Human t–cell lymphotropic virus infection among blood donors in south florida

Knowledge of the epidemiologic pattern of human T–lymphotropic virus (HTLV) in the United States is being enlarged by blood donor screening. We tested stored sera from 29,937 donations made in South Florida in 1984–1985. Twenty–three donors were confirmed as seropositive, a prevalence of 0.8 per 1,000 donations. Specificity was supported by serologic retesting and virus culture of 11 donors located for follow–up. Sex–and age–specific prevalences did not differ significantly; blacks, however, accounted for 65% of seropositive donations. Within South Florida, one section of Miami had a prevalence of 4.5 per 1,000 donations, significantly above the 0.1 to 1.1 per 1,000 rates for other parts. An epidemiologic association with known HTLV–I endemic areas could account for most infections; all seven typed isolates were characterized as HTLV–I. Exposures, however, were diverse, sometimes multiple, and had no necessary relationship to personal lifestyle. This finding suggests that sources of infection were varied. Seropositive family members emphasize familial clustering of HTLV–I infection.