Male whipworm (Trichuris trichiura), a nematode parasite of humans, computer illustration. The front of the worm (upper left) is narrow and pointed like a hair or whip. The rear is five or six times wider. Adult worms live in the intestine with the front end buried in the intestine wall. The worms can live for several years, usually without causing much harm to the host. When the infestation is severe, diarrhoea, dysentery and anaemia can result. The worm's intestine is dark red, the testis, vas deferens and ejaculatory duct are blue, and the nerve ring is purple.