Book Review: The Ghost Map

Set in 19th century London with its open sewers, slaughterhouses and scavengers, Steven Johnson has written a highly compelling book about the cholera epidemic that raged through the streets and the individuals who were able to solve the deadly puzzle through common sense and persistence. Although scientific in its contents with many references to the principles of epidemiology, the book reads like a detective story with villains and heros.

When in 1854 people in the Soho district of London start dying like flies after severe attacks of diarrhoea, sheer panic erupts among local residents. Those able to run, do so in haste and those who cannot, wait in anguish for their fate, hoping the mysterious disease will skip their crowded homes. Within 10 days the casualty rate is up to 500 and rising. Johnson astutely compares the presumed experience of terror to a hypothetical contemporary biological attack gone real: a world where it was not out of the ordinary for a complete family to be wiped out in a matter of 48 hours.


He then skips to describe the life of John Snow, a quiet and humble yet remarkably intelligent anaesthetist whose extensive research on ether and chloroform seems completely unrelated to the previously described devastating epidemic. Johnson seems to encourage the readers’ bewilderment a bit more as he meticulously tells about Dr. Snow administering chloroform to Queen Victoria in order for her to painlessly deliver her eighth child. We begin to acknowledge Dr. Snow’s skills and methodological thinking that Johnson describes as consilience, yet his character remains stiff, unfathomable at times.


Johnson then serves us a surprisingly entertaining look at London’s mid 19th century society and smoothly connects it to the handle of the cholera epidemic. The prevailing explanation on the mortal matter was that the disease transmitted itself through foul air (like mal-aria): the miasma theory. The idea itself was hardly challenged and Johnson even uses brain imaging examples to underline the fact that smell is a powerful tool to provoke feelings of lust or repulsion. It sheds light on the perseverance of the miasma theory and simultaneously on Dr. Snow’s fruitless efforts to question the theory when he discovers that the mortality rate is by no means related to the presence of foul smelling air in the city using the infamous ‘ghost map’.


And here the long awaited detective story finally unwinds: we all know Dr. Snow will eventually uncover the secrets of Vibrio cholerae (although the organism itself was discovered by an Italian) and its transmission but his fastidiousness and methodology in achieving that is simply astonishing; a pure example of a beautifully set up research project with unprejudiced interpretation of yielded results. Eventually Dr. Snow needs the help of a converted local reverend named Henry Whitehead to convince the people that the Broad Street pump is the source of all (their) trouble, but most credits for solving the mystery undoubtedly belongs the former. It is therefore hardly surprising that John Snow is the founder of the London Epidemiology Society and was voted best British physician of all time in 2003. Additionally, there is a John Snow society at the London School of Hygiene and Tropical medicine for students and tutors alike to pay homage to a great scientist and thinker of our time.


Steven Johnson has succeeded in writing a pleasant scientific cops-and-robbers story with plenty of tasteful trivia and references to the past as well as the present. His style makes it accessible for anyone interested: medical and non-medical. That the good-ones eventually prevail and that terror has been defeated in the end only satisfies our instinctive desire for justice.


Steven Johnson, The Ghost Map

ISBN 978-0-141-02936-8

€ 11,99