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What is giardiasis?

Giardiasis is an intestinal illness caused by a microscopic parasite called Giardia lamblia. It is a fairly common cause of diarrheal illness.

Who gets giardiasis?

Anyone can get giardiasis but it tends to occur more often in people in institutional settings, people in day care centers, foreign travelers and individuals who consume improperly treated surface water (such as streams).

Where are the Giardia parasites found?

Giardia has been found in the feces (stool) of infected people (with or without symptoms) and wild and domestic animals.

How is this parasite spread?

Person-to-person transmission due to poor handwashing practices is probably the main way that Giardia parasites are spread, especially in day care centers and institutions. In addition, feces from an infected person or animal may contaminate water or food.

What are the symptoms of giardiasis?

People exposed to Giardia may experience mild or severe diarrhea, or in some instances no symptoms at all. Fever is rarely present. Occasionally, some will have chronic diarrhea over several weeks or months, with significant weight loss.

How soon do symptoms appear?

The symptoms may appear from 3 to 25 days after exposure but usually within 10 days.

How long can an infected person carry Giardia?

Persons may excrete Giardia in their stools from a few weeks to a few months. Treatment may shorten this carrier stage.

How is the disease diagnosed?

Examination of stools under the microscope is the most common way to diagnose giardiasis. Several stool specimens must be obtained because the number of Giardia parasites found in the stool changes from day to day.

Should an infected person be excluded from work or school?

People with diarrhea need to be excluded from day care, patient care, or foodhandling where they may present a risk to others. Most people may return to work or school when diarrhea stops, provided that they carefully wash their hands after each toilet visit, after diapering and before preparing food. The health department will assess each situation in which the person with giardiasis is a food handler, health care worker, or day care worker or attendee.

What is the treatment for giardiasis?

Specific medicines are often prescribed by doctors to treat giardiasis. Some individuals may recover on their own without medication. Persons with diarrhea should drink plenty of fluids.

What can a person or community do to prevent the spread of giardiasis?

Three important preventive measures are:

  • Carefully wash hands thoroughly after using the toilet and diapering and before and after food preparation.
  • Carefully dispose of sewage wastes so as not to contaminate surface or groundwater.
  • Avoid drinking improperly treated water.

Last Updated: 07-30-2011

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