Quantitative study of Babesia bovis infection in beef cattle from Sao Paulo state, Brazil

The qPCR technique with SYBR Green was used to estimate the prevalence and level of Babesia bovis infection in beef cattle raised in areas endemic for babesiosis in Brazil, where the animals were continuously exposed to ticks (Rhipicephalus microplus). This is the first report in which qPCR was used to quantify and compare B. bovis DNA in blood of different cattle breeds. Blood samples were collected from 150 animals (75 cows and 75 calves) of the Angus and Nelore breeds and the first generation of an Angus and Nelore cross (AxN). Blood samples from the jugular vein were used for DNA extraction and determination of packed cell volume (PCV), while samples from peripheral veins were used for microscopic parasite detection. Although no piroplasms of B. bovis were found in blood smears, DNA amplification using qPCR revealed that all of the 150 animals, except two calves and one cow, were positive. The number of copies of B. bovis DNA was higher (p < 0.05) in the Angus than in the Nelore and AxN animals, for both calves and cows, but no significant difference was found between the Nelore and AxN groups. These results suggest that a heterotic effect was present, Since the results from the crossbred animals significantly deviated from the mean of the two parental groups, while closely approaching that of the Nelore group. In the Nelore and AxN groups, calves showed higher infection levels than cows (p