Giardiasis

Description

Giardia is a binucleate, flagellate protozoa that causes enteric infection of dogs and occasionally cats. Transmission is via cysts that are shed in the faeces, and may be direct or indirect. Indirect water-borne transmission is the most common modality and is favoured by cool, moist conditions that prolong cyst survival. Once cysts are ingested, motile trophozoites are released and attach to the cells of the small intestinal mucosa via an adhesive disc.

Diagnosis

Laboratory Tests

• Faecal examination
  • Cysts need to be distinguished from pollen grains and yeasts

• Cyst excretion is intermittent
  • Faeces need to be collected over a 3 day period

• Cysts are heavy
  • Needs higher density flotation fluids
  • Do not float well in saturated sodium chloride solution

• Immunoassays
  • Detect cyst antigen in faeces

Treatment

• Sanitation and hygiene
  • Minimise risk of human infection

• Boil (or sterilise through other means) drinking water in regions of the world where drinking water may be contaminated

• Avoid uncooked foodstuffs
  • Contaminated by washing

References

• Drug Treatments
  • Metronidazole
    • Flagyl, Torgyl
  • Fenbendazole
    • Panacur

• Vaccination
  • Killed trophozoites
  • Available in the USA for cats and dogs
  • Decreases the excretion and viability of cysts
  • Decreases environmental pressure