Pediatric Cutaneous Larva Migrans

Updated: Nov 18, 2022
Author: Theresa M Fiorito, MD, MS, FAAP, CTH®; Chief Editor: Russell W Steele, MD 

Overview

Practice Essentials

Cutaneous larva migrans (CLM) is a serpiginous eruption that can occur anywhere on exposed body parts but is usually confined to the skin of the feet.[1]  It is most often 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

CLM occurs in humans after contact with larvae from animal nematodes (Anyclostomatoidea family). Known species include Ancylostoma braziliense and ​A caninum, among others,[1]  and the hosts are cats and dogs. The roundworm eggs pass through the feces and hatch in warm, shady, moist, sandy soil found in tropical and subtropical areas. Humans are inadvertently infected with the hatched larvae when walking barefoot on the sand.

The larvae quickly penetrate the skin upon contact. The larvae burden, and consequent quantity of tracts noted, ranges from one to hundreds. The rate of larval migration is from 2 mm to 2 cm per day, depending on the species of larva. An allergic immune response of the patient to the larvae or byproducts causes a pruritic erythematous track. The actual location of the larvae is usually 1-2 cm beyond the erythematous track.

The larvae cannot penetrate the epidermal basement membrane of human skin. The larvae roam haphazardly in the epidermis and are unable to complete their life cycle.  

Etiology

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.[6]

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) can cause ground itch. S stercoralis is usually associated with larva currens.

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

Epidemiology

United States statistics

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 the Southeast. CLM has also been reported to be the most frequent etiology for skin disease for those traveling to countries with poor sanitation.

International statistics

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]

Race-, sex-, and age-related demographics

CLM has no racial predilection.

No sex predilection is observed.

CLM affects all ages in the appropriate environment.

Prognosis

Prognosis is excellent. Due to the host-parasite "mismatch," the larvae cannot complete their life cycle, and therefore infection is self-limiting and cannot progress. Even without treatment, the larvae eventually die and the cutaneous lesions resolve in weeks to months.

Morbidity/mortality

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. Associated disruptions in concentration, sleep, and mood have been described. 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.

Complications

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.[12]  In one study, only 12% of patients with Löffler syndrome and CLM had pulmonary symptoms, such as a cough.[13]  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.[14]

Patient Education

Educate travelers on regions where CLM is most common, and tell them to avoid skin contact with moist soil, particularly if contaminated with animal feces.

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.

 

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 and progress millimeters to centimeters per day. Patients may complain of severe itching.

The most common location for penetration is the feet (39%), from walking barefoot in the sand. Cases have been described involving the buttocks and thighs. Presentation on other areas is rare.  

Physical Examination

The migration of the larvae produces a 2-mm to 4-mm wide, erythematous, linear or serpiginous tracks. The rash is associated with significant pruritis. 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.

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

 

DDx

Differential Diagnoses

 

Workup

Approach Considerations

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

Skin biopsy is not usually helpful because the larvae are typically located ahead of the tract.

Tissue specimens may show an inflammatory infiltrate made of eosinophils. The parasite itself is usually not visualized.

 

Treatment

Medical Care

The disease usually is self-limited, with spontaneous cure after several weeks; treatment may hasten resolution of symptoms. 

As CLM is self-limiting, it will resolve within several weeks. However, treatment with antihelminthics may considered to shorten duration of symptoms.[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.

Consultations

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

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.

Prevention

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.

 

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.