ABSTRACT Leptospirosis affects several animal species, including man. This study aimed to evaluate the prevalence of Leptospira spp. and to identify factors associated with the risk of Leptospira spp. in dairy cattle in the municipality of Ji-Paraná, RO, Brazil, sampled by rural sector, from September 2012 to November 2013. Blood samples from 627 dairy cows were randomly collected from 63 farms belonging to six rural sectors. Leptospirosis was diagnosed by the microscopic serum agglutination technique. Of the 627 animals tested, 255 had anti-Leptospira antibodies (40.48%, 95% CI: 36.64-44.31) and 57 of the 63 studied dairy farms (90.5%, 95% CI: 83.23-97.72) had at least one reactive animal. The results indicate that serovar Hardjo had the highest (12.38%. 95% CI: 10.03-15.18) followed by serovars Shermani, Wolffi, Hebdomadis and Canicola occurrence in dairy cows. Additionally, infection was also associated with abortion occurrences in cows of 36 farms (57.14%) and the presence of dogs roaming free with access to pasture, water and cattle in 47 farms (74.60%). Therefore, free-roaming animals are considered a predisposing factor, highlighting the need for adopting prophylactic measures while raising the awareness from rural producers about the importance and the economic losses that leptospirosis may cause.

PREVALENCE OF BRUCELLOSIS IN DAIRY CATTLE AND TRANSMISSION AMONG HUMAN BEINGS. Brucellosis is an infectious disease which attacks human beings and animals. Its etiologic agent is a bacterium of the genus Brucella. Aiming to study the prevalence of brucellosis in animals and humans, and risk factors associated to the transmission among rural families, a random sample of 68 dairy farms in the municipality of Araputanga, MT, were selected. In these farms 189 blood samples from residents were obtained, as well as 2,374 blood samples from lactating cows, for the detection of B. abortus antibodies. A questionaire was applied to identify risk factors for brucellosis. Five people (2.6%) and 140 cows (5.9%) reacted positively to the tests for the diagnosis of brucellosis. In 64.6% of the properties the animals had not been vaccinated and 86.6 % didn't perform tests for brucellosis in the herd; abortions occurred in 47.0% of the farms; and in 62.1% of them non- pasteurised and non-boiled milk was consumed. With respect to the seropositive persons, 80% were male, all were 20 years old or more; on 80% of the farms they didn't boil or pasteurise the milk for consumption; in all the farms there were seropositive cows and in 80% of them abortions were reported. The authors concluded that the use of non-boiled milk or dairy products, the presence of seropositive animals, the lack of vaccination of the females against brucellosis and the occurrence of abortions were the main risk factors associated with the transmission of brucellosis to the residents on the farms.