Evidence for population level declines in adult HIV prevalence in Kenya.

The HIV/AIDS epidemic in Kenya has been tracked through annual sentinel surveillance in antenatal clinics since 1990. The system started with 13 sites and now has over 35. Behaviours have been measured through national Demographic and Health Surveys in 1993, 1998, and 2003. The surveillance data indicate that prevalence has declined substantially starting in 1998 in five of the original 13 sites and starting in 2000 in another four sites. No decline is evident in the other five original sites although the 2004 estimate is the lowest recorded. Nationally, adult prevalence has declined from 10% in the late 1990s to under 7% today. Surveys indicate that both age at first sex and use of condoms are rising and that the percentage of adults with multiple partners is falling. It is clear that HIV prevalence is now declining in Kenya in a pattern similar to that seen in Uganda but seven or eight years later. Although the coverage of preventive interventions has expanded rapidly since 2000 this expansion was too late to account for the beginnings of the decline in prevalence. More work is needed to understand fully the causes of this decline, but it is encouraging to see Kenya join the small list of countries experiencing significant declines in HIV prevalence.

Declines in HIV prevalence can be associated with changing sexual behaviour in Uganda, urban Kenya, Zimbabwe, and urban Haiti.

OBJECTIVE: To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour. METHODS: A mathematical model was developed to explore the relation between prevalence recorded at antenatal clinics (ANCs) and the pattern of incidence of infection throughout the population. To create a null model a range of assumptions about sexual behaviour, natural history of infection, and sampling biases in ANC populations were explored to determine which factors maximised declines in prevalence in the absence of behaviour change. Modelled prevalence, where possible based on locally collected behavioural data, was compared with the observed prevalence data in urban Haiti, urban Kenya, urban Cote d'Ivoire, Malawi, Zimbabwe, Rwanda, Uganda, and urban Ethiopia. RESULTS: Recent downturns in prevalence observed in urban Kenya, Zimbabwe, and urban Haiti, like Uganda before them, could only be replicated in the model through reductions in risk associated with changes in behaviour. In contrast, prevalence trends in urban Cote d'Ivoire, Malawi, urban Ethiopia, and Rwanda show no signs of changed sexual behaviour. CONCLUSIONS: Changes in patterns of HIV prevalence in urban Kenya, Zimbabwe, and urban Haiti are quite recent and caution is required because of doubts over the accuracy and representativeness of these estimates. Nonetheless, the observed changes are consistent with behaviour change and not the natural course of the HIV epidemic.

Differential of HIV prevalence in women and men who attended sexually transmitted disease clinics at HIV sentinel surveillance sites in Kenya, 1990-2001.

Several studies in sub-Saharan Africa have reported that HIV prevalence in young women is higher than in young men. We used data from Kenya HIV sentinel surveillance conducted from 1990 to 2001 among sexually transmitted disease (STD) patients (15-49 years old) to investigate consistency of gender differentials over time and their risk factors. Of the 15,889 STD patients, the HIV prevalence ranged from 16.0% in 1990 to 41.8% in 1997. The odds ratios (ORs) of HIV infection for women compared to men decreased by age; women 15-24 years were nearly twice as likely as men of the same ages to be HIV infected (OR 1.7 [1.5-2.0]), but risk in those >44 years was almost equal (OR 0.8 [95% CI 0.7-1.2]). The odds of HIV infection for women compared to men were twice in unmarried patients (OR 2.1 [95% CI 1.8-2.3]). This association persisted after controlling for age groups or marital status, residence, level of education, and presence of STD syndromes. This pattern had been consistent over 12 years. Adolescent women with symptoms of STDs should be a focus for the HIV/STD intervention programmes because of their high risk for HIV.