Treatment of Pinworm (Enterobius vermicularis) Infection
The recommended first-line treatment for pinworm infection is a single dose of mebendazole 100 mg, pyrantel pamoate (11 mg/kg, maximum 1 g), or albendazole 400 mg, with a repeat dose in 2 weeks to eradicate newly hatched worms. 1, 2, 3, 4
Medication Options
- Mebendazole has a 95% cure rate for pinworm infections and is FDA-approved for this indication 2
- Pyrantel pamoate is dosed at 11 mg/kg (maximum 1 g) as a single dose and can be taken with or without food 3, 4
- Albendazole 400 mg as a single dose is an effective alternative treatment 1, 4
- Both mebendazole and albendazole are adulticidal and ovicidal, whereas pyrantel pamoate is only adulticidal 4
- For pregnant women, pyrantel pamoate is preferred over mebendazole and albendazole due to safety concerns 4
Treatment Protocol
- A second dose of the chosen medication should be administered 2 weeks after the initial dose to kill any newly hatched worms and prevent reinfection 1, 4
- All household members should be treated simultaneously, especially when there are multiple or repeated symptomatic infections 4, 5
- For recurrent infections, a prolonged treatment for up to 16 weeks using a "pulse scheme" may be recommended 5
Diagnostic Considerations
- The cellophane tape test is the preferred diagnostic method for pinworm infection 1, 4
- The sensitivity of a single test is approximately 50%, but increases to about 90% when performed on three different mornings 4
- Direct visualization of worms in the perianal area is diagnostic 4
- Stool examination is not recommended as pinworms and eggs are not usually passed in stool 4
Clinical Presentation
- Nocturnal perianal itching is the most common symptom of pinworm infection 1, 4
- Other symptoms may include irritability, weight loss, diarrhea, and abdominal pain 1
- Female genital tract colonization may occur in girls, causing vaginal discharge 1
- Approximately 30-40% of infected patients are asymptomatic 4
Prevention and Hygiene Measures
- Good personal hygiene practices are essential to prevent reinfection 4, 5:
- Frequent handwashing, especially after bowel movements and before meals
- Clipping fingernails short
- Avoiding finger-sucking and nail-biting
- Avoiding scratching the perianal area
- Daily changing of underwear and bed linens
- Regular cleaning of toilet seats and bathroom surfaces
Common Pitfalls and Considerations
- Reinfection is common even with effective medication due to the short life cycle of pinworms and potential for autoinfection 4, 5
- Treatment failure is often due to inadequate hygiene measures rather than drug resistance 4, 5
- Not treating all household members simultaneously can lead to continued transmission within the household 4, 5
- Forgetting the second dose at 2 weeks can allow newly hatched worms to mature and restart the infection cycle 4