HTLV-ASSOCIATED MYELOPATHY IN A COHORT OF HTLV-I AND HTLV-II-INFECTEDBLOOD-DONORS

Objective: HTLV-I-associated myelopathy (HAM) is a slowly progressive spastic paraparesis caused by infection with human T-lymphotropic viru s type I (HTLV-I). The prevalence of HAM among those infected with HTL V-I is poorly defined, and the association of a similar myelopathy wit h HTLV-II infection has not been confirmed. Design: Cross-sectional ex amination of HTLV-I, HTLV-II, and control subjects from the baseline v isit of a cohort study. Setting/subjects: Persons testing HTLV seropos itive at the time of blood donation at five U.S. blood centers, their seropositive sex partners, and a matched control group of HTLV seroneg ative blood donors. Measurements: HTLV-I and HTLV-II were differentiat ed by serology and/or polymerase chain reaction. All subjects received systematic neurologic screening examinations. Results: A diagnosis of myelopathy was confirmed in four of 166 HTLV-I subjects (2.4%, 95% co nfidence interval 0.7%, 6.1%) and in one of 404 HTLV-II subjects (0.25 %, 95% confidence interval 0.0%, 0.6%). None of the 798 controls had a similar myelopathy, although one had longstanding typical multiple sc lerosis. Conclusions: Our data also suggest that HAM occurs more frequ ently among HTLV-I-infected subjects than reported by previous studies , The HTLV-II infected myelopathy patient identified in this cohort, t ogether with three other case reports in the literature, implies a pat hogenic role for this human retrovirus. The diagnosis of HTLV-associat ed myelopathy should be considered in cases of spastic paraparesis or neurogenic bladder when risk factors for HTLV-I or HTLV-II infection a re present.