Morphologic development of an unidentified species of Sarcocystis associated with encephalitis in a gray fox (Urocyon cinereoargenteus)

Authors: Dubey, Jitender; GUPTA, ADITYA - Oak Ridge Institute For Science And Education (ORISE); ARAUJO, LARISSA - Oak Ridge Institute For Science And Education (ORISE); NEUPANE, SARITA - Texas A&M University; PORTER, BRIAN - Texas A&M University

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2024
Publication Date: 3/4/2025
Citation: Dubey, J.P., Gupta, A., Araujo, L., Neupane, S., Porter, B. 2025. Morphologic development of an unidentified species of Sarcocystis associated with encephalitis in a gray fox (Urocyon cinereoargenteus). Journal of Parasitology. 111(2):91-95. https://doi.org/10.1645/24-107.
DOI: https://doi.org/10.1645/24-107

Interpretive Summary: Parasites in the genus Sarcocystis impair livestock wildlife health and can threaten food safety. Such parasites naturally cycle between carnivorous hosts and the herbivores upon which they prey. Therefore, USDA researchers endeavor to understand which of these parasites occur in food animals and seek to illuminate the diversity and relationships among parasites occurring in wildlife. One of these parasites Sarcocystis neurona causes a neurological disease in horses (Equine Protozoal Encephalitis, or EPM), marine mammals and several other species of animals. Here they describe morphologic development of a parasite that caused a neurologic condition in a gray fox and they distinguished it from Sarcocystis neurona. These results will be of interest to veterinarians, pathologists, and wildlife biologists.

Technical Abstract: Morphologic development of unidentified Sarcocystis sp. schizonts associated with encephalitis in a 9-wk-old gray fox (Urocyon cinereoargenteus) from Texas is described. Sarcocystis schizonts were confined to lesions. They were sparsely distributed and their staining affinity for hematoxylin and eosin varied with developmental stages; immature schizonts were deeply stained compared with mature schizonts. Most parasites were extravascular and the host cell was not identified for those that were intracellular. The parasite divided by endopolygeny, in which the nucleus became lobulated but lobes remained connected. Schizonts were up to 30 µm long and contained up to 32 merozoites/nucleus. The merozoites were slender and unlike any known species of Sarcocystis. The schizonts were distinct from Sarcocystis neurona schizonts, which cause encephalitis in many species of animals.