Cerebral babesiosis outbreak in bovines in the State of Rio Grande do Sul, Brazil

An outbreak of cattle mortality due to Babesia bovis infection in the county of Picada Cafe, Rio Grande do Sul, southern Brazil, in April 2007 is described. Twenty eight heifers (50.9%) died, out of a herd of 55 animals, in five days. The disease occurred approximately 20 days after heifers were transferred to this farm. The clinical signs included fever, anemia, aggressiveness, incoordination, petechiae in the mucous membranes and death after 1 to 2 days. The necropsy revealed pale mucous membranes, splenomegaly, enlarged and yellowish liver, congested and edematous gall bladder containing viscous granular bile. The kidneys and urine were dark red. The gray matter of cerebrum and cerebellum had a characteristic cherry-pink color. Hemorrhage was seen in the epicardium and endocardium. The histological findings consisted of hemoglobinuric nephrosis, paracentral hepatic necrosis, bile stasis, spleen congestion. The gray matter of the brain exhibited congestion with erythrocytes parasitized by Babesia bovis, which were also seen in the brain impression smear. The death of 28 heifers in 5 days was attributed to inadequate immunity against the parasite. The application of imidocarb dipropionate in animals presenting the initial stage of the disease and in all other animals of the herd was adopted as preventive treatment and no new cases of the disease happened in the next two months, when they were sent to slaughter.