Influence of habitat and seasonal variation on wild mammal diversity and distribution with special reference to the Trypanosoma brucei gambiense host-reservoir in Bipindi (Cameroon)

Abstract

To evaluate the role of wildlife in the resurgence and perenisation of human African trypanosomiasis (HAT), we investigated the influence of habitat and seasonal variations on the diversity and spatial distribution of wild mammals, with special reference to those recognised as potential host-reservoirs of Trypanosoma brucei gambiense in Bipindi (southwestern Cameroon). To achieve this, we carried out transect surveys in four habitat types over two years. A total of 31 mammal species were recorded, of which 14 occurred in the undisturbed forest, 9 in cocoa plantations, 11 in farmlands and 11 in village-adjacent gallery forests. Among them, six species ( Cephalophus monticola, Cephalophus dorsalis, Atherurus africanus, Cricetomys emini, Nandinia binotata and Cercopithecus nictitans), known as reservoir hosts of T. b. gambiense, occurred in all kinds of habitats suitable or unsuited to Glossina palpalis palpalis and in all seasons. These species are the most involved in the transmission cycle (human being/tsetse flies/wild animals). Cercopithecus cephus, Miopithecus talapoin and Heliosciurus rufobrachium host Trypanosoma brucei spp.; however, only C. cephus does not occur permanently in the suitable habitat of G. palpalis palpalis. In general, some species ( C. monticola, Tragelaphus spekei and C. emini) showed a slight density increase from the long dry to the heavy rainy season within the undisturbed and farmland habitats, and a slight decrease within cocoa plantations and village-adjacent forests in the same period. The density of A. africanus increased greatly from the long dry season to the heavy rainy season in the undisturbed forest while, the density of primates in this habitat decreased slightly from the long dry season to the heavy rainy season. These variations indicate a permanent movement of wild mammal reservoir or feeding hosts from one biotope to another over the seasons. Thryonomys swinderianus needs to be investigated because it occurs permanently in the suitable habitat of G. palpalis palpalis and Potamochoerus porcus for its genetic similarities to domestic pigs, favourable feeding hosts of G. palpalis palpalis.