When Zimbabwe registered a decline in HIV prevalence rates in 2004, and again in 2006, the news was met with scepticism, but new official figures released on Wednesday indicate the downward trend has continued, with rates falling by 10 percent over the past 5 years.

The Zimbabwe Ministry of Health and Child Welfare, assisted by a group of international experts, based the new seroprevalence rate on HIV infection in pregnant women attending antenatal clinics, and estimate the level among the adult population at 15.6 percent, according to a UN statement.

"Zimbabwe's HIV rate has been falling since the late 1990s. This is a continuing fall," Roeland Monasch, Deputy Representative of the UN Children's Fund (UNICEF), told IRIN. The rate has steadily decreased from 25.7 percent in 2002 to 21.3 percent in 2004, dropping to 17.7 in 2006. Zimbabwe's population is around 11.6 million.

"The biggest falls among pregnant women were recorded among the 15-24 year age group, showing a drop in HIV from 20.8 percent to 13.1 percent in just four years (2002 to 2006)," the statement said.

But Monasch warned that "15.6 percent remains high, and this is not the moment for complacency. Rather, we must take advantage of this positive action by youth and put even greater energy and resources into Zimbabwe's fight against HIV and AIDS."

Sound statistics

Despite some disbelief in previous years, most observers now acknowledge that Zimbabwe's HIV prevalence rate is in fact dropping. "There is not another country in Southern Africa that has this much detailed, scrutinised data, and it shows progressive falls in the HIV rate," Monasch commented.

Representatives from the US Centres for Disease Control and Prevention, the Imperial College, London, the UN Population Fund (UNFPA), UNAIDS, the World Health Organisation and UNICEF were involved in the latest review.

"The drop over the years is statistically significant - pregnant women are a proxy for the overall sexually active population. This information is used as input in the HIV/AIDS epidemiological models to estimate overall prevalence for men and women in reproductive age ... these models are continuously reviewed by independent experts to ensure the most accurate estimates are derived," UNICEF spokesman James Elder explained.

Awareness changes behaviour

The dramatic plunge in prevalence rates has been attributed to the success to programmes aimed at soliciting behavioural change among the country's youth. Survey data showed that the adoption of protective behavioural measures had improved, especially in reducing number of sexual partners and increasing condom use.

Zimbabwe was one of the first countries to develop a comprehensive epidemiological review, which resulted in an evidence-based, behaviour-change strategy with the promotion of partner reduction and consistent condom use at its core. According to Bruce Campbell, the UNFPA representative in Zimbabwe, "young people are having fewer partners and using more condoms. They have heard the messages, taken action, and are being safer."

Given the severe economic and food security difficulties faced by Zimbabweans, some suggest the falling prevalence rates might point to factors other than behaviour, such as mortality, which could mean that the number of people dying from AIDS were outnumbering those newly infected with HIV.

According to 'Evidence for HIV decline in Zimbabwe', a review of the epidemiological data by UNAIDS in late 2005, "the decline in national HIV prevalence between 2000 and 2004 resulted from a combination of declining HIV incidence and rising adult mortality," but also that "sexual behaviour change has contributed to the declines in HIV prevalence and HIV incidence in Zimbabwe."

Monasch said, "Additional research is still [being] done to assess how big each factor is contributing to the decline. This is not an easy or quick exercise, but we remain confident that combined Government and UN behaviour-change strategies throughout the 1990s were absorbed and applied by Zimbabwe's educated populace ... the evidence clearly indicates that mortality alone is not responsible for the drop."

The migration of Zimbabweans to other countries "was not found to be a significant factor," Elder said. The UNAIDS review agreed: "International migration is believed to have been extensive, and the possibility that it contributed in a small way to the decline in HIV prevalence cannot be ruled out ...

"Nonetheless, the evidence available does not support the view that the overall level of migration, and (particularly) the degree of over-representation of symptomatic and asymptomatic HIV-positive individuals amongst migrants needed to cause a decline in national HIV prevalence."

Monasch was confident the positive trend could hold. "It's sustainable, but it requires funds to keep the programmes running. We know what works in Zimbabwe, and it's now been proved that, given the right behaviour change programmes, Zimbabwe's educated youth will absorb the messages and act accordingly," he said.

"Young people are having fewer partners and using more condoms; Zimbabwe has one of the highest rates of condom use in Southern Africa." Nonetheless, he warned that there was room for improvement.

"We must continue our combined efforts to ensure national HIV-prevention programmes are maintained and enlarged. HIV-positive children in need of treatment are still inadequately reached with treatment, and less likely to receive treatment compared to adults."

Mary Sandasi, Executive Director of the Women's AIDS Support Network, told IRIN, "There is a lot of education going out to people and that could assist the fall of HIV infection, but I also look at the deaths that are still happening and there is a lot that can still be done."