title: Sarcocystis neurona n. sp. (Protozoa: Apicomplexa), the etiologic agent of equine protozoal myeloencephalitis.
abstract: Sarcocystis neuronan n. sp. is proposed for the apicomplexan taxon associated with myeloencephalitis in horses. Only asexual stages of this parasite presently are known, and they are found within neuronal cells and leukocytes of the brain and spinal cord. The parasite is located in the host cell cytoplasm, does not have a parasitophorous vacuole, and divides by endopolygeny. Schizonts are 5-35 microns x 5-20 microns and contain 4-40 merozoites arranged in a rosette around a prominent residual body. Merozoites are approximately 4 x 1 micron, have a central nucleus, and lack rhoptries. Schizonts and merozoites react with Sarcocystis cruzi antiserum but not with Caryospora bigenetica. Toxoplasma gondii, Hammondia hammondi, or Neospora caninum antisera in an immunohistochemical test.
authors.affiliation: Livestock and Poultry Sciences Institute, U.S. Department of Agriculture, Beltsville, Maryland 20705.
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
authors.forename: S W
authors.initials: SW
authors.lastname: Davis
authors.forename: C A
authors.initials: CA
authors.lastname: Speer
authors.forename: D D
authors.initials: DD
authors.lastname: Bowman
authors.forename: A
authors.initials: A
authors.lastname: de Lahunta
authors.forename: D E
authors.initials: DE
authors.lastname: Granstrom
authors.forename: M J
authors.initials: MJ
authors.lastname: Topper
authors.forename: A N
authors.initials: AN
authors.lastname: Hamir
authors.forename: J F
authors.initials: JF
authors.lastname: Cummings
authors.forename: M M
authors.initials: MM
authors.lastname: Suter
mesh_terms: D000818:Animals; D004679:Encephalomyelitis / Q000469:parasitology / Q000662:veterinary*; D006734:Horse Diseases / Q000469:parasitology*; D006736:Horses; D008854:Microscopy, Electron; D012522:Sarcocystis / Q000033:anatomy & histology / Q000145:classification* / Q000648:ultrastructure; D012523:Sarcocystosis / Q000469:parasitology / Q000662:veterinary*