Bovine Trypanosomiasis Epidemiology and Tsetse Fly Density in Jimma Arjo District, East Wollega Zone, Oromia Regional State, Ethiopia

Tsetse fly density and trypanosoma infection rate in Bedele and Dabo Hana districts of Buno Bedele Zone, Southwest Ethiopia

BACKGROUND

Trypanosomiasis is an infectious disease caused by parasitic protozoa of the genus Trypanosome and primarily transmitted by tsetse flies. This study aimed to determine the density of tsetse flies and the rate of trypanosome infection in the Bedele and Dabo Hana districts of the Buno Bedele Zone in Ethiopia.

RESULTS

A cross-sectional study was conducted from January to February 2023 to catch tsetse flies, determine tsetse density, and estimate the trypanosome infection rate. We used 100 traps (40 NGU, 30 pyramidal, and 30 biconical) to catch the flies. The following standard procedures were followed to identify the specific trypanosome species in the collected tsetse flies: The flies were dissected, and the salivary glands were removed. We placed the salivary glands in a drop of saline solution on a microscope slide. A coverslip was placed over the salivary glands, the slide was examined under a microscope, and the trypanosomes were identified based on their morphology. A total of 3,740 tsetse flies were captured from 100 traps, resulting in an overall apparent density of 18.7 flies per trap per day. Within the study area, only one species of tsetse fly, Glossina tachinoides, was identified. Of the 1,320 dissected Glossina tachinoides, 1.82% were found to be infected with trypanosome parasites. Among these infections, 58.33% were attributed to Trypanosoma congolense, while the remaining 41.67% were caused by Trypanosoma brucei. The infection rate of trypanosomes was significantly higher in female tsetse flies (87.5%) as compared to male flies (12.5%). Furthermore, a significantly higher infection rate was observed in flies older than 20 days (83.33%) and in hunger stage 1 flies (58.33%) compared to hunger stages 2, 3, and 4.

CONCLUSIONS

This study highlights the necessity of implementing control and suppression measures targeting the vector (tsetse flies) and the parasite (trypanosomes) to effectively manage and prevent pathogenic animal trypanosomiasis.

Prevalence of Cattle Trypanosomosis and Temporal Vector Distribution in Jima Arjo District, Upper Didessa Valley, Western Ethiopia

Trypanosomosis is a protozoan disease, mostly transmitted by the tsetse fly, Glossina species, which causes severe disease of livestock in Ethiopia. The disease is also widespread across the globe especially in sub-Saharan African states. A cross-sectional study with the objectives of determining the prevalence of bovine trypanosomosis and assess the apparent densities of the disease vectors was conducted from October 2019 to July 2020 G.C in Jima Arjo district, east Wollega zone, Oromia regional state, Ethiopia. A parasitological study using conventional buffy coat technique was employed for the determination of prevalence of trypanosomosis and species was identified by Giemsa stain technique, while baited traps were used for the vector survey. The results of parasitological study revealed that the overall prevalence was 36 (8.2%) at 95% CI. From the total trypanosome positive animals 22 (5.0%), 8 (1.82%) and 6 (1.36%) of them harbor T. congolense, T. vivax, and T. brucei, respectively. Relatively higher prevalence (10.91%) was seen in animals with poor body condition than those with medium (7.38%) and good (5.55%), body condition though it is not statistically significant ( $P>0.05$ ). Higher infection rate was observed in male 26 (12.26%) than female 10 (4.39%) due to male cattle more exposed to the tsetse fly area or early released from home for drought reason. Out of the total positive animals, only 12 of them were anemic on buffy coat test of sampled blood. This justifies that animal could be positive for trypanosomosis without showing clinical sign of anemia which is the dominant sign in this disease. A total of 2185 vectors trypanosomes were collected among which 1,569 were tsetse flies and 616 were other biting flies. The density of Glossina species was 15.1 fly/trap/day. Glossina morsitans submorsitans and G. tachnoides were the two dominant species of tsetse flies recorded from the area. The present study indicated that tsetse and non-tsetse fly-borne trypanosomosis is a leading bottle neck for production and health of animals in Jima Arjo districts and similar case was found throughout the country which necessitates a coordinated vector and parasite control in order to alleviate the problem of the disease.