Occurrence of Theileria equi in horses raised in the Jaboticabal microregion, Sao Paulo State, Brazil

Blood and serum samples from 170 horses raised in the Jaboticabal microregion, Sao Paulo State, Brazil, were collected and tested by microscopic examination of blood smears, indirect fluorescent antibody test (IFAT) and nested polymerase chain reaction (nPCR) for Theileria equi infections. The association among the test results was verified by the McNemar test. During the examination of thin blood smears, parasites were detected in six (3.52%) horses. Anti-T. equi antibodies were detected in 100% sera samples, with titers ranging between 1:80 and 1:5120. The nPCR based on the T equi merozoite antigen gene (EMA-1) allowed the visualization of specie-specific amplified product in 108 (63.53%) horses. All six samples judged positive microscopically were also positive for nPCR. Statistical analysis indicated general disagreement (p < 0.0001) between IFAT and nPCR; IFAT and blood smear; and nPCR and blood smear on the detection of parasite carriers. The results of the present study indicate that T equi is widely spread among horses in the Jaboticabal microregion, Northeast region of Sao Paulo State, Brazil.