Giardiasis is more common in places with poor water or sewage treatment. Asia and South America have the highest infection rates. Risk is also higher for people who:
- Live in crowded places with poor sanitation
- Drink untreated water
- Have low stomach acid
- Take stomach acid reducers
- Have oral to anal contact during sex
- Have a weakened immune system
- Are a day care worker or work in a group setting
- Swim in water sources that may be contaminated
Some people do not have signs of illness. Others may have:
- Watery diarrhea
- Loose, greasy, foul-smelling stools
- Belly pain or cramps
- Nausea or vomiting
- Weight loss
- Mild fever
- Hives or other rash
- Swelling of eyes or joints
The infection can pass to others even if symptoms are not present.
To lower your chances of giardiasis:
Wash your hands often and always:
- After use the toilet
- After change a diaper
- Before handle or eat food
- Bring bottled water for drinking, cooking, and brushing teeth.
- Purify untreated water before using. This may mean boil, filter, or sterilize water.
- Wash or peel raw fruits and vegetables before eating.
When traveling overseas:
- Use only bottled water for drinking, cooking, or brushing teeth.
- Only eat food that is well cooked and served steaming hot.
Avoid contact with stool during sex:
- Use a barrier, such as dental dam, during oral-anal sex.
- Wash hands after touching a condom used during anal sex.
- Wash hands after contact with the anal or rectal area.
Treat water in swimming pools as recommended.
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
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Centers for Disease Control and Prevention https://www.cdc.gov
IDSA—Infectious Diseases Society of America http://www.idsociety.org
Canadian Public Health Association https://www.cpha.ca
Health Canada https://www.canada.ca
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Giardiasis. Kids Health—Nemours Foundation website. Available at: https://kidshealth.org/Nemours/en/parents/giardiasis.html. Updated July 2018. Accessed September 26, 2019.
Giardiasis. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/infectious-diseases/intestinal-protozoa-and-microsporidia/giardiasis. Updated October 2018. Accessed September 26, 2019.
Parasites–giardia. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/parasites/giardia. Updated July 22, 2015. Accessed September 26, 2019.
Dental dam use. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/condomeffectiveness/Dental-dam-use.html. Updated August 12, 2016. Accessed September 26, 2019.