The heavier or greater the worm infection, the more severe the symptoms are likely to be. Occasionally, the first sign of infection may be the presence of a worm in vomit or in the stool. A large number of larvae invading the lungs at one time may cause pneumonia. This stage of the disease precedes the intestinal phase by weeks, and the symptoms are difficult to diagnose. Once mature female worms are present in the intestine, however, a doctor can diagnose the infection by finding characteristic eggs in the stool.
Doctors can treat ascariasis successfully with mebendazole, albendazole, or pyrantel pamoate.
One of the most common roundworm infections is hookworm. Like ascarids, people pick up hookworms as a result of unsanitary conditions. Hookworm eggs are passed in human feces onto the ground where they develop into infective larvae. When the soil is cool, the worms crawl to the nearest moist area and extend their bodies into the air. Hookworm is widespread in those tropical and subtropical countries in which people defecate on the ground and soil moisture is most favorable.