Cutaneous larva migrans (CLM), also known as “creeping eruption,” is the most common dermatologic problem following a trip to the tropics. CLM is a worldwide, parasitic infection commonly seen in warm, tropical environments; it is uncommon in developed countries due to shoe-wearing habits and routine deworming of pets.
CLM is most caused by dog and cat hookworms, Ancylostoma caninum and Ancylostoma braziliense; humans are an accidental host. The infected animal passes eggs in its feces where they hatch, molt, and feed on soil bacteria. Upon contact with a human host, the larval worm penetrates the skin and attempts dermal migration. The worm remains under the skin since it lacks collagenase and cannot penetrate deeper layers. The larvae are unable to complete their life cycle, and, if left untreated, are trapped in the epidermis and will die in 2 to 8 weeks.
CLM is commonly seen on the lower extremities of travelers who walk barefoot on beaches with contaminated sandy soil. Symptoms are manifested by an erythematous tract with a distinctive serpiginous dermal pattern. The tract is markedly pruritic and may feel like a thread on palpation.
Cutaneous Larva Migrans. A serpiginous, linear, raised, tunnel-like erythematous lesion outlining the path of migration in the larva. Upon palpation, it feels like a thread within the superficial layers of the skin. (Photo contributor: Janet Rohde.)
Management and Disposition
Treatment of CLM consists of mebendazole, albendazole, ivermectin, or topical application of thiabendazole. Antipruritics may also help.
The lesions advance a few millimeters to several centimeters daily as the larva migrates.
Excoriation and secondary infections frequently occur. This can make the distinctive wandering rash more difficult to visualize.
Biopsy is usually not helpful for diagnosis since the organism lies 1 to 2 cm away from the leading edge of the eruption.
Cutaneous Larva Migrans. CLM with secondary infection on the foot of a toddler from Zambia. (Photo contributor: Meg Jack, MD.)