Some epidemiological features of the human T-cell lymphotropic virus type I (HTLV-I) and ATL in Nigerians.

With a seroprevalence rate (SPR) of 6%-10% among healthy adult blood donors (ABD), Nigeria and other African locales represent an endemic zone for HTLV-I. We studied SPR in patients with leukaemia, lymphomas, solid tumours, and chronic disorders, as well as in groups of men and women with varying sexual lifestyles. Serum specimens were screened with ELISA and then confirmed with Western blot (WB). Sexual practices were investigated among volunteers of different sexual backgrounds by means of a questionnaire. Female prostitutes (FP) (13.0%) and patients with sexually transmitted diseases (STDP) (16.7%) had the highest SPR while a low rate occurred in religious celibate males (RCM) but not in religious celibate females (RCF) (11.8%). Heterosexual activity as well as geographical location of the place of birth constituted the most important risk factors for HTLV-I. HIV antibodies were demonstrable in none of the study subjects. ATL was associated with 100% SPR (4/4) while SPR in other clinical states were not different from normal. Western blot profile was rarely of strong poly band but more frequently of weak oligo band pattern with absent or weak p19 compared to p24. Only 18% of non Hodgkin's lymphoma in Ibadan, Nigeria was seropositive compared to 50% and > 60% in Japanese and Caribbean endemic zones respectively. The high SPR and aberrant WB profiles indicate reactivity to HTLV-I and to an HTLV-II-like activity, probably a new virus in the region. Excluding the aberrant WB profile, SPR based on HTLV-I-related profile was 3.8%-4.8% in ABD, 13% in FP, 10% in STDP, 1.9% in RCM, 0% in RCF, and 25% in ATL patients. The HTLV-II-related profile showed no such heterosexual association, but occurred in 75% of ATL patients. HTLV-I and probably and an HTLV-II-like virus appear to play a role in STD and lymphoma epidemiology in Nigeria.