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Bureau of Disease Control

Facts about Giardiasis

What is Giardiasis?

Giardiasis (GEE-are-DYE-uh-sis) is a diarrheal illness caused by Giardia intetinalis, a parasite that lives in the intestine of people and animals. During the past 20 years, Giardia has become recognized as one of the most common causes of waterborne disease (drinking and recreational) in humans in the United States. The parasite is found in every region of the United States and throughout the world.

What are the symptoms?

Symptoms include diarrhea, loose or watery stool, stomach cramps, and upset stomach. These symptoms may lead to weight loss and dehydration. Symptoms generally begin 1-2 weeks after being infected. In otherwise healthy persons, symptoms may last 2-6 weeks. Occasionally, symptoms last longer. Some people have no symptoms.

How is Giardiasis treated?

Several prescription drugs are available to treat Giardia, so be sure to contact your doctor. Although Giardia can infect all people, young children and pregnant women may be more susceptible to the dehydration resulting from diarrhea and should drink plenty of fluids while ill.

How do people catch this disease?

Giardia live in the intestine of infected humans or animals. You can become infected after accidentally swallowing the parasite. Giardia may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Giardiasis is not spread by contact with blood. Giardiasis can be spread:

  • By putting something in your mouth or accidentally swallowing something that has come in contact with the stool of a person or animal infected with Giardia.
  • By swallowing recreational water contaminated with Giardia. Recreational water is water in swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals.
  • By eating uncooked or undercooked food contaminated with Giardia. Wash with uncontaminated water all vegetables and fruits you plan to eat raw.
  • By accidentally swallowing the parasite picked up from surfaces (such as toys, bathroom fixtures, changing tables, diaper pails) contaminated with stool from an infected person.

What can be done to stop the spread of this disease?

Washing your hands with soap and water after using the toilet, changing diapers, and before eating or preparing food is the best way to stop the spread of Giardia.

Avoid water that might be contaminated. Avoid swallowing recreational water. Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds, and streams. Avoid using ice or drinking untreated water when traveling in countries where the water supply might be unsafe.

Avoid swimming in recreational water (pools, hot tubs, lakes or rivers, the ocean, etc.) if you have Giardia, and for at least 2 weeks after diarrhea stops. You can pass Giardia in your stool and contaminate water for several weeks after your symptoms have ended.

To decrease the risk, avoid fecal exposure during sex.

Avoid food that might be contaminated. Wash and/or peel all raw vegetables and fruits before eating.

Use uncontaminated water to wash all food that is to be eaten raw. Avoid eating uncooked foods when traveling in countries with minimal water treatment and sanitation systems.