Comparative study of two serological tests for detection of anti-Theileria equi antibodies in horses

Abstract

Theileria equi is the causative agent of worldwide piroplasmosis, an important tick-borne disease of equids associated to a lifetime carrier state of infected horses. Since rapid, accessible and reliable tests have been posted as a challenge for clinicians, the aim of the present study was to verify the agreement between an in-house immunofluorescence antibody assay (IFA) and a commercial competitive inhibition enzyme-linked immunosorbent assay (cELISA) in a population of 198 carthorses from Southern Brazil. The horse seroreactivity for T. equi revealed 152/198 (76.8%) positive samples by IFA and 155/198 (78.3%) by cELISA. Using cELISA as gold standard, IFA has shown a sensitivity of 91.6% (95% CI = 86.18-95.03%) and specificity of 76.7% (95% CI = 62.26-86.85%), with a substantial degree of agreement (k = 0.8445). In conclusion, the in-house IFA may be used as a screening test for diagnosis of equine piroplasmosis.