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Veterinary parasitology2001; 95(2-4); 89-131; doi: 10.1016/s0304-4017(00)00384-8

A review of Sarcocystis neurona and equine protozoal myeloencephalitis (EPM).

Abstract: Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in the Americas. The protozoan most commonly associated with EPM is Sarcocystis neurona. The complete life cycle of S. neurona is unknown, including its natural intermediate host that harbors its sarcocyst. Opossums (Didelphis virginiana, Didelphis albiventris) are its definitive hosts. Horses are considered its aberrant hosts because only schizonts and merozoites (no sarcocysts) are found in horses. EPM-like disease occurs in a variety of mammals including cats, mink, raccoons, skunks, Pacific harbor seals, ponies, and Southern sea otters. Cats can act as an experimental intermediate host harboring the sarcocyst stage after ingesting sporocysts. This paper reviews information on the history, structure, life cycle, biology, pathogenesis, induction of disease in animals, clinical signs, diagnosis, pathology, epidemiology, and treatment of EPM caused by S. neurona.
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Publication Date: 2001-02-27 PubMed ID: 11223193DOI: 10.1016/s0304-4017(00)00384-8Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article provides a comprehensive review of Equine protozoal myeloencephalitis (EPM), a neurological disease affecting horses and caused by the protozoan Sarcocystis neurona. The paper covers everything about the disease, from its history and lifecycle to its characteristics, diagnosis, and treatment.

History and Lifecycle of Sarcocystis neurona and EPM

  • The paper delves into the history and the complete lifecycle of Sarcocystis neurona, which ultimately causes EPM in horses. However, it’s vital to note that the complete lifecycle of this protozoan parasite remains undetermined, especially concerning its natural intermediate host.
  • The definitive hosts for this parasite are opossums. Opossums become infected by ingesting the sporocysts present in an infected intermediate host’s tissues. After digestion, the sporocysts release sporozoites, which penetrate the opossum’s intestinal cells, multiplying and eventually forming more sporocysts that are excreted in feces.
  • Horses, which are deemed aberrant hosts, do not typically get infected through the ingestion of sporocysts, but more likely through feeds or water contaminated by opossum feces. Once in the horse’s body, the protozoan migrates to the central nervous system, causing EPM.

Impact of Sarcocystis neurona on other Animals

  • S. neurona doesn’t only impact horses. It can also cause EPM-like disease in several other mammalian species, such as cats, mink, raccoons, skunks, Pacific harbor seals, ponies, and Southern sea otters.
  • Bizarrely, cats can also act as experimental intermediate hosts for the parasite, hosting the sarcocyst stage after ingestion of sporocysts.

Diagnosis, Symptoms, and Treatment of EPM

  • The authors present a comprehensive overview of EPM’s clinical signs and symptoms which primarily manifest as various neurological problems in horses such as imbalance, muscle atrophy, lameness and behavioral changes.
  • The diagnosis of EPM is primarily based on clinical signs, history, and results from diagnostic tests including serological tests, molecular detection methods, analysis of cerebrospinal fluid, and post-mortem examination.
  • The pathology of the disease is also detailed, with the primary pathological change being multifocal non-purulent meningoencephalomyelitis.
  • The research also covers the epidemiology of the disease, shedding light on the distribution and prevalence of this disease.
  • Last, the review delves into various treatment options for EPM, noting that while several drugs are used to treat EPM, their efficacy varies, and certain drugs may contribute to side effects.

Cite This Article

APA
Dubey JP, Lindsay DS, Saville WJ, Reed SM, Granstrom DE, Speer CA. (2001). A review of Sarcocystis neurona and equine protozoal myeloencephalitis (EPM). Vet Parasitol, 95(2-4), 89-131. https://doi.org/10.1016/s0304-4017(00)00384-8

Publication

Veterinary parasitology
ISSN: 0304-4017
NlmUniqueID: 7602745
Country: Netherlands
Language: English
Volume: 95
Issue: 2-4
Pages: 89-131

Researcher Affiliations

Dubey, J P
  • United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Beltsville Agricultural Research Center, MD 20705-2350, USA. jdubey@anri.barc.usda.gov
Lindsay, D S
    Saville, W J
      Reed, S M
        Granstrom, D E
          Speer, C A

            MeSH Terms

            • Animals
            • Antiprotozoal Agents / therapeutic use
            • Cats
            • Encephalomyelitis / drug therapy
            • Encephalomyelitis / parasitology
            • Encephalomyelitis / veterinary
            • Horse Diseases / drug therapy
            • Horse Diseases / parasitology
            • Horses / parasitology
            • Life Cycle Stages
            • Mephitidae / parasitology
            • Mink / parasitology
            • Opossums / parasitology
            • Otters / parasitology
            • Raccoons / parasitology
            • Sarcocystis
            • Sarcocystosis / drug therapy
            • Sarcocystosis / parasitology
            • Sarcocystosis / veterinary
            • Seals, Earless / parasitology

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