Prevalence of HTLV-I-associated myelopathy among HTLV-I carriers in Saga, Japan.

Surveying the disease by sending questionnaires to all physicians of the Saga Medical Association, we tabulated 19 definite cases of HTLV-I-associated myelopathy (7 males and 12 females) as of January 31, 1988. The population at risk of HTLV-I carriers was estimated by applying sex- and age-specific anti-HTLV-I antibody-positive rates among blood donors at the Saga Red Cross Blood Center in the fiscal year of 1986 to the population of Saga Prefecture in 1982. The crude prevalence rates among HTLV-I carriers from 20 to 69 years of age per 100,000 were 65.7 for males and 86.9 for females, respectively. The summary prevalence rates with 95% confidence intervals were 46.5 (14.3-97.3) for males and 74.9 (35.3-129.2) for females. There was no remarkable difference in the age-specific prevalence rates in either sex. The crude and summary rates among females were higher than those among males, but the difference was not statistically significant.