Cutaneous larva migrans (CLM) is the most common tropically acquired dermatosis. It presents as an erythematous, serpiginous, pruritic, cutaneous eruption caused by percutaneous penetration and subsequent migration of larvae of various nematode parasites.
Background: Cutaneous larva migrans (CLM) is the most common tropically acquired dermatosis. It presents as an erythematous, serpiginous, pruritic, cutaneous eruption caused by percutaneous penetration and subsequent migration of larvae of various nematode parasites. It is most commonly found in tropical and subtropical geographic areas and the southwestern United States; however, the ease and the increasing incidence of foreign travel by the world's population have no longer confined CLM to these areas.
Pathophysiology: The life cycle of the parasites begins when eggs are passed from animal feces into warm, moist, sandy soil, where the larvae hatch. They initially feed on soil bacteria and molt twice before the infective third stage. By using their proteases, larvae penetrate through follicles, fissures, or intact skin of the new host. After penetrating the stratum corneum, the larvae shed their natural cuticle. Usually, they begin migration within a few days.
In their natural animal hosts, the larvae are able to penetrate into the dermis and are transported via the lymphatic and venous systems to the lungs. They break through into the alveoli and migrate to the trachea, where they are swallowed. In the intestine they mature sexually, and the cycle begins again as their eggs are excreted.
Humans are accidental hosts, and the larvae are believed to lack the collagenase enzymes required to penetrate the basement membrane to invade the dermis. Therefore, the disease remains limited to the skin when humans are infected.
Frequency:
- In the US: CLM is rated second to pinworm among helminth infections in developed countries.
Mortality/Morbidity: The condition is benign but can cause a disturbing pruritus.
Race: No specific racial predilection exists because CLM depends on exposure.
Sex: CLM demonstrates no specific sexual predilection because CLM depends on exposure.
Age: CLM can affect persons of all ages because it depends on exposure.
History:
- Tingling/prickling at the site of exposure within 30 minutes of penetration of larvae
- Erythematous, often linear lesions that advance
- Often associated with a history of sunbathing, walking barefoot on the beach, or similar activity in a tropical location
- Predispositions include the following:
- Hobbies and occupations that involve contact with warm, moist, sandy soil
- Tropical/subtropical climate travel
- Barefoot beachgoers/sunbathers
Physical:
- Cutaneous signs include the following:
- Pruritic, erythematous papules
- 2- to 3-mm wide, serpiginous (snakelike), slightly elevated, erythematous tunnels tracking 3-4 cm from the penetration siteNonspecific dermatitis
- Vesicles with serous fluid
- Secondary impetiginization
- Tracts advance several millimeters per day
- Systemic signs include peripheral eosinophilia and increased immunoglobulin E (IgE) levels.
- Lesions are distributed on the dorsa of the feet, the interdigital spaces of the toes, the anogenital region, the buttocks, the hands, and the knees.
Causes:
- Common etiologies and where the parasites are most commonly found include the following:
- Ancylostoma braziliense (hookworm of wild and domestic dogs and cats) is the most common cause. It can be found in the central and southern United States, Central America, South America, and the Caribbean.
- Ancylostoma caninum (dog hookworm) is found in Australia.
- Uncinaria stenocephala (dog hookworm) is found in Europe.
- Bunostomum phlebotomum (cattle hookworm)
- Rare etiologies include the following:
- Ancylostoma tubaeforme (cat hookworm)
- Strongyloides papillosus (parasite of sheep, goats, and cattle)
Print
Add Feedback