Prevalence of antibody to human T lymphotropic virus type III by risk group and area, United Kingdom 1978-84.

Antibody to human T lymphotropic virus type III (anti-HTLV-III) was sought in 2150 patients in three groups at risk with a radioimmunoassay and an immunofluorescence test. Results by the two methods were closely concordant. Anti-HTLV-III was already present in some British homosexuals in 1980 and in some British haemophiliacs in 1981, and since then its prevalence has increased. Of homosexual patients needing laboratory tests for hepatitis B virus infection in 1984, 34% of 282 in London and 5% of 955 in five centres outside London were positive for anti-HTLV-III. Of haemophiliacs sampled in 1984, 38% of 81 were anti-HTLV-III positive. Most of the seropositive haemophiliacs were regular recipients of commercial factor VIII concentrates. Few British intravenous drug abusers sampled in 1984 (2.5% of 203) were positive for anti-HTLV-III. These results show that infection with HTLV-III has rapidly become widespread among homosexuals attending sexually transmitted disease clinics and among haemophiliacs receiving pooled blood products. Thus, while many anti-HTLV-III positive individuals may remain asymptomatic, there may soon be a considerable increase in the incidence of the acquired immune deficiency syndrome and related disease in Britain.