Answer: Cholera Outbreaks

In the 1850s, there was an outbreak of cholera in Soho, London. This outbreak, like all serious disease outbreaks in the past, was attributed to pollution or a noxious form of “bad air”, otherwise referred to as the miasma theory of disease transmission. The germ theory of disease didn’t exist yet and it was widely believed that all disease was transmitted by foul air.

The 19th century physician John Snow was a skeptic of this theory and conducted his own research on the outbreak in 1854. With the help of a sympathetic local reverend (Henry Whitehead) from St. Luke’s Church, who knew the neighborhood around the largest outbreak site very well, Snow conducted door-to-door surveys and mapped out occurrences. Through his surveying and mapping, he eventually determined that all of the afflicted people had used water from a specific public water pump on Broad Street. Although his testing of the water was inconclusive, his urging led officials to shut the pump down and the outbreak diminished rapidly thereafter.

Although the individual organisms were undetected by Snow at the time, we now know that cholera is caused by fecal contamination of water sources and that his efforts to shut down the contaminated public water pump did stop the spread of the outbreak. His work on the outbreak case and his efforts to scientifically locate and analyze the source is regarded as the founding moment in the science of epidemiology.