[Epidemiological analysis of adult T-cell leukemia]

Adult T-cell leukemia (ATL) is prevalent in the rural coastal areas of southwestern part of Japan. The geographical distribution of persons with antibody to ATLV which seems to be the decisive causal agent of ATL is very similar to that of ATL patients. The positive rate of anti-ATLA among healthy inhabitants older than 50 years was 32% (21% in males and 39% in females) in Goto Islands in Nagasaki Prefecture. However, positive rates are only 15% in the age group of 30 to 49 years and 4% under 29 years in the same area. From the epidemiological analyses of the mode of anti-ATLA reactivity among married couples and family members with positive and negative anti-ATLA, two routes of transmission of ATLV were suspected. One route is from parents to children and another is the horizontal transmission from new family to woman after marriage. The environmental and socioeconomic factors which had changed remarkably after the World War II and may have influenced the characteristic distribution of ATLV carriers by age and sex in these areas are discussed as the modifying factors for ATLV infection and ATL manifestation from the epidemiological view point.