Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 8, 2001
Publication Date: N/A
Interpretive Summary: Sarcocystis neurona is a single-celled parasite of horses and it causes a fatal disease, equine protozoal myeloencephalitis (EPM) in horses in America. Its complete life cycle is unknown. Opossums are its reservoir hosts and excrete a resistant-stage in their feces. How opossums become infected with the parasite is not fully known. Scientists at the Beltsville Agricultural Research Center and Virginia-Maryland College of Veterinary Medicine, Blacksburg have found antibodies to S. neurona in 58^% of 99 raccoons from several states. Results indicate a widespread exposure of raccoons to S. neurona. These results will be of interest to parasitologists, biologists and horse owners.
Equine protozoal myeloencephalitis (EPM) is the most important protozoal disease of horses in North America and it is cause by Sarcocystis neurona. Natural cases of encephalitis due to S. neurona have been reported in raccoons, Procyon lotor. We examined 99 raccoons for agglutinating antibodies to S. neurona using the S. neurona agglutination test (SAT) employing formalin-fixed merozoites as antigen. Raccoons originated in Florida (N=24, collected in 1999), New Jersey (N=25, collected in 1993), Pennsylvania (N=25, collected in 1999), and Massachusetts (N=25, collected in 1993 and 1994). We found that 58 (58.6%) of the 99 raccoons were positive for antibodies to S. neurona using the SAT; 44 of 99 raccoons (44%) had titer of > 1:500. This prevalence is similar to the reported seroprevalence of 33 to 60% for S. neurona antibodies in horses from the United States using the Western blot test.