SENTINEL SURVEILLANCE FOR HIV-1 AMONG PREGNANT-WOMEN IN A DEVELOPING-COUNTRY - 3 YEARS EXPERIENCE AND COMPARISON WITH A POPULATION SEROSURVEY

Objectives: To establish unlinked, anonymous sentinel surveillance for HIV-1 among pregnant women attending an antenatal clinic, to determin e age-specific seroprevalences, to monitor trends and to compare serop revalence with that detected by a population serosurvey. To establish the sustainability and costs of surveillance. Design: Sentinel surveil lance for HIV through serial collection of unlinked, anonymous seropre valence data from antenatal care; comparison of sentinel data with tho se from a population serosurvey; financial and general audit of the se ntinel surveillance. Setting. A community antenatal clinic in a large urban centre, Mwanza Municipality, Tanzania, eastern Africa, between O ctober 1988 and September 1991. Patients: Pregnant women attending for antenatal care. Main outcome measure: Age-specific HIV-1 seroprevalen ces, trends over time, difference from age-specific population seropre valences, sustainability and costs. Results: Overall HIV-1 seroprevale nce was 11.5% (95% confidence interval, 10.5-12.4); differences in age -specific prevalences were not significant. There was no clear evidenc e of change in seroprevalence over the study period in any age group, although there was some indication of a rise in some age groups in 198 8-1989. Sentinel surveillance among pregnant women may have significan tly underestimated population HIV-1 seroprevalence for women under the age of 35 years. HIV-1 surveillance proved feasible and sustainable. Additional recurrent costs were US$1.7 per specimen for unlinked anony mous testing and US$0.57 per woman for syphilis screening. Conclusions : HIV-1 seroprevalence did not change significantly over 3 years, prob ably implying a substantial incidence of HIV-1 infection. In this sett ing seroprevalence in pregnant women may have underestimated populatio n seroprevalence in women aged under 35 years. With modest inputs and good organization unlinked anonymous HIV-1 sentinel surveillance of pr egnant women can be introduced and sustained in an African setting. Th is may usefully be carried out in conjunction with syphilis screening.