Bovine brucellosis and tuberculosis at a livestock-wildlife interface in Zimbabwe: A nexus for amplification of a zoonosis or a myth?

Abstract

Bovine brucellosis and tuberculosis are important zoonoses affecting both livestock and wildlife. The study aimed to investigate seroprevalence of brucellosis and to isolate Brucella spp. and Mycobacterium bovis in cattle from livestock-wildlife interface areas. Three sites were selected from high, medium and low interface. The high interface was adjacent to the park and separated by a broken fence, while the medium and low interface were 15-20 and 50km from the perimeter fence, respectively. Cattle aged ≥2 years were randomly selected and bled for serology. Culture for brucellae and Mycobacterium species was attempted on lymph nodes collected at the slaughter floor. Sera were screened for Brucella antibodies using the Rose Bengal test and confirmed by the Complement fixation test. Data were analysed using a multivariable logistic regression model. Overall, seroprevalence was 11.7% (125/1068; 95% CI: 9.8-13.6%). High interface areas recorded significantly higher (p < 0.05) seroprevalence of 20.9% (85/406; 95% CI: 17.0-24.9%), compared to low 8.9% (31/350; 95% CI: 5.9-11.8%) and medium interface 2.9% (9/312; 95% CI: 1.0-4.8%). Brucella seropositivity was approximately three times higher (OR = 3.3, 95% CI: 2.1-5.3) for Malipati compared to Chiredzi. Similarly, the odds were twice (OR = 2.0, 95% CI: 1.2-3.5) in cows with history of abortion compared to those without. Brucella and Mycobacterium species were not isolated from all samples. The study highlighted the significance of high interface as a nexus for amplification of brucellosis in cattle. Thus, a brucellosis control programme that takes into consideration limiting livestock-wildlife interaction should be considered.