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

Cristiane Divan Baldani,Rosangela Zacarias Machado,Andrea Cristina Higa Nakaghi

doi:10.1590/s1984-29612010000400007

Abstract

Blood and serum samples from 170 horses raised in the Jaboticabal microregion, São 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 species-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 São Paulo State, Brazil.

Highlights

Theileria equi is a protozoan of the phylum Apicomplexa that is biologically transmitted by ixodid ticks
1 2 3 4 5 6 7 8 9 10 pb Equine piroplasmosis is of great importance due to the international movement of horses, especially for horses that travel to equestrian sport events
The occurrence of T. equi infection in horses of the Jaboticabal microregion was investigated by blood smear identification, indirect fluorescent antibody test (IFAT) and nested polymerase chain reaction (nPCR)

Summary

Introduction

Theileria equi is a protozoan of the phylum Apicomplexa that is biologically transmitted by ixodid ticks. The disease has a worldwide distribution and is endemic in most tropical and subtropical areas as well as in some temperate zones of the world (BRÜNING, 1996; DE WAAL, 1992; SCHEIN, 1988) It has caused important economic losses in the horse industry, being a serious threat to the horse raising industry and international movement of horses (FRIEDHOFF et al, 1990). Despite its high specificity, microscopic examination of blood smears has low sensitivity for the detection of carrier animals (BÖSE et al, 1995). Several studies have showed low sensitivity and specificity of CFT in identifying equine piroplasmosis carriers, and while they rarely give false positive results, it may occasionally result in a negative response in horses with latent infections (WEILAND et al, 1986). ELISA is nowadays an alternative for increased specificity and sensitivity in the detection of acute and latent babesial infections and several procedures of ELISA using recombinant antigen or crude antigen have been standardized (BALDANI et al, 2007; KUMAR et al, 2003; HIRATA et al, 2003; XUAN et al, 2001; KATZ et al, 2000)

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