A retrospective study of risk factors associated to brucellosis seropositivity and bacterial isolation in bovine carcasses with cervical bursitis from the states of Mato Grosso, Pará and Tocantins - Brazil.

Bovine brucellosis is an endemic zoonosis prevalent in Latin America with heterogeneous distribution between and within countries in the region. Cervical bursitis represents a lesion indicative of brucellosis, which may be identified in bovine carcasses during post-mortem meat inspection, thereby enhancing brucellosis monitoring systems. This work aimed to study risk factors for brucellosis seropositivity and for Brucella abortus isolation in bovine carcasses with cervical bursitis from the states of Mato Grosso, Pará and Tocantins - Brazil, through Bayesian Logistic Regression Models (BLRM) in order to provide information to support risk-based sampling. A total of 160 paired samples of serum samples and cervical bursitis were analyzed. Three BLRMs were run in OpenBUGS. The BLRM dependent variables were diagnostic test results (serum agglutination test with 2-mercaptoethanol in model 1, Rose Bengal in model 2, isolation and identification in model 3). State of origin, sex and age of the animals were the explanatory variables. Model 1 fitted better to the data according to DIC and ρD. Carcasses of bovine females with cervical bursitis were 18.54 (95 %CrI 4.727-85.98) times more likely to be seropositive - model 1. There was no risk associated with the age of the animals. The origin of the animals was a factor which reduced the risk for brucellosis in models 1 and 2. Understanding the risk factors for seropositivity and microbiological evidence associated with cervical bursitis in bovine carcasses better directs sample collection for more comprehensive and effective surveillance of brucellosis in slaughterhouses.