Giardiasis is an infection of the small bowel by a single-celled organism called Giardia lamblia. People become infected with the Giardia parasite after swallowing Giardia cysts often found in water contaminated by raw sewage or animal waste.
- Giardiasis can be found among 2% to 5% of people in industrialized nations such as the United States. In developing countries,
up to 33% of the population may have had giardiasis. In the US, it is the most
common intestinal parasitic disease.
- Travelers to foreign countries may develop diarrhea often caused by Giardia.
Giardia cysts are transmitted to humans in various ways.
- Contaminated water supplies: Giardia is one of the most common causes of water-borne diarrhea outbreaks. Sources of contaminated water include public facilities that improperly filter and treat water, water in developing countries, or rivers and lakes used by hikers. Overseas travelers and hikers are at a high risk for infection.
- Contaminated food: Food that may have been washed in contaminated water, exposed to manure, or prepared by an infected person can transmit the disease.
- Person-to-person contact: Infection may be caused by poor hygiene and most commonly occurs in daycare centers, nursing homes, and
during oral-anal sexual contact. Up to 50% of children infected with Giardia in daycare centers, and up to 20% of infected sexually active homosexual males, pass cysts in their stool. Family members, daycare workers, and others in contact with infected stool may then themselves become infected.
Medically Reviewed by a Doctor on 11/16/2012
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