Historical Roots of Epidemiology – Part 2

I am going to take a slightly different approach to my study of Historical Roots. Instead of reviewing every article, I am instead going to discuss important topics that will be covered on the comps. I will use the readings as references to the ideas and points I will try to make. My approach will be that of someone who is trying to explain the topic to a novice.

The first topic is Miasma Theory and Cholera, in which I will discuss the miasma theory of disease within the historical context, the competing theory(ies), and how cholera fits within the picture. I will try to emphasize the important events and characters that shaped this topic.

The miasma theory of disease was one in which diseases (such as cholera) was the result of polluted air caused by foul water, waste, filth, and decomposition of living matter. Removal of waste, improved sanitary conditions, and better ventilation were thought to prevent or cure the disease. It was not an illogical connection given the association of poor sanitation and disease prevalence. It was a popular theory of disease through the Middle Ages and was only later supplanted by the germ theory of disease supported by such figures as John Snow and Robert Koch.

Sir Edwin Chadwick was a 19th social reformer whose primary contribution was to the improvement of sanitary conditions in England. Perhaps his most influential written work 1842 report titled,<!–[if !mso]> st1\:*{behavior:url(#ieooui) } <![endif]–> On an Inquiry into the Sanitary Condition of the Labouring Population of Great Britain. An excerpt of this report is part of the required reading. In brief, the report comes to a number of conclusions about the relationship between sanitary conditions and the presence of bodily and moral diseases in the population. It is interesting that not only does Sir Chadwick champion better public sanitation infrastructure for the laboring classes in order to prevent disease, but that the miasma also contributes to the moral evils of these unsanitary areas.

John Simon was also a 19th sanitation reformer and supporter of the miasma theory. He along with others, including Dr. William Farr, a influential proponent of the miasma theory, published Report of the Committee for Scientific Inquiries in Relation to the Cholera-Epidemic of 1854, which is another of the required readings. In the excerpt, it appears Dr. Simon is discussing environmental factors affecting atmospheric conditions and thus the miasma. Such factors include electrical discharge (lightning in the formation of ozone from oxygen), solar light, atmospheric pressure, temperature, presence of fog, mist, or haze, and lack of air circulation. 

He attempts to note that in a previous outbreak of cholera, (1) that it was characterized by atmospheric conditions (of those mentioned above) that render the air less “pure”, and (2) these factors are more apparent in the areas of London most afflicted with cholera. Then follows a detailed account of examinations of the air and water around London for the presence of organic and chemical products in places where cholera was most frequent and less frequent or absent. While microscopy techniques were available at the time, perhaps it was not developed to the point of identifying something as small as the cholera bacterium.With respect to water purity, they could find no reason to suspect some mineral contaminant and it appears that a parasitic organism was ruled out on the basis that other known parasites do not cause symptoms similar to cholera. However, they seem to not completely rule out that some organic contaminant as a result of some “decaying animal product within or without the body” may be a danger for cholera or like diseases.

Dr. Thomas Southwood Smith was a contemporary and collaborator of Dr. John Simon. He wrote A Treatise on Fever in 1830 within the context of the miasma theory of disease. In the causes of fever, he first distinguishes between immediate causes (which he calls ‘exciting’ causes) and secondary causes that brings the body into the condition to be affected by the primary causes (‘predisposing causes’). He explicitly states the ‘exciting’ cause of fever: “[A] poison formed by the corruption or the decomposition of organic matter”. However, he does note that the specific agent is unknown – only its origin is known. Then he discusses the conditions that support putrification of organic matter – namely, heat and moisture. He then uses an example of where a military battalion with troops stationed in a low area became sick with disease while troops of a higher elevation did not, with the result attributed to free and dry air. Several additional examples follow.

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