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Commentary: Nobody Loves a Critic: Edmund a Parkes and John Snow's Cholera


DOI: 10.1093/ije/dyt194

Koch, T. “Commentary: Nobody Loves a Critic: Edmund a Parkes and John Snow's Cholera.” International Journal of Epidemiology 42.6 (2014): 1553–1559. Web.

p.1553: History is not kind to critics. Its writers typically dismiss where they do not simply ignore those whose careful reviews argue caution in the face of works destined to become, in the future, classics. Think, here, Prince Peter Kropotkin whose naturalist studies focused upon the limits of Charles Darwin’s evolutionary theory and the direction in which research based upon it would be best directed. Only today—more than 130 years later—is the importance of his critique being acknowledged. -- Highlighted mar 15, 2014

p.1553: As an example of a good critic unfairly dismissed by history think Edmund A Parkes, the British physician and researcher who reviewed John Snow’s famous 1855 opus, On the Mode of Communication of Cholera. In a seven-page, approximately 7800-word essay, Parkes carefully considered and found wanting Snow’s argument that cholera (and plague, and typhoid fever) was solely waterborne. Although the myth of Snow's brilliance insists his critics were wrong, a careful reading of Parkes’ concerns insists that the myth of Snow is overstated. Yes, cholera is a waterborne disease. But were we to read Snow’s work with attention but without foreknowledge we, too, would find its argument incomplete. -- Highlighted mar 15, 2014

p.1553: This review of the 19th century debate over cholera has more than historical significance. It pits a simplistic, focused explanation against one that was broad and multifactorial. And, too, it demands attention be paid to the researcher’s methodologies and their sufficiency, not just results. Finally, it pits the myth of the lone researcher against the reality of science as a complex, communal, interactive process. -- Highlighted mar 15, 2014

p.1554: Snow admitted his evidence was ‘scattered and general a nature’, and his theory was thus offered ‘not as matters of certainty, but as containing a greater amount of probability in their favor than any other’ (quoting Snow on the Mode of Communication Cholera). -- Highlighted mar 15, 2014

p.1554: Time and again, Parkes complained that Snow continually stated possibilities as certainties and suppositions as fact. In a review of the Horsleydown data, for example, ‘instead of leaving the origin of the first case uncertain’, Parkes writes, Snow assumed without conclusive evidence its source; at Albion Terrace he insisted without proof that cholera ‘must’ have entered local drainpipes in the water even though other investigators argued different explanations. -- Highlighted mar 15, 2014

p.1554: relevant data by which Snow’s theories might have been rigorously considered within the science of the day were lamentably absent. ‘Now, certainly in no less than seven of the eleven cases’, Parkes concluded, ‘the evidence to prove the effect of the water is so loosely stated, and the accessory circumstance of the outbreaks are so utterly disregarded, that we do not think any one can feel that even a tolerable case is made out in favor of Dr Snow’s opinion’. -- Highlighted mar 15, 2014

p.1554: In 1849 Snow published amonograph arguing cholera as solely waterborne. His argument was based upon what recent biographers have called ‘a complex blend of epidemiological evidence, pathological observations, and bold analogies’. -- Highlighted mar 15, 2014

p.1554: relevant data by which Snow’s theories might have been rigorously considered within the science of the day were lamentably absent. ‘Now, certainly in no less than seven of the eleven cases’, Parkes concluded, ‘the evidence to prove the effect of the water is so loosely stated, and the accessory circumstance of the outbreaks are so utterly disregarded, that we do not think any one can feel that even a tolerable case is made out in favor of Dr Snow’s opinion’. 5 Dr Snow’s opinion’. -- Highlighted mar 15, 2014

p.1554: Perhaps the most famous of Snow’s examples, his analysis of the Broad Street outbreak exemplified for Parkes the author’s conceptual and methodological limits. Snow employed two very different types of analysis, both then common in disease studies. The first included a recitation of case reports and the second was cartographic. -- Highlighted mar 15, 2014

p.1555: Snow provided neither the type of comparative nor even descriptive statistics, then widely employed, that might have strengthened his mapped argument. In the 1854 Broad Street study the local curate, Rev. Henry Whitehead, published in 1854 a monograph replete with descriptive statistics of the outbreak and its relative impact on citizens. Without that type of analysis Snow’s mapped argument was open to multiple interpretations. -- Highlighted mar 15, 2014

p.1555: Recognizing this deficit, perhaps, in an 1855 report to a parish inquiry Snow remapped the data, correcting several small errors, and included an irregular polygon based on greater proximity to the Broad Street well than to all others (Fig. 1). Street well than to all others (Fig. 1). He did not, however, use this to calculate relative mortality among persons living within this area. Nor did he create other polygons around other pumps in a manner that would permit comparisons of mortality based on population between the Broad Street and other pump regions. As a result the map was inconclusive and, in Snow’s study, statistics that might have strengthened his case were largely absent. -- Highlighted mar 15, 2014

p.1558: The myth of Snow’s brilliance is thus transformed from a hero story into a cautionary tale. Snow had a good idea. Indeed, he had a great idea. Cholera is waterborne, after all. But in presenting this idea, and a disease theory tied to it, he failed to employ the best methodologies of the day (cartographic or statistical) and in his enthusiasm rushed to print, again and again, before necessary data were available. In arguing his theories he rarely gave more than grudging attention to other disease theories or to the data that seemed to support them. He refused to modify his arguments or change his methodology, when presented with the work of others that seemed at odds with his own. -- Highlighted mar 15, 2014

p.1558: But, ‘We need heroes, don’t we?’ a member of the conference audience asked plaintively. It does not matter if Snow was a hero or a chump, in other words. We need to believe in the solitary genius as we face the disease challenges of our own time. Snow is a symbol, in other words, and the truth of his work as a researcher does not matter. My reply is a suitable conclusion to this essay and its relevance: ‘Yes, we need heroes. But we don’t need a Lone Ranger who singlehandedly saves the day.’ When we make the hero a solitary figure we forget the cooperative nature of medicine and public health. There are no solitary heroes in the struggle with endemic and pandemic disease, just the many who struggle to treat them and understand their nature. -- Highlighted mar 15, 2014

p.1558: To ignore Snow’s failings because we want a simple hero is to assure the failure of the science we promote and practise. It is to assure that public health disasters will follow. -- Highlighted mar 15, 2014