Alternative Names

Giardia; Traveler’s diarrhea – giardiasis

Definition of Giardiasis

Giardiasis is an infection of the small intestine caused by a microscopic organism (protozoa), .

Causes, incidence, and risk factors

Giardiasis outbreaks can occur in communities in both developed and developing countries where water supplies become contaminated with raw sewage.

Signs and tests

Tests that may be done include:


Some infections go away on their own. Anti-infective medicines may be used.

Expectations (prognosis)

It is common for the infection to go away on its own. However, persistent infections have been reported and need further antibiotic treatment. Some people who have had infections for a long time continue having symptoms even after the infection has gone.


Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; 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. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 5/25/2010

Digestive system
Institutional hygiene
Digestive system organs

ADAM Medical Encyclopedia

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