Enquête épidémiologique pour la recherche des lieux de contamination probables dans un foyer centrafricain de maladie du sommeil

In January-February 1991 an epidemiological survey took place in the Nola-Bilolo foyer (a forested zone) a focus of sleeping sickness in the Central African Republic to learn where patients with sleeping sickness likely became infected. Active case finding during the survey detected 70 cases. Passive case finding in 1990 detected 72 cases. The principal activities which put cases at risk of acquiring African trypanosomiasis were those that took place almost always within a radius of 3 km suggesting that a peridomestic tse-tse fly population was responsible. These activities included working in coffee plantations for men (31%) and the steeping of cassava in rivers for women (20%). Contact with the tse-tse fly within the village and in the forest contributed somewhat to acquisition of sleeping sickness (<12%). Bathing in the rivers was the main activity placing children at risk. The epicenter of the foyer and the principal reservoir of the infective flies was Mpoyo which had 18% of sleeping sickness cases. Other significant foci were Bilolo (9%) Mekara (8%) and Modigui-Kouna Bindjo-Jeolo Ziendi and Domissili all of which had 7% of cases. This survey revealed considerable movements from village to village which seems to be characteristic of this foyer. It also showed that passive case finding from medical registers is adequate in obtaining information about the location of places of transmission and that mobile health teams are a better approach. The case finding approach allowed health workers to identify peoples contact points with the tse-tse fly as well as their place of residence which better depicts reality. It also allows health planners to identify specific priority areas for vector control by trapping which is financially more feasible for West African countries than is trapping the entire foyer. In conclusion the case finding survey showed geographic heterogeneity of transmission of typanosomes.