What Are the Causes of Threadworms?

The class of helminthes known as threadworm (Enterobius vermicularis) is the most common worm parasite to infect humans. The threadworm, also known as pinworm or seat worm, can infect both adults and children, although infection among children is more common.

The threadworm can be found in many environments, but the most common cause of threadworm infection is hygienic. Threadworm is an easy infection to spread.

Where Threadworms Exist

Threadworms can exist in various environments and on many surfaces. They can be found on furniture, bathroom fixtures, toilet seats, door handles, in bedding and in food. They can also be airborne and are often found among dust particles. Due to their availability in many areas, the susceptibility of passing these parasites to other people is very high, especially among children, because of their high rate of interpersonal contact and lack of sufficient personal hygiene habits.

How Threadworms Infect Humans

Once a threadworm invades the body, either by inhaling an airborne parasite, by ingesting them from infected food or from contact with infected skin, an adult female will form. The female will attach itself to the small intestine and then lay eggs, which will be spread to the large intestine. Here the eggs will feed on nutrients in the large intestine and grow into larvae and will mate. In this mating process, the males die and the females mature, migrating to the anus where they lay their eggs.

Preventing Infection

According to Rebecca J. Frey, Ph.D., the best known prevention against threadworm infection is to maintain a rigorous level of hygiene discipline. This may include frequent laundering of bedding and undergarments and intensive cleaning of bathrooms surfaces and other common areas of mutual contact such as door handles, telephones and television remote controls. Habitual hand-washing, especially before food preparation and after using the bathroom, is beneficial in controlling the spread of threadworm parasites.


There are two commonly used medications for threadworm infections. These are Piperazine and pyrantel pamoate (more commonly known as Pin-X). These medications do not require a prescription and can be obtained over the counter. These medications are in the form of one-dose treatments. A follow-up treatment may be needed, since the first dose will usually not kill the eggs. In rare cases of infections found in the vagina, a prescribed medication from a doctor may be necessary to kill the threadworm infection.

Diagnosis and Symptoms

Threadworms are extremely difficult to detect, even in adult form. The adults only grow to a maximum length of less than one inch and are no wider than a cotton thread, hence the name threadworm. A visual inspection of the anal area, especially at night when the female threadworm will be most prevalent, is the best method to detect infestation. Once the eggs are laid and passed with faeces, they are usually too small to detect visually. Indications of infection will be itchiness in the anal area and occasionally bed-wetting.