Sandfly leishmaniasis vector — DTM&H MCQ

Correct answer: A — Phlebotomine sandfly

The correct answer is A, Phlebotomine sandfly. The clinical picture of chronic ulcerating papules on exposed skin following evening bites near rodent burrows, with intracellular amastigotes seen on smear, is classic for cutaneous leishmaniasis, which in the Syria/Middle East region is caused by Leishmania major or L. tropica. These parasites are transmitted exclusively by phlebotomine sandflies, which feed at dusk and night and breed in cryptic sites such as rodent burrows and rubble, explaining the rural, nocturnal exposure pattern in the stem. The amastigote (intracellular) form is diagnostic of Leishmania on Giemsa-stained smear or biopsy, distinguishing it from other vector-borne parasites that circulate as trypomastigotes or microfilariae. Sandfly bite avoidance (bed nets, repellents, avoiding dusk-to-dawn exposure) is the mainstay of prevention in endemic conflict-zone deployments. Why the other options are wrong: D. Triatomine bug: transmits Trypanosoma cruzi (Chagas disease) in the Americas, producing trypomastigotes in blood, not intracellular amastigotes on skin smear, and is not found in Syria. B. Blackfly: transmits Onchocerca volvulus (onchocerciasis), causing subcutaneous nodules and microfilariae in skin snips, not amastigotes. C. Cyclops copepod: is the intermediate host for Dracunculus medinensis (Guinea worm), acquired by drinking contaminated water, not by biting insects or skin ulcers with amastigotes. E. Hard tick: transmits organisms such as Borrelia or Rickettsia, causing eschars or erythema migrans, not chronic ulcers with intracellular amastigotes. Key point: chronic ulcerating skin lesions with intracellular amastigotes after nocturnal bites near rodent burrows in the Middle East point to Leishmania transmitted by the phlebotomine sandfly, not any other arthropod or intermediate host.

Reference: NaTHNaC TravelHealthPro, Leishmaniasis, https://travelhealthpro.org.uk/disease/103/leishmaniasis