/ 10 September 2008

Jury still out on Aids infection levels

The huge variation in levels of HIV infection among pregnant women across South Africa was clearly demonstrated in the latest government report on the state of the epidemic.

Finally released last week, the national HIV and Syphilis Prevalence Survey for 2007 showed that HIV prevalence among women across the country ranged from 7,3% to a high of 41,6%. Using this data, the department of health estimates that 28% of pregnant women are living with HIV.

Using mathematical modelling to extrapolate these findings to the whole population, the department estimates that about 5,27-million South Africans (17,64% of the adult population) are HIV-positive. Of these, 2,8-million are estimated to be women. The number of children living with HIV is estimated to be 84 680.

HIV prevalence is the result of incidence, which is the number of people newly infected with the virus and the number of people who die as a result. Prevalence without incidence gives no indication whether HIV prevention campaigns are succeeding because it is impossible to tell whether it is the number of new infections or deaths that is rising or falling.

The government hopes that an apparent decline in HIV infections among women aged 15 to 19 — women who are likely to have recently started having sex and are therefore likely to be newly infected — indicates a possible decline in incidence, at least in this age group.

But among older women, aged 30 to 24 and 35 to 39, there is a possible increase in HIV prevalence. These findings could mean that women are becoming HIV infected at a later age.

In the most heavily affected province, KwaZulu-Natal, more than a third of pregnant women — 37% — were estimated to be HIV positive. KwaZulu-Natal has consistently had the worst rate of HIV infection in the country. In contrast, in the Western Cape about one in eight women (12,6%) were infected with the virus.

The prevalence survey was drawn from almost 34 000 pregnant women who attended state antenatal care facilities during a 12-month period.