Bovis ISSN 2398-2993

Sarcocystis spp

Contributor(s): Ash Phipps , Andrew Forbes

Introduction

Classification

Taxonomy

  • Phylum: Apicomplexa.
  • Class: Conoidasida.
  • Order: Eucoccidiorida.
  • Family: Sarcocystidae.
  • Genus: Sarcocystis.
  • Species: Sarcocystis cruzi, Sarcocystis hirsute, Sarcocystis hominis and Sarcocystis sinensis.

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Clinical Effects

Epidemiology

Habitat

  • Outlined in lifecycle below.

Lifecycle

  • Prepatent period: 9 to 10 days.
  • Definitive hosts: dogs, foxes, cats and man.
  • Intermediate hosts: cattle.
  • Oocysts are defecated on to the pasture by the definitive host.
  • Within the oocyst sporogony occurs to create two sporocysts (each containing 4 sporozoites). The oocyst wall then lyses releasing the sporocysts into the environment.  
  • The intermediate host (cow) then ingests the sporocysts or sporozoites.
  • The sporozoites are then released and gain entry to the vasculature where two cycles of asexual reproduction occurs. The first cycle of asexual reproduction results in the production of meronts and the second cycle of asexual reproduction results in the production of merozoites (from meronts).
  • The merozoites then enter the mononucleate cells and undergo further asexual reproduction (endodyogeny) resulting in the production of more merozoites that develop further down the vascular system (arterioles, capillaries, venules and veins).
  • The merozoites end up located in musculature where the final asexual replication cycle occurs, forming metrocytes. Many metrocytes accumulate forming a sarcocyst.   
  • As the sarcocyst matures, the non-infective metrocytes become brachyzoites that are infective to the definitive host (this process can take 8 weeks or more).  
  • Once the bradyzoites are consumed by definitive host the parasite undergoes sexual reproduction in the gastrointestinal tract to form macro- and microgamonts.
  • Fusion of the macro- and microgamonts result in the formation of a zygote which then matures into an oocyst.

Transmission

  • Ingestion of sporocysts passed in the feces of an infected carnivore.

Pathological effects

  • Usually asymptomatic.
  • However, in some cases severe disease is observed when the second wave of merozoites are released in the vasculature.
  • Clinical signs include; alopecia around the eyes, neck and tail switch, pyrexia, lethargy, salivation Hypersalivation, paresis, lameness, anemia, myositis Clostridial myositis, encephalomyelitis, lymphadenopathy and anorexia. In pregnant cattle it may cause placentitis and abortion.

Control

Control via chemotherapies

  • Seldom carried out in cattle.

Control via environment

  • Control domestic dogs, wild dog and fox populations to reduce the risk of exposure of Sarcocystis spp to cattle.
  • Remove any dog or fox feces from the environment; particularly from the feeding areas of cattle (feed bunks, calf sheds etc).
The above measures may be difficult to achieve on most farms.

Vaccination

  • No current vaccine available to be used in cattle.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Latif B, Vellayan S, Heo C C, Kannan Kutty M, Omar E, Abdullah S & Tappe D (2013) High prevalence of muscular sarcocystosis in cattle and water buffaloes from Selangor, Malaysia. Tropical biomedicine 30 (4), 699-705 PubMed.
  • Vangeel L, Houf K, Geldhof P, De Preter K, Vercruysse J, Ducatelle R & Chiers K (2013) Different Sarcocystis spp. are present in bovine eosinophilic myositis. Vet parasitol 197 (3-4), 543-8 PubMed.
  • Moré G, Basso W, Bacigalupe D, Venturini M C & Venturini L (2008) Diagnosis of Sarcocystis cruzi, Neospora caninum, and Toxoplasma gondii infections in cattle. Parasitol res 102 (4), 671-5 PubMed.
  • Dubey J P & Lindsay D S (2006) Neosporosis, toxoplasmosis, and sarcocystosis in ruminants. Veterinary clinics: food animal practice 22 (3), 645-671 PubMed.
  • Wouda W, Snoep J J & Dubey J P (2006) Eosinophilic myositis due to Sarcocystis hominis in a beef cow. Journal of comparative pathology 135 (4), 249-253 PubMed.
  • Fayer R (2004) Sarcocystis spp. in human infectionsClinical microbiology reviews 17 (4), 894-902 PubMed.
  • Gunning R F, Jones J R, Jeffrey M, Higgins R J & Williamson A G (2000) Sarcocystis encephalomyelitis in cattle. Vet rec 146 (11), 328 VetMedResource.
  • Savini G, Dunsmore J D, Robertson I D & Seneviratna P (1992) The epidemiology of Sarcocystis spp. in cattle of Western Australia. Epidemiology & infection 108 (1), 107-113 PubMed.
  • Freiler P F, Mayhew I G & Pollock R (1979) Bovine sarcocystosis: pathologic features of naturally occurring infection with Sarcocystis cruzi. Am j vet res 40 (5), 651-7.

Other sources of information

  • Bowman D D (2014) Georgis' Parasitology for Veterinarians-E-Book. Elsevier health sciences.  pp 104-105.
  • Rebhun W C, Guard C & Richards C M (1995) Diseases of dairy cattle. Williams and Wilkins. pp 634.

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