An outbreak of babesiosis by Babesia bovis is reported in cattle in the municipality of Santa Vitória do Palmar, considered a Rhipicephalus (Boophilus) microplus free area, in southern Brazil on a farm located at Latitude S 33°05'23" and Longitude WO 53°09'29". In mid November four bulls, four cows and two heifers originated from the municipality of Minas do Leão, RS, a tick endemic area, located at Latitude S 30°12'07" and Longitude WO 52°03'25" were introduced in the herd. Fourty out of 393 adult cattle died. The first bovine died on January 19 and the last on March 2. The diagnosis of babesiosis was performed by the observation of gross lesions and numerous B. bovis organisms in smears of the cerebral cortex. It is suggested that the mean temperatures between 23.2°C and 23.6°C and the relative humidity between 75.3% and 77.5° observed in the period allowed the occurrence of a tick generation, which caused infection by B. bovis in cattle without immunity.
babesiosis; Babesia bovis; tick borne diseases; Rhipicephalus (Boophilus) microplus; epidemiology
