Prevalence of human T-cell leukemia virus type 1 (HTLV-I) in adult T-cell leukemia (ATL) in non-ATL-endemic Hokkaido of Japan.

Sera and peripheral blood lymphocytes of 40 adult T-cell leukemia (ATL) patients in non-ATL-endemic Hokkaido were examined for the prevalence of human T-cell leukemia virus type 1 (HTLV-I). All patients had HTLV-I-specific antibodies. When the peripheral lymphocytes were assessed after short-term cultivation, HTLV-I antigens and virus particles were detected. The seroprevalence in 96 cases of non-T-cell leukemias and lymphomas and in 30,056 healthy individuals in Hokkaido were 3.1% and 0.7%, respectively. HTLV-I seropositive inhabitants of Hokkaido can be estimated at about 40,000, and one out of every few thousand HTLV-I carriers is likely to develop ATL.