Giardia (gee-ARE-dee-uh)
What is Giardia?

Giardia is a germ that causes diarrhea. Giardia is found in infected people’s stool and cannot be seen by the naked eye. This germ is protected by an outer shell that allows it to survive outside the body and in the environment for long periods of time.
Why should I be concerned about Giardia?
During the past two decades, Giardia has become recognized as one of the most common causes of waterborne illness (drinking water and recreational water) in the United States. The germ is found in every part of the United States and the world.
How is Giardia spread at aquatic facilities?
Giardia is not spread by contact with blood. Giardia can be spread:
- By swallowing recreational water contaminated with Giardia. Recreational water is water from swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals.
- Accidentally swallowing something that has come in contact with the stool of a person or animal infected with Giardia.
- By swallowing Giardia picked up from surfaces (such as lounge chairs, picnic tables, bathroom fixtures, changing tables) contaminated with stool from an infected person.
How do I protect myself and my family?
Healthy Swimming behaviors are needed to protect you and your kids from recreational water illnesses (RWIs) and will help stop germs from getting in the pool in the first place.
Here are six steps that promote Healthy Swimming:
Three Steps for All Swimmers
Keep germs from causing RWIs:
- Please don't swim when you have diarrhea. You can spread germs in the water and make other people sick.
- Please don't swallow the pool water. Avoid getting water in your mouth.
- Please practice good hygiene. Shower with soap before swimming and wash your hands after using the toilet or changing diapers. Germs on your body end up in the water.
Three Steps for Parents of Young Kids
Keep germs out of the pool:
- Please take your kids on bathroom breaks or check diapers often. Waiting to hear "I have to go" may mean that it's too late.
- Please change diapers in a bathroom or a diaper-changing area and not at poolside. Germs can spread in and around the pool.
- Please wash your child thoroughly (especially the rear end) with soap and water before they go swimming. Invisible amounts of fecal matter can end up in the pool.
Division of Parasitic Diseases
National Center for Zoonotic, Vector-borne, and Enteric Diseases
Page last modified: May 15, 2009
