Epidemiological and Interventional Study of Camel Trypanosomosis in Selected Districts of Somali and Oromia Regional States, Ethiopia

Abstract

Camel trypanosomosis (surra) is one of the most important diseases which affects the health and production potential of camels in eastern Ethiopia. A longitudinal study was conducted to investigate the prevalence, associated risk factors and vectors in Babile, Shinile and Fafan districts. In addition, parasite (chemotherapy and chemoprophylaxis) and vector control (pour-on, insecticide-impregnated targets and traps) methods were implemented. Both serum and entomological samples were collected 4 times a year to estimate the seasonal prevalence of T. evansi, and assess the abundance and diversity of vectors, respectively. A total of 1790 blood samples were collected before intervention (358 per season). T. evansi was detected in 5.1% and 8.73% of camels by using the buffy coat method (BCM) and Card Agglutination Trypanosomiasis Test (CATT)/T. evansi), respectively. In this study, the prevalence of camel trypanosomosis was significantly higher in Babile (12.6%) than Shinile (5%) district (P<0.05), in adults (10.4%) than in young (7.7%) camels (P<0.05), in poor (20.8%) than good (3.4%) body condition camels P<0.05, and in wet (14.3%) than early wet (2.2%) season, (P<0.05). The biting fly with the highest apparent density was Stomoxys followed by Tabanus, Chrysops, and Haematopota species. Strong association was observed between the apparent density of biting flies caught and the incidence of T. evansi infection. Moreover, T. evansi infection was higher in anemic than non-anemic animals (P<0.05). The serological prevalence of camel trypanosomosis was significantly lower (P<0.05) after intervention than the pre-intervention periods (95% CI= 6.8-59.3%). During the post-intervention period, the prevalence of camel trypanosome infection was significantly (P<0.05) reduced (95% CI=3.0-7.8%) in comparison to the control Fafan districts (95% CI=10.3-17.7%). The implementation of diverse intervention methods on the parasite and its vectors resulted in a decreased incidence of T. evansi infection. This interventional study might serve as a model for the control of surra in low-income settings with community participatory approach.