A microorganism widely found in nature may be the leading cause of diarrhea lasting more than a week.
What Is/Are Giardia?
Giardia intestinalis is a microscopic parasite that lives in the bowels of many animals, and is passed in feces. It is commonly associated with deer, dogs, beavers, cattle and little children. When it causes diarrhea, the condition is Giardiasis (“JEE-are-DYE-uh-sis”). “Giardia” is a collective noun, so it is plural, but it can be used as a singular noun. “Giardiasis,” the condition is singular. The parasite is sometimes called “Giardia lamblia,” an older name.
The parasite enters the body through the mouth as a microscopic cyst. In the small intestines, cysts mature into trophozoites (see figure), which then multiply into millions of organisms hanging onto the intestinal wall. As they pass down, they revert to cysts and are expelled with feces. Some trophozoites pass, too, but they soon die; cysts can live for months.
Giardia Often Found In Campers, Travelers
To get Giardiasis, an individual usually must have cysts enter the gut via the mouth. (Trophozoites can enter and cause disease also, but trophozoites do not usually live long enough outside the bowel to infect another person.) Among adult humans, people who camp may inadvertently be exposed to contaminated wild animal feces, and ingest cysts by hand to mouth contact. Among children in group settings, if one child has cysts, it is likely that many will soon; the feces-hand-mouth cycle is virtually inevitable in children.
Another risk is unsafe water. Travelers may drink local water that is contaminated. Also, ice can be contaminated, especially in handling. That’s why in many areas travelers’ advice is to drink only bottled water, and avoid ice. Campers may drink untreated or inadequately treated water.
Additionally, Giardia can be picked up by:
- Touching a contaminated surface and inadvertently touching the mouth.
- Swallowing water in a lake or stream contaminated by beavers or other animals.
- Eating uncooked contaminated food.
- Having contact with someone with active disease, or up to a week after, including oral sex
Symptoms begin a week or two after exposure.
Where are Giardia Found?
Giardia are more prevalent in warmer climates and among children.
Diagnosis of Giardiasis
Stool examination by microscope may reveal cysts or trophozoites. However, they are expelled only periodically, so multiple specimens may be necessary. Diagnosis may be aided by antigen testing and immunofluorescence techniques. Other more advanced procedures are available, including PCR.
Treatment of Giardiasis
If you think you might have Giardiasis, contact your health care provider. The course can be shortened with some medications. Many of the medications can be dangerous for pregnant women.
How Did the 55 Year Old Man Get Giardiasis?
The patient had not traveled, nor was he a camper. He didn’t have children in the house. Normally he was careful about hygiene. So it was never known for sure, but the best explanation was he got it from his dog. They lived in the suburbs, where deer often cross the back yard, and other wild animals pass by. The dog loves to consume deer feces, and did have diarrhea a few weeks before the man did.
Fact sheet from the Centers For Disease Control and Prevention
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