SEASONAL PREVALENCE OF BOVINE TRYPANOSOMOSIS AND TSETSE FLY DENSITY IN ZALA DISTRICT, GOFA ZONE, SOUTHERN ETHIOPIA

Abstract

Bovine trypanosomosis is a parasitic disease causing serious economic losses in livestock productivity and agricultural development. However, the seasonal information of bovine trypanosomosis and tsetse fly density is very limited in many parts of the country including the southern rift valley of the country, particularly in Gofa Zone. Therefore, the objectives of this cross-sectional study were to estimate seasonal prevalence of bovine trypanosomosis and to assess tsetse fly apparent density in Zala district. For the parasitological study, a total of 560 animals (280 in each season) were examined for trypanosomosis by using buffy coat technique. For the entomological survey, 80 NGU traps odour-baited with acetone were deployed in watering and grazing points in which the animals and vector are believed to have frequent contact. An overall prevalence of trypanosomosis was 6.96%, of which 4.28% and 9.64% accounted for the dry and wet season, respectively. The prevalence of bovine trypanosomosis was significantly higher during the wet season (OR = 2.38; p < 0.05), in black and black spotted coat colour (OR = 4.61, p < 0.05) and poor body conditioned (OR = 4.55; p < 0.05) animals. Two species of trypanosomes, Trypanosome congolense, 87.18% and Trypanosome vivax, 12.82% were circulating in the area both in dry and wet season. The mean PCV value in infected animals (20.89 ± 4.04) was significantly lower than in non-infected animals (22.9 ± 6.32 %). The entomological study revealed the presence of only one Glossina species, known as G. pallidipes and two species of other biting flies, Stomoxys and Tabanus were distributed in the study area. From all traps deployed in both wet and dry season of the study district, a total of 564 tsetse and other biting flies were caught of which, 56.9% belongs to G. pallidipes and 43.1% were other biting flies. Overall apparent densities of G. pallidipes and biting flies in the study area were 1.38 and 1 flies/trap/day, respectively. Relatively, higher Glossina/trap/day caught in the wet season, (1.78 flies/trap/day) than in the dry season (1 flies/trap/day). Therefore, bovine trypanosomosis is one of the major impediments to livestock development and a potential threat to health and productivity of cattle in Zala district. Hence, the tsetse and trypanosomosis control scheme in tsetse infested areas of the district should be strengthened in coordinated manner to minimize the burden of the disease.