Spatial and Temporal Patterns of Human African Trypanosomosis (HAT) Transmission Risk in the Bipindi Focus, in the Forest Zone of Southern Cameroon

Abstract

Vector control is an effective and cost-efficient way to disrupt the transmission of human African trypanosomosis (HAT); it has nonetheless been little used to date in the disease's foci. With the aim to target trapping more precisely and to develop an optimized vector control system, a transmission risk index was used in the HAT focus of Bipindi, in the forest zone of southern Cameroon. The authors used a simplified version of the index originally developed by Laveissière et al. in 1994. The calculation of this new index only requires knowledge of the proportion of teneral flies and the proportion of flies with human blood meals in samples caught in different biotopes. This makes it possible to identify the biotopes displaying permanent risk, such as riverbanks, as well as biotopes displaying seasonal risk, such as marshy hollows and encampmemts. In the villages, the domestic pig, with 49% of the identified blood meals, is the favorite host of the tsetse flies during the short rainy season. The proportion of blood meals taken on human beings does not significantly increase when domestic pigs are absent. Game animals, contributing to 46% and 64% of the blood meals during the short rainy season and the long dry season, respectively, are also favored as feeding hosts in this particular HAT focus.