John Snow is known as the father of modern epidemiology, best remembered for helping end the 1854 cholera epidemic in London. At the time no one yet knew that cholera is caused by bacteria, but Snow had long suspected that it was transmitted by food or water. In the hard-hit neighborhood of Soho where hundreds had died, Snow mapped the location of the homes of the victims and could see that most lived near the Broad Street water pump (see image below). Snow was able to persuade local officials to remove the handle of the pump and soon the epidemic subsided.