Investigation of outbreaks and risk factors for brucellosis in goat and sheep farms in central Thailand

Background and Aim: Brucellosis is a harmful disease that affects a wide range of animals and adversely affects both animal and human health. Brucella melitensis is a zoonotic disease that causes brucellosis in sheep and goats. This study aimed to identify human index cases, identify risk factors for brucellosis in goat and sheep farms, and establish recommendations for farmers. Materials and Methods: An unmatched case-control study was conducted on goat or sheep farms in central Thailand. We utilized animal disease reports and outbreak investigation data extracted from the Department of Livestock Development, Thailand, and assessed these secondary data. A questionnaire was used to collect data. Serum samples were parallel tested for brucellosis using the modified Rose Bengal test and indirect enzyme-linked immunosorbent assay. Univariate and multivariate logistic regression analyses were performed. Results: An index case of human brucellosis was reported in the province of Chai Nat. Patients who were goat farmers or had previous experience of goat farming were included. Bacteria were introduced into the patient's farms by purchasing goats, grazing in public grassland, and insufficient biosecurity. Multivariable logistic regression analysis identified a higher risk of brucellosis positivity in the large herd than in the small herd (adjusted odds ratio = 8.61; 95% confidence interval = 1.62-45.71). Conclusion: These results suggest that goat or sheep farms with 50 heads should take further measures to prevent disease transmission, such as increasing the frequency of disease testing within the herd and strengthening the biosecurity system. Keywords: brucellosis, goat farms, outbreak investigation, risk factor, sheep farms.