Understanding the Impact of Male Circumcision Interventions on the Spread of HIV in Southern Africa

Abstract

BackgroundThree randomised controlled trials have clearly shown that circumcision of adult men reduces the chance that they acquire HIV infection. However, the potential impact of circumcision programmes – either alone or in combination with other established approaches – is not known and no further field trials are planned. We have used a mathematical model, parameterised using existing trial findings, to understand and predict the impact of circumcision programmes at the population level.FindingsOur results indicate that circumcision will lead to reductions in incidence for women and uncircumcised men, as well as those circumcised, but that even the most effective intervention is unlikely to completely stem the spread of the virus. Without additional interventions, HIV incidence could eventually be reduced by 25–35%, depending on the level of coverage achieved and whether onward transmission from circumcised men is also reduced. However, circumcision interventions can act synergistically with other types of prevention programmes, and if efforts to change behaviour are increased in parallel with the scale-up of circumcision services, then dramatic reductions in HIV incidence could be achieved. In the long-term, this could lead to reduced AIDS deaths and less need for anti-retroviral therapy. Any increases in risk behaviours following circumcision , i.e. ‘risk compensation’, could offset some of the potential benefit of the intervention, especially for women, but only very large increases would lead to more infections overall.ConclusionsCircumcision will not be the silver bullet to prevent HIV transmission, but interventions could help to substantially protect men and women from infection, especially in combination with other approaches.

Optimum resource allocation to reduce HIV incidence across sub-Saharan Africa: a mathematical modelling study

“…We employ a mathematical model that builds upon our previous work [17][18][19] to describe the dynamic spread of HIV. Equations are available in the Supplemental Appendix of the paper by Anderson et al 17 Here we describe key details of the model structure (appendix p. 1).…”

Sex, human rights and AIDS: an analysis of new technologies for HIV prevention in the Brazilian context

“…As circumcision is a technology protecting only heterosexual men, it is questionable whether it would be ethical to be offered, especially considering that the partial protection of men can make it even more difficult to women to negotiate safe sexual practices in contexts of gender inequality. Simulation studies 41 indicate that any behavioral changes among circumcised men may increase the risk of transmission for their female partners and, in the medium term, also increase the incidence among men in the general population. Narrative reviews are intended to discuss theoretically and contextually the development of a theme, based on the literature and critical analysis of its findings, configurng a qualitative approach to the knowledge available.…”

Mathematical models in the evaluation of health programmes

“…The eff ect of the same circumcision intervention in women, uncircumcised men, circumcised men, and overall varies according to the set of parameter used (B). 19 are available, and the method used for this assessment should be clearly reported. When the data available to estimate the parameters are sparse and resulting estimates have wide ranges of acceptable values a model can fi t the data equally well with several diff erent sets of parameters.…”

“…On the basis of measured effi cacy of adult-male circumcision in reducing the acquisition of the infection by circumcised men, models have been used to predict the population level eff ect of circumcision in a range of diff erent types of HIV epidemic. 19,20 In evaluations of complex programmes with many interventions, models can be used to explore the expected contribution of diff erent elements to the overall outcome of interest. In trials, there is a trade-off between the isolation of an individual treatment being evaluated 21 and maximising the expected eff ect size by combining intervention activities and treatments.…”