Section 24. Aquatic Infestations

Cutaneous larva migrans is a skin infestation caused by nematode larvae that penetrate the skin and migrate leaving a characteristic erythematous, serpiginous burrow underneath the skin.

Synonym Creeping eruption.

Epidemiology

Age Children > adults.

Gender M = F.

Incidence Uncommon.

Etiology Hookworm larvae of cats/dogs (Ancylostoma braziliense, Uncinaria stenocephala, A. caninum), cattle (Bunostomum phlebotomum), or other nematodes.

Geography Common in warm, humid, sandy, coastal areas, central United States, southern United States, central America, South America, and the Caribbean.

Pathophysiology

In animal hosts (dogs, cats), the hookworm penetrates the skin and spreads through the lymphatic and venous systems to the lungs, breaks through into the alveoli, migrates to the trachea, and is swallowed. The hookworm then matures in the intestine and produces eggs that are excreted by the animal host. Once the animal defecates infested feces, the hookworm ova in the sand or soil hatch into larvae. The larvae penetrates the skin of accident hosts (humans) when they are stepped on with bare feet, but cannot cross the basement membrane. Thus the larvae wander serpiginously under the skin giving it the nickname “creeping eruption.”

History

Larvae tend to penetrate the skin and begin to migrate at a rate of 1 to 2 cm/d for 4 weeks to 6 months and may cause pruritus. After aimless wandering, the larvae typically die and the cutaneous tracts self-resolve. Systemic symptoms are absent.

Physical Examination

Skin Findings

Type Tracks/burrows (Fig. 24-1).

Color Flesh colored to pink.

Size Width 2 to 3 mm, extending at 1 to 2 cm/d.

Number One, several, or many tracks.

Distribution Exposed sites: feet, lower legs, buttocks, and hands.

General Findings

Visceral larvae (typically Toxocara canis, T. cati, A. lumbricoides) can cause peripheral eosinophilia, hepatomegaly, and pneumonitis.

Differential Diagnosis

The differential diagnosis of cutaneous larvae migrans includes phytophotodermatitis, tinea pedis, erythema chronicum migrans, jellyfish sting, and granuloma annulare.

Laboratory Examinations

Dermatopathology PAS may show larva in a suprabasalar burrow, spongiosis, intraepidermal vesicles, necrotic keratinocytes, chronic inflammatory infiltrate with many eosinophils.

Course and Prognosis

Cutaneous larva migrans is typically self-limited because the human skin is an accidental “dead-end” host. Most larvae die after 2 to 4 weeks of aimless wandering underneath the skin, and the skin rash ...