Detection of Antibodies Against Brucellosis and Associated Risk Factors in Cross Breed Dairy Cattle in Smallholder Farmers, Southern Ethiopia

Abstract

Background A cross-sectional study was conducted in selected districts of Gamo zone, southern Ethiopia over a period of November 2019 and September 2020 to estimate seroprevalence and associated risk factors and assess knowledge and practices of smallholder farmers about bovine brucellosis. Two districts and four kebeles from each district were purposively selected, and individual animals were sampled using a simple random sampling technique. A total of 384 sera samples were collected, and concurrently, 236 dairy cattle owners were interviewed. The samples were tested for antibodies against Brucella using both Rose Bengal Plate test and Complement Fixation test following OIE standard protocol. Risk factors associated with bovine brucellosis were analyzed using univariate and multivariate logistic regressions. Results The survey result has shown that 95% and 97% of the small holder farmers did not know the cause and symptoms of bovine brucellosis, respectively, and the majority have engaged in risky practices. Eight (2.08%) of the collected serum samples were positive with screening test (RBT) and only six (1.5%) were positive with confirmatory test (CFT). Multivariable logistic regression analysis showed a statistically significant association between herd sizes and the disease. The seropositivity of the disease is higher in small-sized herds followed by medium-sized herds. Conclusion The seroprevalence of bovine brucellosis was found to be at a low percentage with confirmatory tests even if there was a presence of associated risk factors for the disease in the study area. Again, the results suggest that smallholder farmers have poor knowledge and risky practices, which expose them to the disease. Awareness creation about the disease is of paramount importance even if the prevalence was low in this serological study. The implementation of a test and slaughter program before the disease becomes widespread, along with the testing of new stock before introduction to the farms is recommended.

Brucellosis and One Health: Inherited and Future Challenges

“…A common mistake is the use of a “confirmatory test strategy”, typically combining the RBT for “screening” with either the complement fixation test or iELISA or cELISAs (or SAT, which is poorly sensitive) as “confirmatory” tests. For example, in a 2016 review of brucellosis in SSA, 17/34 studies used this incorrect strategy [ 52 ], and the problem persists in this subcontinent and elsewhere [ 57 , 58 , 59 , 63 , 67 , 68 , 69 , 73 , 74 , 75 , 76 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 ]. Provided it is properly understood and implemented, this serial RBT/complement fixation strategy can help to minimize the number of animals culled whenever vaccination with S strains (S19 or Rev1) is part of a correctly implemented combined eradication program in which it is feasible to conduct a repeated testing of RBT-positive animals to follow up titer decreases/increases in complement fixation [ 3 ].…”