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2006 Case #6 |
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| This patient was seen in the outpatient department of the Tropical Medicine Institute. |
 History: 31 yo female with 12 days of a pruritic rash characterized by multiple erythematous small papular lesions on the abdomen. A few days into the illness she had the onset of similar lesions on the back, arms, legs and buttocks with a tendency to coalesce. 7 days into the illness the lesions began to extend in a linear manner. Self-treatment with benzyl benzoate for scabies and then with topical clotrimazole was ineffective. The patient reported anorexis and general malaise. No significant past medical history.
Epidemiology: Born in Mexico, currently a biologist living in Arizona, spent the previous month in the jungles of Madre de Dios (Tambopata), Peru studying wildlife. Physical Examination: Afebrile. Chest clear. No lymphadenopathy. Representative skin lesions shown in Images A and B. Laboratory Examination: CBC normal with normal WBC differential. |
| Diagnosis: Cutaneous Larva Migrans due to Ancylostoma braziliense. |
| Discussion: This is a clinical diagnosis with pathognomonic clinical findings as demonstrated in the Images. On further enquiry the patient had been traveling for an extended period in a river taxi laying back on a wet and dirty bag made of jute. Cutaneous larva migrans, or creeping eruption, is the term that describes the characteristic migratory dermatitis caused by initial invasion of the skin by the larva of animal or human nematodes. The larvae of the dog and cat hookworm Ancylostoma braziliense account for almost all of the clinically obvious skin lesions. Because Ancylostoma braziliense does not mature or complete its life cycle in humans, the immature larvae may wander superficially for up to several months before their spontaneous death. The larvae move up to 1-2 cm per day. Biopsy of the lesions is not recommended, as the larvae are rarely isolated. Usually the larvae have migrated ahead of any inflammatory response and it is difficult to know in what direction the larva has advanced. Cutaneous larva migrans is found in any moist warm climate and is found in the southeastern USA as well as throughout the tropics.
Larvae of human hookworm may cause an initial pruritic lesion but rarely migrate in the skin before traveling to the lung and then the intestine as they mature and complete their life cycle. Other causes of creeping eruption include gnathostomiasis [see example in Gorgas Case 2003-01], which tends to cause more hemorrhagic and less distinct linear tracks, and strongyloidiasis, which causes a variant usually called larva currens. Larva currens occurs due to autoinfection whereby filariform larvae of Strongyloides stercoralis passed in the stool invade perianal skin and re-infect the same host. The lesions are usually in the perianal, buttock, or abdominal region only. The lesions are highly pruritic but have a predominant urticarial component and progress up to several cm per day. They may be present for several weeks. Loa loa, a subcutaneous filarial infection of west and central Africa causes a migratory and transient angioedema, predominantly around joints. Linear lesions are not found. Treatment is with ivermectin 12 mg po which can repeated, once, a day later or with Albendazole 400 mg po for 3 days. Most clinicians prefer ivermectin. Thiabendazole topical therapy still mentioned in many textbooks is no longer used and cryotherapy still used by some dermatologists is much less effective. Because of the fecal origin of the larvae, bacterial superinfection can result but antibiotics are generally only recommended if purulent infection is clinically present. The patient had already received ivermectin in the jungle for several days prior to presentation and reported significant improvement in the pruritus though the lesions themselves had not started to resolve. |