Treatment of Pinworm (Enterobius vermicularis) Infection
The first-line treatment for pinworm infection is a single dose of either mebendazole 100 mg or albendazole 400 mg, with a repeat dose after 2 weeks to eradicate newly hatched worms. 1, 2, 3
Medication Options
- Mebendazole 100 mg as a single oral dose is FDA-approved for pinworm treatment with a 95% cure rate 4
- Albendazole 400 mg as a single oral dose is an effective alternative treatment 1, 2, 3
- Pyrantel pamoate (11 mg/kg, maximum 1 g) is another option, particularly preferred for pregnant women 3
- All treatments should be repeated after 2 weeks to kill newly hatched worms and prevent reinfection 2, 4, 3
Clinical Presentation
- Nocturnal perianal itching is the most common symptom of pinworm infection 1, 2, 3
- Other symptoms may include weight loss, irritability, diarrhea, and abdominal pain 1, 2
- Approximately 30-40% of infected patients are asymptomatic 3
- In females, pinworms may colonize the genital tract, causing vaginal discharge or granulomas 2, 5
Diagnosis
- The cellophane tape test (also called "sellotape test") is the preferred diagnostic method 1, 2, 3
- Performed by placing adhesive tape on the perianal skin in the morning before bathing or defecation
- Sensitivity of a single test is around 50%, increasing to approximately 90% with tests performed on three different mornings 3
- Direct visualization of worms in the perianal area or stool is diagnostic 3
- Stool examination alone is not recommended as pinworms and eggs are not usually passed in stool 3
Treatment Considerations
Special Populations
- For pregnant women, pyrantel pamoate is preferred over mebendazole and albendazole 3
- Treatment of all household members should be considered, especially with multiple or repeated infections 3, 6
Prevention of Reinfection
- Good personal hygiene is essential to prevent reinfection 3, 6:
- Frequent handwashing, especially after bowel movements and before meals
- Clipping of fingernails
- Avoidance of finger-sucking, nail-biting, and scratching in the anogenital area
- Regular changing of underwear and bedding
Common Pitfalls and Caveats
- Failure to treat all household members can lead to reinfection cycles 3, 6
- Recurrences are common despite effective treatment due to the short life span of adult pinworms and autoinfection 3
- Ectopic infections can occur, particularly vaginal infections in females, which may serve as a reservoir for reinfection 5
- For recurrent infections, prolonged treatment for up to 16 weeks using a "pulse scheme" may be necessary 6
- Inadequate attention to hygiene measures can compromise treatment success 3, 6