Changes in the transmission dynamics of the HIV epidemic after the wide-scale use of antiretroviral therapy could explain increases in sexually transmitted infections: results from mathematical models

Prevalence of Active Syphilis Infection and Risk Factors among HIV-Positive MSM in Zhejiang, China in 2015: A Cross-Sectional Study

Objectives: To determine the prevalence of active syphilis infection and explore the risk factors for active syphilis in human immunodeficiency virus (HIV)-positive men who had sex with men (MSM) in Zhejiang Province, 2015. Design: Data on HIV-positive MSM living in Zhejiang Province were obtained from the National Center for AIDS/STD Control and Prevention (NCAIDS) reporting system and the Zhejiang provincial AIDS/STD surveillance system between June and December 2015. The information included risky behavior, years with diagnosed HIV, and highly active antiretroviral therapy (HAART). SPSS 19.0 was used for the data analysis. Results: The analysis included 3616 MSM. Of these, 11.3% (407/3616) had active syphilis. Multivariate logistic regression analysis revealed that HAART was significantly associated with an increased risk of active syphilis infection (odds ratio (OR) = 1.760, 95% confidence interval (CI) 1.187–2.611). Compared with participants diagnosed with HIV for <2 years, patients diagnosed with HIV for >5 years had a higher risk of active syphilis infection (OR = 1.707, 95% CI 1.167–2.495). Age and number of sex partners were also independent risk factors for active syphilis infection. Conclusions: The incidence of active syphilis infection is high among HIV-positive MSM in Zhejiang Province; age, number of sex partners, years with diagnosed HIV, and receiving HAART were risk factors. Patients who are elderly, have lived with HIV for a longer period, have more sex partners, and receive HAART should be the focus of interventions to promote changes in behavior and decrease syphilis infection.

Calendar trends in sexual behaviours in a cohort of HIV-infected MSM at the era of treatment as prevention of HIV infection

BACKGROUND

With the advent of treatment as prevention of HIV infection (TasP), we assessed trends in sexual behaviours between 2000 and 2017 among HIV-infected MSM enrolled in the French ANRS PRIMO cohort.

METHODS

At each cohort visit, a clinical questionnaire including laboratory values was completed and a self-administered questionnaire was used to collect sexual behaviours, that is, the number, type (steady/casual) and HIV status (positive or negative/unknown) of partners, and condom use. The possible influence of viral load (undetectable/detectable) measured at the preceding visit on the evolution over time of sexual behaviour was assessed with logistic regression models fitted by generalized estimating equations (GEE), taking into account longitudinal data.

RESULTS

We analyzed data from 10657 follow-up visits by 1364 MSM. Overall, whatever the considered behavioural variable: at least one sexual partner, steady and/or casual, condomless sex with steady, casual partners, serodiscordant or not, we observed a calendar increase with a particularly more marked rise from 2010 (P < 0.0001). Inconsistent condom use did not differ according to the viral load status (detectable vs. undetectable). Trends in inconsistent condom use increased across different generations of MSM, as defined by the year they were diagnosed with HIV infection.

CONCLUSIONS

'Having a sexual partner' and condomless sex, both increased in frequency between 2000 and 2017. Viral load status did not influence condom use as could have been expected from the 2008 Swiss Statement.

Expanded antiretroviral treatment, sexual networks, and condom use: Treatment as prevention unlikely to succeed without partner reduction among men who have sex with men in China

Background

To project the impact of partner reduction on preventing new HIV infections among men who have sex with men (MSM) under varying conditions of enhanced HIV testing and treatment (T&T) and condom use in Beijing, China.

Methods and findings

A complex network model was fitted to predict the number of new HIV infections averted from 2014 to 2023 under four scenarios of sexual behavior risk reduction (S)—S1: Male sexual partners decrease (reduced by a random value m from 1–50) while condom use increases (risk constant p is a random value between 0.2 and 1]); S2: Both sexual partners and condom use decrease (m 1, 50; p 1, 1.8); S3: Sexual partners reduce (m 1, 10) while condom use increases or decreases (p 0.2, 1.8); S4: Only MSM with ≥100 male sexual partners reduce their partners (m 1, 50) while condom use increases (p 0.2, 1).

HIV prevalence will reach 23.2% by 2023 among Beijing MSM if T&T remains at the 2013 level. The three most influential factors are: T&T coverage; partner reduction (m); and the background risk (p). Under scenarios 1–4 of sexual behavioral changes with enhanced T&T interventions, the cumulative HIV new infections prevented over the 10 years will be 46.8% for S1 (interquartile range [IQR] 32.4%, 60.1%); 29.7% for S2 (IQR 18.0%, 41.4%), 23.2% for S3 (IQR 12.2%, 37.0%) and 11.6% for S4 (IQR 4.0%, 26.6%), respectively. The reproduction number R₀ could drop below 1 if there were a substantial reduction of male sexual partners and/or expanded condom use.

Conclusion

Partner reduction is a vital factor within HIV combination interventions to reduce HIV incidence among Beijing MSM, with substantial additional benefits derived from condom use. T&T without substantial partner reduction and increased condom use is less promising unless its implementation were extremely (and improbably) efficient.

Impact of Population Recruitment on the HIV Epidemics and the Effectiveness of HIV Prevention Interventions

Mechanistic mathematical models are increasingly used to evaluate the effectiveness of different interventions for HIV prevention and to inform public health decisions. By focusing exclusively on the impact of the interventions, the importance of the demographic processes in these studies is often underestimated. In this paper, we use simple deterministic models to assess the effectiveness of pre-exposure prophylaxis in reducing the HIV transmission and to explore the influence of the recruitment mechanisms on the epidemic and effectiveness projections. We employ three commonly used formulas that correspond to constant, proportional and logistic recruitment and compare the dynamical properties of the resulting models. Our analysis exposes substantial differences in the transient and asymptotic behavior of the models which result in 47 % variation in population size and more than 6 percentage points variation in HIV prevalence over 40 years between models using different recruitment mechanisms. We outline the strong influence of recruitment assumptions on the impact of HIV prevention interventions and conclude that detailed demographic data should be used to inform the integration of recruitment processes in the models before HIV prevention is considered.

Influence of concurrency, partner choice, and viral suppression on racial disparity in the prevalence of HIV infected women

In 1992, Watts and May introduced a simple dynamical systems model of the spread of HIV based on disease transmission per partnership including the length of partnership duration. This model allowed for the treatment of concurrent partnerships, although it was hampered by the assumption of an important latent phase which generated a non-autonomous system. Subsequent models including concurrency have been based on networks, Monte Carlo, and stochastic simulations which lose a qualitative understanding of the effects of concurrency. We present a new autonomous deterministic model of the effect of concurrent sexual partnerships that allows for an analytical study of disease transmission. We incorporate the effect of concurrency through the newly derived force of infection term in a mathematical model of the transmission of HIV through sexual contact in a population stratified by sexual behavior and race/ethnicity. The model also includes variations in population mixing (partner choice) and non-uniform Highly Active Anti-Retroviral Treatment (HAART) leading to viral suppression. We use this mathematical model to understand the non-uniform spread of HIV in women who were infected through heterosexual contact. In addition, an analytical study shows the importance of continued condom use in virally suppressed MSM. Numerical simulations of the reproduction number as a function of concurrency, viral suppression level, and mixing show a reservoir of disease present in both heterosexual and MSM populations. Statistical analysis of parameter values show that viral suppression level, mixing and progression to AIDS without viral suppression have a strong correlation (either positive or negative) with the number of HIV positive women. Concurrency and assortative mixing are shown to be essential to reproduce infection levels in women, as reported by 2010 data from the Center for Disease Control (CDC).

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

BACKGROUND

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.

METHODS AND FINDINGS

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.

CONCLUSIONS

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.

HIV treatment as prevention: contradictory perspectives from dynamic mathematical models

The preventative effects of antiretroviral therapy for people with HIV have been debated since they were first raised. Models commenced studying the preventive effects of treatment in the 1990s, prior to initial public reports. However, the outcomes of the preventive effects of antiretroviral use were not consistent. Some outcomes of dynamic models were based on unfeasible assumptions, such as no consideration of drug resistance, behavior disinhibition, or economic inputs in poor countries, and unrealistic input variables, for example, overstated initiation time, adherence, coverage, and efficacy of treatment. This paper reviewed dynamic mathematical models to ascertain the complex effects of ART on HIV transmission. This review discusses more conservative inputs and outcomes relative to antiretroviral use in HIV infections in dynamic mathematical models. ART alone cannot eliminate HIV transmission.

The changing relationship between bacterial STIs and HIV prevalence in South Africa - an ecological study

Prevalence estimates of various bacterial sexually transmitted infections in South Africa have declined considerably since the mid-1990s. Syphilis among pregnant women, for example, declined from 10.8% in 1998 to 2.8% in 2001. We used Pearson's correlation coefficients to estimate the association between the prevalence of syphilis/male urethral discharge/male genital ulcers and the peak HIV prevalence at a district and provincial level in the early and late phases of the HIV epidemic in South Africa. Prevalence estimates of syphilis, male urethral discharge and male genital ulcers during the period preceding the peak HIV prevalence were all positively correlated with the peak HIV prevalence at a provincial level (Pearson's correlation coefficient [r] = 0.83, p = 0.006; r = 0.66, p = 0.052; r = 0.79, 0.011, respectively). These relationships all switched to a negative association later in the HIV epidemic at a provincial level (r = -0.53, p = 0.14; r = -0.73, p = 0.130; r = -0.54, p = 0.027, respectively). AIDS mortality may have played an important role in the decline of bacterial sexually transmitted infections such as syphilis in this region. Consequently, the relatively recent scale-up of antiretroviral therapy may result in a resurgence of syphilis and other sexually transmitted infections as observed in high-income countries.

Prevalence of syphilis infection and associations with sexual risk behaviours among HIV-positive men who have sex with men in Shanghai, China

The aims of this study were to understand the prevalence and correlates of syphilis infection among HIV-positive men who have sex with men (MSM) in Shanghai, China. A total of 200 HIV-positive MSM participants were recruited using “snowball” sampling. Participants were tested for syphilis and completed a one-time questionnaire which included demographic characteristics, sexual behaviours with male and female sexual partners, substance use, and use of antiretroviral medications. Prevalence of syphilis infection was 16.5%. Among HIV/syphilis co-infected participants, 63.6% reported having anal sex with male partners and 24.2% did not use condoms consistently during the past six months; 66.7% reported having oral sex with male partners and 51.5% reported unprotected oral sex during the past six months. Factors associated with testing seropositive for syphilis infection included receptive anal sex with a male partner in the past six months (AOR = 12.61, 90% CI = 2.38–66.89), illicit drug use in the past six months (AOR = 11.47, 90% CI = 2.47–53.45), and use of antiretroviral medication (AOR = 4.48, 90% CI = 1.43–14.05). These data indicate a need for “positive prevention” interventions targeting HIV-positive MSM in China.

Modelling the impact of chlamydia screening on the transmission of HIV among men who have sex with men

BACKGROUND

Recent studies have found high prevalences of asymptomatic rectal chlamydia among HIV-infected men who have sex with men (MSM). Chlamydia could increase the infectivity of HIV and the susceptibility to HIV infection. We investigate the role of chlamydia in the spread of HIV among MSM and the possible impact of routine chlamydia screening among HIV-infected MSM at HIV treatment centres on the incidence of chlamydia and HIV in the overall MSM population.

METHODS

A mathematical model was developed to describe the transmission of HIV and chlamydia among MSM. Parameters relating to sexual behaviour were estimated from data from the Amsterdam Cohort Study among MSM. Uncertainty analysis was carried out for model parameters without confident estimates. The effects of different screening strategies for chlamydia were investigated.

RESULTS

Among all new HIV infections in MSM, 15% can be attributed to chlamydia infection. Introduction of routine chlamydia screening every six months among HIV-infected MSM during regular HIV consultations can reduce the incidence of both infections among MSM: after 10 years, the relative percentage reduction in chlamydia incidence would be 15% and in HIV incidence 4%, compared to the current situation. Chlamydia screening is more effective in reducing HIV incidence with more frequent screening and with higher participation of the most risky MSM in the screening program.

CONCLUSIONS

Chlamydia infection could contribute to the transmission of HIV among MSM. Preventive measures reducing chlamydia prevalence, such as routine chlamydia screening of HIV-infected MSM, can result in a decline in the incidence of chlamydia and HIV.

Treatment-related optimistic beliefs and risk of HIV transmission: a review of recent findings (2009-2012) in an era of treatment as prevention

The promising outlook for HIV treatment as prevention (TasP) offered by the recent success in clinical trials has highlighted the need for effort against over-optimism toward anti-retroviral therapy (ART). It has been of a central concern that such optimistic beliefs may fuel an increase in risk behaviors to counter the protective effect of ART on reducing overall transmissibility of HIV. The current review was conducted to provide an updated look at the potential impact of treatment-related optimistic beliefs on the risk of HIV transmission. The review yielded a total of 14 studies published during the past 4 years that have examined the role of treatment-related optimistic beliefs in changing people's adoption of sexual risk behaviors. Findings from quantitative studies were largely in support of an association between optimistic beliefs and risk of HIV transmission. Results from qualitative studies discovered additional information concealed under the numerical associations, and pointed to the need of more rigorous and comprehensive examination of the relationship between optimistic beliefs and HIV transmission risk. Gaps in the current literature were identified and suggestions for future research were provided.

Reaping the prevention benefits of highly active antiretroviral treatment: policy implications of HIV Prevention Trials Network 052

PURPOSE OF REVIEW

This review explores the policy implications of findings from the HIV Prevention Trials Network (HPTN 052) treatment as prevention (TasP) study.

RECENT FINDINGS

To date, the potential of antiretrovirals to prevent sexual transmission of HIV by infected persons has been grounded in observational cohort, ecological, mathematical modeling, and meta-analytic studies. HPTN 052 represents the first randomized controlled trial to test the secondary prevention benefit of HIV transmission using antiretroviral treatment in largely asymptomatic persons with high CD4 cell counts.

SUMMARY

The US National HIV/AIDS Strategy has among its key goals the reduction of incident HIV infections, improved access to quality care and associated outcomes, and the reduction in HIV-associated health disparities and inequities. HPTN 052 demonstrates that providing TasP, in combination with other effective prevention strategies offers the promise of achieving these life-saving goals. But HPTN 052 also highlights the need for cautious optimism and underscores the importance of addressing current gaps in the HIV prevention, treatment, and care continuum in order for 'TasP' strategies to achieve their full potential. Among these are necessary improvements in the capacity to expand HIV testing, facilitate effective linkage and retention in care, and improve treatment initiation, maintenance, and virus suppression.

Risk perceptions after human papillomavirus vaccination in HIV-infected adolescents and young adult women

PURPOSE

To examine risk perceptions (perceived risk of human papillomavirus [HPV], perceived risk of other sexually transmitted infections [STIs], and need for safer sexual behaviors) and to determine factors associated with these risk perceptions after HPV vaccination.

METHODS

Data were collected at the baseline visit of an HPV-6, -11, -16, -18 vaccine clinical trial in 16-23-year-old HIV-infected young women (N = 99). Immediately after receiving the first vaccine dose, participants completed a confidential questionnaire that included three 5-item scales measuring perceived risk of HPV, perceived risk of other STIs, and need for safer sexual behaviors. Linear and logistic regression models were used to examine associations between baseline characteristics (demographic characteristics; cluster of differentiation antigen 4 (CD4(+)) count; HIV viral load; knowledge about HPV and HPV vaccines; sexual behaviors; and STI diagnosis) and each measure of risk perceptions.

RESULTS

Most participants perceived themselves to be at lower risk for HPV (mean scale score = 19.5/50), most perceived that they were not at lower risk for other STIs (mean = 31.2/50), and the vast majority reported that there was still a need for safer sexual behaviors after vaccination (mean = 43.1/50). Multivariate analyses indicated that knowledge about HPV and HPV vaccines was associated with perceived need for safer sexual behaviors (OR = 1.05, 95% CI = 1.0-1.1).

CONCLUSIONS

Although almost all young women in this study believed that safer sexual behaviors were still important after HPV vaccination, a subset believed they were at less risk for STIs other than HPV. Educational interventions are needed to prevent misperceptions and promote healthy behaviors after vaccination.

Knowing your HIV/AIDS epidemic and tailoring an effective response: how did India do it?

Tremendous global efforts have been made to collect data on the HIV/AIDS epidemic. Yet, significant challenges remain for generating and analysing evidence to allocate resources efficiently and implement an effective AIDS response. India offers important lessons and a model for intelligent and integrated use of data on HIV/AIDS for an evidence-based response. Over the past 15 years, the number of data sources has expanded and the geographical unit of data generation, analysis and use for planning has shifted from the national to the state, district and now subdistrict level. The authors describe and critically analyse the evolution of data sets in India and how they have been utilised to better understand the epidemic, advance policy, and plan and implement an increasingly effective, well-targeted and decentralised national response to HIV and AIDS. The authors argue that India is an example of how 'know your epidemic, know your response' message can effectively be implemented at scale and presents important lessons to help other countries design their evidence generation systems.

Mathematical models for the study of HIV spread and control amongst men who have sex with men

For a quarter of century, mathematical models have been used to study the spread and control of HIV amongst men who have sex with men (MSM). We searched MEDLINE and EMBASE databases up to the end of 2010 and reviewed this literature to summarise the methodologies used, key model developments, and the recommended strategies for HIV control amongst MSM. Of 742 studies identified, 127 studies met the inclusion criteria. Most studies employed deterministic modelling methods (80%). Over time we saw an increase in model complexity regarding antiretroviral therapy (ART), and a corresponding decrease in complexity regarding sexual behaviours. Formal estimation of model parameters was carried out in only a small proportion of the studies (22%) while model validation was considered by an even smaller proportion (17%), somewhat reducing confidence in the findings from the studies. Nonetheless, a number of common conclusions emerged, including (1) identification of the importance of assumptions regarding changes in infectivity and sexual contact rates on the impact of ART on HIV incidence, that subsequently led to empirical studies to gather these data, and (2) recommendation that multiple strategies would be required for effective HIV control amongst MSM. The role of mathematical models in studying epidemics is clear, and the lack of formal inference and validation highlights the need for further developments in this area. Improved methodologies for parameter estimation and systematic sensitivity analysis will help generate predictions that more fully express uncertainty, allowing better informed decision making in public health.

Increasing risk behaviour can outweigh the benefits of antiretroviral drug treatment on the HIV incidence among men-having-sex-with-men in Amsterdam

Background

The transmission through contacts among MSM (men who have sex with men) is one of the dominating contributors to HIV prevalence in industrialized countries. In Amsterdam, the capital of the Netherlands, the MSM risk group has been traced for decades. This has motivated studies which provide detailed information about MSM's risk behavior statistically, psychologically and sociologically. Despite the era of potent antiretroviral therapy, the incidence of HIV among MSM increases. In the long term the contradictory effects of risk behavior and effective therapy are still poorly understood.

Methods

Using a previously presented Complex Agent Network model, we describe steady and casual partnerships to predict the HIV spreading among MSM. Behavior-related parameters and values, inferred from studies on Amsterdam MSM, are fed into the model; we validate the model using historical yearly incidence data. Subsequently, we study scenarios to assess the contradictory effects of risk behavior and effective therapy, by varying corresponding values of parameters. Finally, we conduct quantitative analysis based on the resulting incidence data.

Results

The simulated incidence reproduces the ACS historical incidence well and helps to predict the HIV epidemic among MSM in Amsterdam. Our results show that in the long run the positive influence of effective therapy can be outweighed by an increase in risk behavior of at least 30% for MSM.

Conclusion

We recommend, based on the model predictions, that lowering risk behavior is the prominent control mechanism of HIV incidence even in the presence of effective therapy.

'Test-and-treat': the end of the HIV epidemic?

PURPOSE OF REVIEW

The aim is to review recent literature on 'test-and-treat', a prevention strategy that promotes high levels of HIV testing and initiating antiretroviral therapy upon diagnosis, regardless of CD4 cell count. Antiretroviral therapy (ART) has been shown to dramatically reduce viral load which is strongly associated with the risk of transmission, therefore there is the potential to reduce HIV transmissions with ART.

RECENT FINDINGS

Recent papers from observational studies on heterosexual sero-discordant couples found an overall rate of transmission of HIV-1 from ART-treated patients of 0.46 per 100 person-years, confirming the possibility of using ART as a prevention strategy. Several models have been used to predict the effect of this strategy and the potential risks of it. Randomized controlled trials are currently ongoing investigating the effect of ART on reducing infectiousness and the feasibility of this policy.

SUMMARY

More precise estimations of the transmission risk under virally suppressive ART (especially in MSM) and of change in sex risk behaviour at diagnosis and at start of ART are needed. Further, the benefit to individual health of very early ART initiation and the feasibility of this policy need to be evaluated. Achieving very high levels of testing should be a high priority due to the benefits of initiating ART in all those who are in need (CD4 cell count < 350 cells/μl) and potential benefits on incidence due to reductions in risk behaviour in those diagnosed. Use of ART immediately at diagnosis in those with high CD4 cell counts should await results from further studies.

Prevalence of sexually transmitted co-infections in people living with HIV/AIDS: systematic review with implications for using HIV treatments for prevention

Sexually transmitted co-infections increase HIV infectiousness through local inflammatory processes. The prevalence of STI among people living with HIV/AIDS has implications for containing the spread of HIV in general and the effectiveness of HIV treatments for prevention in particular. Here we report a systematic review of STI co-infections in people living with HIV/AIDS. We focus on STI contracted after becoming HIV infected. Electronic database and manual searches located 37 clinical and epidemiological studies of STI that increase HIV infectiousness. Studies of adults living with HIV/AIDS from developed and developing countries reported STI rates for 46 different samples (33 samples had clinical/laboratory confirmed STI). The overall mean point-prevalence for confirmed STI was 16.3% (SD=16.4), and median 12.4% STI prevalence in people living with HIV/AIDS. The most common STI studied were Syphilis with median 9.5% prevalence, Gonorrhea 9.5%, Chlamydia 5%, and Trichamoniasis 18.8% prevalence. STI prevalence was greatest at the time of HIV diagnosis, reflecting the role of STI in HIV transmission. Prevalence of STI among individuals receiving HIV treatment was not appreciably different from untreated persons. The prevalence of STI in people infected with HIV suggests that STI co-infections could undermine efforts to use HIV treatments for prevention by increasing genital secretion infectiousness.

Modelling sexual transmission of HIV: testing the assumptions, validating the predictions

PURPOSE OF REVIEW

To discuss the role of mathematical models of sexual transmission of HIV: the methods used and their impact.

RECENT FINDINGS

We use mathematical modelling of 'universal test and treat' as a case study to illustrate wider issues relevant to all modelling of sexual HIV transmission.

SUMMARY

Mathematical models are used extensively in HIV epidemiology to deduce the logical conclusions arising from one or more sets of assumptions. Simple models lead to broad qualitative understanding, whereas complex models can encode more realistic assumptions and, thus, be used for predictive or operational purposes. An overreliance on model analysis in which assumptions are untested and input parameters cannot be estimated should be avoided. Simple models providing bold assertions have provided compelling arguments in recent public health policy, but may not adequately reflect the uncertainty inherent in the analysis.

Adherence to antiretroviral therapy and HIV transmission risks: implications for test-and-treat approaches to HIV prevention

HIV transmission may be prevented by effectively suppressing viral replication with antiretroviral therapy (ART). However, adherence is essential to the success of ART, including for reducing HIV transmission risk behaviors. This study examined the association of nonadherence versus adherence with HIV transmission risks. Men (n = 226) living with HIV/AIDS and receiving ART completed confidential computerized interviews and telephone-based unannounced pill counts for ART adherence monitoring. Data were collected between January 2008 and June 2009. Results showed that nonadherence to ART was associated with greater number of sex partners and engaging in unprotected and protected anal intercourse. These associations were not moderated by substance use. The belief that having an undetectable viral load leads to lower infectiousness was associated with greater number of partners, including nonpositive partners, and less condom use. Men who had an undetectable viral load and believed that having an undetectable viral load reduces their infectiousness, were significantly more likely to have contracted a recent STI. Programs aimed at testing and treating people living with HIV/AIDS for prevention require attention to adherence and sexual behaviors.

Can we spend our way out of the AIDS epidemic? A world halting AIDS model

Background

There has been a sudden increase in the amount of money donors are willing to spend on the worldwide HIV/AIDS epidemic. Present plans are to hold most of the money in reserve and spend it slowly. However, rapid spending may be the best strategy for halting this disease.

Methods

We develop a mathematical model that predicts eradication or persistence of HIV/AIDS on a world scale. Dividing the world into regions (continents, countries etc), we develop a linear differential equation model of infectives which has the same eradication properties as more complex models.

Results

We show that, even if HIV/AIDS can be eradicated in each region independently, travel/immigration of infectives could still sustain the epidemic. We use a continent-level example to demonstrate that eradication is possible if preventive intervention methods (such as condoms or education) reduced the infection rate to two fifths of what it is currently. We show that, for HIV/AIDS to be eradicated within five years, the total cost would be ≈ $63 billion, which is within the existing $60 billion (plus interest) amount raised by the donor community. However, if this action is spread over a twenty year period, as currently planned, then eradication is no longer possible, due to population growth, and the costs would exceed $90 billion.

Conclusion

Eradication of AIDS is feasible, using the tools that we have currently to hand, but action needs to occur immediately. If not, then HIV/AIDS will race beyond our ability to afford it.

Risky sexual practices among men who have sex with men in Northeast Brazil: results from four sequential surveys

This paper focuses on recent trends in risky sexual practices for HIV/AIDS among men who have sex with men (MSM) in Fortaleza, Ceará State, Brazil. Four cross-sectional surveys were conducted (1995, 1998, 2002, and 2005) among MSM 14 years or older who reported oral or anal sex in the previous 12 months. Sexual practices were considered risky whenever the respondent reported unprotected receptive or insertive anal intercourse in the six months preceding the interview. Different selection techniques were used to recruit the study population: snowball (1995, 1998, 2002 - 32%); time-space sampling (2002 - 68%); and respondent-driven sampling (2005). Analyses were based on the comparison between proportions. High rates of risky sexual practices were reported in 1995 (49.9%), decreasing in 1998 (32.6%), increasing again in 2002 (51.3%), and showing the lowest level in 2005 (31.4%). Participants with more schooling increased their risky practices from 1998 to 2002, decreasing in 2005. Among individuals with medium or low schooling, risky behavior declined from 2002 to 2005. The article highlights the need for behavioral surveillance to properly address STD/HIV prevention.

Impact of human immunodeficiency virus 1 infection and inflammation on the composition and yield of cervical mononuclear cells in the female genital tract

Cervical cytobrush sampling is a relatively non-invasive method for obtaining mucosal cells from the female genital tract. To define mucosal immune cells sampled by cervical cytobrushing and to validate this approach for local immunity studies, we investigated the impact of human immunodeficiency virus (HIV) status and inflammation on the yield and composition of cervical cytobrush specimens. Cervical cytobrush samples were obtained from 89 chronically HIV-infected and 46 HIV-negative women. The HIV-infected women had significantly higher yields of CD3(+), CD45(+), CD19(+), CD14(+), Langerin(+) and CD24(+) cells than the uninfected women. While cytobrush-derived T cells from uninfected women were predominantly CD4(+) (4.2 CD4 : 1 CD8), CD8(+) T cells were predominant in HIV-infected women (0.6 CD4 : 1 CD8). The majority of CD4(+) and CD8(+) T cells from HIV-infected and uninfected women were of the effector memory (CD45RA(-) CCR7(-) CD27(-)) phenotype. HIV-infected women had significantly elevated levels of interleukin (IL)-1beta, IL-6 and IL-8 in cervical supernatants compared with uninfected women. We observed a significant positive correlation between T-cell counts and IL-1beta, tumour necrosis factor (TNF)-alpha and IL-12 concentrations. Neutrophil counts correlated significantly with cervical concentrations of IL-1beta, TNF-alpha, IL-8, IL-6 and IL-10. Antigen-presenting cell numbers correlated significantly with TNF-alpha and IL-12 concentrations. HIV-infected women on antiretroviral therapy had similar levels of cervical lymphocyte infiltration and inflammation to women naïve to therapy. In conclusion, we suggest that inflammation at the cervix and HIV infection are likely to be key determinants in the absolute number of mucosal immune cells recovered by cervical cytobrushing.

Expanded access to highly active antiretroviral therapy: a potentially powerful strategy to curb the growth of the HIV epidemic

We developed a mathematical model using a multiple source of infection framework to assess the potential effect of the expansion of highly active antiretroviral therapy (HAART) coverage among those in medical need on the number of individuals testing newly positive for human immunodeficiency virus (HIV) and on related costs in British Columbia, Canada, over the next 25 years. The model was calibrated using retrospective data describing antiretroviral therapy utilization and individuals testing newly positive for HIV in the province. Different scenarios were investigated on the basis of varying assumptions regarding drug resistance, adherence to HAART, therapeutic guidelines, degree of HAART coverage, and the timing of HAART uptake. Expansion of HAART lead to substantial reductions in the growth of the HIV epidemic and related costs. These results provide powerful additional motivation to accelerate the roll out of HAART programs aggressively targeting those in medical need, both for their own benefit and as a means of decreasing new HIV infections.

Measuring the public-health impact of candidate HIV vaccines as part of the licensing process

The full impact of vaccines against infectious diseases is manifest at both the individual and the community levels. We argue that evaluating the community-level impact of HIV vaccine candidates should be an integral part of the licensing process. We describe a framework for the public-health evaluation of an HIV vaccine, which is based on the interactive use of mathematical models and community randomised clinical trials (C-RCTs) following completion of individual-based clinical trials (I-RCTs). Mathematical models of HIV vaccine can be used to take public-health considerations into account during the licensing process and can also help to select promising vaccine candidates for testing in C-RCTs. We also describe community and individual-based measures useful for defining public-health criteria necessary to guide the licensing process. To move forward, it is crucial to reach a consensus on what should constitute adequate public-health criteria. At the very least, a suitable vaccine would provide some individual benefit to vaccinees and not be detrimental to the population at large. In future I-RCTs and C-RCTs, quantifying each protective vaccine characteristic (eg, reductions in susceptibility or viral load) is important if regulators are to evaluate adequately the potential community-level impact of the vaccine across different settings, populations, and conditions of use.

Mathematical models for HIV transmission dynamics: tools for social and behavioral science research

HIV researchers have long appreciated the need to understand the social and behavioral determinants of HIV-related risk behavior, but the cumulative impact of individual behaviors on population-level HIV outcomes can be subtle and counterintuitive, and the methods for studying this are rarely part of a traditional social science or epidemiology training program. Mathematical models provide a way to examine the potential effects of the proximate biologic and behavioral determinants of HIV transmission dynamics, alone and in combination. The purpose of this article is to show how mathematical modeling studies have contributed to our understanding of the dynamics and disparities in the global spread of HIV. Our aims are to demonstrate the value that these analytic tools have for social and behavioral sciences in HIV prevention research, to identify gaps in the current literature, and to suggest directions for future research.

Population prevalence of reported and unreported HIV and related behaviors among the household adult population in New York City, 2004

BACKGROUND

Surveillance for HIV likely underestimates infection among the general population: 25% of US residents are estimated to be unaware of their HIV infection.

OBJECTIVE

To determine the prevalence of HIV infection and risk behaviors among New York City (NYC) adults and compare these with surveillance findings.

METHODS

The NYC Health and Nutrition Examination Survey (HANES) provided the first opportunity to estimate population-based HIV prevalence among NYC adults. It was conducted in 2004 among a representative sample of adults > 20 years. Previously reported HIV infection was identified from the NYC HIV/AIDS Surveillance Registry. A blinded HIV serosurvey was conducted on archived blood samples of 1626 NYC HANES participants. Data were used to estimate prevalence for HIV infection, unreported infections, high-risk activities, and self-perceived risk.

RESULTS

Overall, 18.1% engaged in one or more risky sexual/needle-use behaviors, of which 92.2% considered themselves at low or no risk of HIV or another sexually transmitted disease. HIV occurred in 21 individuals (prevalence 1.4%; 95% confidence interval (CI), 0.8-2.5]; one infection (5%; 95% CI, 0.7-29.9) was not reported previously and possibly undiagnosed. HIV infection was significantly elevated in those with herpes simplex virus 2 (4%), men who have sex with men (14%), and needle-users (21%) (P < 0.01).

CONCLUSIONS

Among NYC adults, HIV prevalence was consistent with surveillance findings overall. The proportion of unreported HIV was less than estimated nationally, but findings were limited by sample size. Most adults with risky behaviors perceived themselves to be at minimal risk, highlighting the need for risk reduction and routine HIV screening.

Prospective study of attitudinal and relationship predictors of sexual risk in the multicenter AIDS cohort study

We examined the influence of attitudes concerning HIV transmission, safe sex, and sexual sensation seeking, as well as negotiated risk reduction with primary partners, on the proportion of unprotected sexual partners (%UASP) among men who have sex with men (MSM). Participants were 263 HIV-seropositive and 238 HIV-seronegative MSM in the Multicenter AIDS Cohort Study between 1999 and 2003 who completed a 20-item attitude survey twice. Behavioral data were collected concurrently and 6-12 months after each survey. Among seropositives, decreased HIV concern and increased safer sex fatigue were associated with higher %UASP at 6 and 12 months. Among seronegatives, increased %UASP at 12 months was associated with safer sex fatigue. At 6 months and 12 months, risk reduction agreements were associated with increased %UASP among seronegatives in seroconcordant monogamous relationships, reflecting their abandonment of condoms in such partnerships. We conclude that HIV prevention efforts should target modifiable attitudes (reduced concern about HIV and safer sex fatigue) and increases in sexual risk-taking of MSM, particularly among HIV+ men having sex with serodiscordant partners.

The impact of HIV treatment on risk behaviour in developing countries: A systematic review

In developing countries, access to antiretroviral therapy (ART) is improving as HIV treatment becomes a greater priority in the global fight against AIDS. While ART has clearly beneficial clinical effects, increased access to treatment may also affect sexual behaviour. To examine the strength of evidence for the impact of medical treatment for HIV-positive individuals on behavioural outcomes in developing countries, we conducted a comprehensive search of the peer-reviewed literature. Studies were included if they provided clinical treatment to HIV-positive individuals in a developing country, compared behavioural, psychological, social, care, or biological outcomes related to HIV-prevention using a pre/post or multi-arm study design, and were published between January 1990 and January 2006. Only three studies were identified that met the inclusion criteria. All were conducted in Africa, utilized before/after or multi-arm study designs, and relied on self-reported behaviour. In all three studies, a majority of HIV-infected individuals reported being sexually abstinent, and access to ART was not associated with an increase in HIV-related risky sexual behaviours. However, one cross-sectional study found that ART patients were more likely to report STD treatment. The available evidence indicates a significant reduction in risk behaviour associated with ART in developing countries. However, there are few existing studies and the rigor of these studies is weak. More studies are needed to build an evidence base on which to make programmatic and policy decisions.

The resurgence of syphilis among men who have sex with men

PURPOSE OF REVIEW

To identify recent progress and emerging problems in addressing syphilis among men who have sex with men.

RECENT FINDINGS

A resurgence of syphilis has occurred among men who have sex with men in many developed countries. Infection has been associated with HIV coinfection, multiple partners, and recreational drug use. Unlike HIV, oral sex appears to be a common route of syphilis transmission. Many prevention approaches have shown, at best, modest success. Variable clinical presentation and potentially inconclusive lab tests make diagnosis confusing.

SUMMARY

As the infection remains relatively rare, clinicians treating men who have sex with men should maintain a high index of suspicion for syphilis lesions, and should screen their sexually active patients for latent disease. Debates about syphilis control and treatment continue. The clinical manifestations, serologic responses, efficacy of treatment, and complications of syphilis have always been complicated. HIV coinfection adds to the confusion.

HIV-1, Sexually Transmitted Infections, and Sexual Behavior Trends Among Men Who Have Sex With Men in Lima, Peru

OBJECTIVE

To assess and estimate trends in HIV, sexually transmitted infections (STIs), and sexual behavior among men who have sex with men (MSM) in Lima, Peru.

DESIGN

Second-generation HIV sentinel surveillance surveys conducted in 1996, 1998, 2000, and 2002.

METHODS

Adult men reporting sex with at least 1 man during the previous year were eligible to participate. Sexual behavior and serum HIV-1 and syphilis antibodies were assessed. HIV seroincidence was estimated by a sensitive/less-sensitive enzyme immunoassay strategy. Rectal and pharyngeal swabs for Neisseria gonorrhoeae culture and a first-void urine sample for urethral leukocytes for presumptive diagnosis of urethritis were obtained. Herpes simplex virus 2 (HSV-2) antibodies were measured in 2002.

RESULTS

Although HIV prevalence increased from 18.5% to 22.3% from 1996 through 2002, bacterial prevalence declined significantly for syphilis (16.0% to 12.4%), early syphilis (8.6% to 3.4%), and rectal gonorrhea (5.1% to 0.2%). High HIV seroincidence was estimated, with the lowest (4.8%) incidence in 1998. In 2002, HSV-2 seroprevalence was 51.0%. After adjustment for age, education, and self-reported sexual identity, our data suggest that a yearly increase by 6% in the prevalence of HIV occurred among MSM in Lima, with a corresponding decline in syphilis (by 9%), early syphilis (by 18%), and rectal gonorrhea (by 64%). Condom use during last sexual intercourse increased by 26% each year with the most recent male steady partner and, among non-sex workers, by 11% with the most recent casual partner.

CONCLUSIONS

HIV continued to spread among MSM in Lima even when a decline in bacterial STIs and increase in condom use were estimated to occur. Intensification of medical and behavior prevention interventions is warranted for MSM in Peru.

ETHICAL AND REGULATORY ISSUES SURROUNDING AFRICAN TRADITIONAL MEDICINE IN THE CONTEXT OF HIV/AIDS

It has been estimated that more than 80% of people in Africa use traditional medicine (TM). With the HIV/AIDS epidemic claiming many lives in Africa, the majority of people affected rely on TM mainly because it is relatively affordable and available to the poor populations who cannot afford orthodox medicine. Whereas orthodox medicine is practiced under stringent regulations and ethical guidelines emanating from The Nuremburg Code, African TM seems to be exempt from such scrutiny. Although recently there have been calls for TM to be incorporated into the health care system, less emphasis has been placed on ethical and regulatory issues. In this paper, an overview of the use of African TM in general, and for HIV/AIDS in particular, is given, followed by a look at: (i) the relative laxity in the application of ethical standards and regulatory requirements with regards to TM; (ii) the importance of research on TM in order to improve and demystify its therapeutic qualities; (iii) the need to tailor-make intellectual property laws to protect traditional knowledge and biodiversity. A framework of partnerships involving traditional healers' associations, scientists, policy makers, patients, community leaders, members of the communities, and funding organizations is suggested as a possible method to tackle these issues. It is hoped that this paper will stimulate objective and constructive debate that could enhance the protection of patients' welfare.

Increases in sexually transmitted infections and sexual risk behaviour without a concurrent increase in HIV incidence among men who have sex with men in San Francisco: a suggestion of HIV serosorting?

BACKGROUND

Sexually transmitted infections (STI) and unprotected anal intercourse (UAI) have been increasing among men who have sex with men (MSM) in San Francisco. However, HIV incidence has stabilised.

OBJECTIVES

To describe recent trends in sexual risk behaviour, STI, and HIV incidence among MSM in San Francisco and to assess whether increases in HIV serosorting (that is, selective unprotected sex with partners of the same HIV status) may contribute to preventing further expansion of the epidemic.

METHODS

The study applies an ecological approach and follows the principles of second generation HIV surveillance. Temporal trends in biological and behavioural measures among MSM were assessed using multiple pre-existing

DATA SOURCES

STI case reporting, prevention outreach programmatic data, and voluntary HIV counselling and testing data.

RESULTS

Reported STI cases among MSM rose from 1998 through 2004, although the rate of increase slowed between 2002 and 2004. Rectal gonorrhoea cases increased from 157 to 389 while early syphilis increased from nine to 492. UAI increased overall from 1998 to 2004 (p<0.001) in community based surveys; however, UAI with partners of unknown HIV serostatus decreased overall (p<0.001) among HIV negative MSM, and among HIV positive MSM it declined from 30.7% in 2001 to a low of 21.0% in 2004 (p<0.001). Any UAI, receptive UAI, and insertive UAI with a known HIV positive partner decreased overall from 1998 to 2004 (p<0.001) among MSM seeking anonymous HIV testing and at the STI clinic testing programme. HIV incidence using the serological testing algorithm for recent HIV seroconversion (STARHS) peaked in 1999 at 4.1% at the anonymous testing sites and 4.8% at the STI clinic voluntary testing programme, with rates levelling off through 2004.

CONCLUSIONS

HIV incidence among MSM appears to have stabilised at a plateau following several years of resurgence. Increases in the selection of sexual partners of concordant HIV serostatus may be contributing to the stabilisation of the epidemic. However, current incidence rates of STI and HIV remain high. Moreover, a strategy of risk reduction by HIV serosorting can be severely limited by imperfect knowledge of one's own and one's partners' serostatus.

Could the CARE-SHAKTI intervention for injecting drug users be maintaining the low HIV prevalence in Dhaka, Bangladesh?

AIMS

To explore whether the low HIV prevalence observed in Bangladesh results from prevention activities, this study uses mathematical modelling to estimate the impact of a needle/syringe exchange intervention for injecting drug users (IDUs) in Dhaka, Bangladesh.

DESIGN

Epidemiological, behavioural and intervention monitoring data were used to parameterize a dynamic mathematical model, and fit it to National HIV Sero-surveillance data among IDUs (2000-02). The model was used to estimate the impact of the intervention on HIV transmission among IDUs and their sexual partners.

SETTING

Dhaka, Bangladesh, where the HIV prevalence has remained low despite high-risk sexual and injecting behaviours, and growing HIV epidemics in neighbouring countries.

FINDINGS

The model predicts that the intervention may have reduced the incidence of HIV among IDUs by 90% (95% CI 74-94%), resulting in an IDU HIV prevalence of 10% (95% CI 4-19%) after 8 years of intervention activity instead of 42% (95% CI 30-47%) if the intervention had not occurred.

CONCLUSIONS

The analysis highlights the potential for rapid HIV spread among IDUs in Dhaka, and suggests that the intervention may have substantially reduced IDU HIV transmission. However, there is no room for complacency. Sustained and expanded funding for interventions in Dhaka and other regions of Bangladesh are crucial to maintaining the low HIV prevalence.

The economic value of reductions in gonorrhea and syphilis incidence in the United States, 1990-2003

BACKGROUND

Prevention efforts can reduce the considerable health and economic burdens imposed by sexually transmitted diseases (STDs). The objective of this study was to estimate the reduction in direct medical costs associated with reductions in gonorrhea and syphilis incidence in the United States from 1990 to 2003.

METHODS

Using published estimates of the per-case costs of STDs, we estimated the annual costs from 1990 to 2003 of four main outcomes: primary and secondary (P&S) syphilis, congenital syphilis, gonorrhea, and HIV costs attributable to the facilitative effects of gonorrhea and syphilis on HIV transmission and acquisition.

RESULTS

Reductions in syphilis and gonorrhea from 1990 to 2003 have saved an estimated 5.0 billion dollars (in 2003 U.S. dollars): 1.1 billion dollars in costs associated with P&S syphilis, congenital syphilis, and gonorrhea, and 3.9 billion dollars in HIV costs attributable to syphilis and gonorrhea. In additional analyses, the estimated reductions in disease burden were substantially lower (1) when calculated incrementally (rather than cumulatively) and (2) when long-term costs of STDs were excluded.

CONCLUSIONS

These estimated reductions in the burden of gonorrhea and syphilis show the economic benefits of reducing the incidence of these STDs and preventing their resurgence.

Estimated Effectiveness and Cost-Effectiveness of Federally Funded Prevention Efforts on Gonorrhea Rates in the United States, 1971???2003, Under Various Assumptions About the Impact of Prevention Funding

BACKGROUND

Reported gonorrhea incidence rates in the United States declined by 75% from 1975 to 2003 after implementation of a federally funded gonorrhea control program in the mid-1970s. The purpose of this study was to (1) estimate national gonorrhea rates that might have occurred from 1971 to 2003 had there been no federally funded sexually transmitted disease (STD) prevention activities and (2) calculate crude estimates of the cost-effectiveness of these prevention activities.

METHODS

Hypothetical gonorrhea rates had there been no federally funded prevention efforts from 1971 to 2003 were estimated based on (1) the amount of federal funding allocated to state and local health departments for STD prevention and (2) a published estimate of the impact of funding on STD rates in the United States. Standard methods of cost-effectiveness analysis were used to calculate the cost per case of gonorrhea prevented.

RESULTS

Under base case assumptions about the impact of prevention funding on gonorrhea rates drawn from a published study, prevention efforts were cost saving, meaning that the program costs were less than the averted costs of treating gonorrhea and its associated sequelae. Over the 33-year period, an estimated 32 million cases of gonorrhea were averted by prevention efforts.

CONCLUSION

STD prevention efforts appeared to be cost saving when considering only the benefits of gonorrhea prevention. If other benefits were considered (such as the prevention of other STDs), the estimated effectiveness and cost-effectiveness of STD prevention in the United States would be even greater.

[Brazilian psychosocial and operational research vis-à-vis the UNGASS targets]

Items from the UNGASS Draft Declaration of Commitment on HIV/AIDS (2001) are analyzed. The Brazilian experience of new methods for testing and counseling among vulnerable populations, preventive methods controlled by women, prevention, psychosocial support for people living with HIV/AIDS, and mother-child transmission, is discussed. These items were put into operation in the form of keywords, in systematic searches within the standard biomedicine databases, also including the subdivisions of the Web of Science relating to natural and social sciences. The Brazilian experience relating to testing and counseling strategies has been consolidated through the utilization of algorithms aimed at estimating incidence rates and identifying recently infected individuals, testing and counseling for pregnant women, and application of quick tests. The introduction of alternative methods and new technologies for collecting data from vulnerable populations has been allowing speedy monitoring of the epidemic. Psychosocial support assessments for people living with HIV/AIDS have gained impetus in Brazil, probably as a result of increased survival and quality of life among these individuals. Substantial advances in controlling mother-child transmission have been observed. This is one of the most important victories within the field of HIV/AIDS in Brazil, but deficiencies in prenatal care still constitute a challenge. With regard to prevention methods for women, Brazil has only shown a halting response. Widespread implementation of new technologies for data gathering and management depends on investments in infrastructure and professional skills acquisition.

Sexually Transmitted Infection Services as a Component of HIV Care

OBJECTIVES

As Thailand scales up its antiretroviral treatment program, the role of sexually transmitted infection (STI) services to prevent HIV transmission has not been addressed. We provided STI services for HIV-infected women as a component of HIV care and assessed STI prevalence and risk behaviors.

METHODS

HIV-infected women attending an infectious disease clinic and an STI clinic in Bangkok were screened for the presence of genital ulcers by visual inspection, for gonorrhea and chlamydial infection by polymerase chain reaction, for trichomoniasis by wet mount, and for syphilis by serology. Women were asked about sexual risk behavior and use of antiretroviral treatment. Risk-reduction counseling, condoms, and STI treatment were provided.

RESULTS

Two-hundred ten HIV-infected women at an infectious disease clinic (n = 150) and an STI clinic (n = 60) received STI services from July 2003 through February 2004. The prevalence for any STI was 8.0% at the infectious disease clinic and 30.0% at the STI clinic (P < 0.01). Of the 116 (55.2%) sexually active women, 42 (36.2%) reported sex without a condom during the last 3 months. Women receiving antiretroviral treatment reported condom use during last sex more often compared with those not receiving antiretroviral treatment (82.2% vs. 58.8%; P = 0.03).

CONCLUSION

STIs and sexual risk behavior were common among these HIV-infected women, and STI services for HIV-infected persons have been expanded to more clinics in Thailand. Further analysis of HIV transmission risk is necessary for developing a national strategy for prevention of HIV transmission among HIV-infected persons.

Profile of male Brazilian injecting drug users who have sex with men

This study aims to characterize the profile of male injecting drug users who have sex with other men (MSM IDUs) recruited through a cross-sectional multi-city survey (AjUDE-Brasil II Project) in six Brazilian cities, in 2000-2001. MSM IDUs were compared to other male IDUs using bivariate and multivariate procedures (logistic regression and answer tree analysis with the CHAID algorithm). Among the 709 male IDUs, 187 (26.4%) reported ever having had sex with other men, while only 37 reported sex with other men in the previous six months. MSM IDUs were more likely to be unemployed (OR = 2.3), to have injected tranquilizers (OR = 3.6), and to be HIV-seropositive (OR = 2.1), compared to other male IDUs. Male same-sex relations in this subgroup appear to be associated with strategies to finance drug consuming habits, including sex for drugs with occasional female partners or obtaining injection paraphernalia from occasional sex partners. Further studies should focus on this especially vulnerable subgroup of IDUs, due to the bidirectional and complex interrelationships between their drug injecting habits and sexual risk behaviors.

Utilization of HIV/AIDS treatment services: comparing injecting drug users and other clients

This study compared healthcare utilization by injection drug users (IDUs) and non-IDUs. Data were abstracted from patients' medical records, admitted on HIV/AIDS treatment centers, between 1986 and 2002, forming a non-concurrent cohort study. Variables included: sociodemographics, HIV/AIDS exposure group, healthcare utilization (consultations, procedures, and prescriptions). Descriptive analyses included age-period and cohort effects. Out of 170 patients, with an average age of 30 years, 39.4% were IDUs, 71.8% were males and had low levels of education. At the first consultation, 86.5% neither received an ARV prescription nor had a request for CD4 or viral load. Injection drug users, as compared to non-IDUs, were less likely to receive ARV prescriptions and requests for CD4 lymphocyte and viral load counts, even though the number of consultations did not differ between the two groups. Healthcare utilization increased in calendar-year in the non-IDUs group, parallel to the implementation of the Brazilian health policy of universal care. However, this favorable trend was not observed among IDUs. Differential outcomes for HIV/AIDS among IDUs, towards worse prognosis, suggest difficulties in terms of adherence and follow-up of ARV therapy in this population.

Revisiting the ABC strategy: HIV prevention in Uganda in the era of antiretroviral therapy

The ABC strategy is credited for bringing the HIV/AIDS epidemic under control in Uganda. By promoting abstinence, being faithful, and condom use, safe(r) behaviours have been identified that are applicable to people in different circumstances. However, scaling-up of antiretroviral therapy in the country raised concerns that HIV prevention messages targeting the uninfected population are not taking sufficient account of inherent complexities. Furthermore, there is debate in the country over relative importance of abstinence in reduction of HIV incidence as well as over the morality and effectiveness of condoms. The purpose of this paper is to examine each component of ABC in light of current developments. It is argued that there is still a strong justification for condom use to complement abstinence and being faithful. There is an urgent need to update and relaunch Uganda's ABC strategy--its three elements are complementary, synergistic, and inseparable in the national HIV prevention programme.

Optimistic perception of HIV/AIDS, unprotected sex and implications for prevention among men who have sex with men, São Paulo, Brazil

BACKGROUND

This study examines the association between optimistic perceptions about AIDS and unprotected sex among men who have sex with men (MSM) in the city of São Paulo, Brazil.

METHODS

A cross-sectional study was carried out among MSM in leisure areas of São Paulo in 2003. We interviewed 161 participants aged 18-30 years.

RESULTS

Thirty-nine per cent (95% confidence interval 32-47%) reported unprotected anal sex with steady or casual partners in the previous 6 months. The optimistic perception score created for this study was associated with unprotected sex (P = 0.01) and higher education (P = 0.02). The quartile with the most optimistic perception was 1.8 times more likely to engage in unprotected anal sex compared with the quartile with the least optimistic perception.

CONCLUSION

This study suggests that the current situation regarding AIDS, which is seemingly favourable, may create optimistic perceptions leading to unprotected sexual practices. Prevention programmes, particularly for MSM, need to take this into account.

Sentinel surveillance of sexually transmitted infections in South Africa: a review

OBJECTIVES

To review studies of sexually transmitted infection (STI) prevalence in South Africa between 1985 and 2003 in selected sentinel populations. To examine how STI prevalence varies between populations and to identify the limitations of the existing data.

METHODS

Studies of the prevalence of syphilis, chancroid, granuloma inguinale, lymphogranuloma venereum, gonorrhoea, chlamydia, trichomoniasis, bacterial vaginosis, candidiasis, and herpes simplex virus type 2 (HSV-2) were considered. Results were included if they related to women attending antenatal clinics or family planning clinics, commercial sex workers, individuals in the general population (household surveys), patients with STIs, patients with genital ulcer disease (GUD), or men with urethritis.

RESULTS

High STI prevalence rates have been measured, particularly in the case of HSV-2, trichomoniasis, bacterial vaginosis and candidiasis. The aetiological profile of GUD appears to be changing, with more GUD caused by HSV-2 and less caused by chancroid. The prevalence of gonorrhoea and syphilis is highest in "high risk" groups such as sex workers and attenders of STI clinics, but chlamydia and trichomoniasis prevalence levels are not significantly higher in these groups than in women attending antenatal clinics.

CONCLUSIONS

The prevalence of STIs in South Africa is high, although there is extensive variability between regions. There is a need for STI prevalence data that are more nationally representative and that can be used to monitor prevalence trends more reliably.

The impact of the transmission dynamics of the HIV/AIDS epidemic on sexual behaviour: a new hypothesis to explain recent increases in risk taking-behaviour among men who have sex with men

Increases in sexually transmitted infections and related high-risk behaviours have been reported among men who have sex with men (MSM) in industrialised countries when effective antiretroviral therapy against HIV infection has become widely available, in the mid-nineties. The reasons for these increases are not fully understood and often conflicting. Prevention fatigue, relapses to unsafe sex, as well as optimism toward the risk of developing AIDS among people living with HIV are not unique to the era of antiretroviral therapy (ART). This has led researchers to highlight the need to investigate other potential reasons that could explain the increase in high-risk taking following the ART introduction. We put forward the hypothesis that the change in the transmission dynamics of the HIV/AIDS epidemic before and after the introduction of ART has contributed to this change in high-risk behaviour. It is suggested that a decline in sexual risk activities has occurred at the population-level following the initial spread of the HIV/AIDS epidemic because AIDS mortality and severe morbidity disproportionately depleted the pool of high-risk taking individuals. As a result, non-volitional changes may have occurred at the individual-level over time because the depletion of this pool of high-risk individuals made it more difficult for the remaining high-risk taking individuals to find partners to engage in risky sex with. Following its introduction, ART has facilitated the differential replenishment of the pool of individuals willing to engage in high-risk taking behaviours because ART reduces AIDS mortality, and morbidity. Consequently, high-risk taking individuals who had previously reduced their level of risky sex non-volitionally (i.e., as a result of the reduced availability of high-risk partners) were able to resume their initial high-risk practices as the pool of high-risk taking individuals replenished over time. Thus, a fraction of the recently reported increase in high-risk sexual activities may be secondary to the fact that those MSM who were unable to engage in their desired high-risky sexual activities (because of reduced availability) are now able to revert to them as the availability of men willing to engage in risky sexual behaviours increases partly due to ART. Therefore, we suggest that a fraction of the changes in individual behaviour are non-volitional and can be explained by a change in "sexual partner availability" due to the transmission dynamics of HIV/AIDS before and after ART. The hypothesis is formulated and explained using simple social network diagrams and the Theory of Planned Behaviour. We also discuss the implication of this hypothesis for HIV prevention.

The epidemiological impact of antiretroviral use predicted by mathematical models: a review

This review summarises theoretical studies attempting to assess the population impact of antiretroviral therapy (ART) use on mortality and HIV incidence. We describe the key parameters that determine the impact of therapy, and argue that mathematical models of disease transmission are the natural framework within which to explore the interaction between antiviral use and the dynamics of an HIV epidemic. Our review focuses on the potential effects of ART in resource-poor settings. We discuss choice of model type and structure, the potential for risk behaviour change following widespread introduction of ART, the importance of the stage of HIV infection at which treatment is initiated, and the potential for spread of drug resistance. These issues are illustrated with results from models of HIV transmission. We demonstrate that HIV transmission models predicting the impact of ART use should incorporate a realistic progression through stages of HIV infection in order to capture the effect of the timing of treatment initiation on disease spread. The realism of existing models falls short of properly reproducing patterns of diagnosis timing, incorporating heterogeneity in sexual behaviour, and describing the evolution and transmission of drug resistance. The uncertainty surrounding certain effects of ART, such as changes in sexual behaviour and transmission of ART-resistant HIV strains, demands exploration of best and worst case scenarios in modelling, but this must be complemented by surveillance and behavioural surveys to quantify such effects in settings where ART is implemented.

Increasing rates of sexually transmitted diseases in homosexual men in Western europe and the United States: why?

The recent increases in acute STDs among MSM must be viewed in the context of a post-AIDS era that is characterized by demographic shifts,changing sexual attitudes, and rapidly changing social contexts. A key driver seems to be the growing prevalent pool of HIV-positive MSM for whom the crucial motivator for safer sex (primary HIV prevention) no longer exists and where, given the prevalence of seroconcordant sexual mixing, consider-able uncertainty and conflicting advice regarding the rationale and benefits for continued safer-sex practice are unclear [105,106]. Although it is tempting to ascribe these changes to increases in risk behavior, it is essential that the contexts in which the changes are occurring are also considered. It may also be appropriate to contemplate whether further changes to the social environment (eg, structural interventions) are a suitable adjunct to our traditional prevention activities that operate largely in isolation from each other. It seems natural to advocate that interventions that adopt holistic approaches to the sexual health of MSM and that address upstream factors such as mental health, drug use, discrimination, and internalized homophobia should be included in the efforts to create more healthy environments for MSM. However, there is still some way to go in identifying which of these upstream interventions are effective, how they may be implemented within or alongside existing health care systems, and what impact, if any, they are likely to have on STD transmission. Such interventions are also likely to belong on implementation time, require consider political will, and be extremely hard to evaluate, and the benefits may not be seen within the same generation in which they are implemented. Therefore, there must be confidence that this is the appropriate route of travel. The consistency of findings from across industrialized countries confirms an increasing connectivity within the global MSM community;a community that is decreasingly defined by geographic boundaries and, in the era of the Internet and easier foreign travel, increasingly linked by shared interests and social and sexual networks. This is powerfully demonstrated in the near-simultaneous syphilis and LGV outbreaks among MSM in Europe and the United States [29]. In this regard, greater collaboration between researchers and providers working with MSM indifferent countries is now required. More specifically, consideration should be given to creating closer partnerships between sentinel cities, such as London, New York, San Francisco, Berlin, Paris, and Amsterdam, that have large MSM populations and are likely to be emerging, or rapid diffusion sites for new social and sexual trends that may impact on disease transmission. There are many benefits to such cross-national working,including earlier recognition and improved response to emerging threats,sharing innovative practice, avoiding duplication of effort, and creating a united front for dealing with what must be considered a cause for concern domestically and globally.