I was on a bit of a non-fiction/science tear at the end of last year. And yes, I’m still posting on the books that I read last year. I’m only a month behind. The Ghost Map by Steven Johnson is a historical narrative, a cautionary tale, and just good science writing.

Ghost Map Book Cover

The book’s subheading tells the tale: “The Story of London’s Most Terrifying Epidemic - and How It Changed Science, Cities, and the Modern World.” I had learned about the epidemic in some course work, but it turns out that I only knew part of the story. The story that gets passed along in classes is about the great public health pioneer John Snow. John Snow was a ground breaking doctor who also pioneered the safe use of anesthesia for surgery. When an outbreak of cholera struck London, Dr. Snow set out to prove once and for all that foul smells were not the cause of the outbreaks (the “miasma theory” was the prevailing wisdom of the time).

Dr. Snow’s best known contribution to epidemiology was the mapping of cases in an outbreak - the map of the title. Through the use of the map, collected data, and statistics, Dr. Snow was able to show that cholera was a waterborne disease and could be prevented through basic sanitation. (Johnson does a great job of breaking down what this means in simple terms - keep people from drinking poop.) He did this years before microscopes would see the bacterium that causes the disease. Too bad it would be another decade before anyone would believe him (that part is not part of the popular “great man” curriculum).

The part of the story is largely unknown is that Dr. Snow didn’t do it alone. A parish priest, Reverend Whitehead, contributed by setting out to prove Snow wrong. As he began collecting data that he intended to use to disprove Snow, he begas to find pieces of information that actually strengthened Dr. Snow’s case. The connections that Whitehead found would have gone mostly unnoticed by Snow, who was not as knowledgeable about the people and geography of the neighborhood.

Sorry if I’ve lost you by now. This is fascinating stuff to me, and Steven Johnson does a great job presenting the historical facts of the case. Johnson’s real contribution in the book is the connections that he makes between this case and its impacts on modern life. At the time of the outbreak, Johnson tells us, it was not a given that packing millions of people into small geographic areas was a good idea at all. In fact, there were many who predicted that the model would soon fail. They needed only to point to the filth and disease of Victorian London as a clear example of why the idea must fail.

The cholera epidemic described in the book lead directly (in time) to sewer, clean water, and other public health reforms that made living in cities possible. Now, for the first time in human history, more of us live in cities than live in rural areas. Johnson’s epilogue focuses on the promise and the challenges that lie in the future for cities. The model of the cholera epidemic point to how quickly a devastating an little understood disease could impact large numbers of people. To day nothing of terror events mounted by small numbers of people. It’s heady stuff.

Needless to say I though the book was excellent, but it was a perfect fit for my non-fiction interests. If it’s your thing, check it out. Cool fact: In modern London, near ground zero of the outbreak, is a neighborhood pub called The John Snow. Next time I’m in London, it’s on my itinerary.

Ghost Map lagniappe: