Cutaneous Larva  Migrans

Definition:

A serpiginous eruption ( figure 1) usually confined to the skin of the feet, arms, or buttocks, is caused by dog and cat hookworms, which are types of nematodes

(roundworms). Skin findings are due to a hypersensitivity reaction ( figure 2) to the worms and their byproducts.

Commonly is found in tropical and subtropical climates Can also occurs in the temperate zones in the warmer months of the year, infection most.

Pathophysiology:

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. Humans are accidentally infected with the larvae by walking barefoot on the sand. The larvae quickly penetrate the skin upon contact.

In travelers , beaches are the most common reservoir for cutaneous larva migrans; however, infection can occur from sandboxes and soil under houses or at construction sites..

Frequency:

• Internationally: Worldwide distribution is reported predominantly in tropical zones. Indigenous to the Caribbean, Central and South America, Africa, and Southeast Asia.

Morbidity:

• Morbidity is associated with an intensely pruritic rash, and  secondary cellulitis.

History:

• The patient with cutaneous larva migrans may recall a stinging sensation upon initial penetration of the larvae.
• An erythematous papule or  dermatitis can develop hours after penetration. The migration of the larvae produces a 2- to 4-mm wide erythematous, elevated, vesicular serpiginous track (figure 3).

• The most common location for penetration is the feet (walking barefoot in the sand) followed by the hands, arms, and buttocks.

•  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).

Causative organisms:

• Ancylostoma Brazilians, which is a dog and cat hookworm.

Other less common animal roundworms

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

• Bunostomum phlebotomum (ie, cattle hookworm)

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

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

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

• Nematodes that use man as a definitive host, such as Ancylostoma duodenale, Strongyloides stercoralis, and Necator americanus (rare causes of cutaneous larva migrans)

• individuals are at risk:

• Sunbathers – Beach walkers

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

Diagnosis:

• Diagnosis is based on physical examination and history.

• A peripheral eosinophilia may be observed.

Differential diagnosis:

Scabies

Erythema chronicum migrans of Lyme disease
Ground itch
Larva currens
Migratory myiasis
Stings by the Portuguese man-of-war or jellyfish

 Medical Care:

• Treatment involves use of anthelminthics, with pruritus resolving within 24-72 hours and serpiginous tracts resolving within 7-10 days.

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

• Oral antibiotics are used if secondary  cellulitis is present.

1. Anthelmintics

• Albendazole (Albenza: Single 400 mg PO dose.  This drug can be obtain through  Health Canada’s  Emergency Access Program .

• Ivermectin (Stromectol): Single 12mg dose therapy

• Thiabendazole (Mintezol) –25 mg/kg twice daily for 5 days.  Also used  topically  0.5 mg tablet crushed in 5 g of petroleum jelly daily for 5 days (high rate of relapse).

2. Cryosurgery is painful and has very little place with modern antihemintics.

Prognosis:

• Prognosis is excellent in most travelers.

Prevention:

• Prevention 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.

• 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. Walking on the wet – firm  part  of the beach will reduce the risk.
• Preventing dog  access to beaches.

PAUL ASSAD MD

TRAVELDOC@SHAW.CA

H: 604-536-5517

FAX: 604-541-4824

References:

 Mason’s Tropical Diseases: pages1392-  1394.

Internet pictures.