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Giardiasis (gee-are-DYE-a-sis) is a contagious disease caused by a one-celled parasite, Giardia lamblia, which is found in the intestines of many animals. During the past two decades, Giardia infection has become recognized as one of the most common causes of waterborne disease (found in both drinking and recreational water) in the United States. Because the parasite is protected by an outer shell (cyst), it can survive outside the body and in the environment for long periods of time. Concentrations of chlorine used in routine water treatment do not kill Giardia cysts. From 1997-2000, there was an average of 665 cases of giardiasis reported in Indiana every year.
Giardia is passed in the stool, and people become infected by ingesting feces from an infected animal or person (fecal-oral route).
There are several ways to become infected with Giardia:
Giardiasis is more common in children than adults. Large community outbreaks have occurred from drinking treated but unfiltered water. Smaller outbreaks have resulted from contaminated food, person-to-person transmission in day care facilities, and contaminated recreational waters.
Symptoms usually begin within 7-10 days (range of 3-25 days) after exposure and last 2-6 weeks. These symptoms may lead to weight loss and dehydration, but some persons infected may have no symptoms. Infected people may carry Giardia in their bodies for weeks or months without symptoms and unknowingly infect others.
A person having diarrhea lasting more than 24 hours should consult a health care provider. The health care provider may collect several stool samples before the tests are positive for Giardia.
While medications are available for giardiasis, they are not needed if the person does not have diarrhea. Over-the-counter drugs may relieve symptoms but will not get rid of the parasite.
Yes. Health care providers or laboratories must report cases of giardiasis to the local health department (LHD) or the Indiana State Department of Health (ISDH) within 72 hours of diagnosis. The LHD will contact all cases diagnosed with Giardia to determine a possible exposure and help prevent others from becoming ill.
In general, giardiasis can be prevented by strictly adhering to the following guidelines:
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Updated on January 9, 2009