Nematode worms Ascaris lumbricoides. These worms are the largest of the human intestinal parasites; an adult female may measure 35cm in length. Infestation with the worms,called ascariasis,cause abdominal pain,vomiting,constipation,diarrhoea,appendicitis and peritonitis. The sexually mature worm lives in the small intestine,where the female lays a quantity of eggs. These are excreted in the faeces & ingested by a new host through contaminated water or food. The larvae hatch in the small intestine,migrate through the blood & enter the lungs where they can provoke pneumonia. They enter the mouth,are swallowed & return to the intestines to mature |