THE RISK OF TROPICAL SPASTIC PARAPARESIS DIFFERS ACCORDING TO ETHNIC-GROUP AMONG HTLV-I CARRIERS IN INONGO, ZAIRE

Following the finding in 1990 of six HTLV-1-positive cases of tropical spastic paraparesis (TSP/HAM) is a field survey carried out in the ci ty of Inongo (Bandundu, Zaire), the prevalence of HTLV-1 infection has been studied by detection of specific antibodies on a randomized samp le of the general population. Among the 1,162 subjects surveyed, 36 (3 .1%) were found to be HTLV-1 seropositive, giving a seroprevalence of 3.2% (CI: 2.1, 4.3), estimated by direct standardization on age and se x distribution given by the census in the city. Among the five major e thnic groups, the Bolia showed the highest prevalence rate (6.5%) but with no detected TSP/HAM cases, while all six TSP/HAM cases were found among the Ntomba, who showed a prevalence rate of only 2.2%. This fin ding suggests that besides HTLV-1 infection, critical environmental an d/or genetic cofactors play a part in the development of TSP/HAM.