Infrequent detection of TT virus infection in intravenous drug users, prostitutes, and homosexual men.

TT virus (TTV), a recently discovered DNA virus, has been implicated as a cause of non-A to non-C posttransfusion hepatitis. The frequency of TTV in persons considered at high risk for sexual and parenteral infection was investigated (52 prostitutes, 81 homosexual men, 65 intravenous drug users) to assess its mode of transmission. TTV DNA was assayed by polymerase chain reaction using primers from conserved regions in the N22 clone. Viremia frequency was 4.5%-13.0% in study subjects, not significantly different from that in low-risk controls (2 [4.5%] of 44). The frequency of TTV viremia increased significantly with age (P=.018) but was not associated with human immunodeficiency virus coinfection. The low frequency of infection detected in both risk groups suggests that spread by sexual contact or by intravenous drug use is relatively inefficient and unlikely to account for the high prevalence of TTV observed worldwide.