Regional differences in HIV trends in The Gambia: results from sentinel surveillance among pregnant women.

OBJECTIVE: To monitor HIV-1 and HIV-2 trends in The Gambia, West Africa. METHODS: In 1993-1995 a nationwide survey among 29 670 pregnant women attending eight antenatal clinics estimated the seroprevalence of HIV-1 at 0.6%, and of HIV-2 at 1.1%. Five years later, sentinel surveillance in pregnant women was established, using unlinked anonymous testing in four clinics. A dried blood spot on filter paper was obtained and tested for HIV antibodies. RESULTS: Between May 2000 and August 2001, 8054 analysable samples were collected at four sites. The prevalence of HIV-1 rose sharply in one rural area from 0.6 to 3.0% (P < 0.0001), but the increase was small and non-significant in two other rural sites and in the urban site. The prevalence of HIV-2 did not change significantly at any of the sites. The overall prevalence of HIV-1 was 1.0% [95% confidence interval (CI) 0.8-1.3%], and of HIV-2 0.8% (CI 0.6-1.0%). Site, nationality and higher age were significantly associated with HIV-1 infection, and higher parity and site were significantly associated with HIV-2 infection. CONCLUSION: Fifteen years after the first case of HIV-1 was described in The Gambia, the epidemic is still at a low level. There is heterogeneity within the country, with one rural area experiencing a fivefold increase in 6 years. The prevalence of HIV-2 in The Gambia is stable.