Assessment of Brucella melitensis disease burden in lactating goats in Mizque, Bolivia

Abstract

Background: Brucellosis is a zoonotic disease that can be transmitted from goats to people by direct contact or through ingestion of unpasteurized dairy products. In Latin America, where goats are a significant part of agriculture, human cases of brucellosis are reported in Mexico, Argentina, and Peru. In Bolivia, human cases of brucellosis have been described, but there is minimal epidemiologic knowledge. The objective of this study was to assess Brucella melitensis disease burden in lactating goats in Mizque, Bolivia. Methods: Milk and blood samples were collected from 229 lactating goats on 26 farms in Mizque, Bolivia, an agricultural town 100 km from Cochabamba, where human cases of brucellosis have been described. Herds, and goats within herds, were selected via convenience sample. Efforts were made to minimize selection bias. In herds with 16 or fewer lactating goats, all goats were sampled, otherwise, one-third of the lactating goats were sampled. Information from each herd and animal was collected by survey. Milk was analyzed via culture. Serum was analyzed for antibodies using the Rose Bengal plate test and the Lateral Flow Assay. Results: Median herd size was 33 adult goats (range: 10-150). The average reported age of the animals sampled was 3.4 years (SD: ±1.5). None of the animals sampled had a reported history of vaccination against Brucella melitensis. 20 (8.7%) goats sampled from 13 (50%) farms had a reported history of abortion. Of the 229 animals sampled, 0 had positive milk culture and serology results (95% CI = 0 – 1.6%). Conclusion: This region of Bolivia may be free from disease, or may have disease prevalence too low to be detected by the sample size. Given the tendency for disease to cluster within herds, the high disease prevalence in bordering countries, and lack of disease monitoring within Bolivia, the presence of Brucella melitensis in the Bolivian goat population cannot be ruled out. Larger studies conducted in multiple geographic regions of the country are warranted. For example, assuming 100% sensitivity of the tests, a population of 2500 animals, and desiring 95% certainty, the maximum possible prevalence is 1.3% even after finding 0 of 229 positive in this sample. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive