Hail to the Chiefs, Snow and Jenner!
Both John Snow (1832) and Edward Jenner (1768), though separated in time by half a century more or less, were keen observers and listeners in a scientific epoch fraught with superstition and lack of scientific method and technique. The relative tools at their disposal (microscopes, for the most part) were rudimentary and scarce at best, and the mechanisms and biology of their fields of interest, namely cholera and cowpox (Variolae vaccinae), respectively, had as yet to be elucidated. Snow and Jenner, therefore, were epidemiologic pioneers, in the truest sense of the word. They theorized, hypothesized, and postulated, based on their observations and conviction that believing did not mean seeing all things in great detail. In fact, while they strived to maximize their knowledge of the biology and pathogenesis of cholera and cowpox, they were conscious of their limitations and mindful of the fact that they might prevent disease in the absence of pathogenetic omniscience. The inability of our two heroes to view infectious material by the light of day or microscope, in no way lessened their contribution to the definition/individuation of the “morbid matter” or “poison” of cholera and cowpox. Due to the primitive nature of the scientific instrumentation and methodology of their day, Snow and Jenner were constrained (which honed their observational skills, however) to recognize infectious material by effect, not by physical properties. Voilà! The birth of observational epidemiology.
John Snow approached the problem of cholera in Great Britain in a systematic manner. He sought direct physical proof, and studied disease extension indirectly also, in order to clarify disease communication via passage of morbid material from the sick to the healthy. Snow’s insight into the route and mechanism of cholera infection, his definition and individuation of morbid matter, his equation of period of incubation to period of reproduction of infectious progeny, and his targeting of factors favoring spread of cholera and modes of communication, not only saved countless lives and served as a gold standard for the epidemiologic methodology to follow, but also provided a basis for preventive interventions and public policy in mid-19th century England. In fact, based on his observations and recommendations, an Act of Parliament was enacted to regulate common lodging-houses, where cholera festered. This had the effect of reducing fatality rates in later epidemics.
Edward Jenner, in 1768, became convinced that cowpox would confer immunity to smallpox. His inquisitive nature and perseverance served him well from 1768 to 1797, a particularly fertile period for his epidemiologic and experimental research. During that timeframe, by means of observational data collection, monitoring, and surveillance, he elucidated the etiology, route of communication, pathologic anatomy in both cow and human subjects, symptomatology, and progression of the cowpox disease. Jenner noted the similarities and differences between Variolae infectious material and that of other viruses. What makes that a singular feat was the fact that Jenner operated under purely observational criteria, in an 18th century devoid of deep understanding of the workings and biology of the cowpox virus. He set the machine in motion, proposing the hypothesis that infection with cowpox would protect against subsequent smallpox infestation, and then he sought to test that hypothesis in the notable cases of Elizabeth Wynne in 1797 and of William Smith from 1780 to 1795.
We come away from the stories of these two great men with one recurring theme in mind, and it is that incomplete knowledge of the biology and pathogenesis of disease in no way precludes disease prevention. While more is always better, something goes a long way in epidemiology, public heath, and preventive medicine.
Personally speaking, I learned four important lessons from reading about Snow and Jenner’s technical methodologies, which are as valid today as they were in the 18th and 19th centuries. First of all, epidemiologic observations in and of themselves are of little value if not translated into public policy. Secondly, effective preventive services can and must be implemented, regardless of the holes in our scientific knowledge. Next, public health medicine is an entity unto itself, and I would be a fool if I claimed right now to know the similarities and differences between public health medicine and clinical medicine. Finally, prevention and his little brother therapy are not mutually exclusive. While the former should come first, this is not a “chicken and egg” proposition. There is no shame in big brother asking the little fella to lend a hand.
In the days of their unrecognized glory, Snow and Jenner relied on “leg work,” determination, and force of ideas to accomplish what computers and artificial intelligence hands us today on a silver platter. That makes their contribution to the body of epidemiologic and scientific knowledge all the more awe inspiring. The simplicity of Snow’s “shoe leather epidemiology” and Jenner’s unwavering preoccupation with human experimentation (damn the ethical considerations and implications) stand tall in the arena of today’s billion dollar projects, especially when cost-effectiveness (doing the greatest good with the resources available) is a concern.
All hail the chiefs! In a post-9/11 world, we may find ourselves looking more to the likes of Snow and Jenner than to Hubble telescopes.
© 2007, Albert M. Balesh, M.D. All rights reserved.
John Snow approached the problem of cholera in Great Britain in a systematic manner. He sought direct physical proof, and studied disease extension indirectly also, in order to clarify disease communication via passage of morbid material from the sick to the healthy. Snow’s insight into the route and mechanism of cholera infection, his definition and individuation of morbid matter, his equation of period of incubation to period of reproduction of infectious progeny, and his targeting of factors favoring spread of cholera and modes of communication, not only saved countless lives and served as a gold standard for the epidemiologic methodology to follow, but also provided a basis for preventive interventions and public policy in mid-19th century England. In fact, based on his observations and recommendations, an Act of Parliament was enacted to regulate common lodging-houses, where cholera festered. This had the effect of reducing fatality rates in later epidemics.
Edward Jenner, in 1768, became convinced that cowpox would confer immunity to smallpox. His inquisitive nature and perseverance served him well from 1768 to 1797, a particularly fertile period for his epidemiologic and experimental research. During that timeframe, by means of observational data collection, monitoring, and surveillance, he elucidated the etiology, route of communication, pathologic anatomy in both cow and human subjects, symptomatology, and progression of the cowpox disease. Jenner noted the similarities and differences between Variolae infectious material and that of other viruses. What makes that a singular feat was the fact that Jenner operated under purely observational criteria, in an 18th century devoid of deep understanding of the workings and biology of the cowpox virus. He set the machine in motion, proposing the hypothesis that infection with cowpox would protect against subsequent smallpox infestation, and then he sought to test that hypothesis in the notable cases of Elizabeth Wynne in 1797 and of William Smith from 1780 to 1795.
We come away from the stories of these two great men with one recurring theme in mind, and it is that incomplete knowledge of the biology and pathogenesis of disease in no way precludes disease prevention. While more is always better, something goes a long way in epidemiology, public heath, and preventive medicine.
Personally speaking, I learned four important lessons from reading about Snow and Jenner’s technical methodologies, which are as valid today as they were in the 18th and 19th centuries. First of all, epidemiologic observations in and of themselves are of little value if not translated into public policy. Secondly, effective preventive services can and must be implemented, regardless of the holes in our scientific knowledge. Next, public health medicine is an entity unto itself, and I would be a fool if I claimed right now to know the similarities and differences between public health medicine and clinical medicine. Finally, prevention and his little brother therapy are not mutually exclusive. While the former should come first, this is not a “chicken and egg” proposition. There is no shame in big brother asking the little fella to lend a hand.
In the days of their unrecognized glory, Snow and Jenner relied on “leg work,” determination, and force of ideas to accomplish what computers and artificial intelligence hands us today on a silver platter. That makes their contribution to the body of epidemiologic and scientific knowledge all the more awe inspiring. The simplicity of Snow’s “shoe leather epidemiology” and Jenner’s unwavering preoccupation with human experimentation (damn the ethical considerations and implications) stand tall in the arena of today’s billion dollar projects, especially when cost-effectiveness (doing the greatest good with the resources available) is a concern.
All hail the chiefs! In a post-9/11 world, we may find ourselves looking more to the likes of Snow and Jenner than to Hubble telescopes.
© 2007, Albert M. Balesh, M.D. All rights reserved.
posted by Dr. Al at
5/28/2007 07:55:00 AM
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