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PARASITES
PROTOZOA



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
  • Minute protozoan parasite
  • Wide host range
  • 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

  • Direct life cycle
    • Only one host
    • Homoxenous
  • 1 week prepatent period
  • Sporulated oocysts passed in faeces
  • Autoinfection can occur
    • Thin walled oocysts
  • Faecal-oral transmission also occurs
    • Thick walled oocysts

Pathogenesis

  • Causes outbreaks of diarrhoea in young animals
  • 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
  • Good hygiene, adequate bedding and disinfection of calf pens is important
  • Prevention/treatment
    • Halofuginone
      • Halocur or Intervet
      • Oral dosage

Cryptosporidium Flashcards