What is Enterobiasis? How to Prevent Pinworm Infections in Children?

What Causes Pinworm Infections or Enterobiasis?  

Pinworm infections are caused by the parasitic worm Enterobius vermicularis. Also known as Enterobiasis, it is one of the most common parasitic diseases in the world. Enterobiasis affects almost one billion people worldwide, regardless of socioeconomic status [2].

The worms are called pinworms because the females have pin-shaped, pointed ends. Mature worms can look like small, white threads or tiny bits of fluffy cotton to the naked eye. Humans are the parasite’s only hosts. Female adult worms can be 8–13 mm long, and males, 2-5 mm in length [3]. Other names for Enterobiasis are ‘seatworm’ and ‘threadworm’ infections.

History of Pinworm Infections

Pinworms have been around for centuries. Enterobius vermicularis eggs have been discovered in human remains dated 7837 B.C [4]. This is over 10,000 years ago, even before the wheel was invented! According to Cox (2002), Roman physicians were familiar with pinworms or Enterobius vermicularis, roundworms Ascaris lumbricoides, and tapeworms from 25 BC. Arabic doctors from over a thousand years ago have also recorded the Enterobius worms in their records [5].   

The pinworm was named Enterobius vermicularis by Linnaeus, the famous Swedish botanist and the father of modern taxonomy (also the ‘Prince of Botanists,’ and the founder of modern ecology).

How is it Spread?  

Enterobiasis is spread through fecal-oral transmission and is highly contagious. Pinworm eggs can cause itching in the perianal region (around the anus). When an infected person scratches the area, the eggs can get on their fingers and under their fingernails and spread to linen, bedding, clothes, food, and other items. Other individuals who then touch these contaminated surfaces risk ingesting the eggs and getting infected. Pinworm eggs can live on surfaces for about two weeks.

In rare cases, since the eggs are small, they can be airborne and inhaled [6].

Individuals at risk are pre-school and school-aged children, institutionalized individuals and their caregivers, and people who may be around any infected children. It affects boys more than girls at a ratio of 2:1, but there can be higher cases for girls between the ages of 5 and 14 [7].

Pathology: How Do Pinworms Infect Humans?

When pinworm eggs are ingested, they travel to our intestines, and a pinworm infection occurs. The eggs occupy the ileum and cecum regions of our gut and take 1-2 months to develop into mature worms. At night, when the infected child or adult is asleep, female adult pinworms travel to the anus and deposit thousands of eggs in the region that begin to hatch. This activity can cause the area around the anus to itch. When the infected person scratches, it can contaminate their fingers and fingernails. If these hands are not washed properly before touching other surfaces, there is a risk of auto-infection.

Auto-infection in Enterobiasis is when an infected individual scratches their perianal region and transfers pinworm eggs to their mouth directly or through contaminated surfaces. Sometimes, once the eggs hatch, larvae can return to the small intestine where adult males may be present. This process is known as retro-infection, and it is another way for pinworms to continue their life cycle [7] [3].

Sometimes, the perianal region can develop a bacterial infection because of scratching.

Symptoms

Many people with Enterobiasis infections are asymptomatic. Due to scratching in the area, there may be rashes or signs of inflammation. Pinworm infections are characterized by itching around the anus, known as perianal pruritus. A bacterial infection may be present. In some instances, there may be abdominal pain due to inflammation.

The itching at night may also lead to insomnia, irritability, nausea, teeth grinding, loss of appetite, or bedwetting (enuresia) [3] [8].

Diagnosis

The most common way to diagnose a pinworm infection is to attach a transparent sticky tape to the perianal region and then study it under a microscope. Pinworms prefer to migrate at night when their host is still. As a result, a health care provider will conduct a visual examination and an adhesive tape test immediately after the infected person wakes up or a few hours after they fall asleep. The tape test is conducted for 3-5 consecutive days [9].

Stool tests are not needed since minimal worms or eggs are present in the stool.

Treatment

Enterobiasis is treated using anti-parasitic (anthelmintic) medication like Albendazole, Mebendazole, Pyrantel Pamoate. Other medications are ivermectin and piperazine. Since Enterobiasis is contagious and reinfections are common, the entire household, school, or institution can be treated at one time as a preventive measure. The medication is offered in two separate doses, spaced two weeks apart. This is because it does not kill the pinworm eggs effectively with only one dose.

Infected persons are encouraged to shower in the mornings and change their underwear every day to help reduce the risk of contamination. They are also instructed not to co-bathe until the infection is eliminated [7] [10].  

Prevent Pinworm Infections

The best way to prevent pinworm infections is to develop good personal hygiene. Children (and adults) must wash their hands regularly before eating and after using the restroom. Because pinworm eggs can travel under fingernails, it is essential to clean them well and avoid biting fingernails. Children must be educated against touching or scratching their anus and putting their fingers in their mouths.

Bedsheets, linen, and clothes of infected individuals must be washed and dried in high heat to kill pinworm eggs [2] [7] [10].