Giardiasis Causes

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 in sexually active homosexual males. 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.