Cryptosporidium

Overview

Cryptosporidium is the single genus in the cryptosporidiidae family and contains at least 13 recognised species. These small protozoan parasites are able to infect a wide range of hosts including mammals, birds, reptiles and fish.

Recognition

Cryptosporidium parvum - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine

C. muris - Wikimedia Commons

Cryptosporidium Life Cycle - Alexander J. da Silva, PhD/Melanie Moser (PHIL #3386), 2002

Calf - nabrown RVC

Ruminant Cryptosporidium - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

Cryptosporidium species are extremely small in size

• Parasitises epithelial cells lining the alimentary and respiratory tracts

• Developmental stages confined to the microvillous brush border

• C. parvum most associated with disease in domestic animals and in humans
  • Other species affect birds

• Small oocysts of 4-5μm

Life Cycle

Cryptosporidium mostly has a standard coccidial life cycle with a few exceptions. The oocyte does not contain sporocysts, instead the sporozoites are free within the oocyst. The pre patent period of of cryptosporidium is 1 week, after which sporulated oocysts are shed in the hosts faeces.

Pathogenesis

• Causes outbreaks of diarrhoea in young animals

• Common cause of calf-hood scours
  • Older animals may be asymptomatic carriers
  • Contributes to undifferentiated neonatal calf diarrhoea which is a mixed viral enteritis in calves

• Common infection in AIDS patients

Epidemiology

• Direct faecal-oral infection
  • E.g. School parties visiting farms

• Water-borne infection
  • E.g. contaminated water supply may infect hundreds of people
  • Difficult to locate source

Diagnosis

• Faecal smear
  • Ziehl-Neelson (ZN) stain
  • Oocysts stain red against a blue/green background

• Immunoassays
  • Detect oocysts in faeces

Control

• Isolate/quarantine bought-in calves
  • Treat if signs of diarrhoea present

• Good hygiene, adequate bedding and disinfection of calf pens is important

• Prevention/treatment
  • Halofuginone
    • Halocur or Intervet
    • Oral dosage

Villus Atrophy in Enteritis

• Affects calf, lamb, piglet, kitten.
• Increasingly important as part of the neonatal diarrhoea complex in calves.
• Zoonosis.

Pathology

Gross

• Intestines diffusely reddened, with fluid contents.

Histological

• Tiny parasites on surface of epithelium.
• Villus atrophy and fusion.
• Iinflammation (mainly lymphoid) in crypts and lamina propria.

Cryptosporidia Flashcards