SEROINCIDENCE OF HIV-1 INFECTION IN AFRICAN WOMEN OF REPRODUCTIVE AGE- A PROSPECTIVE COHORT STUDY IN KIGALI, RWANDA, 1988-1992

Objective: To estimate the seroincidence of HIV-1 infection among wome n of reproductive age in Kigali, Rwanda. Design: Fixed prospective coh ort followed for 36 months between November 1988 and June 1992, as par t of an ongoing study of mother-to-child transmission of HIV-1. Settin g: Centre Hospitalier, Kigali, Rwanda. Subjects: A total of 216 HIV-se ronegative women were enrolled at delivery between November 1988 and J une 1989. Methods: A blood sample was obtained at delivery to test for HIV antibodies (by enzyme-linked immunosorbent assay and Western blot ). Serum was tested every 3 months during follow-up. Incidence density rates of HIV seroconversion were estimated. Results: The follow-up ra te after 3 years was 89%, assessed by the maximum person-years method. The seroincidence density rate was 3.5 per 100 women-years (95% confi dence interval, 1.9-5.0). It decreased linearly from 7.6 during the fi rst 6-months postpartum to 2.5 per 100 women-years during the last 6 m onths of the third year of follow-up. Maternal age did not affect HIV incidence rates. We examined the role of the cohort, counselling, and the first 6-month postpartum effects on this estimate. Conclusion: Thi s fixed cohort provided an overall estimation of the HIV infection inc idence rate and its dynamics. These figures could be used for programm ing future HIV preventive vaccine efficacy trials in Rwanda.