Question

{"given":"Kala-azar (visceral leishmaniasis) and oriental sore (cutaneous leishmaniasis) are diseases caused by the protozoan parasite Leishmania.","key_observation":"Leishmania is a digenetic parasite; its intermediate (vector) host is the sand fly of the genus Phlebotomus, which transmits the disease to humans.","option_analysis":[{"label":"(A)","text":"Housefly","verdict":"incorrect","explanation":"Houseflies are mechanical vectors for diseases like typhoid and cholera, but they do not transmit Leishmania."},{"label":"(B)","text":"Bed bug","verdict":"incorrect","explanation":"Bed bugs are associated with skin irritation and are not vectors for Leishmania."},{"label":"(C)","text":"Sand fly","verdict":"correct","explanation":"The female sand fly (genus Phlebotomus) is the intermediate host and vector for Leishmania donovani (causing kala-azar) and Leishmania tropica (causing oriental sore)."},{"label":"(D)","text":"Fruit fly","verdict":"incorrect","explanation":"Fruit flies (Drosophila) are model organisms in genetics and are not disease vectors for Leishmania."}],"answer":"(C)","formula_steps":[]}