Which protozoan organism has been implicated in waterborne and foodborne outbreaks in the United States?

Giardia lamblia is a protozoan organism known for being a significant cause of waterborne and foodborne illnesses, particularly giardiasis, which is an intestinal infection that can result from consuming contaminated water or food. This organism is commonly found in the intestines of infected animals and can easily contaminate drinking water supplies through improper sanitation or human fecal contamination. In the United States, outbreaks linked to Giardia lamblia have been documented in various settings, including recreational waters, municipal water systems, and through food prepared by individuals who are infected.

The reason for its prevalence in outbreaks can be attributed to its resistance to chlorine and its ability to form cysts that survive in the environment for extended periods. This resilience makes it particularly challenging to control in water supplies, further contributing to its status as a prominent cause of waterborne disease in the U.S.