Seroconversion to human immunodeficiency virus (HIV) in persons attending an STD clinic in Copenhagen

1,182 males and 155 females attending an STD clinic from June 1984 to October 1985 were investigated for the presence of antibodies to human immunodeficiency virus (HIV). 348 (29.5%) of the males and 5 (3.2%) of the females were antibody positive (ab+). 237 of the males were initially antibody negative (ab-) and were tested more than once, and during a 16-month period 40 of these seroconverted from ab- to antibody positive. The mean follow-up period of these 40 patients was 7.1 months, and thus the seroconversion rate is estimated to be 2.4% per month. Samples from 37 of these were available for HIV antigen testing. 19 of the patients were antigen positive in the latest ab- sample and accordingly, 18 patients were antigen negative in the latest ab- sample. No difference was found between the mean follow-up periods of those with and those without HIV antigen in the latest ab- serum and the presence of HIV antigen in serum was not associated with symptoms of acute HIV infection. After 20 months of follow-up, none (0.0-8.8%, 97.5% confidence limits) of the 40 patients have developed AIDS or AIDS-related complex.