Pinworms, also known as threadworms, are common parasitic worms that can reside in the human large intestine. These tiny worms affect people globally, with infections frequently observed in children due to their close interactions and hygiene habits. While often harmless, pinworm infections can cause discomfort and are highly contagious, requiring specific measures for identification and management.
Identifying Pinworms
Pinworms are small, slender, and appear white or grayish-white, resembling tiny pieces of thread. Adult female pinworms measure about 8 to 13 millimeters (approximately 0.3 to 0.5 inches) in length, while males are smaller, ranging from 2 to 5 millimeters. These worms can sometimes be observed around the anus, especially at night, as female pinworms migrate out of the rectum to lay their eggs on the surrounding skin. Individuals might also notice them in stool, on underwear, or in bedsheets.
The presence of pinworms often leads to a primary symptom: intense itching around the anus, particularly during the night. This itching occurs because female pinworms deposit thousands of microscopic, sticky eggs, along with a jelly-like substance, which irritates the skin. In some instances, pinworms may migrate to the vaginal area in females, causing itching and irritation there. However, many individuals with a pinworm infection may not experience any noticeable symptoms.
How Pinworms are Contracted and Spread
Pinworm infection begins when a person swallows microscopic pinworm eggs. These eggs hatch in the small intestine, and the larvae mature into adult worms within the large intestine over several weeks. During the night, adult female worms migrate from the intestine to the skin around the anus to lay their eggs.
When an infected person scratches the itchy anal area, the eggs can easily transfer to their fingers and become lodged under fingernails. From there, the eggs can spread directly to other people through contact or indirectly to various surfaces such as bedding, clothing, toys, toilet seats, and other household items. These eggs are resilient and can survive on surfaces for up to two to three weeks. Infection occurs when new eggs are ingested, often through hand-to-mouth transfer after touching contaminated surfaces. This ease of transmission makes pinworm infections highly contagious, especially within households, schools, and daycare settings.
Next Steps and Treatment
If pinworms are suspected or identified, seeking medical consultation for proper diagnosis and treatment is recommended. Healthcare providers can diagnose pinworm infection by examining the perianal area for worms or by using a “tape test” to collect eggs for microscopic examination. Treatment typically involves oral anti-parasitic medications, such as mebendazole, albendazole, or pyrantel pamoate. Pyrantel pamoate is available without a prescription, while mebendazole and albendazole usually require a prescription.
These medications are usually taken in two doses: an initial dose followed by a second dose two weeks later. The second dose is important because the medications kill the adult worms but not the eggs, ensuring that newly hatched worms are eliminated. To prevent reinfection, all household members should receive treatment simultaneously. Alongside medication, thorough hygiene practices are important, including frequent handwashing after using the bathroom and before eating, and keeping fingernails short and clean. Washing bedding, clothing, and towels in hot water and drying them on high heat can help destroy any remaining eggs. Regular cleaning of household surfaces, including toilets and doorknobs, helps prevent further spread.