FAMILIAL AGGREGATION OF TRYPANOSOMA-BRUCEI-GAMBIENSE TRYPANOSOMIASIS IN A VERY HIGH-INCIDENCE COMMUNITY IN ZAIRE

Familial aggregation of Trypanosoma brucei gambiense human African try panosomiasis (HAT) was investigated in 3 adjacent villages of central Zaire where 318/1431 inhabitants had previously suffered fi om HAT. N either spatial nor familial aggregation was detected when analysing th e distribution of cases in the whole community using Poisson, negative binomial and pairwise odds ratio models. However, clustering of cases was observed when specific familial relationships were examined. The risk of HAT for a child was significantly increased if the mother had also had HAT, but it was not influenced by a past history of HAT in th e father. Sisters and brothers of cases of HAT had a higher risk of HA T than siblings of individuals who had never had HAT,but no such assoc iation was documented for half-sisters and half-brothers. Among marrie d couples, a past history of HAT in one spouse had no impact on the ot her spouse's risk of HAT. Indirect arguments suggested that familial c lustering was a consequence of shared exposure, either sequential or s imultaneous, rather than of genetic susceptibility. The existence of f amilial clustering should be kept in mind when implementing passive or active case-finding activities.