Enterobius vermicularis is a type of parasite called a nematode, or roundworm. This organism most often is transmitted via what is known as the fecal-oral route. Infection typically is not dangerous, but secondary infections sometimes develop because of skin irritation caused by itching. An enterobiasis infection is often called a pinworm infection, or pinworms.
This worm species spends most of its life in the colon and rectum. After mating, females migrate to the skin around the exterior of the anus, where they release several thousand eggs. Within just a few hours of release, the eggs become infectious. They can remain in the environment for two to three weeks and can contribute to reinfection.
Enterobius vermicularis is an obligate human parasite, which means that humans are the only natural host of this roundworm species. Infection is passed from person to person via the fecal-oral route, typically via handling of inanimate objects. This means that the most common route of enterobiasis infection is via infectious eggs on unwashed hands, which are transmitted to inanimate objects such as clothing and toys. After an infected person has touched the objects, anyone who subsequently touches them might also become infected.
The most common symptom of enterobiasis is itching of the anal area. This symptom is thought to contribute to reinfection, because itching of the anus can deposit eggs under the fingernails, and these eggs can be later transmitted to the mouth. Children with this infection often are restless sleepers and might be more likely to wet the bed at night. If itching is excessive, constant scratching could cause secondary bacterial infection around the anal area. In a heavy infestation, worms might be present in feces, most often in the first bowel movement of the day.
Enterobiasis infection is most common in children of 9 years old and younger, but infection can occur in someone of any age. Reinfection of children in a small population, such as a school class or family group, is very common. The method of transmission of the infection means that home or other environmental sanitary conditions do not affect the infection rate.
Treatment of the infection is via anti-parasite medications such as mebendazole and albendazole. Topical medications can be used to reduce itching and reduce the risk of enterobiasis reinfection. In addition, children should be encouraged to wash their hands thoroughly after bowel movements or itching, because this can help prevent reinfection. Although sanitary conditions do not influence whether a child will contract the infection, measures such as more frequent washing of bedclothes, dusting and vacuuming can reduce the likelihood that reinfection will occur. All measures taken to prevent reinfection should be maintained for two to three weeks, because eggs can remain infectious for approximately 20 days.