Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2000
Publication Date: N/A
Citation: Interpretive Summary: Sarcocystis neurona is a single-celled parasite that causes a neurological syndrome in horses called equine protozoal myeloencephalitis (EPM). The disease has not been experimentally induced in horses. A horse model of EPM is needed to test the efficacy of drugs and potential vaccines. Scientists at the Beltsville Agricultural Research Center and the Auburn University inoculated Sarcocystis neurona parasites directly in the spinal cord of 5 horses. The horses developed antibodies to S. neurona in the blood as well as in the cerebrospinal fluid but did not develop clinical disease. These results will be of interest to pathologists, parasitologists and biologists.
Technical Abstract: Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. A horse model of EPM is needed to test the efficacy of chemotherapeutic agents and potential vaccines. Five horses that were negative for antibodies to S. neurona in their serum and cerebrospinal fluid (CSF) were injected in the subarachnoid space with living merozoites of the SN2 strain of S. neurona. None of the horses died or developed clinical disease over a 132 day observation period. All 5 horses developed antibodies to S. neurona in their CSF and serum 3 to 4 weeks after injection. Two of the horses were examined at necropsy and no parasite induced lesions were observed in their tissues and no parasites were recovered from portions of their spinal cords inoculated on to cell cultures. Results of this study demonstrate that merozoites of the SN2 strain of S. neurona will induce seroconversion but not clinical infection when inoculated directly in to the CSF of nonimmune horses.