Enterobiasis (Pinworm Infection)
- Etiology & Transmission:
- Organism: Enterobius vermicularis (human pinworm).
- Epidemiology: Most common in children aged 5–10 yrs; spread via fecal-oral autoinoculation or fomites.
- Clinical Presentation:
- Hallmark: Nocturnal perianal pruritus (female worms migrate to perianal skin at night to lay eggs). c
- Associated: Insomnia, irritability, perianal excoriations, vulvovaginitis in young girls.
- Systemic signs: Absent (no fever, no weight loss).
- Diagnosis:
- Best Initial & Gold Standard: Scotch tape test (morning perianal tape placement) → microscopy shows oval, flat-sided/asymmetric eggs.
- Stool O&P: Incorrect (low yield; eggs deposited perianally, not excreted in stool).
- Labs: Normal eosinophil count (worms do not invade systemic tissues).
- Management:
- First-line Meds: Single oral dose of Albendazole, Mebendazole, OR Pyrantel pamoate (OTC).
- Critical Dosing Strategy: Repeat 2nd dose in 2 weeks (kills newly hatched larvae before egg production; original dose does not kill eggs).
- Household Strategy: Treat ALL household contacts simultaneously regardless of symptoms to prevent re-infection.
- Non-Pharm: Hot-water washing of bed linens/clothing, trim fingernails short.
- High-Yield Differential:
- Perianal Streptococcal Dermatitis: Bright, sharply demarcated perianal erythema, pain with defecation, rectal bleeding. (-) Tape test. Tx: Oral Penicillin or Amoxicillin.