Giardiasis (patient information)

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Giardiasis
Overview
What are the symptoms?
What are the causes?
Who is at highest risk?
When to seek urgent medical care?
Diagnosis
Treatment options
Where to find medical care for Giardiasis?
What to expect (Outlook/Prognosis)?
Possible complications
Prevention
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor-in-Chief: Cassandra Abueg, M.P.H [2]

Overview

Giardiasis is a diarrheal disease caused by the microscopic parasite Giardia. A parasite is an organism that feeds off of another to survive. Once a person or animal (for example, cats, dogs, cattle, deer, and beavers) has been infected with Giardia, the parasite lives in the intestines and is passed in feces(poop). Once outside the body, Giardia can sometimes survive for weeks or months. Giardia can be found within every region of the U.S. and around the world.

What are the symptoms?

Giardia infection can cause a variety of intestinal symptoms, which include:

• Dehydration
• Diarrhea
• Gas or flatulence
• Greasy stool that can float
• Headache
• Loss of appetite
• Low-grade fever
• Stomach or abdominal cramps
• Swollen or distended abdomen
• Upset stomach or nausea
• Vomiting

These symptoms may also lead to weight loss. Some people with Giardia infection have no symptoms at all. The time between infection and developing symptoms is 7 - 14 days.

What are the causes?

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

It can be contracted by drinking water from lakes or streams where water-dwelling animals such as beavers and muskrats, or domestic animals such as sheep, have caused contamination. It is also spread by direct person-to-person contact, which has caused outbreaks in institutions such as day care centers.

Anything that comes into contact with feces (poop) from infected humans or animals can become contaminated with the Giardia parasite. People become infected when they swallow the parasite. It is not possible to become infected through contact with blood.

Who is at highest risk?

Though giardiasis is commonly thought of as a camping or backpacking-related disease and is sometimes called "Beaver Fever," anyone can get giardiasis. People more likely to become infected include:

• Children in child care settings, especially diaper-aged children
• Close contacts (for example, people living in the same household) or people who care for those sick with giardiasis
• People who drink water or use ice made from places where Giardia may live (for example, untreated or improperly treated water from lakes, streams, or wells)
• Backpackers, hikers, and campers who drink unsafe water or who do not practice good hygiene (for example, proper handwashing)
• People who swallow water while swimming and playing in recreational water where Giardia may live, especially in lakes, rivers, springs, ponds, and streams
• International travelers
• People exposed to human feces (poop) through sexual contact

Diagnosis

Your health care provider will ask you to submit stool (poop) samples to see if you are infected. Because testing for giardiasis can be difficult, you may be asked to submit several stool specimens collected over several days.

Tests that may be done include:

• Enteroscopy
• Stool antigen test to check for Giardia
• Stool ova and parasites exam
• String test (rarely performed)

This disease may also affect the results of the following tests:

• D-xylose absorption
• Small bowel tissue biopsy
• Smear of duodenal aspirated fluid

Treatment options

Some infections go away on their own. Anti-infective medicines may be used. Cure rates are generally greater than 80%. Drug resistance may be a factor in treatment failures, sometimes requiring a change in antibiotic therapy.

Although the Giardia parasite can infect all people, infants and pregnant women may be more likely to experience dehydration from the diarrhea caused by giardiasis. To prevent dehydration, infants and pregnant women should drink a lot of fluids while ill. Dehydration can be life threatening for infants, so it is especially important that parents talk to their health care providers about treatment options for their infants.

What to expect (Outlook/Prognosis)

It is common for the infection to go away on its own. Persistent infections have been reported and need further antibiotic treatment. Some people who have had Giardia infections for a long time continue having symptoms even after the infection has gone. In otherwise healthy people, symptoms of giardiasis may last 2 to 6 weeks. Occasionally, symptoms last longer. Medications can help decrease the amount of time symptoms last.

Possible complications

• Dehydration
• Malabsorption (inadequate absorption of nutrients from the intestinal tract)
• Weight loss

Prevention

To prevent and control infection with the Giardia parasite, it is important to:

• Practice good handwashing and hygiene
• Avoid water (drinking or recreational) that may be contaminated
• Avoid eating food that may be contaminated
• Safe sexual practices, especially regarding anal sex, may decrease the risk of contracting or spreading giardiasis

References

• http://www.cdc.gov/parasites/giardia/gen_info/faqs.html
• http://www.nlm.nih.gov/medlineplus/ency/article/000288.htm