UNDERSTANDING THE EPIDEMIC OF HIV IN SOUTH-AFRICA - ANALYSIS OF THE ANTENATAL CLINIC SURVEY DATA

Objectives. To investigate the magnitude and the time course of the HI V epidemic in the provinces of South Africa from the antenatal clinic HIV surveys. Design. We analysed the data on the provincial prevalence s of HIV infection from 1990 to 1996 using maximum likelihood methods to determine the intrinsic growth rate and probable asymptotic prevale nce of HIV among women attending antenatal clinics. Subjects. Women at tending antenatal clinics and included in the national HIV prevalence surveys conducted by the Department of Health, Results. 1. In KwaZulu- Natal the epidemic is likely to peak at a prevalence of about 23% (95% confidence interval (CI) 19 - 36%). 2. The intrinsic doubling time do es not differ significantly among the provinces. 3. The average length of the intrinsic doubling time is 12.0 months (95% CI 11.3 - 12.3 mon ths). 4. The force of infection is approximately 1.00/year at age 16 y ears and declines at a rate of about 5% per year of age above 16 years . Conclusions. South Africa is likely to experience one of the worst H IV epidemics in Africa. The lack of statistically significant differen ces between the growth rates of the epidemic in the various provinces constrains the possible explanations that can be advanced to explain t he time course of the epidemic and may in part be a consequence of mig rancy. The intrinsic growth rate is higher than previous estimates and it is possible that in those provinces where the prevalence is still low it will eventually reach the same levels as in KwaZulu-Natal.