A microscopic protozoan parasite which causes giardiasis.
A genus of parasitic pear-shaped protozoa inhabiting the small intestine of man. They have four pairs of flagella, two nuclei, and two sucking disks used for attachment to the intestinal wall. Giardia is usually harmless but may occasionally cause diarrhea.
A genus of protozoa possessing flagella. They inhabit the small intestine of humans and other animals, are pear shaped, and have two nuclei and four pairs of flagella. They attach themselves to the cells of the intestinal mucosa, from which they absorb nourishment. Cysts can survive in water for up to 3 months. The concentration of chlorine routinely used in treating domestic water supplies does not kill Giardia cysts, but boiling water inactivates them.