Risk factors and seroprevalence of Brucella spp. in cattle from Western Amazon, Brazil. RISK FACTORS AND SEROPREVALENCE OF BRUCELLA SPP. IN CATTLE FROM WESTERN AMAZON, BRAZIL

The seroprevalence of Brucella spp. and the possible associated risk factors were estimated for 2,109 adult cows in Monte Negro county, State of Rondônia, Brazil. A questionnaire was completed for each farm where cattle were sampled. Laboratory tests were Rose-Bengal Agglutination, Standard Tube agglutination, and Mercaptoethanol. The adjusted overall prevalence of Brucella spp. seropositive cows for Monte Negro county was 15% and at least 54 herds (63%) were positive. A logistic regression analysis suggested that the herd size of more than 25 cows and the presence of pigs were significant factors associated with the seropositivity (herd size: OD = 2.8; P=0.02; presence of pigs: OD = 2.5; P = 0.04). Other significant variables associated to the infection, analysed by Chi-Square were the presence of seropositivity cows with the herd that were repeat breeders and birth of weak calves (P < 0.05).