Diversity of tsetse flies and trypanosome species circulating in the highly infested cattle rearing area of the Faro and Deo subdivision, Adamawa region, Cameroon

Abstract

Animal African Trypanosomiasis (AAT) remains an animal health problem in sub-Saharan Africa and in Cameroon in particular. Despite more than 40 years of fighting against AAT in some tsetse infested areas, the disease prevalence is still a concern. Improving the control strategies in different settings requires to understand the current epidemiological situation of AAT. The aim of the present study was to update our knowledge on the diversity of tsetse fauna and trypanosome species in the tsetse infested area of Faro and Deo division, Adamawa region, Cameroon. Tsetse flies were caught using Vavoua trap in two villages and the apparent density per trap (ADP) were estimated. After morphological identification of tsetse fly species, flies were dissected and their midguts recovered. The presence of blood meal residues was recorded. Trypanosomes species were checked in the flies' midguts by microscopy followed by PCR method. The vertebrate taxa on which tsetse flies have taken blood meal were determined using the heteroduplex-PCR method. A total of 338 tsetse flies including 11 teneral flies (10 Glossina palpalis palpalis and 01 G. morsitans submorsitans) and 327 non-teneral were trapped in Mayo Lainde and Tchabal Mbabo. Amongst the caught tsetse flies, of the 327 non-teneral flies, 315 (96.3%) were G. p. palpalis, 8 (2.4%) were G. morsitans submorsitans and 4 (1.2%) G. fuscipes fuscipes. Trypanosome infections including Trypanosoma congolense forest (19.88%) and savanah (2.53%) "types", T. brucei s.l. (7.30%) and T. vivax (2.85%) were identified in 45.08% of non-teneral flies (32.38% for single infection and 12.70% for mixed infection). Amongst the 54 blood meals identified in tsetse midguts, 41% were from humans, 33% from cattle and 26% from other vertebrate hosts. About 51.9% of blood meals were found with various trypanosome species including 42.6% with T. congolense and 24% with T. brucei s.l. This study revealed the presence of three tsetse taxa and the circulation of four trypanosome taxa in villages of the Faro and Deo division. About 45% of captured tsetse fly are infected with trypanosome species causing AAT. Tsetse flies feed on humans, cattle and many other vertebrates. Strategies to eliminate the vectors must be improved to reduce the pathological impacts of trypanosome infections in this area.

Keywords: AAT; Cameroon Adamawa region; Glossina species prevalence; Origin of flies' blood meals; Trypanosoma species diversity; Tsetse fly infection rates.