Frequency of blood donors with HIV antibodies in the Fundação Hemocentro de São Paulo

The frequency of "ELISA"-positive blood donors tested for HIV antibodies at Fundacao Hemocentro de Sao Paulo was 0.45% (526/116,354). Of these positive donors 38 in 100 tested (0.38% were confirmed by Western blot, giving a projected frequency of truly positive HIV antibody and "ELISA"-positive) of 0.171%. The higher the absorbance in the "ELISA" test the bigger the probability of having a positive band (p24) in the Western blot.