(Lamblia intestinalis, Giardia lamblid), a parasitic protozoan of the class Mastigophora, first described in 1859 by V. D. Lambl.
Lamblia is pear-shaped and is 10-20 microns long. The dorsal side is convex; the ventral side is concave, forming a sucker for temporary attachment to the epithelial cells of the host’s intestine. There are two oval nuclei and four pairs of flagella. Lamblia inhabits the intestine of man (primarily children) and is found chiefly in the duodenum. Less often, it lives in the bile duct and gall bladder. Lambliasis, or infection with Lamblia, is often an asymptomatic condition. Infection occurs by means of cysts formed when Lamblia enters the lower sections of the intestine. Other species of Lamblia (more than ten) parasitize the intestines of a variety of other mammals (mice and rabbits). One species is a parasite of amphibians.