Cutaneous Larva Migrans

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

• 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.