May also be called: Giardia Intestinalis, Giardia Lamblia, Giardia Duodenalis

Giardiasis (jee-ar-DYE-uh-sis) is an illness of the digestive tract (stomach and intestines). People mostly get it from drinking water that's contaminated with a tiny parasite called Giardia lamblia.

More to Know

Giardia is one of the main causes of diarrhea in the United States. Young kids are more likely to have giardiasis than adults, but anyone can become infected. Most people who are infected with Giardia may have no signs of illness, even though the parasite is living in their intestines.

Giardiasis often starts with watery diarrhea. Kids may also get belly cramps and gas. They might feel sick or throw up. Some kids may have a low-grade fever.

Giardiasis is contagious. It spreads through feces (poop) that might get into food or water, or on hands. Giardiasis can spread to people from infected animals, even a family dog. 

Giardiasis is treated with prescription medicine to kill the parasites.

Keep in Mind

Washing hands well and often can help stop giardiasis from spreading. Kids should wash after playing in lakes, ponds, rivers, streams, aquariums, or "touch tanks." Only drink water that's approved by local health authorities or have well water tested often.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.