Pinworm is the most common worm infection in the United States. School-age children, followed by preschoolers, have the highest rates of infection. In some groups nearly 50% of children are infected. Infection often occurs in more than one family member. Adults are less likely to have pinworm infection, except mothers of infected children. Child care centers, and other institutional settings often have cases of pinworm infection.
The pinworm lives in the lower part of the small intestine and the upper part of the colon. It is found worldwide, and causes the most common infection enterobiasis in humans. Unlike many other intestinal parasites, the pinworm does not usually enter the bloodstream or any other organs besides the intestines. Only in rare cases disoriented pinworms are found in the vagina, and even more rarely in the uterus, fallopian tubes, liver, and peritoneum, but the worms cannot survive long in these places.
The itching from the pinworms might wake you up in the middle of the night and make you squirm a lot. So if you’re itchy and sore on your backside, tell your mom or dad. And if you see worms in your underwear or in the toilet, you should tell a parent right away. You should know, though, that some people with pinworms don’t have any symptoms at all.
Causes of Pinworms
Pinworms are the most common worm infection in the United States, primarily affecting school-age children. Pinworm eggs are spread directly from person to person or by touching bedding, food, or other items contaminated with the eggs.
Typically, children are infected by unknowingly touching pinworm eggs and putting their fingers in their mouths. The eggs are swallowed, and eventually hatch in the small intestine. The worms mature in the colon. Female worms then move to the child’s anal area, especially at night, and deposit more eggs. This may cause intense itching and the area may even become infected.
When a person scratches the itchy area, the microscopic eggs cling to fingers and are then transferred to other surfaces, such as food, liquids or other people. Pinworm eggs can survive for two to three weeks on these surfaces. A new infection starts when the eggs reach another person’s mouth from these contaminated surfaces. You can also reinfect yourself by unknowingly swallowing the eggs again.
Infection can also be spread when a person inhales airborne eggs, but this is rare. On rare occasions, pinworm infection persists because eggs hatch outside the anus and the young worms crawl back inside the body.
Symptoms of Pinworms
The symptoms of pinworm infection are caused by the female pinworm laying her eggs. Indeed, most infected individuals have few or no symptoms but, if the infection is heavy, the symptoms can be correspondingly more severe
Symptoms include anal or vaginal itching and irritation, as well as possible irritability, fatigue, weight loss, behavior problems and night-waking/nightmares.
The most common symptom of pinworms is itching around the anus. It is worse at night when the female worm deposits her eggs on the person infected. This can lead to difficulty getting a good night’s sleep.
In girls, pinworm infection can cause vaginal itching and irritation (vaginitis). In severe cases, weight loss, restlessness, irritability, and loss of appetite may occur. In a few rare cases, attacks of appendicitis may have been caused by pinworms blocking the appendix.
The itching is usually worse at night and is caused by worms migrating to the area around the rectum to lay their eggs. When a child scratches the itchy area, the result can be eczema or a bacterial infection around the rectum. In girls, pinworm infection can spread to the vagina and cause a vaginal discharge.
Mild pinworm infections — with only a small number of adult worms in your body — may cause no symptoms. Symptoms occur with moderate or heavy infections.