What is Cutaneous Larva Migrans (CLM)?
The cutaneous larva migrans is common skin disease caused by hookworm larvae. These nematodes are infect domestic dogs and cats (Ancylostoma caninum, A. braziliense and Uncinaria stenocephala). The infection is usually acquired by walking barefoot on the soil contaminated with animal feces, but other parts of the body can become infected by coming into contact with contaminated soil or sand.
Although cutaneous larva migrans has a worldwide distribution, it is most often seen in warm climates, such as the southeastern United States, Central and South America, Africa, and other tropical areas. The larvae enter the skin and begin a prolonged process of migration within the epidermis. With rare exceptions, the parasite remains confined to the epidermis, producing visible tracts and intense itching.The parasite lacks collagenase, enzyme which is necessary to alter the base memento membrane. Reason why this disease affect the cornea layer of the human skin.
Symptoms of Cutaneous Larva Migrans
Patients have intense localized pruritus that begins shortly after the hookworm penetrates the skin. Several days later, pruritus is associated with small vesicles and / or one or more serpiginous edematous “tracts”. Each larva produces a tract and migrates at a speed of 1 to 2 cm per day. The frequent location is the distal lower extremities or the buttocks. It can include the hands, the thighs and, rarely, the perianal area. In severe infections, hundreds of such injuries can be found in a single patient.
If left untreated, a single larval tract can progress, then disappear for a few days, reappear to advance a little more, and so on, for weeks or months, after which it will resolve spontaneously. Unlike human hookworm and strongyloidiasis, larvae rarely progress beyond the skin and systemic manifestations such as migratory pulmonary infiltrates and peripheral eosinophilia (Loeffler’s syndrome) are rarely observed. The only common systemic finding is moderate eosinophilia in the peripheral blood. Due to intense pruritus and scratches, superimposed bacterial infections can complicate the clinical picture. Vesicles and blisters may develop in previously sensitized patients
Diagnosis of Cutaneous Larva Migrans.
Although the diagnosis is usually made clinically, depending on the characteristic lesions and the history of recent exposure (eg, naked-skin biopsies are performed). It is not common to see the parasite in the biopsy samples, but occasionally the larva can be identified inside the epidermis. commonly, the cavities left by the parasite are located within the stratum corneum and are associated with spongiosis. In the dermis, there is a mixed inflammatory infiltrate composed of lymphocytes, histiocytes and numerous eosinophils. Occasionally, collections of eosinophils may be present in the epidermis and within the hair follicles
Cutaneous Larva Migrans Treatment
Although cutaneous larva migrans is self-limiting, its potential complications (for example, impetigo and allergic reactions), together with intense pruritus and significant duration of the disease (sometimes several months), usually require treatment. It has been suggested to freeze the anterior edge of the skin line (cryotherapy), but this modality is rarely sufficient.
Adult and children over 2 year of age.
- Administration of a single oral dose of 400 mg of albendazole produces cure rates of 45-100%.
- A dose of 400-800 mg / day in children, 10-15 mg / kg / day with a maximum of 800 mg / day) 3-5 days results in more consistent efficacy (cure rates of 80-100%)
- A single dose of ivermectin 12 mg in adults or 150 mcg / kg in children leads to cure rates of 80-100% .
- Topical application of a 10-15% thiabendazole solution or ointment in the affected areas may be performed for localized disease, but it has a limited value for multiple lesions and requires application three times a day for at least 15 days.
Oral thiabendazole is also effective but is less tolerated than albendazole or ivermectin