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Iowa Department of Health and Human Services



Giardiasis is an illness caused by a microscopic parasite that lives in the intestines of people and animals. Giardia is one of the most common causes of waterborne disease in the United States. The parasite can be found in streams, lakes, wells, and recreational waters.

Giardiasis is reportable to the Iowa Department of Public Health by Iowa Administrative Code 641 IAC 1.


Symptoms include:

  • Watery diarrhea
  • Vomiting
  • Stomach cramps
  • Loss of appetite
  • Weight loss

Symptoms generally begin seven to 10 days after infection, but can range from three to 25 days. Some people have no symptoms. The illness usually lasts about two to six weeks in healthy persons.


Giardia can be found in soil, food, water, or any surfaces that have been contaminated with the feces from infected humans or animals. Infection occurs when you accidentally ingest the parasite. Three common ways for this to happen is by eating contaminated food, drinking contaminated water, or through person-to-person contact.

Risk Factors

Anyone can become infected with Giardia, but children are infected more often than adults. It occurs frequently in hospitals, prisons, or child cares. Persons who travel overseas or who drink untreated water also have a higher risk of giardiasis.


Ways you can prevent giardiasis include:

  • Hand washing after using the bathroom
  • Hand washing after changing diapers
  • Hand washing before food handling or eating
  • Hand washing after contact with farm animals or playing with pets
  • Don’t drink untreated water
  • Avoid swallowing water in rivers and lakes unless you filter it or boil it for 10 minutes at 158 degrees F.


Many people who experience symptoms often get better without treatment. If signs and symptoms persist or become more severe, oral antibiotics can be prescribed.


Giardiasis activity typically peaks in late summer or early fall. In 2021, there were 173 cases reported in Iowa, 5.4 per 100,000 population.

For more detailed information and statistics on all notifiable diseases, please see our current annual report located in the reports section of the CADE homepage.

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