* Origin of samples was Eldorado/Japorã, State of Minas Gerais. Ct (cycle threshold) corresponds to the number of cycles required for a given sample to reach the threshold above which it is considered positive. A sample was considered positive when the Ct value was lower than 40, and inconclusive when the Ct value was higher than 40. CPE = cytopathic effect; ND = not determined. Only samples that resulted in CPE were processed for indirect sandwich ELISA.