Tumbu fly myiasis — DTM&H MCQ

Correct answer: A — Cordylobia anthropophaga

The correct answer is A, Cordylobia anthropophaga (tumbu fly). This blowfly is endemic across sub-Saharan and Central Africa and is the classic cause of furuncular cutaneous myiasis in travellers and residents of this region. Its defining epidemiological feature, and the discriminator in this stem, is that gravid females lay eggs on clothing or bedding left outdoors to dry, particularly on the ground or on low washing lines; the eggs hatch and larvae penetrate intact skin on contact with the garment, aided by host body heat. This behaviour distinguishes it from other myiasis-causing flies, which use different transmission strategies. Prevention centres on ironing or hot-drying laundry, or drying it off the ground, which kills the eggs before contact with skin. Why the other options are wrong: C. Dermatobia hominis: This is the New World botfly of Central and South America, not Central Africa; it uses a phoretic mechanism, attaching its eggs to a mosquito or other arthropod that then deposits the larva onto the host during a blood meal, not via clothing. D. Cochliomyia hominivorax: The New World screwworm, found in Central/South America, causes wound myiasis by laying eggs directly on necrotic or open wounds of living hosts, not on drying clothing. B. Chrysomya bezziana: The Old World screwworm is found in Africa and Asia but causes obligate wound myiasis, with eggs laid on wounds or mucous membranes, not on garments. E. Wohlfahrtia magnifica: This fly is found in southern Europe, the Middle East and parts of Asia and, like screwworms, oviposits on wounds or soiled areas of skin rather than on laundry. Key point: Only Cordylobia anthropophaga transmits via eggs laid on clothing dried outdoors, making this behaviour pathognomonic for tumbu fly myiasis in a Central African patient.

Reference: CDC DPDx, Myiasis, https://www.cdc.gov/dpdx/myiasis/index.html