People living in the low-lying marshes around Rome suffered fevers with unusual frequency. At the time, they blamed the murky, damp air rising from the swamps — the "bad air." In Italian, bad is mala and air is aria, and combined they were called mala aria. This phrase entered English in the 18th century as the single word malaria. The real culprit, however, was not the air but the mosquitoes breeding in those marshes. That a mosquito-borne parasite caused the disease was not discovered until the late 19th century, and even after the truth came out, the name never changed. So to this day we still call this disease by the name of an old misunderstanding: "bad air."