HTLV-I seroprevalence in patients with undefined uveitis in central Japan.

Recently, human T-lymphotropic virus type I (HTLV-I) has been shown to cause endogenous uveitis, HTLV-I associated uveitis. To investigate the association of hereditary or environmental factors with the incidence of this uveitis, HTLV-I seroprevalence was studied in patients with undefined uveitis in central Japan, where HTLV-I infection has not been considered highly endemic. Of 129 patients with undefined uveitis, 6 (4.6%) were seropositive, and 4 of these 6 seropositive cases with undefined uveitis were born in southwestern Japan, where HTLV-I infection is highly endemic. As regards the incidence rate of uveitis, 4 of 9 (44.4%) seropositive cases from southwestern Japan developed uveitis, whereas only 2 of 21 (9.5%) seropositive cases from central Japan developed uveitis. The difference was statistically significant (P < 0.05). This results suggests that the incidence of HTLV-I associated uveitis could be influenced by environmental or hereditary factors including HLA.