What is the diagnosis and treatment process for a patient suspected of having enterobiasis (pinworms)?

Diagnosis and Treatment of Pinworm Infection

How to Check for Pinworms

Use the cellophane tape test (also called Scotch-tape test) performed first thing in the morning before bathing or using the toilet, repeated on three consecutive mornings to achieve approximately 90% sensitivity. 1

Performing the Test

• Apply the sticky side of clear cellophane tape to the perianal skin in the morning before bathing, then examine the tape under a microscope for eggs or adult worms 1, 2
• A single test has only 50% sensitivity, but performing the test on three different mornings increases sensitivity to approximately 90% 3
• The test works because female pinworms migrate to the perianal area at night to lay eggs, making early morning the optimal collection time 1

What NOT to Do

• Do not rely on stool examination - pinworms and eggs are not typically passed in stool, making stool ova and parasite examination ineffective for diagnosis 1, 2, 3

Clinical Clues

• The hallmark symptom is nocturnal perianal itching, though 30-40% of infected patients are asymptomatic 1, 2, 3
• Other symptoms may include weight loss, irritability, diarrhea, and abdominal pain 1, 2
• In females, pinworms may colonize the genital tract causing vaginal discharge 1, 2

How to Treat Pinworms

Take a single dose of mebendazole 100 mg, albendazole 400 mg, or pyrantel pamoate 11 mg/kg (maximum 1 gram), then repeat the same dose in exactly 2 weeks. 2, 4, 5, 3

Medication Options (All Equally Effective)

Mebendazole 100 mg:

• Single tablet, chewed or swallowed, repeated in 2 weeks 5
• Can be crushed and mixed with food 5
• Both kills adult worms and eggs 3
• No fasting or purging required 5

Albendazole 400 mg:

• Single 400 mg dose regardless of age, repeated in 2 weeks 2
• Both kills adult worms and eggs 3
• If used for more than 14 days (not typical for pinworms), monitor for hepatotoxicity and leukopenia 2

Pyrantel pamoate:

• Dose: 5 mg per pound (11 mg/kg) body weight, maximum 1 gram 4
• Can be taken any time of day, with or without food, with milk or fruit juice 4
• Only kills adult worms, not eggs 3
• Preferred option during pregnancy 3
• No laxative needed 4

Critical Treatment Considerations

Treat the entire household simultaneously, especially if there are multiple or repeated symptomatic infections, as reinfection is extremely common 4, 3

• The 2-week repeat dose is essential to kill newly hatched worms from eggs that survived the first treatment 2
• Treatment failure is rare; persistent symptoms usually indicate reinfection rather than medication resistance 2
• Recurrences are common due to repeated cycles of autoinfection and the short life span of adult pinworms 3

Prevention Measures to Prevent Reinfection

• Frequent handwashing, especially after bowel movements and before meals 3
• Clip fingernails short 3
• Avoid finger-sucking, nail-biting, and scratching the anogenital area 3
• These hygiene measures are critical because transmission occurs through ingestion and inhalation of infective eggs 6

When to Seek Further Evaluation

• If symptoms or pinworms persist after treatment, consult a physician 4
• If worms other than pinworms are visualized, seek medical evaluation 4
• Consider genitourinary examination in females with vaginal discharge not responding to standard therapies 1, 6