Giardia can be found in every region of the United States and around the world. In the United States, Giardia infection is the most common intestinal parasitic disease, and it affects more than 1 million people per year. Certain factors can increase your risk of getting sick from Giardia:
- Children are at much higher risk for Giardia infection than adults and have higher infection rates.
- Giardia infection rates tend to rise in late summer in the United States.
- Travelers to areas with poor sanitation are more likely to get infected with Giardia.
How do you get giardiasis and how is it spread?
You can get giardiasis if you swallow the Giardia parasite (germ). Giardia—or stool (poop) from people or animals infected with Giardia—can contaminate anything it contacts. Giardia spreads very easily; even getting tiny amounts of poop in your mouth could make you sick.
Giardiasis can be spread by:
- Swallowing unsafe food or water contaminated with Giardia germs
- Having close contact with someone who has giardiasis, particularly in childcare settings
- Traveling within areas that have poor sanitation
- Exposure to poop through sexual contact from someone who is sick or recently sick with Giardia
- Transferring Giardia parasites picked up from contaminated surfaces (such as bathroom handles, changing tables, diaper pails, or toys) into your mouth
- Having contact with infected animals or animal environments contaminated with poop
Symptoms of giardiasis normally begin 1 to 2 weeks after a person has been infected.
People at Risk
Anyone can become infected with Giardia. However, those at greatest risk are:
- People in childcare settings
- People who are in close contact with someone who has the disease
- Travelers within areas that have poor sanitation
- People who have contact with poop during sexual activity
- Backpackers or campers who drink untreated water from springs, lakes, or rivers
- Swimmers who swallow water from swimming pools, hot tubs, interactive fountains, or untreated recreational water from springs, lakes, or rivers
- People who get their household water from a shallow well
- People with weakened immune systems
- People who have contact with infected animals or animal environments contaminated with poop
The chances of people getting a Giardia infection from dogs or cats are small. The type of Giardia that infects humans is usually not the same type that infects dogs and cats. Learn more about Giardia and pets.