细菌学与寄生虫学杂志

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Small Animal Brucellosis: Associated Risk Factors, Seroprevalence and Characterization of Brucella Isolates in Two Districts of South Omo Zone Ethiopia

Feyera Gemeda Dima*, Maryam Dadar

Brucellosis is one of the highly contagious zoonotic bacterial diseases, with a significant impact on the livestock industry. It is caused by Gram-negative bacteria from the Genus Brucella, and distributed worldwide including Ethiopia. However, there was a scarcity of epidemiological data on its occurrence in pastoral areas. A cross-sectional investigation was conducted from September 2018 to June 2019, to estimate the seroprevalence of brucellosis and to characterized main Brucella isolates infecting small ruminants in two randomly selected pastoral districts of the South Omo Zone, Ethiopia. A pre-tested questionnaire was used and collected data were subjected to statistical analyses (multivariate logistic regression). For the serological test, blood samples were drawn from a total of 124 small ruminants with a history of abortion. Subsequently, 30 vaginal swabs were sampled from seropositive animals for Brucella isolation. All collected sera were first screened serologically using the modified Rose Bengal Plate Test (mRBPT) and Brucella seropositivity was further confirmed by the Complement Fixation Test (CFT). The seroprevalence of brucellosis among small ruminants with a history of abortion was 21% (26/124; 95% CI: 0.14- 0.28). Multivariable logistic regression analysis showed that the main risk factors related to Brucella spp. infections were history of abortion (OR: 0.28, 95% CI: 0.18-0.43) and parity numbers (OR: 0.20, 95% CI: 0.059-0.72). Brucella spp. were also isolated from 5 (16.7%) of the 30 vaginal swabs cultured on Brucella Selective Agar. The isolates were identified as B. melitensis based on biochemical and bacteriological culture results. In conclusion, the present study showed that brucellosis is highly prevalent in small ruminants in the studied area. Therefore, regular testing of breeding animals is necessary to reduce brucellosis and its economic impact in the region.