Browsing by Author "Williams, Brian G."

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Epidemiological impact of Tenofovir gel on the HIV epidemic in South Africa.
(Lippincott Williams & Wilkins., 2011) Williams, Brian G.; Abdool Karim, Salim Safurdeen.; Abdool Karim, Quarraisha.; Gouws, Eleanor.
Background: Tenofovir gel, an antiretroviral-based vaginal microbicide, reduced HIV acquisition by 39% in women in a recent randomized controlled clinical trial in South Africa. Methods: To inform policy, we used a dynamical model of HIV transmission, calibrated to the epidemic in South Africa, to determine the population-level impact of this microbicide on HIV incidence, prevalence, and deaths and to evaluate its cost-effectiveness. Results: If women use tenofovir gel in 80% or more of sexual encounters (high coverage), it could avert 2.33 (0.12 to 4.63) million new infections and save 1.30 (0.07 to 2.42) million lives and if used in 25% of sexual encounters (low coverage), it could avert 0.50 (0.04 to 0.77) million new infections and save 0.29 (0.02 to 0.44) million deaths, over the next 20 years. At US $0.50 per application, the cost per infection averted at low coverage is US $2392 (US $562 to US $4222) and the cost per disability-adjusted life year saved is US $104 (US $27 to US $181); at high coverage the costs are about 30% less. Conclusions: Over 20 years, the use of tenofovir gel in South Africa could avert up to 2 million new infections and 1 million AIDS deaths. Even with low rates of gel use, it is highly cost-effective and compares favorably with other control methods. This female-controlled prevention method could have a significant impact on the epidemic of HIV in South Africa. Programs should aim to achieve gel use in more than 25% of sexual encounters to significantly alter the course of the epidemic.
The impact of incident and prevalent herpes simplex virus-2 infection on the incidence of HIV-1 infection among commercial sex workers in South Africa.
(Lippincott Williams & Wilkins., 2004) Ramjee, Gita.; Williams, Brian G.; Gouws, Eleanor.; Van Dyck, Eddy.; De Deken, Benedicte.; Abdool Karim, Salim Safurdeen.
This study investigated the impact of prevalent and incident HSV-2 infection on the incidence of HIV-1 infection in a cohort of female commercial sex workers in KwaZulu-Natal, South Africa. Prior to a vaginal microbicide trial, 416 women were screened for antibodies to HIV-1 and herpes simplex virus-2 (HSV-2) infections and a questionnaire was used to establish behavioral, social, and demographic characteristics. A total of 187 HIV-1-seronegative women were followed up at monthly intervals when blood was drawn and used to detect HIV-1 and HSV-2 antibodies. The median duration of follow-up was 2.2 years. At screening 50% of the women were HIV-1 seropositive and 84% were HSV-2 seropositive. The hazards of HIV-1 among women who were HSV-2 seropositive or seronegative throughout, or among those who seroconverted during the study, were not significantly different. When HSV-2 seroconversion was analyzed as a time-dependent covariate, the hazard ratio for HIV-1 seroconversion was 6.0 (95% CI: 2.6–14.0) times greater among women with incident than among women with prevalent HSV-2 infections. Drawing on other recent studies these data suggest that incident HSV-2 infection increases the risk of HIV-1 infection; the effect wanes with time since infection; and the effect is significantly greater for men than it is for women.