based surveys with HIVdata collection

Another major development is the implementation of national population-based surveys with HIVdata collection. Such surveys had been conducted by several countries in Eastern Africa in the, but only Rwanda carried out a national survey in the nineties. During 2001-2002
Burundi, Mali, Niger, South Africa, Zambia, and Zimbabwe conducted national surveys which
included men and women of reproductive ages. Zanzibar also conducted a HIV survey of its adult
population.
Several countries are planning a survey in the coming years. The population-based surveys not
only provide HIV prevalence data on all men and women but are also a unique opportunity to
assess the extent to which the antenatal clinic-based surveillance system provides accurate data
on the spread of HIV. In addition, Eritrea, Guinea and Mali conducted national surveys among a
range of high and low risk populations. Table 1 summarizes the most recent HIV surveillance
activities by country।
Estimating HIV Prevalence over time in Countries
with Generalized Epidemics
In countries with generalized epidemics, the procedures use HIV prevalence in pregnant women
to approximate prevalence in all adults, male and female, between the ages 15-49. Estimates of
HIV prevalence among pregnant women and in community surveys among all men and women
aged 15-49 are available from a number of sites.
Prevalence in pregnant women is a good proxy measure of adult prevalence. Prevalence data
from pregnant women are sorted into two geographic categories: major urban areas and outside
major urban areas. Epidemic curves are then fit to these data sets using the UNAIDS Estimation
and Projection Package (EPP).
The fitted curves give yearly HIV point prevalence estimates for urban and non-urban areas. The
actual prevalence used for the non-urban areas is adjusted as many countries’ surveillance
systems do not cover rural areas well. It is assumed that HIV prevalence is lower in rural areas
and therefore if a country’s system does not reflect the population in those areas the non-urban
prevalence produced by EPP is adjusted downwards by 20% to reflect this bias.