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Abstract
The potential benefits of expanded male circumcision programs in Africa: predicting the population-level impact on heterosexual HIV transmission in Soweto
K. Mesesan1, D.K. Owens2, A.D. Paltiel1
1Yale University School of Medicine, Department of Epidemiology & Public Health, New Haven, United States, 2VA Palo Alto Health Care System & Stanford University, Department of Medicine, Palo Alto, United States
Background: Male circumcision was recently shown to dramatically reduce individual-level female-to-male heterosexual transmission of HIV in South Africa, with additional results from Kenya and Uganda pending. We considered the impact of expanded circumcision programs on HIV prevention.
Methods: We developed a mathematical model to simulate the population-level impact of various male circumcision programs on HIV transmission in Soweto, South Africa. We calculated annual rates of movement between population groups defined by gender, male circumcision status, and disease stage. Model parameters included
(1) 823,000 sexually-active, anti-retroviral-naïve men/women,
(2) 12%(male) and 20%(female) initial HIV prevalence,
(3) 35% male circumcision,
(4) 61% circumcision protective effect,
(5) male-negotiated condom use, and
(6) varying contact (0-3 partners annually) and infectivity (0.068-0.270 per-partnership) rates by disease stage.
We evaluated potential 5-year male circumcision programs by assessing HIV prevalence and total infections prevented over a 20-year period.
Results: When the reduction in HIV transmission from circumcision is ignored, the model forecasts 318,000 new HIV infections over the next 20 years, and overall HIV prevalence increases from 16% to 23%. Incorporating the transmission reduction (61%) from current circumcision rates (35%) reduces predicted new HIV infections to 244,000 and 20-year HIV prevalence to 17%. A 5-year prevention program targeting an additional 10% of uncircumcised males each year would prevent 32,000 infections and decrease 20-year HIV prevalence to 14%. A program targeting 20% of uncircumcised males each year would prevent 53,000 infections and decrease HIV prevalence to 13%. Outcomes are sensitive to potential changes in risk behavior: e.g. if overall condom use decreased by 30%, the latter program would prevent only 18,000 infections.
Conclusions: For South Africa and countries with similar epidemic profiles, even modest programs offering male circumcision would confer enormous benefits in terms of HIV infections averted. Because increases in sexual risk behaviors could diminish these benefits, programs should continue emphasizing risk-reduction counseling.
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