10.4.3 (Cutaneous) Larva migrans (CLM)
Cutaneous larva migrans is the most commonly disease transmitted by animal feces through direct contact with skin. It usually affects inhabitants or tourists in wet tropical and subtropical climates (southeastern United States, Latin America, the Caribbean, Southeast Asia, and Africa).
Infection by multiple types of hookworms.
Aetiology & Pathogenesis
CLM is caused by animal hookworms (most commonly Ancylostoma braziliense, Ancylostoma ceylanicum, and Ancylostoma Caninum), present in sand or soil contaminated with animal feces.
Larvae attach to the skin of their animal host (usually nondomesticated cats or dogs) are swallowed and enter the gastrointestinal tract, where they shed eggs, which are eliminated with the feces in sand or soil. The mature filariform larvae then penetrate the corneal layer by secreting a hyaluronidase, burrow through the superficial cutaneous layers of human skin in a snake-like fashion. Due to the lack of a specific collagenase, they cannot penetrate the basal membrane to enter lymphatic vessels. They die without reproducing and completing their life cycle after approximately 2-8 weeks and therefore the disease is self-limited.
Signs & Symptoms
Erythematous, pruritic eruption with papules or a linear or serpiginous snake-like elevated mobile track. The hookworm migrates through the skin at about 1 mm to 3 cm per day.
The most commonly affected areas are the feet, buttocks, thighs, and lower legs, but lesions can appear anywhere.
Laboratory & other workups
Not needed; dermatoskopy; biopsy usually not needed. Eosinophilia and increased immunoglobulin E levels may occur.
Spongiotic dermatitis with vesicles, containing neutrophils and eosinophils. Larvae may be found in the epidermis or below surrounded by eosinophilic infiltrate.
Resolution without treatment. However pruritus may persist over weaks or months.
Superinfection (Staphylococcus aureus and Streptococcal species) caused by scratching, excoriations, vesiculobullous lesions.
Complications include secondary infection, most commonly with Staphylococcus aureus and Streptococcal species. Visceral disease has been rarely reported.
(Travel-) history (walking barefoot and exposure to contaminated sand or soil) and typical clinical feature showing the classic serpiginous rash.
Scabies, loiasis, myiasis, schistosomiasis, tinea corporis, and contact dermatitis may have some overlapping features. The most similar disease is the migrating lesion of Strongyloides stercoralis, moving much faster and termed larva currens. Non-infectious linear or serpiginous, non-migratory dermatoses: jellyfish stings, lichenoid eruptions, and phytophotodermatitis.
Prevention & Therapy
Prevention: wearing protective footwear.
The disease is self-limited.
Topical thiabendazole 10% solution or 15% ointment, applied 2 to 3 times daily for 5 to 10 days.
Ivermectin (0.15-0.2 mg/kg QD PO 3 1 or 2 days) can help to shorten the clinical course of the disease and to prevent superinfection.
Local disease has historically been treated with cryotherapy. However, freezing the leading edge of the skin with either liquid nitrogen, solid carbon dioxide, or ethylene chloride spray has been shown to be largely ineffective and should be avoided.
Freezing (cryotherapy) with either liquid nitrogen, solid carbon dioxide, or ethylene chloride spray has been shown to be largely ineffective and should be avoided.
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