Giardia duodenalis (syn. G. lamblia/G. intestinalis) is a protozoan flagellate (Diplomonadida) ^[1], responsible for human giardiasis.

Distributed on a global scale as a cause of gastroenteritis in both developed and resource limited nations, it has been estimated that Giardia parasites infect more than 200 million individuals every year ^[2].

Giardiasis is a nationally reportable disease and is one of the most common causes of waterborne disease in the United States (US). Regularly associated with waterborne parasite outbreaks in summer months, infection is underreported at 20,000 cases in the US each year, with real cases estimated at 1-2 million.^[3,4]

 Giardia infection rarely causes death in the US, however, 4,600 people are hospitalized with giardiasis each year.^[4] Giardia parasites are commonly found in bodies of water, particularly untreated or poorly treated water sources such as rivers, lakes, ponds, and streams but also in public water supplies and swimming pools.^[5]