Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


Giardiasis can present as either acute or chronic diarrhea. It usually occurs in patients with exposure to infected water supplies, although person-to-person transmission can occur. Symptoms usually include diarrhea, nausea, abdominal cramps, bloating, flatulence, and foul-smelling stools. Fever is uncommon.


  1. Giardia is the most common parasitic cause of diarrhea in the United States.

  2. Most infections in the United States result from ingestion of contaminated water from streams and lakes but can also be transmitted by foodborne and fecal-oral routes.

  3. Incidence peaks annually during the summer and early fall when people most commonly participate in water sports and camping.

  4. Although usually sporadic, there are occasional outbreaks related to contamination of bodies of water used for recreation and drinking supplies.

  5. Common symptoms

    1. Diarrhea occurs in 96% of cases.

    2. Weight loss is present in 62% of cases.

    3. Abdominal cramps occur in 61% of cases.

    4. Greasy stools are present in 57% of cases.

    5. Belching, flatulence, and foul-smelling stools are commonly reported.

  6. Fever is uncommon.


  1. Enzyme immunoassay has a sensitivity of over 90%.

  2. Sensitivity of microscopic examination of stool for ova is 50–70% for 1 stool sample and 90% for 3 samples.


  1. The treatment of choice for G lamblia infection is oral metronidazole.

  2. If a patient has recurrence or severe disease with Giardia, immunosuppression (including HIV infection or immunoglobulin deficiency) should be suspected.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.