Isolation of brucella strains in cattle from sedentary and nomadic communities and its public health implication

Abstract

Background: Brucellosis is a highly infectious disease caused by bacteria of the genus brucella affecting animals leading to high economic loss and an impediment to livestock exportation. It also infects man with serious public health consequences. The disease is one of the world's most important neglected tropical zoonoses. Brucellosis is considered endemic in Nigeria and current information on isolation in sedentary and nomadic cattle is required. We carried out an active surveillance in sedentary cattle in Kachia Grazing Reserve (KGR), Kaduna State and in nomadic communities on the Jos Plateau to isolate brucella organisms and carry out phenotypic and molecular characterization of the isolates to species level. Methods & Materials: A total of 63 vaginal swabs, 36 milk samples, and 2 hygroma fluids were collected from cattle in KGR while 70 vaginal swabs, 50 milk samples and 2 hygroma fluids were collected from cattle on the Jos Plateau using a purposive sampling technique. Only animals that had history of abortion or infertility were sampled. They were cultured on serum dextrose agar with addition of antibiotic supplement (Oxoid) and incubated at 37 °C for 3 days in 5% CO2 atmosphere. Brucella strains isolated were biotyped along with eight archived isolates according to classical Brucella biotyping method. Isolates were further subjected to Bruce-ladder multiplex PCR according to established protocol. Results: Three and four B. abortus strains were isolated from KGR and Jos Plateau respectively. Biotyping revealed that all the 15 isolates were B. abortus biotype 3. Bruce-ladder multiplex PCR showed bands consistent with B. abortus. Conclusion: The study established the endemicity of brucellosis due to B. abortus biotype 3 in the two study areas. These findings have great veterinary and public health implications as healthy animals and the farmers are at high risk of infection due to contact with infected animals, consumption of raw milk and other products. Farmers were advised to boil their milk before consumption, isolate infected animals, maintain good level of hygiene and use protective wears in handling their animals as preventive measures. The study recommends vaccination of cattle against brucellosis in the areas.