1. Epidemiology:
the branch of medicine that deals with the incidence, distribution, and possible control of diseases and other factors relating to health.

2. Epidemiology:
Epidemiologists collect tons of data and then statistically analyze it to interpret patterns in health and the spread of disease

3. Epidemiology:
First used by a British physician named John Snow who collected data in 1854 to find the source of a Chloera epidemic in London

4. Epidemiology:
By plotting incidences of cholera on a neighborhood map, Snow found the source was from a water pump on Broad street that was being contaminated with waste water.

5. The Broad Street pump today
Epidemiology:
Authorities removed the handle from the water pump and the cholera epidemic subsided.
The Broad Street pump today