Objective: To assess the likely impact on HIV incidence of increased condom use, a reduction in casual sexual partners, treatment programmes for other sexually transmitted diseases (STD) and combinations of these in rural Uganda.
Methods: A simulation model for the transmission dynamics of HIV infection and STD was employed, drawing on data from a rural population cohort in South-West Uganda with an HIV prevalence of 9% among adults in 1990.
Results: For the scenario most consistent with data from the study population, 39% of all adult HIV infections were averted, in the 10 years from 1990, when condoms were used consistently and effectively by 50% of men in their contacts with one-off sexual partners (such as bar girls and commercial sex workers). Reducing by 50% the frequency of men's sexual contacts with one-off partners averted 68% of infections. Reducing by 50% the duration of all STD episodes averted 43% of infections. Combining these three interventions averted 82% of all adult infections in the 10 years from 1990.
Conclusion: A substantial proportion of HIV infections may be averted in general populations through interventions targeted only on less regular sexual partnerships.
PIP: Simulation modelling was used to improve understanding of the transmission of human immunodeficiency virus (HIV) and other sexually transmitted diseases (STDs) in rural Uganda and assess the effectiveness of various preventive interventions. Each individual in the simulated population was represented by a set of characteristics (e.g., age, sex, HIV and STD status, type of sexual relationship, identity of all sexual partners) existent in a rural population cohort in South West Uganda in 1990 with an adult HIV prevalence rate of 9%. HIV transmission per sexual contact was assumed to be enhanced 10-fold (low co-factor scenario) or 100-fold (high co-factor scenario) during episodes of ulcerative STD. Even under the high co-factor conditions, 50% condom use resulted in a 39% reduction in HIV over 10 years. A 50% reduction in the frequency of sexual contacts with one-off partners (e.g., prostitutes) averted 68% of infections. When the duration of all STD episodes was reduced by 50%, 43% of infections were averted by the year 2000. If all three of these interventions were combined, 82% of HIV incidence was averted by the year 2000. These findings suggest that a substantial proportion of HIV disease can be prevented through interventions that target only casual sexual partners.