Giardiasis

Overview

Definition

Giardiasis is a common infection of the intestines. It is found all around the world.

The Intestines
The Intestines
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Causes

Giardiasis is caused by a parasite. It can easily pass into humans after:

  • Eating food or drinking water that has parasite
  • Swimming in water that has the parasite
  • Contact with a person's hands contaminated by human or animal stool
  • Oral to anal contact during sex

Risk Factors

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

SymptomsandDiagnosis

Symptoms

Some people do not have signs of illness. Others may have:

  • Watery diarrhea
  • Loose, greasy, foul-smelling stools
  • Belly pain or cramps
  • Bloating
  • Gas
  • Nausea or vomiting
  • Weight loss
  • Rarely:
    • Mild fever
    • Hives or other rash
    • Swelling of eyes or joints

The infection can pass to others even if symptoms are not present.

Diagnosis

The doctor will ask about your symptoms. They will ask about housing, health and travel history. The answers and a physical exam may point to an infection. The doctor will often test a sample of your stool to confirm giardiasis.

Others in your home will also need testing.

Treatments

Treatment

Medicines will treat the infection.

Prevention

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

When camping:

  • 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.

RESOURCES

Centers for Disease Control and Prevention https://www.cdc.gov 

IDSA—Infectious Diseases Society of America http://www.idsociety.org 

CANADIAN RESOURCES

Canadian Public Health Association https://www.cpha.ca 

Health Canada https://www.canada.ca 

References

Giardiasis. EBSCO DynaMed Plus website. Available at:  http://www.dynamed.com/topics/dmp~AN~T113949/Giardiasis  . Updated June 4, 2018. Accessed September 26, 2019.

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.