It is a flagellated parasitic microorganism, mainly exists in the form of a trophozoite which is pear shaped. t is bilaterally symmetrical and all organs of body are paired. They have two median bodies, two axostyle, two nuclei and four pairs of flagella. Cytoplasm is uniform and nucleus contains a large karyosome.
Mode of transmission-
Man is the main reservoir of Giardia. Infection is acquired due to poor hygiene conditions, contaminated food and water and through Sexual transmission-oral-anal and oral-genital sex.
It is an intestinal parasite and lectins present on its surface helps it to bind to the enterocytes of the intestines. Enterocytes damage begin when these trophozoites divide rapidly and tremendously inside the intestines. Giardiasis results in decreased jejunal electrolyte water and glucose absorption, and damages to intestinal epithelium.