Each adult female worm produces egg or ova are passed out in the faeces. When worms are ingested by humans (through food, water, hands contaminated with faeces), the larva is released into the small intestine, which penetrates the intestinal wall and migrates through the blood stream or via lymphatics to the heart and lungs. The larvae reach the lungs in about 4 days, where they mature within the alveoli in approximately 10 days. They then pass up via bronchi and the trachea, subsequently return to the small intestine (last moult). Again they release out the worm through faeces. On re - entering the intestine, they mature into adult worms.