We live longer now than we used to, you know? One thing I've learned from books I've read is that cancer probably appears to be increasing because people live longer, and cancer is mostly a disease of older people. But we're living longer in part because we're much better at preventing and treating other diseases – diseases that used to kill lots of people – like cholera, which you rarely hear about anymore.* Now we understand what causes those diseases and how they spread. Before scientists had powerful microscopes and understood the role of germs, the theory was that most illness and even epidemics were due to "miasmas," which is a Greek word for polluted or unhealthy air. After all, a truly awful smell can affect both your nose and your stomach if it's strong enough, and might even inhibit your mental capabilities.
But in 1854 a cholera epidemic broke out in the Soho area of London and affected both upper and lower-classes of people, and both clean and filthy houses. But two people who spent a great amount of time visiting those afflicted in the area – without becoming sick themselves – were able to pinpoint the cause of the problem. One was an English physician named Dr. John Snow. He visited the houses affected and concluded correctly that the water from the Broad Street pump was the culprit. Even though not everyone was convinced, the pump handle was removed and the epidemic died out. The Reverend Henry Whitehead also visited those afflicted and was able to prove Dr. Snow's conclusion, even tracking down the exact source – both the individual and the defective sewer that had leaked cholera into the water supplied by the Broad Street pump.
The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World
by Steven Johnson was incredibly fascinating. The detail of how Dr. Snow came to his conclusion and how Rev. Whitehead proved and tracked it back to the source; the descriptions of how cholera is transmitted and what it does to the body; and the explanations of how it affected the city and those who suffered had me hanging on every word. If Mr. Johnson had stopped there I'd be singing his praises, but... the "ghost map" comes up in the lengthy conclusion and epilogue when he compares the mapping efforts by Dr. Snow, the Rev. Whitehead, William Farr, and others with today's disease tracking methods. Unfortunately, he strains credibility by stretching this idea further into Google and Yahoo maps for coffee shops, etc. then goes on a rant about the "population explosion" and the benefits and problems of densely populated cities. In fact, while the idea of urban environments is a thread throughout the book, he tries to analyze their value as a solution to global warming against potential nuclear disasters and terrorist attacks (with a lengthy discussion of Sept 11). While I highly recommend the history in the book, the author's attempts to apply the lessons (however tenuously) to several modern-day concerns was dull and I found myself wishing the book would just end.
So, watch what you drink and skip the epilogue.
* Although cholera is unheard of here in the U.S., it still affects 3-5 million people worldwide and as many as 130,000 die each year (2010 estimate), primarily in developing countries.