Increasing prevalence of HIV antibody among blood donors monitored over 9 years in one blood bank.

To determine the time trend of HIV infection among non-professional blood donors at the Christian Medical College and Hospital, Vellore, the annual HIV prevalence among them for the years 1993-1997 was compared with that of the previous 5 yr. Since confirmed number of HIV positive blood donors is required for calculation of prevalence, the serum samples which were reactive for HIV 1/2 antibody by ELISA, were confirmed by Western blot. The annual prevalence of HIV antibody gradually increased from 1.6 per 1000 in 1988-1989, to 3.8 per 1000 in 1996-1997. The mean tri-annual prevalences for the years 1988-91, 1991-94 and 1994-97 were 1.3, 2.7 and 3.6 per 1000 respectively, suggesting a slow but steady increase in HIV prevalence over time. Our findings provide an insight into the dynamics of HIV infection in the general population of our country, whom the nonprofessional blood donors at our hospital represent.