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Summary

Giardiasis is an illness caused by a parasite called Giardia intestinalis. It lives in soil, food, and water. It may also be on surfaces that have been contaminated with waste. You can become infected if you swallow the parasite. You can also get it if you're exposed to human feces (poop) through sexual contact.

The risk of getting giardia is higher for travelers to countries where it is common, people in child care settings, and those who drink untreated water.

Diarrhea is the main symptom of giardia infection. Others include:

• Passing gas
• Greasy stools
• Stomach cramps
• Upset stomach or nausea

These symptoms may lead to weight loss and loss of body fluids. Some people have no symptoms at all. Symptoms of infection often last two to six weeks. Stool sample tests can diagnose it. You often need to collect several samples to test. Doctors use several drugs to treat it.

The best way to prevent giardia infection is to practice good hygiene, including frequent hand washing. You should not drink water that may be contaminated. You should also peel or wash fresh fruit and vegetables before eating.

Centers for Disease Control and Prevention

Start Here

• About Giardia (Centers for Disease Control and Prevention)
• Giardia Infection (Giardiasis) (Mayo Foundation for Medical Education and Research) Also in Spanish
• Giardiasis (American Academy of Family Physicians) Also in Spanish

Symptoms

• Symptoms of Giardia Infection (Centers for Disease Control and Prevention)

Diagnosis and Tests

• Diagnosis of Parasitic Diseases (Centers for Disease Control and Prevention)
• Ova and Parasite Test (National Library of Medicine) Also in Spanish
• String test for intestinal parasites (Medical Encyclopedia) Also in Spanish

Prevention and Risk Factors

• Giardia Infection Prevention and Control (Centers for Disease Control and Prevention)

Treatments and Therapies

• Treatment of Giardia Infection (Centers for Disease Control and Prevention)

Related Issues

• About Giardia and Pets (Centers for Disease Control and Prevention)
• Germs That Can Contaminate Tap Water (Centers for Disease Control and Prevention)
• Water Disinfection for Travelers (Centers for Disease Control and Prevention)

Clinical Trials

• ClinicalTrials.gov: Giardiasis (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

• Article: Establishment of an in vitro co-infection model of Cryptosporidium parvum and...
• Article: Prevalence of Nitroimidazole-Refractory Giardiasis Acquired in Different World Regions, Sweden, 2008-2020.
• Article: Global prevalence of Giardia infection in nonhuman mammalian hosts: A systematic...
• Giardia Infections -- see more articles

Find an Expert

• Centers for Disease Control and Prevention Also in Spanish
• National Institute of Allergy and Infectious Diseases

Children

• Giardiasis (For Parents) (Nemours Foundation) Also in Spanish

Patient Handouts

• Giardiasis (Medical Encyclopedia) Also in Spanish
• Stool ova and parasites exam (Medical Encyclopedia) Also in Spanish