Cholera
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A person may get cholera by drinking water or eating food contaminated with the cholera bacterium. In an epidemic, the source of the contamination is usually the feces of an infected person. The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water.
Shellfish eaten raw have been a source of cholera, and a few persons in the United States have contracted cholera after eating raw or undercooked shellfish from the Gulf of Mexico. Cholera is common in many non-industrial areas of the world and epidemic outbreaks sometimes occur. Cholera is of particular risk after natural disasters in areas with poor or no water treatment.
Superstition
A widely-held theory in western Europe during the Middle Ages was that disease was caused by a miasma, i.e., an atmosphere polluted by air from decaying bodies or from swamps. Risky areas could be identified by a bad smell.
Epidemiology
During an outbreak of cholera in London in 1854, John Snow plotted on a map the location of all the cases he learned of. Water in that part of London was pumped from wells located in the various neighborhoods. Snow's map revealed a close association between the density of cholera cases and a single well located on Broad Street. Removing the pump handle of the Broad Street well put an end to the epidemic. This despite the fact that the infectious agent that causes cholera was not clearly recognized until 1905.
Summary
For thousands of years it was believed that disease arose from "bad air," organisms were spontaneously generated from muck, and that the supernatural made it impossible for man to control the conditions of his life. These ideas were slowly eroded by experiments that
clearly demonstrated cause and effect - organisms came only from their parents and disease was caused by germs.
Excerpted and adapted from: Cholera, Miasma theory of disease, Epidemiology
Reference: Broad Street Pump Outbreak
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