What is the most common cause of cutaneous larva migrans?

Cutaneous Larva Migrans: Etiology and Management

Cutaneous larva migrans is primarily caused by dog hookworm larvae (Ancylostoma caninum), which penetrate the skin and create characteristic serpiginous tracks. 1

Etiology and Pathophysiology

Cutaneous larva migrans (CLM), also known as "creeping eruption," is caused by the penetration of animal hookworm larvae into human skin. The primary causative agents are:

• Dog hookworm larvae (Ancylostoma caninum) - most common cause 1
• Ancylostoma braziliense - another common dog/cat hookworm species 2

The infection occurs when humans come into contact with soil or sand contaminated with animal feces containing hookworm larvae. The larvae penetrate the skin but cannot complete their life cycle in humans, making humans accidental "dead-end" hosts 2.

Epidemiology

• Worldwide distribution with predominance in warmer regions 1
• Most commonly acquired in tropical and subtropical areas 3
• Frequently seen in travelers returning from tropical destinations 4
• Risk factors include walking barefoot on contaminated beaches or soil 2

Clinical Presentation

The clinical presentation is highly characteristic:

• Serpiginous, erythematous, raised tracks that migrate at 1-2 cm per day 1
• Intensely pruritic lesions 3
• Most commonly affects feet, buttocks, and areas in contact with soil 5
• May be associated with eosinophilia 1
• Bacterial superinfection can occur due to scratching 3
• Usually self-limiting but can persist for weeks to months if untreated 6

Diagnosis

Diagnosis is primarily clinical, based on:

• Characteristic serpiginous, migratory rash 1
• History of exposure to potentially contaminated soil 5
• No specific laboratory tests are required for diagnosis 1

Treatment

Treatment options are highly effective:

First-line options:

• Ivermectin PO 200 μg/kg as a single dose 1
• Albendazole PO 400 mg once daily for 3 days 1, 5

Both treatments have high cure rates (81-100%), with ivermectin potentially offering the advantage of single-dose therapy 4.

Alternative options:

• Topical thiabendazole 10-15% solution or ointment applied three times daily for at least 15 days (less convenient for multiple lesions) 4, 6

Prevention

Preventive measures include:

• Avoiding walking barefoot on beaches or soil in endemic areas 3
• Regular deworming of dogs and cats 3
• Restricting animals from beaches and playgrounds 3

Prognosis

• Excellent prognosis with appropriate treatment
• Without treatment, the condition is self-limiting but may persist for weeks to months 6
• Complications are rare but can include secondary bacterial infections 3

Important Considerations

• CLM is the most common tropically acquired dermatosis 2
• The condition is easily treatable but often misdiagnosed, leading to prolonged discomfort 6
• Freezing the leading edge of the skin track is rarely effective 4
• Repeat treatment may be necessary in some cases 1