Oxyuriasis is a disease caused by infestation with the threadworm, a common intestinal parasite, and it affects more than 200 million people throughout the world, especially children. The colourless worms live at the junction of the large and small intestine, or sometimes in the caecum, and feed on their contents. The male worms, 3-5 mm in length, remain in the same place, but the females, 9-12 mm long, move, usually at night, to the skin around the anus as soon as they begin to ovulate and lay their eggs there, after which they die. Threadworms have a life-span of 6 to 8 weeks. The larvae in the eggs develop very quickly, and can cause infestation within 5 to 6 hours or even sooner. The worms and deposited eggs cause anal itching. Children in particular tend to scratch, and eggs stick to their