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Giardia infection

Giardia; G. duodenalis;  G. intestinalis; Traveler's diarrhea - giardiasis

Giardia, or giardiasis, is a parasitic infection of the small intestine. A tiny parasite called Giardia lamblia causes it.

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Digestive system
Giardiasis
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Causes

The giardia parasite lives in soil, food, and water. It may also be found on surfaces that have come into contact with animal or human waste.

You may become infected if you:

Travelers are at risk for giardiasis throughout the world. Campers and hikers are at risk if they drink untreated water from streams and lakes.

Symptoms

The time between becoming infected and symptoms is 7 to 14 days.

Diarrhea is the main symptom. Other symptoms include:

Some people who have had a giardia infection for a long time continue having symptoms, even after the infection is gone.

Exams and Tests

Tests that may be done include:

Treatment

If there are no symptoms or only mild symptoms, no treatment may be needed. Some infections go away on their own within a few weeks.

Medicines may be used for:

Antibiotic treatment is successful for most people. These include tinidazole, nitazoxanide or metronidazole. A change in the type of antibiotic will be tried if symptoms do not go away. Side effects from some of the medicines used to treat giardia are:

In most pregnant women, treatment should not start until after delivery. Some drugs used to treat the infection can be harmful to the unborn baby.

Possible Complications

These complications can occur:

When to Contact a Medical Professional

Call your health care provider if:

Prevention

Purify all stream, pond, river, lake, or well water before drinking it. Use methods such as boiling, filtration, or iodine treatment.

Workers in daycare centers or institutions should use good handwashing and hygiene techniques when going from child to child or person to person.

Safer sexual practices may decrease the risk for getting or spreading giardiasis. People practicing anal sex should be especially careful.

Peel or wash fresh fruits and vegetables before eating them.

Related Information

Dehydration
Malabsorption
Weight loss - unintentional
Diarrhea - what to ask your health care provider - adult
Diarrhea - what to ask your doctor - child

References

DuPont HL. Approach to the patient with suspected enteric infection. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 283.

Haines CF, Sears CL. Infectious enteritis and proctocolitis. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 110.

Nash TE, Hill DR. Giardiasis. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 351.

Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 140.

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Review Date: 2/24/2018  

Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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