Fact Sheet Giardiasis is an intestinal disease caused by a parasite The parasite, called Giardia lamblia , causes people to have diarrhea. Anyone can get giardiasis. Giardia can be shed in the feces for weeks to months, even if the person has no symptoms.
Outbreaks often occur in child care centers.
Feces also can contaminate lakes, reservoirs, and streams, and giardiasis can result when people drink the untreated water. Many people can catch giardiasis or carry the organisms without having any symptoms. It takes 5 days to 4 weeks from exposure to the onset of symptoms Treatment with specific medications can shorten illness. Wash hands after using the bathroom, after handling diapers, and before fixing food or drink. Avoid drinking improperly treated water, for example, when camping or during foreign travel.