skip to main content

Brown recluse spider bite — DTM&H MCQ

Instant feedback + full explanation. One question, done properly.

ModerateEnvironmental HealthBrown recluse spider biteDTM&H

A 28-year-old aid worker in Somalia develops a slowly expanding necrotic skin ulcer on the forearm after handling an unknown arthropod. The lesion has a central black eschar surrounded by vesicles. What is the most likely cause?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Brown recluse spider (Loxosceles) bite

Necrotic arachnidism with a central eschar, surrounding vesicles, and progressive necrosis is characteristic of Loxosceles (brown recluse) spider bite. The venom contains sphingomyelinase D causing local tissue necrosis. Treatment is supportive with wound care, antibiotics for secondary infection, and possibly dapsone for severe necrosis. Scorpion stings cause intense pain but typically not necrotic ulcers.

Reference: Manson's Tropical Diseases; Swanson & Vetter, NEJM