Cryptosporidium

PARASITES PROTOZOA

Recognition

• Minute protozoan parasite

• Wide host range

• Parasitises epithelial cells lining the epithelial cells lining the ailimentary and respiratory tracts

• Developmental stages confined to the microvillous brish 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 past 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 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-bourne 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 brought-in calves
  • Treat if signs of diarrhoea present

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

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