I recently finished reading The Ghost Map by Steven Johnson, a gripping account of a deadly cholera outbreak that struck London in the summer of 1854. Scientists of the time were convinced that cholera was an air-born disease brought on by the appalling sanitary conditions of Victorian-era London. Yes, London was a squalid place and inadequate waste and garbage removal was responsible for the potent smell that permeated the city. However, the root of the problem was not in the air but in the water. The water-born theory was first proposed by Dr. John Snow, based on his observations of the number of victims who were clustered near a particular fresh water pump. Snow was convinced that the pump was infected with the cholera bacteria and that drinking water from the pump was responsible for so many deaths. To help visualize the theory, he drew a black line on a map to indicate where each victim resided at the time of death. The map also pointed out the location of all water pumps in the area. Clearly there was a correlation between the pump and the number of deaths near it. Superstitions die hard, but eventually the map helped sway opinion away from the air-born theory.
It’s thrilling to see how innovative thinking and good information graphics played a heroic role in solving a frightening medical mystery. Yes, good infographics can save lives.