A historical study of human T lymphotropic virus type I transmission in Barbados.

A 1972 historic sera collection from two health districts in Barbados, British West Indies, was evaluated for risk factors and epidemiologic patterns of HTLV-I (human T cell leukemia virus type I) during a time prior to the first report of its discovery in 1980. HTLV-I seroprevalence is 4.2% (43 of 1,012) and is consistent with current estimates in endemic areas in the Caribbean. Age-dependent rise (P less than .01) and higher seroprevalence rates for females (P less than .01) are indistinguishable from the pattern in contemporary Caribbean and Japanese populations. HTLV-I seropositivity was 4 times higher in women (P less than .003) and 2.6 times higher in men (P = .32) with treponemal antibodies, supporting a role for sexual transmission. Children who were positive in a household were more likely to have a seropositive mother than a seropositive father. This pattern is consistent with transmission of the virus from mother to child. Our results document that rates of infection and modes of transmission of HTLV-I are persistent.