Pinworm Infection: Symptoms and Treatment
Primary Symptoms
The most common presenting symptom of pinworm infection is intense nocturnal perianal itching (pruritus ani), though 30-40% of infected patients remain completely asymptomatic. 1
Additional clinical manifestations include:
- Perianal pruritus that worsens at night when female worms migrate to lay eggs 2, 1
- Weight loss, irritability, diarrhea, and abdominal pain in some cases 2
- Vaginal discharge in females when worms colonize the genital tract 2, 3
- Occasionally colitis with eosinophilia 2
Diagnosis
The "sellotape test" (adhesive tape test) is the diagnostic method of choice, performed by placing the sticky side of clear tape on the perianal skin in the morning before bathing, then examining it microscopically for eggs. 2, 4
- A single test has approximately 50% sensitivity 1
- Performing the test on three consecutive mornings increases sensitivity to approximately 90% 1
- Stool examination is NOT recommended as pinworms and eggs are rarely passed in stool 1
- If adult worms are visualized in the perianal area or stool, pathological examination provides definitive diagnosis 1
First-Line Treatment
The drugs of choice are mebendazole 100 mg, albendazole 400 mg, or pyrantel pamoate 11 mg/kg (maximum 1 gram), all given as a single oral dose and repeated in two weeks. 2, 4, 1
Specific Dosing Details:
Mebendazole:
- 100 mg as a single dose, may be chewed, swallowed, or crushed and mixed with food 5
- Repeat dose in 2 weeks 1
- Both adulticidal and ovicidal 1
Albendazole:
Pyrantel pamoate:
- 11 mg/kg (maximum 1 gram) as a single dose 6, 1
- Can be taken any time of day, with or without meals 6
- Only adulticidal (not ovicidal) 1
- Preferred agent in pregnancy 1
Treatment Efficacy:
Mebendazole and albendazole are currently the best available drugs given their safety, effectiveness (success rates up to >90%), and dual action against both adult worms and eggs. 1, 7
Household and Contact Management
Treatment of ALL household members should be strongly considered, especially with multiple or repeated symptomatic infections, as reinfection is extremely common. 1, 7
- When one individual has pinworms, the entire household should be treated 6
- Sexual partners must be included in treatment 7
- Involvement of all household contacts is a prerequisite to lasting treatment success 7
Management of Recurrent Infections
For recurrent infections despite appropriate treatment, prolonged "pulse scheme" therapy for up to 16 weeks is recommended. 7
- Recurrences are common due to repeated cycles of reinfection and autoinfection 1
- The short life span of adult pinworms contributes to reinfection patterns 1
- If symptoms or pinworms persist after treatment, consult for extended therapy 6
Essential Hygiene Measures
Good personal hygiene is critical and must accompany pharmacologic treatment to prevent reinfection:
- Frequent handwashing, especially after bowel movements and before meals 1
- Clipping fingernails short 1
- Avoiding finger-sucking, nail-biting, and scratching the anogenital area 1
- Daily morning bathing to remove eggs deposited overnight 7
- Changing and washing underwear, nightclothes, and bed linens frequently in hot water 7
- Supervised body hygiene in young children 7
Common Pitfalls to Avoid
- Do NOT rely on stool examination for diagnosis—eggs are eliminated intermittently and rarely found in stool 2, 1
- Do NOT treat only the symptomatic individual—household transmission makes treating all contacts essential 6, 1, 7
- Do NOT forget the second dose at 2 weeks—this is critical to eliminate worms that hatched from eggs after initial treatment 1
- Do NOT use mebendazole or albendazole in pregnancy—pyrantel pamoate is the preferred agent 1
Special Populations
In pregnant women, pyrantel pamoate is preferred over mebendazole and albendazole due to safety considerations. 1