Stable antenatal HIV-1 seroprevalence with high population mobility and marked seroprevalence variation among sentinel sites within Nairobi, Kenya

Objectives: To monitor and analyse trends in HIV-1 seroprevalence among ant enatal women in Nairobi, Kenya. Design: Six sequential surveys were carried out among antenatal clinic atte nders at four Nairobi City Council health centres between November 1991 and April 1997. Methods: A total of 6828 women attending for first antenatal clinic visit w ere administered a standard questionnaire to obtain demographic information and were screened for HIV-1. Results: HIV-1 seroplevalence rose from 12.1% in the first survey to 16.2% in the third, completed in October 1993. No rise was observed in subsequent surveys, and seroprevalence among women under the age of 20 declined after the third survey. Significant differences in seroprevalence (P < 0.001) we re observed in all survey rounds between women who reported that their prov ince of origin was Nyanza (22.4% overall), compared with those from other p rovinces in western Kenya (14.1%), and the eastern group of provinces (8.9% ). The rise in HIV-1 seroprevalence observed between 1991 and 1993 was almo st entirely attributable to the rising seroprevalence among women from Nyan za. There were considerable differences in HIV-1 seroprevalence among the f our health centres, paltry accounted for by differences in the proportion o f clinic attenders from different provinces of origin, which also changed s ignificantly over time, Conclusions: HIV-1 seroprevalence has stabilized in antenatal women attendi ng these health centres in Nairobi, and may be declining among women in the youngest age group. This may reflect stabilization of HIV-1 incidence, but further observation is required. The levels of infection among Nairobi res idents reflect the evolution of the HIV epidemic in their provinces of orig in, and changing client composition influences HIV-1 seroprevalence at diff erent clinics. HIV sentinel surveillance should be carried out at multiple sites in large urban centres to monitor accurately the evolution of the HIV epidemic and the impact of control efforts in reducing transmission. (C) 1 999 Lippincott Williams & Wilkins.