Most doctors believed cholera arose from miasmas, or bad air. Others thought it was contagious and spread from person to person by touch. Neither was true. The fruitless attempts of health boards to locate the source of the disease stimulated satire, as in the cartoon below.
The main source of cholera infection was/is water polluted by human wastes. The first person to demonstrate the water borne theory was John Snow, a London surgeon, in 1855. But some people suspected the water well before Snow. In the cartoon from 1832 below, George Cruikshank indicates that some people even then pointed to the sewage-polluted Thames as the source of cholera in London. "We shall all have the cholera" one person cries, as sewers empty their contents into the river.