A sex-role-preference model for HIV transmission among men who have sex with men in China

Jie Lou,Jianhong Wu,Yiming Shao,Yuhua Ruan,Li Chen

doi:10.1186/1471-2458-9-s1-s10

Abstract

BackgroundMen who have sex with men (MSM) are much more likely to be infected with HIV than the general population. China has a sizable population of MSM, including gay, bisexual men, money boys and some rural workers. So reducing HIV infection in this population is an important component of the national HIV/AIDS prevention and control program.MethodsWe develop a mathematical model using a sex-role-preference framework to predict HIV infection in the MSM population and to evaluate different intervention strategies.ResultsAn analytic formula for the basic reproduction ratio R0 was obtained; this yields R0 = 3.9296 in the current situation, so HIV will spread very fast in the MSM population if no intervention measure is implemented in a timely fashion. The persistence of HIV infection and the existence of disease equilibrium (or equilibria) are also shown. We utilized our model to simulate possible outcomes of antiretroviral therapy and vaccination for the MSM population. We compared the effects of these intervention measures under different assumptions about MSM behaviour. We also found that R0 is a decreasing function of the death rate of HIV-infected individuals, following a power law at least asymptotically.ConclusionHIV will spread very fast in the MSM population unless intervention measures are implemented urgently. Antiretroviral therapy can have substantial impact on the reduction of HIV among the MSM population, even if disinhibition is considered. The effect of protected sexual behaviour on controlling the epidemic in the MSM population largely depends on the sex-ratio preference of different sub-populations.

Highlights

Men who have sex with men (MSM) are much more likely to be infected with HIV than the general population
Since HAART predictably decreases plasma HIV-1 RNA levels to below the level of detection of currently available assays [12], we assume that individuals taking HAART are no longer infectious. This reduction of plasma HIV-1 leads to an increase in adverse behaviour, and we model this behaviour change by reducing condom use between MSM from c to zero
Persistence of HIV infection By Thieme's persistence theory, we prove that the system is persistent of HIV infection when R0 > 1; i.e., when R0 > 1, HIV will spread in the MSM population so long as one infected MSM is introduced in this population, regardless of whether he is an Only-Top, a Versatile or an Only-Bottom

Summary

Introduction

Men who have sex with men (MSM) are much more likely to be infected with HIV than the general population. The report from the American Foundation for AIDS Research [1] suggests that the group originally at the most risk of HIV - gay and bisexual men - still remains at the highest risk. This is largely due to anal sex which, when unprotected, carries a high risk of HIV transmission, especially for the receptive partner. Men who have sex with men (MSM) are 19 times more likely to be infected with HIV than the general population.

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Conclusion