What is the diagnosis and treatment for a 5-year-old boy with a red, raw perianal area and worms in his stool?

Pinworm Infection (Enterobiasis)

This 5-year-old boy has pinworm infection (enterobiasis), and you should treat him with a single dose of albendazole 400 mg orally, repeated in 2 weeks, and simultaneously treat all household members with the same regimen to prevent reinfection. 1, 2

Diagnosis

The visible worms in the stool combined with perianal irritation (red, raw perianal area) are pathognomonic for pinworm infection caused by Enterobius vermicularis. 2

• The cellophane tape test is the gold standard for diagnosis, applied to the perianal area in the morning before bathing or defecation. 3
• A single tape test has only 50% sensitivity, but three tests on consecutive mornings increase sensitivity to 90%. 3, 2
• Do not rely on stool examination for diagnosis—this is a common pitfall, as adult pinworms reside in the cecum and ascending colon, making stool examination unreliable. 3
• However, in this case, the clinical presentation with visible worms and perianal irritation is sufficient for diagnosis without formal tape testing. 2

Treatment Regimen

First-line treatment is albendazole 400 mg orally as a single dose, repeated in 2 weeks. 1, 4, 2

• Albendazole is both adulticidal and ovicidal, making it superior to alternatives. 2
• Alternative option: Mebendazole 100 mg orally as a single dose, repeated in 2 weeks. 1, 5, 2
• Both medications should be taken with food to enhance absorption. 4
• Pyrantel pamoate (11 mg/kg, maximum 1 g) is an alternative but is only adulticidal (not ovicidal), making it less effective. 2

Critical Management Point: Treat All Household Contacts

Simultaneously treat all household members with the same single-dose regimen, even if asymptomatic. 1, 2

• Pinworms are highly contagious, with transmission occurring via the fecal-oral route through contaminated hands, bedding, and even airborne eggs. 5, 2
• Reinfection rates are extremely high without treating contacts, as eggs can survive on surfaces and become airborne. 5, 2
• This is especially important in households with multiple or repeated symptomatic infections. 2

Prevention Measures to Prevent Reinfection

Implement strict hygiene measures during and after treatment:

• Hand hygiene: Wash hands and fingernails with soap frequently, especially before eating and after using the toilet. 1, 5
• Nail care: Keep fingernails short and discourage nail-biting, finger-sucking, and scratching the perianal area. 5, 2
• Clothing: Wear tight-fitting underwear day and night, changed daily. 5
• Bedding: Wash bed linens and nightclothes in hot water after treatment (do not shake them, as this disperses eggs). 5
• Environmental cleaning: Vacuum or damp-mop bedroom floors for several days after treatment; avoid dry sweeping that stirs up dust. 5
• Toilet hygiene: Keep toilet seats clean. 5

Common Pitfalls to Avoid

• Do not assume a single treatment dose is sufficient—the 2-week repeat dose is essential to kill newly hatched worms from eggs that survived the first dose. 2
• Do not treat the child alone—failure to treat household contacts is the most common reason for treatment failure and reinfection. 1, 2
• Do not order stool ova and parasite examination—this is unreliable for pinworm diagnosis and wastes time and resources. 3
• Recurrences are common even with effective treatment due to reinfection (particularly autoinfection), not treatment failure. 2

Special Considerations

• Approximately 30-40% of infected patients are asymptomatic, so household contacts may be infected without symptoms. 2
• The perianal irritation and "red, raw butt hole" result from nocturnal migration of female worms to lay eggs, causing intense pruritus and excoriation from scratching. 5, 2
• Restless sleep is a frequent sign of pinworm infection in children due to nocturnal pruritus. 5