Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #315795

Title: Sarcocyst development in raccoons (Procyon lotor) inoculated with different strains of Sarcosytis neurona culture-derived merozoites

item DRYBURGH, ELIZABETH - The Ohio State University
item MARSH, ANTOINETTE - The Ohio State University
item Dubey, Jitender
item HOWE, DAN - University Of Kentucky
item REED, STEVEN - Rood And Riddle Equine Hospital
item BOLTEN, KAREN - The Ohio State University
item PEI, WEI - The Ohio State University
item SAVILLE, WILLIAM - The Ohio State University

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2015
Publication Date: 8/1/2015
Publication URL:
Citation: Dryburgh, E., Marsh, A., Dubey, J.P., Howe, D., Reed, S., Bolten, K., Pei, W., Saville, W. 2015. Sarcocyst development in raccoons (Procyon lotor) inoculated with different strains of Sarcosytis neurona culture-derived merozoites. Journal of Parasitology. 101(4):462-467.

Interpretive Summary: Sarcocystis neurona is a single celled parasite previously misidentified as Toxoplasma gondii. It causes a fatal illness in horses and several other species of animals. The clinical syndrome was called “Equine Protozoal Myeloencephalitis” before ARS researchers in collaboration with scientists from several universities identified, isolated it, and named it Sarcocystis neurona in 1991. The host range for S. neurona keeps expanding and this parasite is now recognized as a major cause of fatal neurological disease in various mammals, including sea otters. The parasite is not yet known to cause neurological disease in human beings, but the public health importance of this infection deserves greater scrutiny, especially in light of the cerebral infections that can occur in immune-compromised people infected with this parasite’s relative, T. gondii. Completion of the life cycle of S. neurona in the laboratory is difficult because of wild hosts involved. In the present paper authors found that they can infect raccoons with culture-derived organisms and produce the encysted stage, the sarcocyst. Thus, overcoming one obstacle. This paper should be of interest to biologists, parasitologists, and veterinarians.

Technical Abstract: Sarcocystis neurona is considered the major etiologic agent of equine protozoal myeloencephalitis (EPM), a neurological disease in horses. Raccoon (Procyon lotor) is considered the most important intermediate host in the life cycle of S. neurona in the USA; S. neurona sarcocysts do mature in raccoon muscles, and raccoon also develop clinical signs simulating EPM. The focus of this study was to determine if sarcocysts would develop in raccoons experimentally inoculated with different host-derived strains of in vitro-cultivated S. neurona merozoites. Four raccoons were inoculated with strains derived from a raccoon,a sea otter,a cat, and a horse. Raccoon tissues were fed to laboratory raised opossums (Didelphis virginiana), the definitive host of S. neurona. Intestinal scraping revealed sporocysts in opossums who received muscle tissue from raccoons inoculated with the raccoon-derived or the sea otter-derived isolates. These results demonstrate that sarcocysts can mature in raccoons inoculated with in vitro-derived S. neurona merozoites. In contrast, the horse and catderived isolates did not produce microscopically- or biologically-detected sarcocysts. Immunoblot analysis revealed both antigenic and antibody differences when testing the inoculated raccoons. Immunohistochemical staining indicated demonstrated differences in staining between the merozoite and sarcocyst stages. The successful infections achieved in this study indicates that the life-cycle can be manipulated in the laboratory without affecting subsequent stage development, thereby allowing further purification of strains and artificial maintenance of the life cycle.