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Gorgas Case 2007-11 |
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We hope you have enjoyed the 2007 series of live cases each week from Peru. The Gorgas Diploma Course runs annually in February and March and we will be in touch at the beginning of next year's case series.
The following patients were seen in the outpatient department of the Tropical Medicine Institute.   History: Two brothers 13 and 11 had spent 2 weeks on vacation in Mexico, with the last week at the beach in Puerto Vallarta. Just prior to return home the older brother noted the onset of a pruritic linear rash on the foot, which has migrated and advanced 1-2 cm per day over 2 weeks. A few days into the illness multiple similar lesions appeared over the right arm. The younger brother had onset of his lesions 3 days after his older brother. Epidemiology: Lifelong residents of an upper class district of Lima. No recent domestic travel in Peru. Physical Examination: Afebrile. Chest clear. No lymphadenopathy. Skin lesions shown in Images A (13-year-old's foot), B (13-year-old's arm), and C (11-year-old's foot). Laboratory Tests: CBC normal with normal WBC differential.
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Diagnosis: Cutaneous Larva Migrans due to Ancylostoma braziliense.
Discussion: This is a clinical diagnosis with pathognomonic clinical findings as demonstrated in the Images. 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. Travelers should be warned against bare feet when going to beaches in tropical areas where local dogs and cats may be present. As the larvae can penetrate intact skin anywhere on the body, avoidance of any direct contact of exposed skin with the sand should be recommended. 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 2003-1], 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 be 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.
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