Parasitic Organism - Giardia lambia

Giardia lamblia

Compiled By: Julie A. Albrecht, Ph.D., Associate Professor

The Organism: Giardia lamblia is a flagellate protozoa (single cell animal). In the stable cyst stage, the organism can be shed in the feces of infected humans. The cyst cannot multiply outside of a living host.

  PDF Fact Sheet

Sources of the organism:

  • Intestinal tracts of infected animals and humans
  • Water

Associated foods:

  • Water
  • Any food handled by an infected food handler

Organism Characteristics:

  • Protozoa which can survive normal water chlorination.

The Disease: Giardiasis results from the consumption of the cyst stage of the Giardia lamblia protozoa.

Symptoms include:

  • Diarrhea
  • Flatulence
  • Bloating

Onset time:

  • 1-4 weeks

Infective Dose:

  • Consuming 1 or more cysts may cause the symptoms of the illness to develop.

Duration of symptoms:

  • Weeks


  • Proper disposal of feces and wastewater treatment.
  • Proper filtration before chlorination of the water supply.
  • Cooking contaminated foods.
  • Boiling suspect water.
  • Use proper hand washing techniques and practice good personal hygiene procedures.