Bovis ISSN 2398-2993

Cryptosporidium parvum

Contributor(s): Ash Phipps , Andrew Forbes

Introduction

Classification

Taxonomy

  • Phylum: Apicomplexa.
  • Class: Conoidasida.
  • Subclass: Coccidasida.
  • Order: Euccidiorida.
  • Family: Cryptosporididae.
  • Genus: Cryptosporidium.
  • Species: C. parvum.
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Clinical Effects

Epidemiology

Habitat

  • Cryptosporidium parvum infects most species of animal, the predilection site being epithelial cells of the posterior small intestine but occasionally also epithelial cells throughout the gastrointestinal tract and in the respiratory tract.
  • Parasites are intracellular, but extracytoplasmic, lying in a parasitophorous vacuole on the brush border of the villi.
  • Oocysts in the environment (especially water sources).

Lifecycle

  • Oocyst - releases sporozoites.
  • Sporozoites - (infective stage) ingested and infect host enterocyte cells.
  • Trophozoite.
  • Schizonts.
  • Merozoites.
  • Gametocytes.
  • Zygote (formed by micro- and macrogamates).
  • Thin-walled oocysts - sporulated and capable of autoinfection.
  • Thick-walled oocysts – sporulated and exit host.

Transmission

  • Fecal-oral route.
  • Infection may be acquired by direct contact with and ingestion of these.
  • The highest numbers of oocysts are excreted in the feces of young.
  • Autoinfection: thin-walled oocysts produced in the intestine can excyst in the intestine so the sporozoites initiate autoinfection in the same individual. First generation schizogony produces merozoites that can re-initiate first generation schizogony and so autoinfect the same individual.

Pathological effects

  • Protective immunity and decreased susceptibility to infection with age do develop.
  • Immaturity of the immune system allows heavy infection to develop.
  • There is loss of microvilli, villous atrophy, villous fusion and crypt hyperplasia with replacement of the epithelium by flattened cells. This occurs particularly in the ileum and results in maldigestion and malabsorption .
  • Inflammatory cell infiltration, particularly neutrophils and monocytes, and edema are apparent in the lamina propria.
  • Hypersecretion of fluid means the intestine becomes filled with gas and a yellow, watery fluid.
  • In these severely affected cases, there is profuse watery (+/- blood present) diarrhea (often with tenesmus), dehydration, anorexia and weight loss.
  • Deaths result from the dehydration, acid-base abnormalities or secondary bacterial infections if left untreated.

Other Host Effects

  • Obligate, intracellular parasite lying within a parasitophorous vacuole.

Control

Control via animal

  • No specific treatment for affected animals. Supportive therapies include:
  • Isolate sick calves or the pen in which the sick calves were in.

Control via chemotherapies

  • No effective treatment has been identified.
  • As a preventative halofuginone lactate [Halofuginone lactate] can be administered orally for the first 7 days of life to reduce the severity of disease.  
This does not prevent infection.
  • Oocyst are susceptible to ammonia hydroxide, hydrogen peroxide, chlorine dioxide and formalin.

Control via environment

  • Clean calving environment.
  • Clean calf rearing environment.

Vaccination

  • No vaccination is currently available.

Other countermeasures

  • Ensure good hygienic practices are carried out in the calf pens; clean the bedding regularly, minimize contact between sick and healthy calves, feed sick calves last and have separate feeding utensils and thoroughly clean all feeding equipment.

Diagnosis

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Borowski H, Thompson R C A, Armstrong T & Clode P L (2010) Morphological characterization of Cryptosporidium parvum life-cycle stages in an in vitro model system. Parasitology 137 (1), 13-26 PubMed.
  • Villacorta I, Peeters J E, Vanopdenbosch E, Ares-Mazas E & Theys H (1991) Efficacy of halofuginone lactate against Cryptosporidium parvum in calves. Antimicrobial agents and chemotherapy. 35 (2), 283-287 VetMedResource.

Other sources of information

  • Barr S & Mulcahy G (2017) Felis: Cryptosporidium parvum. Vetlexicon Felis. [online]. Website: www.vetstream.com. Last accessed 28th January 2018.
  • Parkinson T J, Vermunt J J & Malmo J (2010) Diseases of cattle in Australasia: a comprehensive textbook. New Zealand veterinary association foundation for continuing education. pp 644-645.
  • Anderson D E & Rings M (2008) Current veterinary therapy: food animal practice. Elsevier Health Sciences. pp 71.
  • Foreyt W (2001) Veterinary parasitology reference manual. 5th edn. Blackwell publishing company. pp 92-93.
  • Blood D C, Gay C C, Radostits O M & Hinchcliff K W (2000) Veterinary medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses. WB saunders company limited. pp 1311-1314.
  • Urquhart G, Armour A, Duncan J, Dunn A & Jennings F (1996) Veterinary parasitology. 2nd edn. Blackwell publishing company. pp 233-234.

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