Experiences with a strategy to investigate bovine brucellosis in a rural area in Southwest Uganda

Abstract

Forty-three dairy herds comprising 1094 cattle, 22 sheep and 102 goats were enrolled in a bovine brucellosis cross-sectional study. As an initial herd screening test the milk ring test conducted with bulk milk samples was chosen. Ten percent of the herds were MRT positive. Due to a low percentage of lactating cows within the herds (on average 25%), false positivity and spoilage of milk samples, MRT was found to be unsatisfactory in detecting infected herds. Therefore, 756 cattle, 22 sheep and 79 goats were screened individually by the Rose Bengal plate test (RBPT) and subsequently subjected to the complement fixation test (CFT). The agreement of RBPT and CFT was determined as moderate in this study. Based on CFT results the Brucella abortus overall prevalence rate was then 3% (23/756). Fifty-two percent of the seropositive cows were older than 6 years. Seropositive animals were five times more likely to previously have had an observed abortion than seronegative animals. The herd prevalence rate was calculated as 25% (10/40) and the prevalence rate within the herd ranged from 1.5 to 20.4% with a mean of 5.6%. All service bulls, goats and sheep were seronegative and thus played no apparent role in the transmission of brucellosis in the area. The test-systems applied (MRT, RBPT and CFT) are discussed and recommendations for further bovine brucellosis investigations are given.