Prevalence and risk factors for bovine brucellosis in the state of Pará, Amazon region of Brazil.

Bovine brucellosis is an endemic zoonosis in Brazil and the target of a national program for its control and eradication. A sectional study was carried out in Pará to define the best strategies for combating the disease. The state was divided into 3 regions; in each, a random sample of farms was drawn; within each property, blood was collected from a pre-established number of animals to characterize the property as brucellosis infected or free. The animals were screened using the Buffered Acidified Antigen test, followed by retesting of positives using the Complement Fixation test. A total of 9170 animals from 976 farms were tested. The prevalence of infected farms and seropositive animals for the state were 25.7% [CI 95%: 22.9-29.0] and 5.6% [CI 95%: 4.1-8.0], with heterogeneities among regions. Within regions, there was no difference between the prevalence of infected farms for dairy, beef, or mixed ones. The introduction of animals was identified as a risk factor for the disease (OR = 1.38 [CI 95%: 1.01-1.89]). To mitigate the risk of exposure of animals and humans to brucellosis, the state should implement an efficient vaccination program with B19 and RB51 vaccines, seeking to reduce the prevalence of infected farms and animals at low cost. Additionally, to reduce the speed at which the disease spreads, educational actions should be implemented so that cattle and buffalo farmers test animals for brucellosis before introducing them onto their farms.