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The Journal of parasitology2001; 86(6); 1276-1280; doi: 10.1645/0022-3395(2000)086[1276:COTLCO]2.0.CO;2

Completion of the life cycle of Sarcocystis neurona.

Abstract: Sarcocystis neurona is the most important cause of a neurologic disease in horses, equine protozoal myeloencephalitis (EPM). The complete life cycle of S. neurona, including the description of sarcocysts and intermediate hosts, has not been completed until now. Opossums (Didelphis spp.) are definitive hosts, and horses and other mammals are aberrant hosts. In the present study, laboratory-raised domestic cats (Felis domesticus) were fed sporocysts from the intestine of a naturally infected opossum (Didelphis virginiana). Microscopic sarcocysts, with a maximum size of 700 x 50 microm, developed in the muscles of the cats. The DNA of bradyzoites released from sarcocysts was confirmed as S. neurona. Laboratory-raised opossums (D. virginiana) fed cat muscles containing the sarcocysts shed sporocysts in their feces. The sporocysts were approximately 10(-12) x 6.5-8.0 microm in size. Gamma interferon knockout mice fed sporocysts from experimentally infected opossums developed clinical sarcocystosis, and S. neurona was identified in their tissues using S. neurona-specific polyclonal rabbit serum. Two seronegative ponies fed sporocysts from an experimentally-infected opossum developed S. neurona-specific antibodies within 14 days.
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Publication Date: 2001-02-24 PubMed ID: 11191904DOI: 10.1645/0022-3395(2000)086[1276:COTLCO]2.0.CO;2Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

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 explores the life cycle of Sarcocystis neurona, a notable neurologic disease-causing parasite in horses, revealing that the cycle includes opossums as definitive hosts and domestic cats as intermediate hosts.

Life Cycle of Sarcocystis neurona

The purpose of this study was to complete the understanding of the life cycle of Sarcocystis neurona, a parasite known to cause a serious neurological illness called equine protozoal myeloencephalitis (EPM) found in horses.

  • The researchers used domestic cats (Felis domesticus) bred in a laboratory for the experiment. Sarcocystis neurona sporocysts, taken from a naturally infected opossum’s (Didelphis virginiana) intestine, were fed to the cats.
  • Sarcocysts microscopic in size (approx. 700 x 50 microm) developed in the cat’s muscles.
  • When bradyzoites (a stage of the parasite) were released from the sarocysts, DNA testing confirmed that these were indeed Sarcocystis neurona.

Role of Opossums and Mice in the Life Cycle

The study further investigates the role of opossums and mice in the parasite’s life cycle.

  • Laboratory-raised opossums were fed muscles from the previously mentioned cats, which contained the sarcocysts. In turn, these opossums started shedding sporocysts in their feces.
  • These sporocysts were measured to be about 10(-12) x 6.5-8.0 microm in size.
  • Gamma interferon knockout mice were then fed these sporocysts. These mice subsequently developed clinical sarcocystosis (a form of the disease), and Sarcocystis neurona was identified in their tissues using a specific polyclonal rabbit serum.

Implication for Horses

The study also takes a look at the implications for horses, which are most significantly affected by this pathogen.

  • Two ponies that did not initially have the parasite were fed sporocysts from the experimentally-infected opossum. Days later, these ponies developed Sarcocystis neurona-specific antibodies, indicating that they too have been infected.
  • As the sporocysts are instead shed in the feces of the intermediate host (opossums), horses may ingest them through contaminated feed or water. This cycle, therefore, presents a transmission mechanism for how horses can acquire the disease.

In conclusion, this research has successfully traced a complete life cycle of the Sarcocystis neurona parasite, identifying definitive and intermediate hosts which may facilitate the transmission of EPM in horses.

Cite This Article

APA
Dubey JP, Saville WJ, Lindsay DS, Stich RW, Stanek JF, Speert CA, Rosenthal BM, Njoku CJ, Kwok OC, Shen SK, Reed SM. (2001). Completion of the life cycle of Sarcocystis neurona. J Parasitol, 86(6), 1276-1280. https://doi.org/10.1645/0022-3395(2000)086[1276:COTLCO]2.0.CO;2

Publication

The Journal of parasitology
ISSN: 0022-3395
NlmUniqueID: 7803124
Country: United States
Language: English
Volume: 86
Issue: 6
Pages: 1276-1280

Researcher Affiliations

Dubey, J P
  • United States Department of Agriculture, Agricultural Research Service, Livestock, and Poultry, Sciences Institute, Beltsville, Maryland 20705-2350, USA.
Saville, W J
    Lindsay, D S
      Stich, R W
        Stanek, J F
          Speert, C A
            Rosenthal, B M
              Njoku, C J
                Kwok, O C
                  Shen, S K
                    Reed, S M

                      MeSH Terms

                      • Animals
                      • Antibodies, Protozoan / blood
                      • Cats
                      • Horses
                      • Life Cycle Stages
                      • Mice
                      • Mice, Knockout
                      • Opossums / parasitology
                      • Parrots
                      • Sarcocystis / growth & development
                      • Sarcocystis / immunology
                      • Sarcocystis / isolation & purification
                      • Sarcocystosis / parasitology

                      Citations

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