The most common worm in humans in the United States and the European Union is the pinworm. In developing countries where there is not enough clean water, the most common worms are roundworms, hookworm, and whipworm. Overall, around 3 billion people around the world are infected with parasitic worms. This means, nearly half of all humans are infected with worms.

The pinworm belongs to the family Oxyuridae, order Oxyuroidea, and the phylum Nematoda. The pinworm is classified as Enterobius vermicularis. While pinworm is most commonly found in school-aged children, it can occur in adults as well. Humans may become infected with pinworm after drinking water or eating food contaminated with pinworm eggs. Pinworm eggs are ovoid on one side and approximately .55 mm x .25 mm in size. The eggs can last for twenty days in most moist environments — even in sewage.

The adult pinworm, which is small, white and threadlike, develops in the body’s large intestine and lays its eggs in the anal region. The female pinworm can lay up to 15,000 eggs at a time.

In some cases, individuals that become infected with pinworms will not experience any symptoms while others will experience mild to moderate symptoms. The most common pinworm symptom is itching around the anus. The itching becomes more intense at night when the female pinworm lays her eggs on the skin of infected person. Pinworms rarely cause symptoms in other areas such as the vagina or urinary tract. If they do, which is extremely rare, any irritation will go away on it’s own along with the pinworms. Pinworms just cannot survive in these areas of the human body.

Pinworms are easy to detect by sight. They are most active at night, so this is the best time to look for them. Pinworms can also be seen on the outside of the infected person’s stool. Fortunately, there are several effective treatments for pinworms. According to MedicineHealth:

“Albendazole (Albenza) is the most common treatment for pinworms. Treatment is a single tablet, which kills the worms. There are different strengths for adults and children younger than 2 years. To lessen the chance of reinfection, the infected person will have to take a second dose two weeks after treatment. Pinworm eggs can survive for a few weeks. Other treatments such as Mebendazole (Vermox) and pyrantel pamoate (Pin-Rid, Pin-X) also work. They are also taken in a single dose and repeated 2 weeks later.”

There are several things that must be done after treatment (and beyond) to prevent reinfection. The treated individual should:

• Avoid biting the fingernails.
• Clean and vacuum play areas. Continue this practice indefinitely.
• Get into the habit of thoroughly washing the hands after using the bathroom, before and after eating, and before preparing food.
• Launder all bedding every 3-7 days for 3 weeks.
• Make sure the child or infected person changes his/her underwear daily.
• Thoroughly wash all bedding, clothing, pajamas, and toys with hot water and soap to destroy any lingering eggs.
• Wash underwear and pajamas daily for 2 weeks.

If you have been treated for pinworms and you have carefully followed all of the steps listed above and you still become reinfected, do not get discouraged. It is common to become reinfected several months or so after treatment. Simply call your doctor to get started on another round of treatment.