Modelling the spread of HIV/AIDS in China: The role of sexual transmission

Abstract

The study presented here is an exploration of the implications of patterns of sexual behaviour for the spread of HIV in China, using a bio-behavioural macrosimulation model. To reflect the uncertainty surrounding key parameters, analyses of varied scenarios are used to show a range of possible outcomes consistent with variations in selected biological and behavioural inputs. The latter are estimated from a nationwide survey of sexual behaviour recently conducted in China, a country with an emerging HIV/AIDS epidemic, where it is feared that HIV/AIDS will spread to the general population via heterosexual transmission. The results highlight the primacy of the levels and distribution of sexual activity in the population. They offer some guidelines for understanding and interpreting the potential implications of current and prospective changes in sexual behaviour for the spread of HIV/AIDS in the world's largest population, and also highlight the need to collect better data on sexual behaviour for the estimation of key model inputs.

Masculine sex ratios, population age structure and the potential spread of HIV in China

“…The average HIV infectivity enhanced by co-infection with chlamydia for each group was then determined by the probability of HIV transmission per coital act, that group's own chlamydia prevalence, the chlamydia prevalence among partners, and the chlamydia infectivity cofactor. Computational examples of the average HIV infectivity with co-infection of chlamydia were first illustrated by Bracher, Santow, and Watkins (2003) and were also presented in Merli et al (2006).…”

“…For the purposes of these analyses, the original model has been modified to represent the Chinese pattern of sexual relations (Merli et al 2006), to accommodate multiple scenarios of sexual activity and sexual mixing (Hertog 2007), and, in the present paper, to estimate the number of surplus males unable to find a partner as a result of age-sex demographic imbalances.…”

“…Input parameters draw upon a diverse set of empirical data sources variously describing China's demographic characteristics, patterns and trends in partnership formation and sexual behavior, and the epidemiology of HIV/AIDS. Although mathematical models of HIV transmission dynamics have been largely unsuccessful in accurately reproducing epidemic curves (Leclerc and Garenne 2007) and have proven inadequate to accurately predict the course of the Chinese epidemic (Merli et al 2006), they are useful for understanding the dynamic relationship between macro-demographic changes and micro-behavioral adaptations and their implications for the spread of HIV.…”

“…The extent to which HIV will continue to spread to the general population in China depends largely on the levels and distribution of sexual activity. Results of an empirically grounded compartmental model suggested that in China, overall levels of sexual activity (identified by the rate of partner change) and the fraction of the population with multiple partners would have to be significantly higher than those currently observed in order for HIV prevalence to exceed one percent at any time during a 50-year simulation cycle (Merli et al 2006). These results, however, do not imply that concerns about continued spread of HIV in China's general population are unwarranted.…”

“…We employ a mathematical model used previously to assess the role of sexual transmission for the spread of HIV in China (Merli et al 2006). By uniting a population projection with an epidemiological model of HIV transmission, the model allows us to simulate concurrently three related processes over time: population change, the sexual partnership market, and the HIV epidemic.…”