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Mathematical modelling of male circumcision in sub-Saharan Africa predicts significant reduction in adult HIV prevalence even when it is limited to certain age groups
Presented by Gregory Londish, Australia.
Londish G.1, Murray J.1
1University of New South Wales, School of Mathematics, Sydney, Australia
Objectives: Observations that reduced adult HIV prevalence in sub-Saharan Africa are correlated with levels of male circumcision have suggested that male circumcision could be used as a preventative measure against HIV infection. The exact benefits of this intervention are uncertain. Moreover if this is infeasible for the whole male population, which groups should be targeted?
Methods: A deterministic, compartmental mathematical model simulated observed levels of HIV prevalence under the complete range of current levels of circumcision. Increased male circumcision from 2007 was incorporated in this model and HIV prevalence in 2020 was simulated.
Results: Simulations predict that complete male circumcision in an average country could reduce HIV prevalence in 2020 from 8.3% to 5.3% and incidence from 13.5 seroconversions per thousand to 7.3 per thousand. The results were scaled in proportion if a lower level of circumcision was achieved. Also, targetting only 20 to 30 year old men or men with greater sexual activity produced the most cost-effective reduction in HIV prevalence, 2.0% and 1.1% respectively. These benefits are lessened with increasing sexual activity in men who have been circumcised, with complete negation of the intervention occuring once a lower bound of 40% of men increase their activity.
Conclusions: Male circumcision provides an effective intervention in sub-Saharan Africa to reduce HIV prevalence that is not vulnerable to lessening of effect through drug resistance or lack of availability of other prevention measures. Where it is not feasible to provide complete coverage, targeting young men or more sexually active men can still produce a significant reduction in HIV prevalence. However an intervention will fail if steps are not taken to prevent the majority of men increasing their sexual activity due to overestimation of circumcision´s benefits.
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