Seropositivity and risk factors for Brucella in dairy cows in Asella and Bishoftu towns, Oromia Regional State, Ethiopia

A cross-sectional study was conducted in Asella and Bishoftu towns of Oromia Regional State of Ethiopia to determine seropositivity and associated risk factors exposing dairy cattle to brucellosis from December, 2013 to March, 2014. A total of 570 dairy cattle from 35 herds were purposely selected for inclusion in the study based on abortion history. From 35 farms studied, 80, 55.56 and 100% of the farm owners in small, medium and large herd sizes responded as they were aware of brucellosis, respectively. It was also found out that all farm owners of the study area were dependent on culling of the known Brucella infected animals, while most of the farm owners dispose the after birth to open dump in small and medium herd size farms. All sera sample collected were tested and confirmed serologically using the card test (CT), rose Bengal plate test (RBPT), indirect enzyme linked immuno sorbent assay (i-ELISA) and complement fixation test (CFT). Out of 570 samples tested in the present study, an overall sero prevalence was estimated 1.4% (95% CI: 0.241, 3.461) by complement fixation test (CFT). Among the tested samples, 13 (2.28%), 15 (2.63%) and 16 (2.81%) were found positive by the aforementioned tests, respectively. The higher seroprevalence, 3.23% (95% CI: 3.0, 7.4) was observed in Asella compared to Bishoftu (0.52%) town. A Chi-square computed statistical analysis indicated that origin (χ2=6.63; P<0.05), breed type (χ2= 8.49; P<0.05), abortion history (χ2=92.43; P<0.001) and abortion period (χ2=192.97; P<0.001) were the major risk factors for Brucella infection in the study areas. Multivariable logistic regression statistical analysis revealed that origin and breed type were significantly associated with Brucella seropositivity (P<0.05). Consequently, origin was statistically identified to be the major risk factor for brucellosis to occur in relation to other factors (OR=7.56). In conclusion, the prevailing Brucella seropositivity in most of the dairy farms of the study areas signifies the economic importance of brucellosis in the dairy cattle industry and the potential public health implication for human population. Therefore, more proactive measures should be taken to protect the cattle populations from Brucella infection to reduce its economic impact to the dairy industry and the risk of zoonotic infection in exposed human population in the study areas.