Cutaneous Larva Migrans

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CLM Etiopathogenesis - Uninvited Skin Crawlers

  • Causative Agents: Primarily zoonotic hookworm larvae. Humans are accidental, dead-end hosts.
    • Ancylostoma braziliense (cats, dogs) - Most frequent.
    • Ancylostoma caninum (dogs).
    • Uncinaria stenocephala (dogs).
    • Bunostomum phlebotomum (cattle).
  • Transmission:
    • Filariform (L3) larvae in warm, moist, sandy soil contaminated with animal feces.
    • Larvae penetrate intact or abraded human skin upon contact.
  • Pathogenesis:
    • Larvae migrate within the epidermis or at the dermo-epidermal junction (stratum basale).
    • Cannot invade deeper dermis (lack collagenases for human basement membrane).
    • Intense, localized eosinophilic inflammatory response (Th2-mediated) to larval antigens and movement causes characteristic pruritic, erythematous, serpiginous (

CLM Clinical Features - Serpentine Skin Signs

Cutaneous larva migrans lesions on ankle

  • Hallmark: Intensely pruritic, erythematous, serpiginous, or linear tracts.
    • Lesions are typically 1-5 mm wide.
    • Raised, palpable burrows are characteristic.
  • Progression: Tracts advance as larvae migrate.

    ⭐ Larvae typically migrate 1-2 cm per day.

  • Common Sites: (Areas of skin contact with contaminated soil/sand)
    • Feet (most common)
    • Buttocks
    • Thighs
    • Hands
  • Associated Features:
    • Vesicles or bullae may form along the tracts.
    • Excoriations due to intense itching.
    • Secondary bacterial infection (e.g., impetigo) is common from scratching.
  • Symptoms:
    • Intense itching (pruritus), often worse at night.
    • Tingling or stinging sensation at the site of larval penetration.
    • Pain is uncommon unless secondarily infected.
  • 📌 Mnemonic: S.C.R.A.T.C.H. (Serpiginous, Creeping, Red, Advancing, Tracts, Causing, Horrible itch)

CLM Diagnosis - Spotting the Squiggle

  • History: Exposure to soil/sand contaminated by animal (dog/cat) feces; travel to endemic tropical/subtropical areas.
  • Clinical Findings:
    • Intensely pruritic, erythematous, raised, serpiginous/linear tracts ("creeping eruption").
    • Track advances 1-2 cm/day. Width: 2-3 mm.
    • Common sites: Feet, buttocks, hands, thighs.
  • Investigations (Usually not needed):
    • Dermoscopy: May show larva at advancing end of the burrow.
    • Biopsy (rare): Eosinophilic infiltrate. Peripheral eosinophilia possible.

⭐ Diagnosis is primarily clinical; biopsy is rarely indicated and usually not necessary for confirmation based on the characteristic presentation and history of exposure in endemic regions for Cutaneous Larva Migrans (CLM).

CLM Management - Evicting the Itch

  • Goal: Kill larva, relieve itch, prevent secondary infection.
  • Topical Therapy (mild/localized):
    • Thiabendazole (10-15% solution/cream) BID-TID for 7-10 days.
    • Cryotherapy (liquid nitrogen) to advancing end of burrow.
  • Systemic Therapy (widespread/severe/failed topical):
    • Ivermectin: 200 µg/kg single dose (preferred).
    • Albendazole: 400 mg daily for 3-7 days.
  • Symptomatic Relief:
    • Antihistamines for pruritus.
    • Antibiotics if secondary bacterial infection.

⭐ Oral Ivermectin (200 µg/kg single dose) or Albendazole (400 mg daily for 3-7 days) are effective systemic treatments.

  • Prevention: Avoid skin contact with fecally contaminated soil (e.g., wear footwear, use protective barriers on beaches).

High‑Yield Points - ⚡ Biggest Takeaways

  • Caused by larvae of animal hookworms (e.g., Ancylostoma braziliense) from fecally contaminated soil.
  • Presents as intensely pruritic, erythematous, raised, serpiginous tracts on skin - "creeping eruption".
  • Larvae migrate 1-2 cm/day within the epidermis; humans are accidental dead-end hosts.
  • Common sites: feet, buttocks, thighs, hands (areas of direct skin contact with soil).
  • Diagnosis is clinical, based on characteristic lesions and exposure history.
  • Treatment: Oral Albendazole or Ivermectin; topical Thiabendazole.

Practice Questions: Cutaneous Larva Migrans

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Which among the following occupations is a risk factor for cutaneous larva migrans?

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Flashcards: Cutaneous Larva Migrans

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The most common type of leprosy in India is _____

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The most common type of leprosy in India is _____

Borderline Tuberculoid (BT)

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