Human T-lymphotropic virus type II seroprevalence among emergency department and clinic patients

To determine the seroprevalence of human T-lymphotropic virus types I and II (HTLV-I and HTLV-II) among emergency department and clinic patients at a San Francisco, California, hospital, consecutive patients from 4 outpatient settings-emergency department, medical clinic, antenatal clinic, and neighborhood health centers-were tested for antibody to 1 of the viruses using an enzyme-linked immunosorbent assay and Western blot test. Of 4,019 patients, 169 (4.2%) had antibody to HTLV-I or -II; the seroprevalence of HTLV-II (3.5%) was greater than that of HTLV-I (0.7%). Seroprevalence for HTLV-II was highest in the emergency department (6.9%) and neighborhood clinics (3.9%) and in those aged 30 to 59 years (5.9%). Crude HTLV-II prevalence was higher in men (5.2%) than in women (2.2%), but sex was not an independent risk factor after age and location were controlled for. This study showed a higher seroprevalence of HTLV-I and HTLV-II among outpatients than did previous studies, probably because of a high proportion of injection-drug users. In view of the recent description of HTLV-II-associated myelopathy, studies of neurologic disease in this population may be warranted. HTLV-II should be included in the list of occupationally transmitted infections for hospitals with many injection-drug-using patients.