pinworms

Pinworms, or Enterobius vermicularis, are small white nematodes that cause enterobiasis, one of the most common human helminth infections worldwide. They are particularly prevalent in children and in crowded environments such as schools and dormitories. The adult worms inhabit the large intestine, especially the cecum and appendix region, and the female migrates to the perianal area at night to lay eggs.

Life cycle: Eggs deposited around the anus by female worms during the night. The eggs become infective within hours and can survive on surfaces for days to weeks. Autoinfection occurs when people scratch the itchy area and contaminate hands or bedding, leading to ingestion of eggs.

Symptoms: Most infections are mild or asymptomatic. The hallmark is itching around the anus, especially at night. Scratching can cause skin irritation and secondary bacterial infection; girls may experience vulvar irritation.

Transmission: Fecal-oral spread through hand-to-mouth contact; eggs contaminate bedding, clothing, towels, and surfaces. Close contact in households and schools facilitates transmission.

Diagnosis: The most common test is the tape test, conducted in the morning before bathing or using the toilet to collect eggs from the perianal skin. Eggs may also be seen around the anus or in stool, but stool tests are less sensitive.

Treatment and prevention: Anthelmintic medications such as mebendazole, albendazole, or pyrantel pamoate are used, usually with a second dose after about two weeks. All household members and close contacts are typically treated to prevent reinfection. Preventive measures include good hand hygiene, regular washing of bedding and underwear, short fingernails, and cleaning of surfaces and toys. Pinworm infections are endemic worldwide, most common in children aged 5–10.