HTLV-I among U.S. Marines stationed in a hyperendemic area: evidence for female-to-male sexual transmission.

Among 5,255 active duty United States Marines on permanent tour in Okinawa, Japan, screened for human T-cell leukemia/lymphoma virus type I (HTLV-I) seropositivity, 3 (0.06%) were confirmed by Western blot analysis to have core and envelope reactivity. All three seropositive individuals have a history of prolonged sexual contact with Okinawan women, and two of the three individuals are married to seropositive Okinawan wives. Two gave a prior history of gonorrhea, while all three were negative for syphilis (MHA-TP) and hepatitis B. No other risk factors associated with HTLV-I seropositivity in the United States were identified. A banked sample from one individual, obtained 8 months after initial sexual relations with his HTLV-I-seropositive Okinawan spouse and 20 months before being retested in the survey, showed a pattern suggesting seroconversion. Although based on small numbers, these data suggest that female-to-male transmission of HTLV-I occurs in the absence of other cofactors, e.g., ulcerative genital lesions.