Contagious: Giardia

Contagion discussion: Giardia lives in the intestine of infected humans or animals. Millions of germs can be released in a bowel movement from an infected human or animal. 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. Giardia is not spread by contact with blood. Giardia 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 food contaminated with Giardia. Thoroughly wash with uncontaminated water all vegetables and fruits you plan to eat raw. See below for information on making water safe.
• By accidentally swallowing Giardia picked up from surfaces (such as toys, bathroom fixtures, changing tables, diaper pails) contaminated with stool from an infected person.

Giardia can be very contagious. Follow these guidelines to avoid spreading Giardia to others.

• Wash your hands with soap and water after using the toilet, changing diapers, and before eating or preparing food.
• 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. This has resulted in outbreaks of Giardia among recreational water users.
• Avoid fecal exposure during sex.

Some common diseases are occasionally foodborne, even though they are usually transmitted by other routes.  These include infections caused by Shigella, hepatitis A, and the parasites Giardia lamblia and Cryptosporidia.  Even strep throats have been transmitted occasionally through food.  ²

People, including babies, with diarrhea caused by Cryptosporidia or other diarrhea- causing microbes, such as Giardia and Salmonella, can infect others while using swimming pools, waterparks, hot tubs, and spas. ³

Footnotes:
1. excerpt from Giardiasis: DPD
2. excerpt from Foodborne Infections General: DBMD
3. excerpt from Microbes in Sickness and in Health - Publications, National Institute of Allergy and Infectious Diseases: NIAID

Last revision: May 27, 2003

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