. The first and latest epidemics were comparatively small-scaled; spreading among the local Chinese MSM while sauna-visiting was found to be the major sex partner sourcing reservoir for the first subtype B epidemic. However, the second epidemic was spread in a large-scale among local Chinese MSM with a number of them having sourced their sex partners through the internet. The epidemic virus was estimated to have a divergence date in 1987 and the infected population in Hong Kong had a logistic growth throughout the past 20 years. Our study elucidated the evolutionary and demographic history of HIV-1 subtype B virus in Hong Kong MSM population. The understanding of transmission and growth model of the subtype B epidemic provides more information on the HIV-1 transmission among MSM population in other Asia Pacific high-income countries.

  3. A passive-flow microfluidic device for imaging latent HIV activation dynamics in single T cells.

    Science.gov (United States)

    Ramji, Ramesh; Wong, Victor C; Chavali, Arvind K; Gearhart, Larisa M; Miller-Jensen, Kathryn

    2015-09-01

    Quantifying cell-to-cell variability in drug response dynamics is important when evaluating therapeutic efficacy. For example, optimizing latency reversing agents (LRAs) for use in a clinical "activate-and-kill" strategy to purge the latent HIV reservoir in patients requires minimizing heterogeneous viral activation dynamics. To evaluate how heterogeneity in latent HIV activation varies across a range of LRAs, we tracked drug-induced response dynamics in single cells via live-cell imaging using a latent HIV-GFP reporter virus in a clonal Jurkat T cell line. To enable these studies in suspension cells, we designed a simple method to capture an array of single Jurkat T cells using a passive-flow microfluidic device. Our device, which does not require external pumps or tubing, can trap hundreds of cells within minutes with a high retention rate over 12 hours of imaging. Using this device, we quantified heterogeneity in viral activation stimulated by transcription factor (TF) activators and histone deacetylase (HDAC) inhibitors. Generally, TF activators resulted in both faster onset of viral activation and faster rates of production, while HDAC inhibitors resulted in more uniform onset times, but more heterogeneous rates of production. Finally, we demonstrated that while onset time of viral gene expression and rate of viral production together predict total HIV activation, rate and onset time were not correlated within the same individual cell, suggesting that these features are regulated independently. Overall, our results reveal drug-specific patterns of noisy HIV activation dynamics not previously identified in static single-cell assays, which may require consideration for the most effective activate-and-kill regime.

  4. Decay dynamics of HIV-1 depend on the inhibited stages of the viral life cycle.

    Science.gov (United States)

    Sedaghat, Ahmad R; Dinoso, Jason B; Shen, Lin; Wilke, Claus O; Siliciano, Robert F

    2008-03-25

    The time to suppression of HIV-1 viremia to below the limit of detection of standard clinical assays is an important prognostic indicator for patients on highly active antiretroviral therapy (HAART). Recent clinical trials of the integrase inhibitor raltegravir have demonstrated more rapid viral decay than previously seen with reverse transcriptase (RT) or protease inhibitor-based regimens. Because of the therapeutic importance of drugs that target different steps in the virus life cycle, it is imperative to consider whether viral dynamics are affected by the stage of the viral life cycle at which an antiretroviral drug acts. We use a mathematical model to investigate the effects of various drug classes on the dynamics of HIV-1 decay and show that the stage at which a drug acts affects the dynamics of viral decay. We find that the drug class acting latest in the viral life cycle dictates the dynamics of HIV-1 decay. In general, we find that the later in the life cycle an inhibitor acts, the more rapid the decay in viremia, and we illustrate this by comparing the effect of RT and integrase inhibitors on viral dynamics. We conclude that the rapid decay observed in patients on integrase-inhibitor-containing regimens is not necessarily an indication of greater drug efficacy but rather an expected consequence of the fact that this drug acts later in the life cycle. We propose that clinically observed viral decay rates for HAART regimens should be evaluated in the context of the drug classes that are represented.

  5. An analysis of epidemic trend of HIV infection among MSM from 2008 to 2011 in Tianjin%天津市2008-2011年MSM人群HIV流行趋势分析

    Institute of Scientific and Technical Information of China (English)

    郭燕; 董笑月; 王欣; 柏建芸; 周宁

    2013-01-01

    Objective To analyze the epidemic characteristics of HIV/AIDS among men who have sex with men (MSM) from 2008 to 2011 in Tianjin,so as to provide evidence for the development of prevention and control measures. Methods The data of the newly reported cases of HIV/AIDS, serological surveillance among MSM and the cross-sectional surveys of MSM from 2008 to 2011 were analyzed. Results The cases of MSM accounted for the highest proportion among the newly reported cases of HIV/AIDS from 2008 to 2011. The proportion of MSM transmission was high and the increase of cases of MSM transmission was the fastest in comparison with that of other routes of transmission. Among the cases of MSM transmission, the floating population accounted for 53. 3% , unmarried individuals accounted for 61.0%, those with high middle schooling or above accounted for 69.6%, and those aged 15- 29 years accounted for 47. 2%. Among the newly reported cases detected from unpaid blood donors and VCT services, those of MSM transmission accounted the highest proportion. Serological surveillance showed that the rate of HIV infection remained at a high level among MSM in Tianjin. Meanwhile, cross-sectional surveys showed that among the MSM 35. 85% (median) used condom consistently when having sex with men in the last six months, and 59. 55% (median) used condom in the last sexual behavior with men, and 18. 05% (median) had heterosexual behaviors in the past 6 months. The detection rate of syphilis was 18. 25% (median), while that of HIV infection was 6. 25% (median). Conclusion MSM is the main population of HIV/AIDS infection in Tianjin, and the epidemic of HIV/AIDS among them is becoming serious. The HIV infection related risk behavior is common a-mong MSM, therefore, effective measures should be taken to control and prevent HIV/AIDS spreading.%目的 了解天津市2008-2011年男男性行为人群(MSM)艾滋病病毒(HIV)的流行趋势,为在该人群中开展相关控制措施提供依据.方法

  6. Age-dependent partnering and the HIV transmission chain: a microsimulation analysis.

    Science.gov (United States)

    Bershteyn, Anna; Klein, Daniel J; Eckhoff, Philip A

    2013-11-06

    Efficient planning and evaluation of human immunodeficiency virus (HIV) prevention programmes requires an understanding of what sustains the epidemic, including the mechanism by which HIV transmission keeps pace with the ageing of the infected population. Recently, more detailed population models have been developed which represent the epidemic with sufficient detail to characterize the dynamics of ongoing transmission. Here, we describe the structure and parameters of such a model, called EMOD-HIV v. 0.7. We analyse the chains of transmission that allow the HIV epidemic to propagate across age groups in this model. In order to prevent the epidemic from dying out, the virus must find younger victims faster than its extant victims age and die. The individuals who enable such transmission events in EMOD-HIV v. 0.7 are higher concurrency, co-infected males aged 26-29 and females aged 23-24. Prevention programmes that target these populations could efficiently interrupt the mechanisms that allow HIV to transmit at a pace that is faster than the progress of time.

  7. Scaling law characterizing the dynamics of the transition of HIV-1 to error catastrophe

    Science.gov (United States)

    Gupta, Vipul; Dixit, Narendra M.

    2015-10-01

    Increasing the mutation rate, μ , of viruses above a threshold, {μ }c, has been predicted to trigger a catastrophic loss of viral genetic information and is being explored as a novel intervention strategy. Here, we examine the dynamics of this transition using stochastic simulations mimicking within-host HIV-1 evolution. We find a scaling law governing the characteristic time of the transition: τ ≈ 0.6/≤ft(μ -{μ }c\\right). The law is robust to variations in underlying evolutionary forces and presents guidelines for treatment of HIV-1 infection with mutagens. We estimate that many years of treatment would be required before HIV-1 can suffer an error catastrophe.

  8. Transmission dynamics of HIV-1 subtype B in the Basque Country, Spain.

    Science.gov (United States)

    Patiño-Galindo, J A; Thomson, Michael M; Pérez-Álvarez, Lucía; Delgado, Elena; Cuevas, María Teresa; Fernández-García, Aurora; Nájera, Rafael; Iribarren, José A; Cilla, Gustavo; López-Soria, Leyre; Lezaun, María J; Cisterna, Ramón; González-Candelas, F

    2016-06-01

    This work was aimed to study the HIV-1 subtype B epidemics in the Basque Country, Spain. 1727 HIV-1 subtype B sequences comprising protease and reverse transcriptase (PR/RT) coding regions, sampled between 2001 and 2008, were analyzed. 156 transmission clusters were detected by means of phylogenetic analyses. Most of them comprised less than 4 individuals and, in total, they included 441 patients. Six clusters comprised 10 or more patients and were further analyzed in order to study their origin and diversification. Four clusters included men who had unprotected homosexual sex (MSM), one group was formed by intravenous drug users (IDUs), and another included both IDUs and people infected through unprotected heterosexual sex (HTs). Most of these clusters originated from the mid-1980s to the mid-1990s. Only one cluster, formed by MSM, originated after 2000. The time between infections was significantly lower in MSM groups than in those containing IDUs (P-value Country is significant. Public health control measures should be reinforced to prevent the further expansion of transmission clusters and resistant mutations occurring within them.

  9. Estimation of HIV-1 incidence among five focal populations in Dehong, Yunnan: a hard hit area along a major drug trafficking route

    Directory of Open Access Journals (Sweden)

    Jia Manhong

    2010-04-01

    Full Text Available Abstract Background Since 1989 when the first 146 HIV positives in China were identified, Dehong Prefecture had been one of the areas hardest-hit by HIV in China. The local and national governments have put substantial financial resources into tackling the HIV epidemic in Dehong from 2004. The objective of this study was to track dynamic changes in HIV-1 prevalence and incidence among five focal populations in Dehong and to assess the impact of HIV prevention and control efforts. Methods Consecutive cross-sectional surveys conducted in five focal populations between 2004 and 2008. Specimens seropositive for HIV were tested with the BED IgG capture enzyme immunoassay to identify recent seroconversions (median, 155 days using normalized optical density of 0.8 and adjustments. Results From 2004 to 2008, estimated annual HIV incidence among injecting drug users (IDUs decreased significantly [from 15.0% (95% CI = 11.4%-18.5% in 2004 to 4.3% (95% CI = 2.4%-6.2% in 2008; trend test P Conclusions The HIV epidemic in Dehong continued to expand during a five-year period but at a slowing rate among IDUs, and HIV incidence remains high among IDUs and discordant couples. Intensive prevention measures should target sub-groups at highest risk to further slow the epidemic and control the migration of HIV to other areas of China, and multivariate analysis is needed to explore which measures are more effective for different populations.

  10. Mental health and HIV sexual risk behaviour among University of ...

    African Journals Online (AJOL)

    income countries, with depression constituting the heaviest disease burden.[3] The HIV epidemic ... use, and HIV risk behaviour, such as multiple sexual partners and unprotected sex.[6-13] ... HIV prevention in Africa. Objective. To determine ...

  11. Role of CCL3L1-CCR5 Genotypes in the Epidemic Spread of HIV-1 and Evaluation of Vaccine Efficacy

    Science.gov (United States)

    2008-08-01

    The rarity of HIV infection via cross- species transmission from chimpanzee to Pygmies contrasts with the fact that documented zoonosis of other viruses...viral zoonosis ? In this respect, it is noteworthy that compared to other African populations that reside in geographical proximity (e.g., non-Pygmy

  12. A Test of Major Assumptions about Behavior Change: A Comprehensive Look at the Effects of Passive and Active HIV-Prevention Interventions Since the Beginning of the Epidemic

    Science.gov (United States)

    Albarracin, Dolores; Gillette, Jeffrey C.; Earl, Allison N.; Glasman, Laura R.; Durantini, Marta R.; Ho, Moon-Ho

    2005-01-01

    This meta-analysis tested the major theoretical assumptions about behavior change by examining the outcomes and mediating mechanisms of different preventive strategies in a sample of 354 HIV-prevention interventions and 99 control groups, spanning the past 17 years. There were 2 main conclusions from this extensive review. First, the most…

  13. Concurrent sexual partnerships and associated factors: a cross-sectional population-based survey in a rural community in Africa with a generalised HIV epidemic

    Directory of Open Access Journals (Sweden)

    Karabarinde Alex

    2011-08-01

    Full Text Available Abstract Background Although concurrent sexual partnerships may play an important role in HIV transmission in Africa, the lack of an agreed definition of concurrency and of standard methodological approaches has hindered studies. In a long-standing general population cohort in rural Uganda we assessed the prevalence of concurrency and investigated its association with sociodemographic and behavioural factors and with HIV prevalence, using the new recommended standard definition and methodological approaches. Methods As part of the 2010 annual cohort HIV serosurvey among adults, we used a structured questionnaire to collect information on sociodemographic and behavioural factors and to measure standard indicators of concurrency using the recommended method of obtaining sexual-partner histories. We used logistic regression to build a multivariable model of factors independently associated with concurrency. Results Among those eligible, 3,291 (66% males and 4,052 (72% females participated in the survey. Among currently married participants, 11% of men and 25% of women reported being in a polygynous union. Among those with a sexual partner in the past year, the proportion reporting at least one concurrent partnership was 17% in males and 0.5% in females. Polygyny accounted for a third of concurrency in men and was not associated with increased HIV risk. Among men there was no evidence of an association between concurrency and HIV prevalence (but too few women rep