The Ghost Map.

Our current understanding of the ways in which diseases spread goes back to a little-remembered cholera epidemic that devastated a London neighborhood in 1854, when a physician-scientist and a minister began working, first on their own and then together, to trace the outbreak’s origins. In a time of superstition and errant beliefs in “miasmas,” these two men realized through hard work, going door to door at one point to ascertain where each household obtained its water, that the agent causing the disease was spread through human waste that contaminated a particular water supply. In The Ghost Map: The Story of London’s Most Terrifying Epidemic – And How It Changed Science, Cities, and the Modern World, author Steven Johnson tells this story in the fashion of a medical mystery – until a pointless epilogue full of speculation about the future of epidemics and treatments that has aged very poorly in the 16 years since its publication.

Cholera today is a disease of extreme poverty, and even more so of the lack of infrastructure that accompanies it; nearly all cholera outbreaks occur in desperately poor (or desperately corrupt) countries, or in those ravaged by war. Large outbreaks occurred in Syria during the early part of its civil war and Yemen during its endless civil/proxy war. In the third quarter of 2023, the hardest-hit countries, measured by cholera cases per capita, were Syria and Afghanistan, followed by Haiti, Bangladesh, and several countries in sub-Saharan Africa. The disease, caused by the bacterium Vibrio cholerae, first emerged in India in 1817 and then spread around the world, killing over 35 million people, with multiple pandemics affecting Europe and North America, until advances in sanitation and public health helped eliminate the disease in more affluent countries. Those advances, and the lives saved, all came about because of the work of physician and scientist John Snow and Anglian priest Henry Whitehead.

Snow was an avid researcher and experimented with ether and later with chloroform, developing more reliable methods of anesthetizing patients that brought him significant renown, to the point where Queen Victoria called on him to assist her with chloroform during the birth of her eighth child, Prince Leopold. He took a general interest in cholera’s spread during the pandemic that first reached England in 1848, publishing a paper that argued that the prevailing theory that it was spread via polluted air, the “miasma” theory, was wrong. That outbreak eventually petered out, but cholera returned to England in 1854, leading to a horrific outbreak near Broad Street in London’s Soho district. Snow created a dot map to track cholera cases in the neighborhood, gaining help from Whitehead in going door to door to ask families about cases in the house – including houses where the majority of family members had died – and, after Snow’s initial research identified the Broad Street pump as a possible link between nearly all of the cases, where they got their water.

When Johnson tells this history, which takes up about 80% of the book, it’s fantastic. He balances the historical details, the science, and the biographies of the two main characters in the story well enough to maintain the interest level without ignoring the significance of the effort or the context in the history of science. He also has quite a bit of detail on some of the families destroyed by the outbreak, and on the quotidian lives of the inhabitants of this overcrowded part of what was becoming a massively overcrowded city. It’s a great, brisk history of science book.

If he’d stopped there, around page 200, I’d be raving. Unfortunately, there’s a long, tacked-on epilogue that goes well beyond the scope of the book in both its historical and scientific aims. Johnson couldn’t have known that we’d have several epidemics and one global pandemic before 20 years were up, but the larger point is that this book is about history, not predictions, and his don’t hold up particularly well. I read the epilogue wondering if an editor had asked him to add it, because it’s so out of character with the rest of the book.

That’s not a reason to skip The Ghost Map – you can always choose not to read the last bit – and the story it’s telling remains extremely relevant. The work the CDC and the WHO did to track SARS-CoV-2 in 2020, or that they’re doing right now to track current epidemics like chikungunya in Burkina Faso or Mpox in the Democratic Republic of the Congo, is a direct ancestor of the work that Snow and Whitehead did in 1854. If the field of epidemiology has an origin point, it’s their efforts, and we have them to thank for all of the outbreaks of highly infectious diseases that never reach our shores.

Next up: I just finished R.F. Kuang’s Babel and started Tana French’s In the Woods.