In the Beginning
Almost two hundred years ago, the methodology for investigating the occurrence and movement of infectious diseases in populations was born. It happened in London during the cholera epidemic of 1836 with the work of the English physician John Snow (1, p.246). It was an era in which epidemics of infectious diseases caused by yet unidentified “things” were decimating populations throughout Europe.
Dr. Snow studied the eating and living habits of patients who had cholera and neighboring townspeople who did not have cholera for the purpose of identifying the similarities and differences between the groups. It is noteworthy that Dr. Snow examined people who did not get cholera as well as those who did. As a result of the current disregard in medical research of this practice of looking at both sick and non-sick people, important lessons available from subjects who are resistant to disease remain unrecognized.
Dr. Snow ultimately found a strong association between cases of cholera and a public well into which sewage was found to be draining. Dr. Snow requested that the pump handle of the offending well be removed. The immediate cessation of new cases of cholera was his proof that sewage-contaminated water was a cause of cholera.