At Home - Bill Bryson [196]
The miasma theory had just one serious flaw: it was entirely without foundation. Unfortunately only one man saw this, and he couldn’t get others to see it with him. His name was John Snow.
Snow was born in York in 1813 in modest circumstances—his father was a common laborer—and however much that might have colored his life socially, it served him well in terms of insightfulness and compassion, for almost uniquely among medical authorities he did not blame the poor for their own diseases, but saw that their conditions of living left them vulnerable to influences beyond their control. No one had ever brought that kind of open-mindedness to the study of epidemiology before.
Snow studied medicine in Newcastle, but settled in London. There he became one of the leading anesthesiologists of his day, at a time when anesthesia was still an unnervingly unproven field. Rarely has the word practice been more apposite with respect to a doctor’s endeavors. Even now anesthesia is a delicate business, but in the early days when dosages were based on little more than hunches and hopeful assumptions, coma, death, and other dire consequences were all too common. In 1853, Snow was called in to administer chloroform to Queen Victoria as she underwent labor in her eighth pregnancy. The use of chloroform was highly unexpected because it was not only new—it had been discovered, by a doctor in Edinburgh, just six years before—but also decidedly dangerous. Many people had died under its application already. To use it merely to help the queen cope with the pain of childbirth would be, in the view of most medical men, wildly incautious. The Lancet reported the matter as a worrying rumor and professed itself astonished that any qualified medical man would take such risks with the royal personage in any circumstance less than a crisis. Yet Snow seems to have had no hesitation in applying chloroform then or later, even though he was vividly and continually reminded of the risks of anesthetics in his practice. In April 1857, for instance, he killed a patient by experimenting on him with a new type of anesthetic, amylene, and misguessing what was the tolerable dosage. Exactly one week later he was applying chloroform to the queen again.
When not helping people lose consciousness before surgery, Snow spent a great deal of time trying to understand where diseases came from. He particularly wondered why cholera devastated some neighborhoods while sparing others. In Southwark, the rate of cholera deaths was six times higher than in next-door Lambeth. If cholera was caused by bad airs, then why would people in contiguous boroughs, breathing the same air, have such discrepant rates of infection? Besides, if cholera was spread by smell, then those who dealt most directly with bad odors—toshers, flushermen, nightsoil handlers, and others whose livelihood was human waste—ought to be the most frequent victims. But they weren’t. After the 1848 outbreak, Snow couldn’t find a single flusherman who had died of cholera.
Snow’s lasting achievement was not just to understand the cause of cholera but also to collect the evidence in a scientifically rigorous manner. He made the most careful maps showing the exact distributions of where cholera victims lived. These made intriguing patterns. For instance, Bethlehem Hospital, the famous lunatic asylum, had not a single victim, while people on facing streets in every direction were felled in alarming numbers. The difference was that the hospital had its own water supply, from a well on the grounds, while people outside took their water from public wells. In the same way,