John Snow, Inc. - About JSI

Creative thinking about seemingly intractable problems, uncovering new perspectives, finding simple solutions, and implementing them is JSI's mission. By offering innovative, clear, and practical consulting services, we work in the spirit of John Snow and hope to continue the work he began many decades ago.

Dr. John Snow

Dr. John Snow (1813 - 1858)
"The prevention of epidemic or communicable diseases is a subject that deserves increased investigation, for diseases influence the life, the death, and the numbers of the human race, more than all others."

In 1854 a cholera epidemic raged across Europe. The onset of the disease is sudden and death can result in as little as a week. In London, one devastating outbreak at the beginning of September claimed the lives of over 500 people in just ten days. The search for the cure and the cause was fast and furious, but no one seemed able to stop the insidious epidemic.

That is until one man with a hypothesis successfully traced the source of infection. Dr. John Snow had observed cholera first-hand in 1831 as an apprentice surgeon, but it was only 17 years later, in 1848-1849, that he developed a new theory for the mechanism of cholera transmission. Contrary to the prevailing belief, Snow argued that cholera was a disease of the gut and that the causal agent must enter through the mouth and then multiply within the gut of the sufferer, subsequently spreading to others. Dr. Snow reasoned that broad transmission of cholera had to be due to drinking water contamination.

In September 1854, when Dr. Snow was called on to examine the causes of the cholera epidemic, he turned immediately to the water supply. His previous research suggested that the localized nature of the outbreak would mean that the cause had to be a contaminated pump or well, rather than a problem with the general water supply. He discovered that while there were five water pumps in the neighborhood, most of the deaths took place near the pump on Broad Street. Upon further investigation he discovered that among the deaths of people situated farther from the Broad Street pump, half of the deceased preferred the water from the Broad Street pump to their nearer pump, and another third attended school near the ill-fated pump. Upon presentation of his findings to community leaders, the handle of the Broad Street pump was removed, and the epidemic quickly abated. Further investigation of the well discovered that a sewer pipe underground was leaking raw sewage into the drinking water of the Broad Street pump.

Broad Street water pump
London

Dr. John Snow realized that a spot map illustrating the location of the deaths in the Broad Street cholera outbreak would be a useful addition to his report. Snow’s famous map was first exhibited at a meeting of the Epidemiological Society of London in December 1854.

2004 marks the 150th anniversary of Dr. John Snow’s investigation of the Broad Street pump handle—one of the earliest examples of epidemiological research. Dr. Snow has received many accolades and his work continues to be celebrated. Known as the "father of modern epidemiology," Snow was voted the greatest doctor ever in a Hospital Doctor poll in March 2003. The John Snow Society promotes his life and works, and organizes the annual Pump handle Lecture Series. With over 1000 members, the Society brings together the world’s preeminent epidemiologists.

Find out more about Dr. John Snow, a legendary figure in the history of public health, epidemiology and anesthesiology.