What are the signs and symptoms of enterobiasis (pinworm infection) and how is the cellophane tape test used for diagnosis, and is ivermectin (antiparasitic medication) indicated for treatment?

Pinworm Infection: Signs, Symptoms, Diagnosis, and Treatment

Albendazole 400 mg or mebendazole 100 mg as a single dose (repeated in two weeks) is the first-line treatment for pinworm infection, with ivermectin 200 μg/kg as an effective alternative when first-line treatments fail or are unavailable. 1, 2, 3

Clinical Presentation of Pinworm Infection (Enterobiasis)

Enterobiasis is a common parasitic infection caused by Enterobius vermicularis, affecting approximately 30% of children worldwide and up to 60% in some developing countries 3. The infection presents with:

Common Signs and Symptoms

• Intense perianal pruritus (itching), particularly at night, which is the most characteristic symptom 1, 3
• Weight loss, irritability, and diarrhea 1
• Abdominal pain 1
• Occasionally colitis with eosinophilia 1
• Female genital tract colonization causing vaginal discharge 1

Important Note

• Approximately 30-40% of infected individuals are asymptomatic 3
• Children aged 5-14 years show the highest prevalence 3

Diagnosis: The Cellophane Tape Test

The cellophane (or "sellotape") test is the gold standard for diagnosing pinworm infection:

1. Procedure: Place the adhesive side of transparent tape on the perianal skin, preferably in the early morning before bathing or defecation 1, 2
2. Examination: The tape is then examined under a microscope for pinworm eggs 1
3. Sensitivity: A single test has approximately 50% sensitivity, but this increases to about 90% when performed on three consecutive mornings 2, 3
4. Important note: Stool examination alone is not recommended as pinworms and eggs are not usually passed in stool 2, 3

Treatment Options

First-Line Treatments

• Albendazole: 400 mg as a single dose 1, 2, 3
• Mebendazole: 100 mg as a single dose 1, 2, 3

Alternative Treatment

• Ivermectin: 200 μg/kg as a single dose 1, 2, 4
  • Particularly useful for resistant cases or when first-line treatments are contraindicated
  • Effective in treating pinworm infections, though not as commonly used as first-line agents

Important Treatment Considerations

1. Repeat dosing: Treatment should be repeated after 2 weeks to kill newly hatched larvae 2, 3
2. Household treatment: All household members should be treated simultaneously to prevent reinfection 2, 3
3. Pregnancy: Pyrantel pamoate is preferred over albendazole and mebendazole in pregnant women 2, 5
4. Children: Children ≥2 years should receive the same doses as adults, while treatment for children 12-24 months should be discussed with a specialist 2

Prevention and Control Measures

To prevent reinfection and transmission:

• Hand hygiene: Frequent handwashing with soap, especially after using the toilet and before eating 2
• Nail care: Keep fingernails short and clean to reduce egg harboring 2, 3
• Clothing: Daily changing of underwear 2
• Environmental cleaning: Washing bed linens and night clothes in hot water, vacuuming or damp mopping bedroom floors 2
• Avoid behaviors: Discourage nail-biting, finger-sucking, and scratching in the anogenital area 3

Common Pitfalls to Avoid

1. Inadequate diagnosis: Relying solely on stool examination instead of the cellophane tape test 2
2. Incomplete household treatment: Failing to treat all household members simultaneously 2, 3
3. Insufficient hygiene measures: Not implementing proper hygiene practices during and after treatment 2
4. Single treatment only: Not repeating treatment after 2 weeks to kill newly hatched larvae 3
5. Overlooking resistant cases: Not considering alternative treatments like ivermectin when first-line treatments fail 2, 4

By following these diagnostic, treatment, and prevention guidelines, pinworm infections can be effectively managed with excellent outcomes for morbidity, mortality, and quality of life.