Pediatric Cutaneous Larva Migrans 

Updated: May 23, 2018
Author: Martha L Muller, MD; Chief Editor: Russell W Steele, MD 

Overview

Practice Essentials

Cutaneous larva migrans (CLM) is a serpiginous eruption usually confined to the skin of the feet, buttocks, or abdomen caused by dog and cat hookworms, which are types of nematodes (roundworms).[1] Skin findings are due to a hypersensitivity reaction to the worms and their byproducts.[2, 3]

Although CLM can occur in the temperate zones in the warmer months of the year, infection is most commonly found in tropical and subtropical climates. Modern ease of travel necessitates inclusion of CLM in the differential diagnosis of serpiginous pruritic lesions, regardless of the location of practice.[4, 5] See the images below.

Cutaneous larva migrans involving the foot with er Cutaneous larva migrans involving the foot with erythematous, edematous, serpiginous tracks. Infestation has caused a cellulitis.
Cutaneous larva migrans involving the dorsal foot. Cutaneous larva migrans involving the dorsal foot. Graphic courtesy of Dr Sara K. Ward.

Pathophysiology

Larvae from animal nematodes that infect humans usually cause CLM. The normal hosts for these hookworms are cats and dogs, in which the roundworm eggs pass through the feces. The eggs optimally hatch in warm, shady, moist, sandy soil found in tropical and subtropical areas. Humans are infected with the larvae by walking barefoot on the sand. The larvae quickly penetrate the skin upon contact.

Beaches are the most common reservoir for the larvae that cause CLM; however, infection can occur from sandboxes and soil under houses or at construction sites.[6] The prohibition of dogs and cats on beaches is a way to limit transmission of the infection.

Epidemiology

Frequency

United States

Exact incidence is unknown; however, Jelinek et al reported that 6.7% of the 13,300 travelers visiting a travel-related disease clinic presented with CLM.[7] In the United States, most cases occur in eastern and southern coastal areas from New Jersey to Texas. The highest incidence is in Florida.

International

Worldwide distribution is predominantly reported in tropical zones, although cases acquired in France and Portugal illustrate the broad distribution of the causative organisms.[8, 9] CLM is indigenous to the Caribbean, Central and South America,[10] Africa, Southeast Asia, and Australia.[11]

Mortality/Morbidity

Mortality from the infection is not reported. Most episodes of CLM resolve with or without treatment and with no long-term adverse consequences. Morbidity is associated with an intensely pruritic rash, which leads to secondary impetiginization and cellulitis. In rare incidents of CLM in which nematodes use a human as a definitive host, infection can lead to the completion of the nematode life cycle with adult worms residing in the intestines. This causes diarrhea, malabsorption, and malnutrition.

Race

CLM has no racial predilection.

Sex

No sex predilection is observed.

Age

CLM affects all ages in the appropriate environment.

 

Presentation

History

The patient with cutaneous larva migrans (CLM) may recall a stinging sensation upon initial penetration of the larvae.

An erythematous papule or a nonspecific dermatitis can develop hours after penetration.

The most common location for penetration is the feet (39%), from walking barefoot in the sand, followed by the buttocks (18%) and the abdomen (16%).

Physical

The migration of the larvae produces a 2-mm to 4-mm wide, erythematous, elevated, vesicular serpiginous track. Vesiculobullous and papular lesions may be observed in association with the linear track.

Migration of the larvae through the skin occurs from a week to several months after initial penetration, depending on the type of roundworm. The rate of larval migration is from 2 mm to 2 cm per day, depending on the species of larva. Unlike in animals, the larvae are unable to penetrate the epidermal basement membrane of human skin; therefore, the larvae roam haphazardly in the epidermis and are unable to complete their life cycle.

An allergic immune response of the patient to the larvae or byproducts causes the pruritic erythematous track. The actual location of the larvae is usually 1-2 cm beyond the erythematous track.

Untreated lesions resolve after the larvae die (ie, within weeks to months).

Causes

The most common cause of CLM is Ancylostoma braziliense, which is a dog and cat hookworm found in the United States, Central America, South America, and the Caribbean.[12]

Other reported, less common, animal roundworms that cause CLM include the following:

  • Ancylostoma tubaeforme, Ancylostoma caninum, Ancylostoma ceylanicum, and Uncinaria stenocephala (ie, dog hookworms)

  • Bunostomum phlebotomum (ie, cattle hookworm)

  • Gnathostoma species (ie, cat, dog, and pig roundworms)

  • Capillaria species (ie, whipworms found in rodents, cats, dogs, and poultry)

  • Strongyloides myopotami, Strongyloides papillosus, and Strongyloides westeri (found in the small intestine of mammals)

  • Nematodes that use a human as a definitive host, such as Ancylostoma duodenale, Strongyloides stercoralis, and Necator americanus (rare causes of CLM): A duodenale and N americanus usually cause ground itch. S stercoralis is usually associated with larva currens.

CLM should not be confused with visceral larva migrans and ocular larva migrans, which are due to the ingestion of the eggs of the parasite Toxocara canis or Toxocara cati. Children with pica or people eating unwashed raw vegetables have the greatest risk of acquiring visceral and ocular larva migrans.

The following individuals are at risk of infection with CLM:

  • Sunbathers

  • Fishermen

  • Hunters

  • Gardeners

  • Construction workers

  • Pest exterminators

  • Children

  • Anyone with skin contact to sand or soil in warm areas

 

DDx

Differential Diagnoses

 

Workup

Laboratory Studies

Diagnosis of cutaneous larva migrans (CLM) is based on physical examination and history.

Skin biopsy is not usually helpful because the larvae are usually located several centimeters from the edge of the track.

A peripheral eosinophilia may be observed.[13]

Imaging Studies

A new technique, optical coherence tomography, has been found to identify the larvae in the epidermis, allowing direct removal.[14]

 

Treatment

Medical Care

Treatment of cutaneous larva migrans (CLM) is anthelminthics, with pruritus resolving within 24-72 hours and serpiginous tracts resolving within 7-10 days.[15, 16]

Antihistamines and topical corticosteroids can be used in conjunction with anthelminthics for symptomatic relief of pruritus.

Oral antibiotics are used if secondary impetiginization or cellulitis is present.

Surgical Care

Prior to the availability of anthelminthics, treatment by cryosurgery with liquid nitrogen, ethyl chloride spray, or carbon dioxide slush was effective in 60-70% of individuals with CLM.

Cryosurgery is painful and often requires multiple treatments. Cryosurgery at the leading edge of the track was imprecise because the migrating larvae are usually located several centimeters beyond this point.

Consultations

Consultation with a dermatologist, infectious diseases specialist, or both may be appropriate.

 

Medication

Anthelmintics

Class Summary

Anthelmintics are the drug of choice for cutaneous larva migrans (CLM). Parasite biochemical pathways are different from the human host; thus, toxicity is directed to the parasite, egg, or larvae. Mechanism of action varies within the drug class. Antiparasitic actions may include the following:

- Inhibition of microtubules causes irreversible block of glucose uptake

- Tubulin polymerization inhibition

- Depolarizing neuromuscular blockade

- Cholinesterase inhibition

- Increased cell membrane permeability, resulting in intracellular calcium loss

- Vacuolization of the schistosome tegument

- Increased cell membrane permeability to chloride ions via chloride channels alteration

Ivermectin (Stromectol)

Broad-spectrum anthelmintic that is not FDA approved for the treatment of CLM but is suggested as DOC by many studies. Single-dose therapy makes this drug convenient. Available in the United States because of FDA approval for treatment of onchocerciasis and strongyloidiasis. Selectively binds with glutamate-gated chloride ion channels in invertebrate nerve and muscle cells, causing cell death. Half-life is 16 h; metabolized in liver. Available in 3 mg tabs.

Albendazole (Albenza)

Broad-spectrum antihelminthic drug used in nematode and cestode infestations; not FDA approved for treatment of CLM but has been shown by many studies to be highly effective with no or minimal adverse effects. Available in the United States because of FDA approval for treatment of hydatid disease and neurocysticercosis. Decreases ATP production in worm, causing energy depletion, immobilization, and, finally, death.

Thiabendazole (Mintezol)

Standard treatment of CLM has been topical thiabendazole; however, high rate of relapse is noted. Also, with less common causes due to human nematodes, does not prevent development of systemic illness or eliminate intestinal reservoir. PO thiabendazole is only FDA-approved drug for treatment of CLM. Therapy with PO formulation has been fraught with adverse effects.

Mebendazole (Vermox)

Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell.

 

Follow-up

Deterrence/Prevention

See the list below:

  • Prevention of cutaneous larva migrans (CLM) is critical.

  • Advise patients to avoid sitting, lying, or walking barefoot on wet soil or sand.

  • Advise individuals to cover the ground with an impenetrable material when sitting or lying.

  • Pets should be dewormed.

  • Beaches that allow cats and dogs should be avoided.

Complications

See the list below:

  • Severely excoriated lesions causing secondary infection with Staphylococcus aureus or Streptococcus pyogenes may lead to edema, making the tracks less visible.

  • Heavy infestation of larvae may lead to Löffler syndrome, which is characterized by pulmonary infiltrates and eosinophilia.[17] In one study, only 12% of patients with Löffler syndrome and CLM had pulmonary symptoms, such as a cough.[18] Larvae localized to the skin may elicit a generalized sensitization with soluble antigens in the lung to cause the pulmonary infiltrates.

  • If human nematodes (ie, A duodenale, N americanus, S stercoralis) are the cause of CLM, topical treatments such as cryosurgery or 10% thiabendazole solution do not prevent systemic involvement. Monitor patients for several months after treatment for gastrointestinal and respiratory symptoms.

  • One individual with CLM reportedly experienced complications caused by erythema multiforme.[19]

Prognosis

See the list below:

  • Prognosis is excellent.

  • Even without treatment, the larvae eventually die and the cutaneous lesions resolve in weeks to months.

Patient Education

See the list below:

  • Advise individuals to cover sandboxes when not in use.

  • When on beaches, advise people to lie on beach towels, not directly on the sand, and to wear sandals or water socks.