Giardiasis is an infection of the small intestine caused by a tiny parasite (protozoa) called Giardia lamblia.
The 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.
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.
Tests that may be done include:
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:
Treatment is successful for most people. A change in antibiotic therapy will be tried if symptoms do not go away. Side effects from some of the medications used to treat this condition include:
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.
Call your health care provider if:
Purify all stream, pond, river, lake, or well water before drinking it. Use methods such as boiling, filtration, or iodine treatment.
Workers in day care centers or institutions should use good handwashing and hygiene techniques when going from child to child or patient to patient.
Safer sexual practices may decrease the risk of getting or spreading giardiasis. People practicing anal sex should be especially careful.
Peel or wash fresh fruits and vegetables before eating them.
Giardia; G. duodenalis;G. intestinalis; Traveler's diarrhea - giardiasis
DuPont HL. Approach to the patient with suspected enteric infection. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsever Saunders; 2011:chap 291.
Giannella RA. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 107.
Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsever Saunders; 2011:chap 142.
Updated 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, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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