Cutaneous larva migrans — DTM&H MCQ

Correct answer: B — Ivermectin or albendazole

The correct answer is B, ivermectin or albendazole, because this vignette describes cutaneous larva migrans (CLM), caused by penetration of the skin by dog or cat hookworm larvae (typically Ancylostoma braziliense) after barefoot contact with faecally contaminated sand, classically on Caribbean or other tropical beaches. The intensely pruritic, serpiginous, migrating track on the sole is pathognomonic. Although self-limiting, treatment is recommended to relieve severe itch, shorten the clinical course and prevent secondary bacterial infection from scratching. Oral anthelmintics (ivermectin as a single dose, or albendazole for three to five days) are the systemic treatments of choice, with topical thiabendazole reserved for early, very localised lesions. Why the other options are wrong: A. Topical steroid alone: this only dampens the inflammatory itch response and does nothing to kill the migrating larva, so the track will continue to advance and symptoms will recur once the steroid is stopped. E. Metronidazole: this is an antiprotozoal and antibacterial agent active against organisms such as Giardia, Entamoeba and anaerobes; it has no activity against migrating hookworm larvae. C. Praziquantel: this is the treatment for trematode and cestode infections (schistosomiasis, tapeworms); it is not effective against nematode larvae such as those causing CLM. D. Chloroquine: this is an antimalarial with no anthelmintic activity, and there is no history here suggestive of malaria (no fever, no mosquito exposure implied, and the lesion is cutaneous and serpiginous, not systemic). Key point: a serpiginous, intensely itchy track on the sole after walking barefoot on a tropical beach is classic cutaneous larva migrans, treated with oral ivermectin or albendazole.

Reference: DermNet NZ, Cutaneous larva migrans (2024), https://dermnetnz.org/topics/cutaneous-larva-migrans