Molecular detection of Brucella abortus in hygromas and cow’s milk in the Chari Department of Chad

Brucellosis is a major notifiable zoonotic disease that affects domestic, wild, and marine animals, as well as humans. It is caused by a bacterial infection of the genus Brucella. The objective of this study was to detect Brucella abortus in bovine hygromas and cow’s milk using conventional Polymerase Chain Reaction (PCR). Two primer pairs were used to amplify DNA fragments present in the collected samples. Gel electrophoresis results showed electrophoretic profiles for the Brucella abortus strain at approximately 223 base pairs and another strain at approximately 100 to 120 base pairs. Of 50 hygromas and 50 raw milk samples collected from cattle, 36 samples were PCR-positive, representing an overall prevalence of 72%. The study revealed a co-infection with Brucella abortus and Brucella melitensis, with a prevalence of 34.0%. Females were more frequently infected with Brucella abortus than males, with a rate of 76.2% in females and 50% in males. Transhumant cattle had an infection rate of 83.3%, while sedentary cattle had a rate of 65.6%, resulting in a crude odds ratio of 2.62 (χ²=1.021; p=0.312). Prevalence ranged from 52.9% (Medina villages) to 87.5% (Shilo camps). The study showed that two strains of Brucella abortus circulate in the Chari department with high prevalence. Control and prevention strategies will be necessary for effective management, as brucellosis is included on the Chadian government’s list of priority diseases to be monitored and eradicated. Keywords: Brucella abortus, hygroma, milk, Chad