Serologic prevalence of Sarcocystis neurona, Toxoplasma gondii, and Neospora caninum in houses in Brazil

Objective-To determine serologic prevalence of Sarcocystis neurons, Toxopla sma gondii, and Neospora caninum in horses in Brazil. Design-Prevalence survey. Animals-101 Thoroughbreds in Brazil. Procedure-Blood samples were obtained from horses and tested for serum anti bodies against S neurona by use of an immunoblot procedure with culture-der ived S neurona merozoites as antigen, and for serum antibodies against T go ndii and N caninum by use of a modified agglutination test with formalin-pr eserved tachyzoites and mercaptoethanol. Results-Antibodies against S neurona and T gondii were detected in 36 and 1 6 of 101 horses, respectively. Cross-reactivity between antibodies against T gondii and S neurona was not detected. Antibodies against N caninum were not detected in any samples. Conclusions and Clinical Relevance-The high prevalence of antibodies agains t S neurona detected in clinically normal horses emphasizes the importance of examining CSF for antibodies when establishing a diagnosis of equine pro tozoal myeloencephalitis.