/ 29 November 2005

Mystery of Zim Aids statistics

South Africa, the economic powerhouse of Southern Africa, continues to see an escalating HIV epidemic, while economically crippled Zimbabwe has apparently brought down levels of HIV infection among its people.

According to the latest United Nation’s figures, one in three pregnant women in South Africa is HIV-positive, the highest level yet recorded. In contrast, Zimbabwe may be showing signs of falling infection rates, at least for the years between 2002 and 2004. During that period, the UN says, infection levels among pregnant women dropped from 26% to 21%.

The evidence at the moment remains scant, pending next month’s release of a report confirming the good news.

Prevalence, which measures the ongoing level of HIV infection, is not particularly informative without knowing the incidence, or the rate at which new infections are occurring. A falling prevalence rate may reflect that the number of people dying because of the virus is outnumbering those newly infected with it.

Given the economic and food security difficulties in Zimbabwe, high numbers of deaths could be behind the apparent decline in HIV infections. In addition, there are reports that hospitals in Zimbabwe are running out of anti-retroviral drugs, a problem attributed to the country’s foreign exchange problems.

However, the UN report, which is based on governmental and NGO research, appears confident.

UNAids regional director for Eastern and Southern Africa Mark Stirling said the tentative signs of success across Africa reflected consistent and sustained prevention campaigns, which were “evidence-based rather than ideologically-based”.

The assumption is that Zimbabwe’s sustained HIV prevention campaigns, dating back to the 1980s, have encouraged safer sexual behaviour. The golden trinity of behavioural change to stop HIV is to reduce the number of sexual partners, increase the age of sexual debut and increase the use of condoms. Last year researchers found that 86% of men and 83% of women report using condoms during casual sex. HIV levels among young women (aged 15 to 24 years), which is used as a rough proxy for incidence, has dropped from just less than 30% in 2000 to 20% in 2004.

The Aids Epidemic Update also reports that mortality rates are levelling off in some parts of the country, “which further supports the view that declines in HIV incidence accelerated by changes in sexual behaviour are driving the apparent decline in prevalence”.

In announcing the news, Stirling, said the apparent fall in HIV infection levels applied to the years reported, and could not necessarily be extrapolated forward, given the levels of social disruption in Zimbabwe.

In contrast, the Aids Epidemic Update describes the “astonishing speed” at which levels of infection among South African adults have leapt to almost 25%, compared to only 1% in 1990. Just less than 30% of pregnant women tested positive for HIV in 2004, although this conceals strong regional variations, with prevalence estimated at 40% in KwaZulu-Natal.

The Aids epidemic is also taking its toll, with Statistics South Africa reporting a huge jump in adult mortality, with the number of deaths between the ages of 24 and 44 almost doubling between 1997 and 2002.

Stats vary throughout Africa

Last year, 43 of every 100 pregnant women in Swaziland were HIV-positive; more than one in two women aged 25 to 29 have the virus.

Lesotho saw a small drop in HIV infection among pregnant women, from 29% in 2003, to 27% in 2004.

In Botswana, for the past four years one in three pregnant women has tested positive for the virus. Especially worrying for a government that has been forthright about the HIV/Aids epidemic is the lack of knowledge: a quarter of people surveyed this year did not know that consistently using condoms protects against HIV.

Namibia has geographically disparate levels of HIV infection. In the Caprivi Strip — between Angola, Botswana and Zambia — 42% of pregnant women are HIV-positive, but in the north-west of the country the figure is just 8,5%. Although last year’s annual survey in antenatal clinics suggested a slight decline in infections this is a tentative finding.

Striking geographic differences are also seen within Malawi, where more than one in three pregnant women in the south of the country tested HIV-positive in 2003, compared to 7% in the central area. While overall prevalence appears to stay steady at 20%, this may have been affected by the lack of food security in the region, which may be contributing to more deaths from Aids. HIV infection levels appear to be rising rapidly in rural areas and among younger pregnant women.

Despite decades of war, Angola has low levels of HIV infection for the region, with just an estimated 2,8% of pregnant women testing positive in 2004. But the potential for the epidemic to grow is seen among sex workers in the country’s capital, Luanda, where one in three is reported to be carrying the virus.

In Zambia, HIV has maintained a steady presence, with between 18% and 20% of pregnant women testing positive each year since 1994. The highest infection levels are to be seen in the areas around major transport routes. Similarly in Mozambique, the transport routes with Zimbabwe, Malawi and South Africa are accompanied by higher HIV infection. In three years the HIV prevalence among pregnant women living on the main rail link to southern Malawi increased from 7% in 2001 to 19% in 2004. — Belinda Beresford