Studies of brucellosis in lactating cows in Babati district, Tanzania

Abstract

The present cross-sectional study was carried out to determine prevalence and risk factors for transmission of brucellosis in lactating cows in Babati district. Rose Bengal plate test (RBPT), buffered acidified plate test (BAPA), competitive enzyme-linked immunosorbent assay (c-ELISA) and polymerase chain reaction (PCR) tests were used in this study to determine the presence of antibodies against Brucella and Brucella genome. Milk and blood samples from 192 randomly selected lactating cows were collected. Furthermore, questionnaires were administered to 66 milk producers to determine the risk factors for the transmission of brucellosis in between animal populations. The RBPT and BAPA results showed 4.7% (nine cows) and 5.2% (10 cows) seroprevalence, respectively. When RBPT and BAPA positive samples were tested using c-ELISA for serologic confirmation, only eight cows (4.2%) turned out to be positive. The milk samples from eight cows that were positive for Brucella antibodies using c-ELISA were tested for the presence of Brucella DNA using PCR. Three out of the eight milk samples were positive for Brucella abortus indicating shedding of Brucella in milk. Analysis of risk factors for transmission of brucellosis by Fisher‘s exact test or Chi-square showed that livestock mixing with different herds (P=0.0097, OR=11.3333), farming system of cattle (P=0.0400, OR=3.9474), breed of cattle (P=0.0284, OR=1.9860), herd size of cattle (P=0.0030, OR=1.9537) and movement of animals through selling and purchasing (P=0.0500, OR=5.0588) were statistically associated with Brucella positivity. This study provides evidence of brucellosis in lactating cows of Babati district and shedding of Brucella in milk. Institution of appropriate control measures including public health education, surveillance of animals accompanied with removal of positive cases according to laws and immunisations of cattle are highly recommended.

Key words: Seroprevalence, Brucella, Rose Bengal plate test,