Mortality among Inhabitants of an HTLV‐I Endemic Area in Japan

A community‐based cohort study was conducted to clarify the risk of human T‐cell leukemia virus type I (HTLV‐I) infection for cause‐specific deaths. A total of 1,997 individuals (751 men and 1,246 women) aged 30 or older in A‐IsIand, Nagasaki Prefecture, Japan who had voluntarily attended annual mass health examinations, including serum HTLV‐I antibody test, were followed up for a mean period of 5.3 years. In a Cox proportional hazards analysis adjusted for age at baseline, the HTLV‐I seropositivity was found to be associated with mortality from all causes in men (hazard ratio (HR) 1.89; 95% confidence interval (CD 1.01–3.54) and women (HR 1.94; 95% CI 1.16–3.22). When the effects of 2 deaths (1 man and 1 woman) from adult T‐cell leukemia/lymphoma (ATL) were excluded, the mortality risk decreased slightly but was still significantly or marginally significantly greater than 1 in both men (HR 1.77; 95% CI 0.93–3.37) and women (HR 1.87; 95% CI 1.12–3.12). Further analysis of cause‐specific deaths revealed a significant increase in the risk for non‐neoplastic diseases but not for neoplasms excluding ATL. These findings suggest that long‐term HTLV‐I infection represents a health hazard greater than just that for the development of ATL. It was difficult, however, to draw a conclusion regarding the association between HTLV‐I infection and cancer risk, because the number of cancer deaths was small and the incidence of cancer was not investigated.