title: Sarcocystis fayeri in skeletal muscle of horses with neuromuscular disease.
abstract: Recent reports of Sarcocystis fayeri-induced toxicity in people consuming horse meat warrant investigation on the prevalence and molecular characterization of Sarcocystis spp. infection in horses. Sarcocysts in skeletal muscle of horses have been commonly regarded as an incidental finding. In this study, we investigated the prevalence of sarcocysts in skeletal muscle of horses with neuromuscular disease. Our findings indicated that S. fayeri infection was common in young mature horses with neuromuscular disease and could be associated with myopathic and neurogenic processes. The number of infected muscles and number of sarcocysts per muscle were significantly higher in diseased than in control horses. S. fayeri was predominantly found in low oxidative highly glycolytic myofibers. This pathogen had a high glycolytic metabolism. Common clinical signs of disease included muscle atrophy, weakness with or without apparent muscle pain, gait deficits, and dysphagia in horses with involvement of the tongue and esophagus. Horses with myositis were lethargic, apparently painful, stiff, and reluctant to move. Similar to humans, sarcocystosis and cardiomyopathy can occur in horses. This study did not establish causality but supported a possible association (8.9% of cases) with disease. The assumption of Sarcocysts spp. being an incidental finding in every case might be inaccurate.
authors.affiliation: Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA. Electronic address: mraleman@ucdavis.edu.
authors.forename: Monica
authors.initials: M
authors.lastname: Aleman
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Shapiro
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sisó
authors.affiliation: The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Diane C
authors.initials: DC
authors.lastname: Williams
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rejmanek
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Aguilar
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Conrad
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D003933:Diagnosis; D004195:Disease Models, Animal; D006734:Horse Diseases / Q000473:pathology; D006736:Horses; D018482:Muscle, Skeletal / Q000378:metabolism / Q000469:parasitology* / Q000473:pathology; D009210:Myofibrils / Q000473:pathology; D009218:Myosins / Q000378:metabolism; D009468:Neuromuscular Diseases / Q000469:parasitology* / Q000473:pathology* / Q000662:veterinary; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D012189:Retrospective Studies; D012522:Sarcocystis / Q000502:physiology*; D012523:Sarcocystosis / Q000150:complications*; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D012337:RNA, Ribosomal, 18S; D013385:Succinate Dehydrogenase; D000251:Adenosine Triphosphatases; D009218:Myosins
keywords: Equine; Muscle; Parasites; Protozoa