Giardiasis, << `jee` ahr DY uh sihs, >> is a common intestinal disease. It is caused by a protozoan (one-celled organism) that lives as a parasite in human beings and animals. The scientific name for this parasite is Giardia lamblia. Giardiasis is characterized by mild to severe diarrhea. Other symptoms may include abdominal swelling, cramps, nausea, and weight loss. The infection commonly lasts several weeks, but some cases become chronic and may last for years.
People become infected with G. lamblia by drinking contaminated water or from close contact with an infected person. The parasite moves through the digestive system and attaches to the inner surface of the small intestine. There, it interferes with the body’s ability to absorb fat and vitamins, leading to diarrhea. The parasite eventually passes out of the body in the feces (solid body waste).
Giardiasis occurs throughout the world in areas with contaminated water supplies. Animals can spread the parasite. For example, beavers can contaminate water upstream from areas where outbreaks of giardiasis have occurred. Each year in the United States, many people become infected by drinking water directly from mountain streams. Physicians use the drugs quinacrine and metronidazole to treat the disease.
