NEMATODES - Infection by the nematode Ascaris lumbricoides and is characterized by an early pulmonary phase related to larval migration and a later, prolonged intestinal phase. Adult worms are 15-40 cm in length and maintain themselves in the lumen of the small intestine. Infection occurs after ingesting eggs contained in contaminated food, or more commonly, by transmission to the mouth by the hands after contact with contaminated soil. Treatment is with mebendazole or pyrantel pamoate.