Infectious disease and the birth of the modern city

by Tara Smith     Department: Health & Life Sciences

Today's New York Times has an interesting story discussing how infectious diseases have helped to shape the modern city, centering on a 1832 outbreak of cholera. Cholera is a potentially deadly water-borne disease caused by the bacterium Vibrio cholerae. The bacterium itself is somewhat of a boomerang or kidney bean shape, and can be found in a number of aquatic environments of varying salinity. Cholera has killed millions over the past 200-odd years, frequently re-appearing in pandemic form after initially emerging from India in the early 1800s. Infection with the bacterium can lead to severe gastrointestinal problems, and the production of copious amounts of "ricewater stool." Death is generally due to severe dehydration. It's also a bacterium that has played a key role in the development of the very science of epidemiology. John Snow, considered the "grandfather" of epidemiology, became famous for tracing a 1854 outbreak of cholera in London to a contaminated well, introducing the basic principles of epidemiology along the way. (This outbreak was discussed in a recent book, The Ghost Map.)

Because of the copious amounts of body fluids that could be expelled by a cholera victim, living in an overcrowded, filthy mid-19th century city was an ideal way to contract the disease. Especially in the more impoverished areas, people lived in crowded squalor; night soil--aka human waste--spilled out of open sewers and into the streets, and contaminated nearby rivers and wells: an excellent way to spread a bacterium like cholera. I mentioned in my previous post how critical clean water and sanitation are; the cholera outbreaks of the past in America and Europe demonstrate quite clearly just how far we've come, and the possibilities that exist for other countries still trying to modernize.

Like today, those with the means were fairly well-protected from diseases resulting from a lack of sanitation. In the heat of the summer, many of a city's wealthier inhabitants would simply flee to country homes and escape from the putrid stench, looking down upon the city's poor. Many believed the lower classes deserved the diseases that resulted from living in such filthy slums:

Unlike most upper-class residents, John Pintard, the respected civic leader who was the historical society's founder, remained in the stricken city. His letters to one of his daughters are included in the exhibition ["Plague in Gotham! Cholera in Nineteenth-Century New York," at the New-York Historical Society].

The epidemic, he wrote in an attitude typical of his peers, "is almost exclusively confined to the lower classes of intemperate dissolute & filthy people huddled together like swine in their polluted habitations."

In another letter, his judgment was even harsher. "Those sickened must be cured or die off, & being chiefly of the very scum of the city, the quicker [their] dispatch the sooner the malady will cease."

During the 1832 outbreak in New York, the general consensus was that it was these noxious vapors--"miasmas" ("bad air")--that caused disease. John Snow's investigations into the source of cholera--dealing the miasmatic theory a striking blow--were still more than 20 years in the future, and the experiments of Pasteur, Koch, and others which led to the formulation of the modern germ theory of disease were another couple of decades beyond that. While this scientific understanding of illness has provided us with ways to prevent and treat disease, the construction of modern cities--and their oft-overlooked marvels of engineering, their sewers--has provided us another.

Tags: bacteria, Cholera, public health, sanitation