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The Ghost Map: The Story of London’s Most Terrifying Epidemic—and How It Changed Science, Cities, and the Modern World

By Steven Johnson

Reviewed by PSR member John Lamperti

I do most of my impulse buying in discount book stores, and I recently acquired a treasure: The Ghost Map, The Story of London’s Most Terrifying Epidemic–and How It Changed Science, Cities, and the Modern World by Steven Johnson (Riverhead Books, 2006). As the subtitle makes clear, this book tells the story of London’s sudden and deadly cholera outbreak in August, 1854, and how Dr. John Snow correctly traced it to a certain public water pump in the heart of the Soho district. Snow managed to have that pump disabled, which apparently ended the epidemic after some 500 people had died in only ten days.

When I joined PSR many years ago, this story was an important theme for the organization. Certainly it showed Dr. Snow epitomizing the ideals of careful and logical analysis, followed by action to put the conclusions to socially beneficial use. In some versions of the story, Snow removed the pump’s handle himself in an act of civil disobedience to save lives. PSR developed its “Broad Street Pump Award”, named for Snow’s act, to recognize outstanding service to public health by activists over the years, and a new generation of PSR activists are now emerging to follow Dr. Snow’s example. Meanwhile, Dr. John Snow’s original contributions are deservedly remembered; for many, he is the “father of epidemiology.” An excellent web site devoted to Snow’s life and work is a continuing project of Ralph R. Frerichs of UCLA.

The Ghost Map tells this story accurately and in detail, and makes fascinating reading. Some corrections were needed. For example, Snow did not remove that pump handle himself but somehow persuaded local authorities to do it – even though they did not believe his diagnosis of water-borne disease. Also, disabling the Broad Street pump apparently did not itself stop the first cholera outburst which was already declining. However, as Johnson explains, it very probably did prevent a second deadly outbreak from the same source.

At the time, belief in airborne transmission of many diseases including cholera, the “miasma” theory, was the mainstream view. Sanitary conditions in poor sections of London were appalling, and the pervasive odor of animal and human excrement combined with rotting garbage and industrial stenches made the foul air explanation seem plausible. Overcoming this general belief required the careful assembling of convincing evidence, and this Snow did with help from a local minister; his famous map plotting the cholera deaths helped cement the case.  Even so, the general shifting of medical opinion took years to complete.

John Snow’s career did not begin with cholera. Coming from extremely humble beginnings—his father was a rural laborer—Snow was a rare example of social mobility.  His best known prior achievement was making anesthesia practical and safe, greatly expanding its use.  Unlike his cholera theory, this advance was widely accepted.  That Snow provided anesthesia for Queen Victoria’s last two childbirths was a dramatic testimony to his professional and social success.

The Ghost Map tells much more than the story of Dr. John Snow, and more than the story of Vibrio Cholerae; it sketches the evolution, and speculates on the future, of urban civilization itself. The book begins with a vivid look at 1850s London, describing its army of scavengers, densely crowded districts, and tens of thousands of cesspools, many of them overflowing into basements and yards.  New sewers were being constructed to carry that waste directly into the River Thames, polluting it horribly in only a few years. This was considered a public health advance since it reduced the stench in city neighborhoods (miasma theory of disease), even while much of London’s population of some 2 ½  million was drinking the increasingly filthy river water. Such conditions are largely foreign to today’s “developed world”—but not everywhere, since the World Health Organization reports that “there are an estimated 3–5 million cholera cases and 100,000–120,000 deaths due to cholera every year.”  All of them could be prevented; it is not knowledge but political will that is lacking.

The Ghost Map presents one physician’s inspiring example of social responsibility; Dr. Snow could qualify as PSR’s patron saint. The book is a fascinating read as well.  I recommend it to PSR’s members, and urge our organization to restore the Broad Street Pump Award to a prominent and visible place in PSR’s public image.

Image: Wellcome Images / Wikipedia

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John Lamperti is a professor emeritus of mathematics at Dartmouth College. Since 1985, one of his main interests has been Central America; he is the author of Enrique Alvarez Cordova: Life of a Salvadoran Revolutionary and Gentleman. He has been a PSR member for more than 30 years.