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.
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http://dx.doi.org/10.1645/24-107 | DOI Listing |
J Parasitol
March 2025
Department of Veterinary Pathobiology, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77845.
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.
View Article and Find Full Text PDFInt J Parasitol
February 2025
Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN, USA. Electronic address:
Proteins released by the club-shaped, apically located, specialized secretory organelles called rhoptries play an essential role in host cell invasion and intracellular survival of apicomplexans. Sarcocystis neurona, the apicomplexan responsible for equine protozoal myeloencephalitis (EPM), lacks rhoptries in its asexual developmental stages, viz., merozoites and schizonts.
View Article and Find Full Text PDFJ Vet Diagn Invest
February 2025
Department of Pathology, Microbiology and Immunology, University of California-Davis, Davis, CA, USA.
is an apicomplexan protozoal parasite that was first recognized during a mass mortality event in juvenile grey seals () in the northwest Atlantic Ocean. Since its identification, this parasite has been reported in various pinniped species and has been associated with fatal necrotizing hepatitis. Little is known of the host range of .
View Article and Find Full Text PDFJ Vet Med Sci
August 2024
Laboratory of Veterinary Pathology, Cooperative Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, Tokyo, Japan.
mSphere
June 2024
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky, USA.
Unlabelled: Asexual replication in the apicomplexan involves two main developmental stages: the motile extracellular merozoite and the sessile intracellular schizont. Merozoites invade host cells and transform into schizonts that undergo replication via endopolygeny to form multiple (64) daughter merozoites that are invasive to new host cells. Given that the capabilities of the merozoite vary significantly from the schizont, the patterns of transcript levels throughout the asexual lifecycle were determined and compared in this study.
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