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Understanding the impact of male circumcision interventions on the spread of HIV in southern Africa.

Hallett TB, Singh K, Smith JA, White RG, Abu-Raddad LJ, Garnett GP - PLoS ONE (2008)

Bottom Line: 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.In the long-term, this could lead to reduced AIDS deaths and less need for anti-retroviral therapy.Circumcision 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom. timothy.hallett@imperial.ac.uk

ABSTRACT

Background: Three 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.

Findings: Our 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.

Conclusions: Circumcision 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.

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Related in: MedlinePlus

Interaction of circumcision interventions with existing behaviour change programmes.Four epidemic projections show: (i) no interventions, (ii) circumcision intervention with 90% coverage, (iii) a behaviour change intervention that leads to an average 30% reduction in partner change rate and 30% increase in condom use with casual partners, (iv) both the circumcision intervention and the behaviour change intervention. The output is HIV incidence per 100 person-years at risk (pyar). The time-scale relates to years since the circumcision intervention starts. (Note: Unlike in other simulations, here no compensation is made for the potential effects of AIDS mortality modifying the risk distribution in the population (see text S1 for details)).
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pone-0002212-g004: Interaction of circumcision interventions with existing behaviour change programmes.Four epidemic projections show: (i) no interventions, (ii) circumcision intervention with 90% coverage, (iii) a behaviour change intervention that leads to an average 30% reduction in partner change rate and 30% increase in condom use with casual partners, (iv) both the circumcision intervention and the behaviour change intervention. The output is HIV incidence per 100 person-years at risk (pyar). The time-scale relates to years since the circumcision intervention starts. (Note: Unlike in other simulations, here no compensation is made for the potential effects of AIDS mortality modifying the risk distribution in the population (see text S1 for details)).

Mentions: Other models have indicated that with high coverage and with circumcised men less likely to transmit infection to women then circumcision could be used to eventually eliminate HIV [51]. However, in our analysis this does not appear to be possible, although the intervention does make HIV infectious spread unsustainable in some lower risk groups. A key result from early studies of infectious disease epidemiology [52] is that several interventions tend to operate synergistically (the specific contribution of alternative types of intervention will be determined by the epidemiological context [53]). That is, a circumcision intervention applied at the same time as other behavioural changes take place will lead to a much greater impact than would be expected on the basis of either in isolation. Figure 4 shows the incidence rate following different kinds of intervention: a circumcision intervention, a behaviour change intervention and both combined. In combination, the two interventions can drive the HIV epidemic to much lower levels.


Understanding the impact of male circumcision interventions on the spread of HIV in southern Africa.

Hallett TB, Singh K, Smith JA, White RG, Abu-Raddad LJ, Garnett GP - PLoS ONE (2008)

Interaction of circumcision interventions with existing behaviour change programmes.Four epidemic projections show: (i) no interventions, (ii) circumcision intervention with 90% coverage, (iii) a behaviour change intervention that leads to an average 30% reduction in partner change rate and 30% increase in condom use with casual partners, (iv) both the circumcision intervention and the behaviour change intervention. The output is HIV incidence per 100 person-years at risk (pyar). The time-scale relates to years since the circumcision intervention starts. (Note: Unlike in other simulations, here no compensation is made for the potential effects of AIDS mortality modifying the risk distribution in the population (see text S1 for details)).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2387228&req=5

pone-0002212-g004: Interaction of circumcision interventions with existing behaviour change programmes.Four epidemic projections show: (i) no interventions, (ii) circumcision intervention with 90% coverage, (iii) a behaviour change intervention that leads to an average 30% reduction in partner change rate and 30% increase in condom use with casual partners, (iv) both the circumcision intervention and the behaviour change intervention. The output is HIV incidence per 100 person-years at risk (pyar). The time-scale relates to years since the circumcision intervention starts. (Note: Unlike in other simulations, here no compensation is made for the potential effects of AIDS mortality modifying the risk distribution in the population (see text S1 for details)).
Mentions: Other models have indicated that with high coverage and with circumcised men less likely to transmit infection to women then circumcision could be used to eventually eliminate HIV [51]. However, in our analysis this does not appear to be possible, although the intervention does make HIV infectious spread unsustainable in some lower risk groups. A key result from early studies of infectious disease epidemiology [52] is that several interventions tend to operate synergistically (the specific contribution of alternative types of intervention will be determined by the epidemiological context [53]). That is, a circumcision intervention applied at the same time as other behavioural changes take place will lead to a much greater impact than would be expected on the basis of either in isolation. Figure 4 shows the incidence rate following different kinds of intervention: a circumcision intervention, a behaviour change intervention and both combined. In combination, the two interventions can drive the HIV epidemic to much lower levels.

Bottom Line: 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.In the long-term, this could lead to reduced AIDS deaths and less need for anti-retroviral therapy.Circumcision 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom. timothy.hallett@imperial.ac.uk

ABSTRACT

Background: Three 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.

Findings: Our 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.

Conclusions: Circumcision 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.

Show MeSH
Related in: MedlinePlus