Despite the limited, 13-week lifespan of individual pinworms, autoinfection (infection from the original host to itself), either through the anus-to-mouth route or through retroinfection, causes the pinworms to inhabit the same host indefinitely. Life cycle
The life cycle begins with eggs being ingested. The eggs hatch in the duodenum (first part of the small intestine). The emerging pinworm larvae grow rapidly to a size of 140 to 150 micrometres, and migrate through the small intestine towards the colon. During this migration they moult twice and become adults. Females survive for 5 to 13 weeks, and males about 7 weeks. The male and female pinworms mate in the ileum (last part of the small intestine), whereafter the male pinworms usually die, and are passed out with stool. The gravid female pinworms settle in the ileum, caecum (beginning of the large intestine), appendix and ascending colon, where they attach themselves to the mucosa and ingest colonic contents. Almost the entire body of a gravid female becomes filled with eggs. The estimations of the number of eggs in a gravid female pinworm ranges from about 11,000 to 16,000. The egg-laying process begins approximately five weeks after initial ingestion of pinworm eggs by the human host. The gravid female pinworms migrate through the colon towards the rectum at a rate of 12 to 14 centimetres per hour.
Pinworm infection (threadworm infection in the UK), also known as enterobiasis, is a human parasitic disease caused by the pinworm. The most common symptom is itching in the anal area. This can make sleeping difficult. The period of time from swallowing eggs to the appearance of new eggs around the anus is 4 to 8 weeks. Some people who are infected do not have symptoms.The disease is spread between people by pinworm eggs. The eggs initially occur around the anus and can survive for up to three weeks in the environment. They may be swallowed following contamination of the hands, food, or other articles. Those at risk are those who go to school, live in a health care institution or prison, or take care of people who are infected. Other animals do not spread the disease. Diagnosis is by seeing the worms which are about one centimetre long or the eggs under a microscope.Treatment is typically with two doses of the medications mebendazole, pyrantel pamoate, or albendazole two weeks apart. Everyone who lives with or takes care of an infected person should be treated at the same time. Washing personal items in hot water after each dose of medication is recommended. Good handwashing, daily bathing in the morning, and daily changing of underwear can help prevent reinfection.Pinworm infections commonly occur in all parts of the world. They are the most common type of worm infection in Western Europe and the United States. School-aged children are the most commonly infected.