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Dynamic sex roles among men who have sex with men and transmissions from primary HIV infection.

ABSTRACT: Previous studies estimating the fraction of transmissions from persons with primary HIV have not focused on the effects of switching sex role in male homosexual populations. Such behavioral fluctuations can increase the contribution of primary HIV in the overall population.We modeled HIV transmission with 8 compartments defined by 4 behavioral groups, with different anal-insertive and anal-receptive combinations, and 2 stages of infection. We explored the effects of fluctuating behavioral categories on endemic prevalence and the fraction of transmissions from primary HIV. We varied transition rates to develop the theory on how behavioral fluctuation affects infection patterns, and we used the transition rates in a Netherlands cohort to assess overall effects in a real setting.The dynamics of change in behavior-group status over time observed in the Netherlands cohort amplifies the prevalence of infection and the fraction of transmissions from primary HIV, resulting in the highest proportions of transmissions being from people with primary HIV. Fluctuation between dual- or receptive-role periods and no-anal-sex periods mainly determines this amplification. In terms of the total transmissions, the dual-role risk group is dominant. Fluctuation between insertive and receptive roles decreases the fraction of transmissions from primary HIV, but such fluctuation is infrequently observed.The fraction of transmissions from primary HIV is considerably raised by fluctuations in insertive and receptive anal sex behaviors. This increase occurs even when primary HIV or later infection status does not influence risk behavior. Thus, it is not simply biology but also behavior patterns and social contexts that determine the fraction of transmissions from primary HIV. Moreover, each primary HIV transmission has a larger population effect than each later infection transmission because the men to whom one transmits from primary HIV carry on more chains of transmissions than the men to whom one transmits later in infection. Reducing transmissions from primary HIV should be a primary focus of HIV control efforts.

SUBMITTER: Alam SJ

PROVIDER: S-EPMC3021127 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Dynamic sex roles among men who have sex with men and transmissions from primary HIV infection.

Alam Shah Jamal SJ Romero-Severson Ethan E Kim Jong-Hoon JH Emond Gilbert G Koopman James S JS

Epidemiology (Cambridge, Mass.) 20100901 5

<h4>Background</h4>Previous studies estimating the fraction of transmissions from persons with primary HIV have not focused on the effects of switching sex role in male homosexual populations. Such behavioral fluctuations can increase the contribution of primary HIV in the overall population.<h4>Methods</h4>We modeled HIV transmission with 8 compartments defined by 4 behavioral groups, with different anal-insertive and anal-receptive combinations, and 2 stages of infection. We explored the effec ...[more]

PMID: 20585251

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Project description:ObjectivesNingxia Hui Autonomous Region, an important area for ethnic Hui settlement in Northwest China, is a low HIV prevalence region. However, HIV infection rates among men who have sex with men (MSM) in Ningxia have increased to an alarming level, despite scale-up of control measures in recent years. This study aimed to understand the demographical and sexual behavior dynamics of MSM and to explore the factors associated with HIV infection.MethodsAnnual cross-sectional surveys were carried out among MSM during 2011~2017 in Yinchuan, the capital city of Ningxia. Information regarding social demographics, sexual behavior and HIV prevention knowledge was collected. Blood samples were taken for HIV, HCV serological and genetic analysis, and syphilis serological analysis. The dynamic trend was analyzed with trend χ2 test and factors associated with HIV infection were identified by multivariate logistic regression analysis.ResultsThe study found a decreasing trend for mean age of the MSM population over the study period. MSMs with a college education or higher increased significantly, while the proportions that were in a marriage significantly decreased over the study period. The rate of HIV positive among MSM increased during the study period (p<0.05), however, the rate of recently diagnosed infections decreased from 2012 (p<0.05). Overall, a very high proportion (98%) of MSM had basic knowledge of HIV prevention, however, only approximately 40% of them used condoms consistently during anal sex with male partners. Unprotected anal sex was identified as a risk factor associated with HIV infection, as was syphilis infection. Local residency status and MSM who received intervention and detection services were the factors that decreased HIV infection risk. Sequence analysis identified the HIV-1 CRF55_01B subtype from MSM for the first time in Yinchuan.ConclusionThe reduction of recent HIV diagnoses is an encouraging sign of successful HIV control measures in MSM in Ningxia. The finding that a high proportion of MSM had knowledge of HIV prevention but still conducted unprotected sex highlights the need for further control measures to change unsafe sexual practices among MSM.

Project description:Elucidating virus-host interactions responsible for HIV-1 transmission is important for advancing HIV-1 prevention strategies. To this end, single genome amplification (SGA) and sequencing of HIV-1 within the context of a model of random virus evolution has made possible for the first time an unambiguous identification of transmitted/founder viruses and a precise estimation of their numbers. Here, we applied this approach to HIV-1 env analyses in a cohort of acutely infected men who have sex with men (MSM) and found that a high proportion (10 of 28; 36%) had been productively infected by more than one virus. In subjects with multivariant transmission, the minimum number of transmitted viruses ranged from 2 to 10 with viral recombination leading to rapid and extensive genetic shuffling among virus lineages. A combined analysis of these results, together with recently published findings based on identical SGA methods in largely heterosexual (HSX) cohorts, revealed a significantly higher frequency of multivariant transmission in MSM than in HSX [19 of 50 subjects (38%) versus 34 of 175 subjects (19%); Fisher's exact p = 0.008]. To further evaluate the SGA strategy for identifying transmitted/founder viruses, we analyzed 239 overlapping 5' and 3' half genome or env-only sequences from plasma viral RNA (vRNA) and blood mononuclear cell DNA in an MSM subject who had a particularly well-documented virus exposure history 3-6 days before symptom onset and 14-17 days before peak plasma viremia (47,600,000 vRNA molecules/ml). All 239 sequences coalesced to a single transmitted/founder virus genome in a time frame consistent with the clinical history, and a molecular clone of this genome encoded replication competent virus in accord with model predictions. Higher multiplicity of HIV-1 infection in MSM compared with HSX is consistent with the demonstrably higher epidemiological risk of virus acquisition in MSM and could indicate a greater challenge for HIV-1 vaccines than previously recognized.

Project description:BACKGROUND:New HIV infections in men who have sex with men (MSM) have increased in Switzerland since 2000 despite combination antiretroviral therapy (cART). The objectives of this mathematical modelling study were: to describe the dynamics of the HIV epidemic in MSM in Switzerland using national data; to explore the effects of hypothetical prevention scenarios; and to conduct a multivariate sensitivity analysis. METHODOLOGY/PRINCIPAL FINDINGS:The model describes HIV transmission, progression and the effects of cART using differential equations. The model was fitted to Swiss HIV and AIDS surveillance data and twelve unknown parameters were estimated. Predicted numbers of diagnosed HIV infections and AIDS cases fitted the observed data well. By the end of 2010, an estimated 13.5% (95% CI 12.5, 14.6%) of all HIV-infected MSM were undiagnosed and accounted for 81.8% (95% CI 81.1, 82.4%) of new HIV infections. The transmission rate was at its lowest from 1995-1999, with a nadir of 46 incident HIV infections in 1999, but increased from 2000. The estimated number of new infections continued to increase to more than 250 in 2010, although the reproduction number was still below the epidemic threshold. Prevention scenarios included temporary reductions in risk behaviour, annual test and treat, and reduction in risk behaviour to levels observed earlier in the epidemic. These led to predicted reductions in new infections from 2 to 26% by 2020. Parameters related to disease progression and relative infectiousness at different HIV stages had the greatest influence on estimates of the net transmission rate. CONCLUSIONS/SIGNIFICANCE:The model outputs suggest that the increase in HIV transmission amongst MSM in Switzerland is the result of continuing risky sexual behaviour, particularly by those unaware of their infection status. Long term reductions in the incidence of HIV infection in MSM in Switzerland will require increased and sustained uptake of effective interventions.

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Dynamic sex roles among men who have sex with men and transmissions from primary HIV infection.

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Dynamic sex roles among men who have sex with men and transmissions from primary HIV infection.

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