Epidemiology of Bovine Trypanosomosis and Vector Distribution in Didessa River Basin, Ethiopia

Tsetse-transmitted trypanosomosis much depends on the distribution and capacity of Glossina species responsible for transmission.

A cross-sectional study based on parasitological and entomological studies was conducted from October to June 2018 to determine the epidemiology, distribution, and magnitude of the vector, the disease and Analyze associated risk factors.

Based on implemented entomological study, Didessa river basin has a total apparent fly density of 5.33 Fly/Trap/Day (FTD); similarly, Glossina species accounted about 4.04 and 1.29 were other biting flies (Stomoxys and Tabanus). The composition of Glossina species identified in the study were 3335 (98.56%) Glossina tachinoides and 49 (1.44%) Glossina fuscipes. Comparatively higher and lower FTD found in altitude ranges from 1317 m above sea-level Bedele District (FTD = 5.19) and 1334 m above sea-level Boracha District (FTD = 1.88). Furthermore, from the total of n = 1517, local breeds of cattle examined for the infection of parasite and 82 cattle were found infected with an overall prevalence of 5.41%. The resulted overall prevalence was composed of Trypanosome congolense and Trypanosome vivax, 59 (3.89%) and 23 (1.52%), respectively. Among studied Districts; Goma, Limukosa, Limuseka, Bedele, Boracha, and Gechi prevalence of bovine trypanosomosis was 6.56%, 6.48%, 7.56%, 3.56%, 6.71%, and 1.60%, respectively. Based on parasitological study, statistically significant prevalence was demonstrated between Districts of Limuseka 7.56% and Gechi 1.60% with highest and lowest, respectively. During the early dry season, the prevalence of Trypanosome vivax 0.53% was significantly lower than that of late rainy season 0.99%; however, the higher number of Trypanosome congolense 2.44% resulted during the late rainy season. The study also demonstrated that trypanosomosis strongly causes anemia with mean pcv of infected cattle 20.93 ± 3.93 and non-infected cattle 26.74 ± 3.81 (Mean pcv ± SD) with 95% CI, Pr (T > t) = 0.0000. Moreover, trypanosomosis-related anemia was highly associated with T. congolense with mean pcv result of 18.80 ± 4.66 [mean pcv ± SD, Pr (T > t) = 0.0000] when compared with T. vivax 27.53 ± 4.47 (Mean pcv ± SD, Pr (T > t) = 0.6222).

Finally, the research demonstrated the new local demographic occurrence of G.f. fuscipes in the Didessa river basin which was not reported by other studies so far, therefore, the current finding invites further studies and investigations.