Sarcocystis fayeri in skeletal muscle of horses with neuromuscular disease

Monica R Aleman, Karen Shapiro, Silvia Sisó, Diane C. Williams, Daniel Rejmanek, Beatriz Aguilar, Patricia A Conrad

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)85-93
Number of pages9
JournalNeuromuscular Disorders
Issue number1
StatePublished - Jan 1 2016


  • Equine
  • Muscle
  • Parasites
  • Protozoa

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Medicine(all)
  • Neurology
  • Clinical Neurology
  • Genetics(clinical)


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