Giardia /jē·är″dē·ə/ [Alfred Giard, French biologist, 1846–1908] , a common genus of flagellate protozoans and a major cause of nonbacterial diarrhea in North America and of intestinal disease globally. Many species of Giardia normally inhabit the digestive tract and cause inflammation in association with other factors that produce rapid proliferation of the organism. See also giardiasis.
