Disease Fact Sheet Series:

What is giardiasis?

Giardiasis is an intestinal illness caused by a microscopic parasite called Giardia lamblia. It is a very commonly reported cause of diarrheal illness in Wisconsin with an average of 1200-1300 cases reported in Wisconsin each year. Cases may occur sporadically or in outbreaks.

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 (lakes, rivers, streams, etc).

How is this parasite spread?

The giardia parasite is passed in the feces (stool) of an infected person or animal and may contaminate water or food. It can also be spread by direct or indirect contact with fecal material from an infected person or animal. This may occur in day care centers or in settings where handwashing practices are poor.

What are the symptoms of giardiasis?

Many people with giardiasis do not experience any symptoms. Those who become ill have symptoms that include mild to severe diarrhea, increased flatulence, abdominal cramps, weight loss and bloating. Fever is rarely present.

How soon do symptoms appear?

The symptoms may appear from 3 to 25 days after exposure but usually within 7-10 days.

How long can an infected person carry Giardia?

The carrier stage generally lasts from a few weeks to months. Treatment with specific antibiotics may shorten the carrier stage.

Should an infected person be excluded from work or school?

People with active diarrhea need to be excluded from settings where they may spread the illness such as school, day care centers or other group activities, until the diarrhea stops. In addition, some local health departments may require follow-up stool testing to confirm that the person can no longer spread the illness.

What is the treatment for giardiasis?

Specific antibiotics are often prescribed by doctors to treat giardiasis. However, some individuals may recover on their own without medication.

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

Three important preventive measures are:

• Wash hands thoroughly after toilet visits.

• Carefully dispose of sewage and disposable diaper wastes so as not to contaminate surface or groundwater.
• Avoid consuming improperly treated water. Emergency water supplies are best boiled or treated with hypochlorite or iodine (2 to 4 drops of household bleach or 0.5 ml of 2% tincture of iodine per quart for 20 minutes, or longer if the water is cold or turbid.)

  For more information, contact your
  Local Public Health Department

  Back to Communicable Disease Fact Sheet Series Index Page

  PDF: The free Acrobat Reader^® software is needed to view and print portable document format (PDF) files.  Learn more

  Last Revised: June 21, 2011