Identificação de bovinos portadores sadios de Babesia bigemina (Smith & Kilborne, 1893) através da técnica de reação em cadeia da polimerase- PCR

Abstract

Bovine babesiose is a disease caused by the hemoprotozoa Babesia bovis and Babesia bigemina that is transmitted by the Boophilus microplus tick. It is responsible for high morbidity and mortality in bovine herds, causing important economic losses for the beef and dairy industry. In the present study the technique of polymerase chain reaction (PCR) was evaluated as method of diagnosis of bovine healthy carrier of Babesia bigemina. The experiment was conducted in the laboratories of Animal Genetics and Hemoparasitology at Embrapa South Livestock (Bagé/RS). Nine sensitive cows, without any previous contact with the hemoparasite, were inoculated with B. bigemina and the clinical infection was confirmed by parasitism detected in the blood smear. Nine months after the experimental infection, the animals no longer presented any clinical sign and blood parasitism, the PCR technique was able to demonstrated that 66% of experimental infected cows remains carriers after the inoculation, the infection was also confirmed by the presence of antibodies anti-B.bigemina by indirect immunofluorescence technique. In order to confirm the sub-clinical infection nine splenectomized calves was subiinoculated with blood from the experimentally infected cows, where 44,4% of this calves showed clinical signs and blood parasitism, confirming the healthy carriers status of experimental infected cows. The results of this study suggested that the polymerase chain reaction technique can be used as diagnosis tool to identify healthy carriers of the B. bigemina.