Analytics Stories

CHAPTER 41What Caused the 1854 London Cholera Outbreak?

Epidemiology is the branch of medicine and public health that attempts to determine the causes and risk factors that result in people getting diseases. English physician John Snow (1813–1856) is considered by many to be the founder of modern epidemiology (see www.ph.ucla.edu/epi/snow/fatherofepidemiology.html). In this chapter, we will explore John Snow's incredible work that showed that water contaminated with the bacterium Vibrio cholerae caused terrible cholera epidemics in nineteenth-century England.

Cholera

Cholera is a dreaded infectious disease that causes severe diarrhea. If left untreated, cholera can lead to dehydration and death. Cholera is treated with intravenous fluids, antibiotics, and zinc supplements. There are still between one million and four million cases per year of cholera. Before the amazing work of Dr. Snow, many doctors believed in the Miasma theory, which posited the existence of particles in the air, miasmata, that traveled through the air and infected people with cholera (see www.ph.ucla.edu/epi/snow/choleratheories.html). Snow believed (correctly) in the germ theory, which states that cholera entered an individual through drinking infected water or eating infected food. Then, cholera spread through germ cells. As you will see, Dr. Snow collected data that tipped the scales in favor of the germ theory.

Snow and the Broad Street Pump

In late August 1854, a terrible cholera outbreak hit ...