Care and support for people living with HIV/AIDS

Annex 1.How reliable are estimates of HIV infection and AIDS deaths?ies in urban and rural communities have made it possible to validate the results ofsentinel surveillance in pregnant women. These studies offer important insights intothe differentials of HIV infection by age and sex. They also confirm that sentinel surveillancein pregnant women yields remarkably robust estimates for HIV prevalencein the general population of reproductive age, as shown in Figure 28.Figure 28. HIV prevalence rates among pregnant women and amongall adults aged 15-49%3530pregnant womenall adults2520151050Lusaka,Zambia1994-1996MposhiZambia1994-1996Mwanza,Tanzania1990-1991Rakai,Uganda1990Rakai,Uganda1991Rakai,Uganda1992Kisumu,Kenya1998Source: Sentinel surveillance data from antenatal clinics and population-based studies, selected Africancountries, 1990-1998In countries where the HIV epidemic is concentrated in a few groups with high-riskbehaviour – mostly drug injectors and men who have sex with men, as well as sexworkers and their clients – the methods for estimating HIV prevalence are different.This is the case in most countries in Asia, the Americas and Europe. Here, becausethere are very few HIV infections in the general population, and because many of theinfections are in groups largely or entirely made up of men, data from pregnantwomen are of very limited use. Rather, HIV estimates in such cases are based oninformation on HIV prevalence in each group of people with high-risk behaviour,together with estimates of the size of each of these populations. Since these behavioursare often socially unacceptable and sometimes illegal, information on both HIVprevalence levels and the size of the population affected can be much harder tocome by. Consequently, uncertainties around these estimates may well be greaterfor countries where the epidemic is concentrated in specific groups.117