Epidemiological analysis of the distribution of antibody to adult T-cell leukemia-virus-associated antigen: possible horizontal transmission of adult T-cell leukemia virus.

About 20% of healthy inhabitants in the endemic area of adult T-cell leukemia/lymphoma (ATL) in Nagasaki Prefecture showed a positive antibody to adult T-cell leukemia virus (ATLV)-associated antigen (ATLA), while none of the inhabitants in a non-endemic area in Aichi Prefecture showed a positive anti-ATLA. The age-specific positive rate of anti-ATLA in the endemic area increased with age, especially in females. The positive rate of anti-ATLA among inhabitants older than 40 years was 21% in males and 36% in females. From epidemiological analyses of the mode of anti-ATLA reactivity among married couples and some family members and relatives with positive and negative anti-ATLA, two routes of transmission of ATLV were suggested. One route is from parents to children, either vertically or horizontally, and the other route is horizontal transmission between spouses, especially from husband to wife. The presence of some vectors of ATLV in the endemic area of ATL is discussed.