HIGH-RATE OF NONSPECIFIC ANTI-HEPATITIS-C REACTIVITY AMONGST HOMOSEXUAL MEN IN COMPARISON WITH THAT FOUND IN OTHER SEXUALLY ACTIVE GROUPS AND BLOOD-DONORS

Objectives. To investigate the concordance of antihepatitis C virus (a nti-HCV) reactivity by a second-generation enzyme immunoassay (EIA-2) and by a four-antigen recombinant immunoblot assay (4-RIBA) in homosex ual men, in comparison with that found in other sexually active groups and blood donors. Design. Prospective study. Setting. Tertiary referr al centre, Seville, Spain. Subjects. A total of 1203 subjects were stu died. Eight hundred and three were sexually active individuals: 547 fe male prostitutes, 88 heterosexual men who had frequent sexual intercou rse with prostitutes, and 168 homosexual men. All of them denied blood transfusion and parenteral drug use. In addition, 400 voluntary blood donors were selected at random. Main outcome measures. All serum samp les were screened for anti-HCV by EIA-2 and repeatedly reactive sera w ere tested by 4-RIBA. Homosexual men were also screened for anti-human immunodeficiency virus (anti-HIV), hepatitis B virus (HBV) markers an d gammaglobulin concentration. Finally, serum samples from homosexual men reactive for anti-HCV by EIA-2 were analyzed for HCV-RNA by polyme rase chain reaction (PCR). Results. Concordance between EIA-2 and 4-RI BA in female prostitutes (71.4%), clients of prostitutes (75.0%), and blood donors (83.3%) was significantly higher than in homosexual men ( 38.8%) (P < 0.04). In this collective the concordance between 4-RIBA a nd PCR was 85.7% for positive cases and 88.8% for negative ones, and E IA-2 ratios in reactive sera were significantly higher in 4-RIBA confi rmed cases (P < 0.0001). No correlation between false positive EIA-2 r esults and presence of HIV infection, HBV markers or hypergammaglobuli naemia was found in homosexual men by univariate analysis. Conclusions . There is a high level of non-specific anti-HCV reactivity by EIA-2 a mongst homosexual men in comparison with that found in other sexually active groups and blood donors. The true prevalence of HCV infection a mongst homosexual men could be even lower than previously described.