Reviewed by Robin Lewis
Steven Johnson’s The Ghost Map is the story of how logic and compassion converged through two individuals, John Snow and Henry Whitehead, to help develop epidemiological science in the face of a dogmatic insistence on theories of miasma and a prevailing sentiment that disease was primarily a problem of the lower moral and socioeconomic classes.
The Ghost Map is the story of the Broad Street Epidemic, an outbreak of cholera in 1854 London, and two individual’s combined efforts to understand and prevent the suffering and death associated with the disease.
This is a Victorian detective mystery worthy of Sherlock Holmes. Dr. Snow had knowledge of the then nascent understanding of microorganisms and how they contribute to disease and Mr. Whitehead began recording the fatalities on his ghost map. What became clear was that there was a connection to the Broad Street Pump, known for its clear and pleasant water, which furnished water to the neighborhood. Further investigations showed that there were no cases of cholera among the poor and morally suspect inmates of the nearby workhouse who had their own well, or from the workers in the local brewery who sampled their own products and had little reason to drink from the Broad Street well, yet who breathed the same air.
The story and the issues faced by Snow and Whitehead are not so different than some we face today, where insistence on unproven and unhealthy, but accepted, medical practices reduces quality of life. and where better ideas struggle to be accepted.
Quoting from The Lancet of that time, “Why is it then that Dr. Snow is so singular in his opinion? Has he any facts to show us proof? No!” Dr. Snow did have convincing evidence in the form of Whitehead’s map of the contagion and the histories of the people shown on it, but as is said in the book, “It takes time to believe in logic.”
An important lesson to be taken from the book is the advantage held by those with direct experience when combined with advanced education. Snow, as a physician, had studied the appropriate science and was ready to apply it to the situation at hand, but without Whitehead’s local knowledge, and his recording of what was happening, Snow’s knowledge might well have remained theory.
Whitehead’s map may have shown a pattern, and possibly people might have been stopped from using the well if enough people could have been convinced, but by then the epidemic may well have completed its cycle.
The observations made thorough direct personal contact on a daily basis are indispensible to understanding how best to provide vision care. Clinical practice provides the largest and arguably most compelling evidence base in vision care. Visual science helps us gain fresh insight into the evidence base. It took Whitehead’s map to define the pattern, and Snow’s research to help understand it.