Source: Health & Place 10, 115-116, 2004.


Cholera, chloroform, and the science of medicine: a life of John Snow

Peter Vinten-Johansen, Howard Brody, Nigel Paneth, Stephen Rachman, and Michael Rip; Oxford University Press, New York, Oxford, UK, 2003, ISBN: 0-19-513544-X

For those interested in the relation between health and place, few thinkers have been more seminal than the 19th century anesthesiologist and researcher John Snow. In the 20th century, his mid-19th century studies of cholera took on mythic proportions in all the fields whose concern is the spread of endemic and especially epidemic disease.

Over the last decade this myth of the lone genius researcher, the man who "discovered" the cause of cholera, medical mapping, and modern epidemiology, has been attacked by a range of writers (McLeod, 2000, for example). As a result, it has become almost as common to disparage the myth of John Snow as it is to teach the tale of his 19th cholera investigations in a simplistic way. It is one thing to know the myth is overblown and that the iconic maps Snow constructed are perhaps just maps. When the myth is deconstructed and the icon smashed, however, the problem becomes how to understand what's left.

The answer lies in this new work's detailed reconstruction of Snow's work and the context intellectual, medical, and social in which he created his singular studies in anesthesia and disease transmission, especially his seminal studies on cholera. The authors ignore the myth and concentrate on the history of Snow's work, building a detailed argument on the nature of his theories and the body of work that he left. The result is not simply a new look at Snow but a detailed example of how to consider the relation between health and place.

The son of a Yorkshire farmer, John Snow was a medical apprentice at the time of the first cholera pandemic that began in England 1831. At that time Snow was in charge of the medical care, under his medical senior, of coal miners severely effected by the outbreak. In his later works Snow would argue repeatedly, within his greater argument on disease transmission, a correlation between the mine environment and the severity of the outbreak (Snow, 1849, 1854). The lack of appropriate cooking, sanitation, or water facilities in the mine created, for Snow, a perfect context for the interpersonal transmission of disease.

"The mining population of this country has suffered more from cholera than any other, and there is a reason for this. There are no privies in the coal pits and I believe this is true of other mines: as the workers stay down the pit about 8 hours at a time, they take food down with them which they eat, of course, with unwashed hands, as soon as one pitman gets the cholera, there must be great liability of get their hands contaminated, and to acquire the malady" (Snow, 1854).

It was the perceived relationship between the environment and the diseases they encouraged that helped propel Snow's general thesis of cholera transmission. As the authors of this new work note, Snow's theories were built upon clinical experience in not only the Newcastle-area mines but also the homes of densely settled urban areas like the Soho, London neighborhood where he lived when cholera returned in 1849 and 1854.

Where drinking and washing waters co-mingled, and where people lived, ate, and died together in a single room it was inevitable, Snow wrote, that, "they must accidentally swallow some of the excretion, and leave some on the food they handle or prepare, which has to be eaten by the rest of the family, who amongst the working classes often have to take their meals in the sick room" (Snow, 1854).

Snow was neither the first person to argue a sanitarian position nor the first to use maps to attempt to show a correlation between environmental conditions and disease. In the 1790s Seaman mapped a New York City yellow fever outbreak, for example (Stevenson, 1965). A generation later, Pascalis mapped another outbreak in the same area of New York City (Stevenson, 1965; Shannon, 1981). In both cases the researchers argued foul, odiferous local waste materials, found in the area of greatest occurrence, were the causes of the outbreak.

What truly distinguished Snow's work from that of his predecessors, or his contemporaries, the authors of this work argue, was both the nature of his thesis and the manner he developed for its testing. They point out his rejection of the miasmatic theory of disease generated by foul odors in the air owed much to his standing as an anesthesiologist with a special understanding of gasses. "He knew from years of research, most recently on the properties of anaesthetic agents, that gases were injurious to health only at a close range in very high concentration" (Vinten-Johnsen et al., 2003, p. 9). That, combined with his clinical experience and the simple observation that choleric symptoms were gastrointestinal rather than pulmonary led to his theory of contamination from ingestion and person-to-person transmission at three different scales: that of the individual, of the neighborhood, and in the greater population.

Snow tested his theory at two different scales of analysis, that of the outbreak in the Soho area in which he lived and the greater epidemic outbreak occurring in South London. Others had seen the potential of Snow's thesis but could conceive of no way to test it. Using the General Register Office's weekly return of births and deaths in London, and "shoe leather research", he developed the studies for which he remains famous today.

This new work is equally powerful in its reconstruction of Snow's thinking and of the research itself. The famous Soho outbreak, and Snow's study of it, are reconstructed on a daily basis, with maps orienting the reader to the deaths in the densest area of the outbreak near the Broad Street pump. Equally important is the detailed description of Snow's statistical analysis of the South London epidemic. It is this recreation of Snow's thinking and work that adds enormously to previous descriptions of Snow's pivotal studies.

The authors provide a superb discussion of Snow's Soho outbreak maps both the iconic 1854 map and one drawn for an 1855 parish report (Snow, 1855) as well as those of others made by his contemporaries. Surprisingly, however, they neither critically discuss Snow's map of the South London study nor include it in this work. Both as a map and as an attempt at describing environmental conditions that promote a disease outbreak this was the more most ambitious of Snow's studies, and of his use of maps to summarize complex arguments. The failure to give it sufficient attention may be, for some, a lack in this otherwise quite complete and wholly innovative study of Snow's oeuvre.

One reason for this omission may be the authors' more general contention that medical mapping is typically an illustrative adjunct to medical investigation but rarely integral to medical or epidemiological studies, including Snow's. In the final chapter's discussion of Snow's cartographic legacy they are dismissive of the uses made of the Soho outbreak map by more contemporary researchers and cartographers. The desire for a "foundation myth in medical cartography, particularly GIS, contributes to the remarkable persistence of false versions of the Broad Street incident and Snow's role as an investigator and public health figure" (Vinten-Johnsen et al., 2003, pp. 398-399).

Even if true, and the point is debatable, this begs the question whether the problem is with medical cartography generally (illustrative but not substantive), GIS mapping specifically, or represents something entirely different (Koch, in press). However it is interpreted, the authors' critique of contemporary medical mapping stands as a challenge to those believe it a valuable tool in public health, and more generally in consideration the relation between health and place.

Issues of mapping aside, this new book must be perceived as the critical text, the standard by which any future work on Snow and his fundamentally ecological perspective is to be considered. It takes the myth of the lone investigator, the singular genius, and replaces it with a detailed description of a collegial researcher who helped create the type of modern investigation of health and illness that is public health, epidemiology, and perhaps, medical geography today.


Koch, T., in press. The map as intent: variations on the theme of John Snow. Cartographica.

McLeod,K., 2000. McLeod, K., 2000. Our sense of Snow: the myth of John Snow in medical geography. Social Science & Medicine 7&8, 923-936.

Shannon, G.W., 1981-2. Disease mapping and early theories of yellow fever. Professional Geographer 33, 221-227.

Snow, J., 1849. On the Mode of Transmission of Cholera. Churchill, London.

Snow, J. 1854. On the Mode of Transmission of Cholera, 2nd Edition ed., Churchill, London.

Snow, J. 1855. Dr. Snow's report. Parish of St. James, Report of the Cholera Outbreak in the Parish of St. James, Westminster, during the Autumn of 1854. Churchill, London, pp. 97 120.

Stevenson, L.G., 1965. Putting disease on the map: the early use of spot maps in the study of yellow fever. Journal of the History of Medicine and Allied Sciences 20, 226-261.

Vinten-Johnsen, P., Brody, H., Paneth, N., Rachman,. S., Rip, M., 2003. Cholera, Choloroform, and the Science of Medicine: A Life of John Snow, Oxford University Press, New York, London.

T. Koch

University of British Columbia, 1984 West Mall Vancouver, British Columbia V6T 1Z4, Canada

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