Article

Quantitative assessment of the role of male circumcision in HIV epidemiology at the population level

Vaccine and Infectious Disease Institute, Program in Biostatistics and Biomathematics, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, WA 98109, USA.
Epidemics 09/2009; 1(3):139-52. DOI: 10.1016/j.epidem.2009.08.001
Source: PubMed

ABSTRACT Three recent randomized trials have shown that male circumcision (circumcision) reduces HIV incidence in heterosexual men by about 60%. Mathematical models are needed to assess the historical role of circumcision in the observed disparate levels of prevalence in sub-Saharan Africa and to translate these findings into estimates of the population-level impact of circumcision on HIV prevalence.
A deterministic compartmental model of HIV dynamics with circumcision was parameterized by empirical data from the Rakai, Masaka, and Four-City studies. Circumcision was found to account for about two-thirds of the differential HIV prevalence between West Africa and East and Southern Africa. We found that in Kisumu, Kenya, and in Rakai, Uganda, universal circumcision implemented in 2008 would reduce HIV prevalence by 19% and 14%, respectively, by 2020. In Kisumu, a setting with high HIV prevalence, about 6 circumcisions would be needed for each infection averted while in Rakai, 11 circumcisions would be needed. Females will also benefit from circumcision with a substantial reduction in prevalence of about 8% in Kisumu and 4% in Rakai within a few years of universal circumcision. The beneficial impact of circumcision for both males and females will not be undermined by risk behavior compensation unless the increase in risk behavior is in excess of 30%. The effectiveness of circumcision as an intervention is maximized by universal circumcision within 2-3 years.
In West Africa, circumcision may have "quarantined" the spread of HIV by limiting sustainable transmission to within high risk groups and bridge populations. Our findings indicate that circumcision is an effective intervention in both high and intermediate HIV prevalence settings. Circumcision coverage should be expanded as soon as possible to optimize the epidemiological impact.

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Available from: Laith J Abu-Raddad, Sep 04, 2014
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    • "Several mechanisms may contribute to explaining these findings . The spatial differences in HIV prevalence declines may reflect dynamical effects related to how far is HIV transmission in the general population from the epidemic threshold of sustainability (Abu-Raddad et al., 2008; Alsallaq et al., 2009; Anderson and May, 1991; Awad et al., 2012; Cuadros et al., 2013). They may also reflect heterogeneity in epidemic phases or changes in sexual risk behavior, or uptake of prevention and treatment interventions. "
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    ABSTRACT: Evidence suggests substantial declines in HIV prevalence in parts of sub-Saharan Africa. However, the observed aggregate declines at the national level may obscure local variations in the temporal dynamics of the infection. Using spatial scan statistics, we identified marked spatial variability in the within-country declines in HIV prevalence in Tanzania, Malawi, Kenya, and Zimbabwe. Our study suggests that the declines in the national HIV prevalence in some of the SSA countries may not be representative of downward trends in prevalence in areas of high HIV prevalence, as much as the result of sharp declines in prevalence in areas of already low HIV prevalence. Our findings provide insights for resource allocation and HIV prevention interventions in these countries.
    Health & Place 04/2014; 28C:45-49. DOI:10.1016/j.healthplace.2014.03.007 · 2.44 Impact Factor
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    • "Several mechanisms may contribute to explaining these findings . The spatial differences in HIV prevalence declines may reflect dynamical effects related to how far is HIV transmission in the general population from the epidemic threshold of sustainability (Abu-Raddad et al., 2008; Alsallaq et al., 2009; Anderson and May, 1991; Awad et al., 2012; Cuadros et al., 2013). They may also reflect heterogeneity in epidemic phases or changes in sexual risk behavior, or uptake of prevention and treatment interventions. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Evidence suggests substantial declines in HIV prevalence in parts of sub-Saharan Africa. However, the observed aggregate declines at the national level may obscure local variations in the temporal dynamics of the infection. Using spatial scan statistics, we identified marked spatial variability in the within-country declines in HIV prevalence in Tanzania, Malawi, Kenya, and Zimbabwe. Our study suggests that the declines in the national HIV prevalence in some of the SSA countries may not be representative of downward trends in prevalence in areas of high HIV prevalence, as much as the result of sharp declines in prevalence in areas of already low HIV prevalence. Our findings provide insights for resource allocation and HIV prevention interventions in these countries.
    Health & Place 01/2014; 28:45–49. · 2.44 Impact Factor
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    ABSTRACT: Mathematical modelling has indicated that expansion of male circumcision services in high HIV prevalence settings can substantially reduce population-level HIV transmission. However, these projections need revision to incorporate new data on the effect of male circumcision on the risk of acquiring and transmitting HIV. Recent data on the effect of male circumcision during wound healing and the risk of HIV transmission to women were synthesised based on four trials of circumcision among adults and new observational data of HIV transmission rates in stable partnerships from men circumcised at younger ages. New estimates were generated for the impact of circumcision interventions in two mathematical models, representing the HIV epidemics in Zimbabwe and Kisumu, Kenya. The models did not capture the interaction between circumcision, HIV and other sexually transmitted infections. An increase in the risk of HIV acquisition and transmission during wound healing is unlikely to have a major impact of circumcision interventions. However, it was estimated that circumcision confers a 46% reduction in the rate of male-to-female HIV transmission. If this reduction begins 2 years after the procedure, the impact of circumcision is substantially enhanced and accelerated compared with previous projections with no such effect-increasing by 40% the infections averted by the intervention overall and doubling the number of infections averted among women. Communities, and especially women, may benefit much more from circumcision interventions than had previously been predicted, and these results provide an even greater imperative to increase scale-up of safe male circumcision services.
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