An intestinal parasite infection is a condition in which a parasite infects the gastro-intestinal tract of humans and other animals. Such parasites can live anywhere in the body, but most prefer the intestinal wall.Routes of exposure and infection include ingestion of undercooked meat, drinking infected water, fecal-oral transmission and skin absorption.Some types of helminths and protozoa are classified as intestinal parasites that cause infection—those that reside in the intestines. These infections can damage or sicken the host. If the intestinal parasite infection is caused by helminths, the infection is called helminthiasis.