Giardia was initially described by van Leeuwenhoek in 1681 as he was examining his own diarrheal stools under the microscope (66). The organism was described in greater detail by Lambl in 1859, who thought the organism belonged to the genus Cercomonas and named it Cercomonas intestinalis (172).

Where is Giardia most commonly found?

Giardia parasites are found in lakes, ponds, rivers and streams worldwide, as well as in public water supplies, wells, cisterns, swimming pools, water parks and spas.

When was Giardia officially declared a human pathogen?

Anton van Leeuwenhoek first identified Giardia in his own diarrheal stool in 1681, but the parasite did not become an officially WHO-recognized pathogen until 1981.