Global epidemiology of HIV infection in men who have sex with men

Abstract

Epidemics of HIV in men who have sex with men (MSM) continue to expand in most countries. We sought to understand the epidemiological drivers of the global epidemic in MSM and why it continues unabated. We did a comprehensive review of available data for HIV prevalence, incidence, risk factors, and the molecular epidemiology of HIV in MSM from 2007 to 2011, and modelled the dynamics of HIV transmission with an agent-based simulation. Our findings show that the high probability of transmission per act through receptive anal intercourse has a central role in explaining the disproportionate disease burden in MSM. HIV can be transmitted through large MSM networks at great speed. Molecular epidemiological data show substantial clustering of HIV infections in MSM networks, and higher rates of dual-variant and multiple-variant HIV infection in MSM than in heterosexual people in the same populations. Prevention strategies that lower biological transmission and acquisition risks, such as approaches based on antiretrovirals, offer promise for controlling the expanding epidemic in MSM, but their potential effectiveness is limited by structural factors that contribute to low health-seeking behaviours in populations of MSM in many parts of the world.

Conflict of interest statement

Conflicts of interest

We declare that we have no conflicts of interest.

Copyright © 2012 Elsevier Ltd. All rights reserved.

Figures

Figure 1. Global prevalence of HIV in MSM compared with regional adult prevalence reported by UNAIDS, 2010

We obtained prevalence estimates of HIV reported in MSM by country from reports published after 2007 from studies done during or after 2000. Prevalence in all adults was from UNAIDS 2010. We include prevalence reported from biobehavioural surveillance without methods, sample size, or number positive in the prevalence map but not regional prevalence estimates. Error bars are 95% CIs. MSM=men who have sex with men.

Figure 2. Global HIV prevalence in MSM, from studies published 2007–11

Data are prevalence (95% CIs). Sources listed in the appendix. MSM=men who have sex with men.

Figure 3. HIV incidence in MSM populations, 1995–2010

Dashed lines represent cohort studies that report only total incidence over the study period. Authors were contacted for yearly incidence but these data were not provided. MSM=men who have sex with men.

Figure 4. Molecular epidemiology of HIV subtypes in MSM, 2007–11

Study details and references in the appendix. MSM=men who have sex with men. *Proportions by subtype not reported. †Proportions for all samples, MSM proportions not reported.

Figure 5. Agent-based stochastic modelling results for HIV infection in MSM in urban Peruvian and urban US scenarios

Percent reduction in cumulative incidence for each scenario and location, for runs with 15% initial prevalence. In the role segregation scenario, all men are assigned fixed and mutually exclusive roles in anal sex, 50% insertive and 50% receptive, mimicking heterosexual networks. MSM=men who have sex with men. UAI=unprotected anal intercourse.