Giardiasis fact sheet

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 and it is estimated that several hundred cases occur in upstate New York each year. Cases may occur sporadically or in clusters or outbreaks. Now that giardiasis must be reported to the Health Department, it is hoped that much more will be learned about the disease.

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. Homosexual males may also be at increased risk of contracting giardiasis.

How is this parasite spread?

The giardia parasite is passed in the feces of an infected person or animal and may contaminate water or food. Person to person transmission may also occur in day care centers or other settings where handwashing practices are poor.

What are the symptoms?

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 five to 25 days after exposure but usually within 10 days.

How long can an infected person carry giardia?

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

Where are the giardia parasites found?

Giardia has been found in infected people (with or without symptoms) and wild and domestic animals. The beaver has gained attention as a potential source of giardia contamination of lakes, reservoirs and streams, but human fecal wastes are probably as important.

Should an infected person be excluded from work or school?

People with active diarrhea who are unable to control their bowel habits (infants, young children, certain handicapped individuals, for example) may need to be excluded from settings such as day care or group activities where they may present a risk to others. After they have been treated and have recovered, they may be permitted to return. In addition, some local health departments may require follow-up stool testing to confirm that the person is no longer contagious. Individuals who are not in high-risk settings may return to their routine activities when they have recovered, provided that they carefully wash their hands after each toilet visit.

What is the treatment for giardiasis?

Antibiotics such as atabrine, metronidazole or furizolidone 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:

• Carefully wash hands thoroughly after toilet visits.
• Carefully dispose of sewage wastes so as not to contaminate surface water or groundwater.
• Avoid consuming improperly treated drinking water.

[Source: New York State Department of Health]