コロナパンデミックで進んだ空気感染(=airborne transmission)の概念｜空気感染が否定されてきた歴史(2022.8.25作成) #エアロゾル #新型コロナウイルス #水疱瘡 #麻疹

Prof. Jose-Luis Jimenez @jljcolorado

16/ Throughout much of subsequent human history, the belief persisted that diseases were transmitted through air Because the actual agents remained a mystery for centuries, explanations were given in general terms such as “miasmas,” or “bad air” en.wikipedia.org/wiki/Miasma_th… pic.twitter.com/YibfCHW46t

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Prof. Jose-Luis Jimenez @jljcolorado

17/ For example, the etymological root of the term "malaria" (a disease that we now know is transmitted by mosquitos) is “mala aria,” medieval Italian for “bad air” doi.org/10.1186/1475-2…

Prof. Jose-Luis Jimenez @jljcolorado

17/ Some origin theories were more specific. E.g. Roman scholar Varro (116–27 BCE) wrote that swamps were a particular breeding ground for minute creatures that “float in the air and enter the body through mouth & nose and there cause serious diseases.” doi.org/10.1186/1475-2…

Prof. Jose-Luis Jimenez @jljcolorado

18/ Thus it became a policy of the Roman Empire to drain swamps, removing breeding grounds for mosquitos, reducing malaria, an example of a mistaken theory giving good results and increasing faith on the theory We see this many times through history doi.org/10.1186/1475-2…

Prof. Jose-Luis Jimenez @jljcolorado

19/ The concept of person-to-person contagion came much later, most clearly in work of Italian physician Girolamo Fracastoro in 1546 [This is actually a subject of current debate, with some scholars thinking that the role of F may have been overstated] en.wikipedia.org/wiki/Girolamo_… pic.twitter.com/c68tQC1MuI

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Prof. Jose-Luis Jimenez @jljcolorado

20/ What ensued after Fracastoro, however, was a centuries-long debate between “miasmatists,” who held fast to the idea that diseases floated through the air over distances, and “contagionists,” who accepted person-to-person spread of disease sciencedirect.com/science/articl…

Prof. Jose-Luis Jimenez @jljcolorado

21/ Because it was (and it still IS) very difficult to determine how, why, and from where someone became infected, the miasmas vs. contagion debate failed to reach a resolution and persisted for centuries.

Prof. Jose-Luis Jimenez @jljcolorado

22/ A middle ground was proposed, “contingent contagionism”: malaria, or cholera might be contagious in an impure atmosphere, but not in a healthy atmosphere This idea therefore captured some grains of truth (eg. now we know ventilation reduces airborne) archive.org/details/390020…

Prof. Jose-Luis Jimenez @jljcolorado

23/ Miasma theory was dominant till the mid/late 19thy Century. Florence Nightingale (1820–1910) like most Victorians was raised to believe that diseases were caused by ‘miasma’ or foul air. en.wikipedia.org/wiki/Florence_… pic.twitter.com/OQcCgoyYdb

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Prof. Jose-Luis Jimenez @jljcolorado

24/ In her Notes on Hospitals, Nightingale referred to the idea of contagion as absurd: [She was nevertheless very practical and effective in reducing disease, e.g. with ventilation and phys. distance, and later accepted germ theory, as we'll see later] play.google.com/store/books/de… pic.twitter.com/6oDa9JTvUl

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Prof. Jose-Luis Jimenez @jljcolorado

25/ We enter a critical period around 1850. Miasma theory is still dominant, although contagion (mostly through the air) also has proponents. Microorganisms have been observed for 2 centuries since the invention of the microscope, but haven't clearly been connected to disease

Prof. Jose-Luis Jimenez @jljcolorado

26/ Cholera strikes London in 1854. The public health establishment believed it to be caused by a miasma. English sanitary reformers (e.g. Chadwick), who initiated many modern public health practices, found miasma appealing, as it appeared to explain... en.wikipedia.org/wiki/Edwin_Cha… pic.twitter.com/wLody0swl3

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Prof. Jose-Luis Jimenez @jljcolorado

27/ ...the prevalence of diseases in the undrained, filthy, and foul-smelling areas where the poor lived, and helped justify their efforts to address those conditions. [They had made a huge error, and they resisted accepting it, just as @WHO today] doi.org/10.1136/bmj.32…

Prof. Jose-Luis Jimenez @jljcolorado

28/ John Snow was a wealthy doctor but outsider to public health. His work in anesthesia made him familiar with the behavior of gasses. He realized that the spread of chlore was NOT consistent with what would be expected for a gas. en.wikipedia.org/wiki/John_Snow pic.twitter.com/3638JqLC6U

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Prof. Jose-Luis Jimenez @jljcolorado

29/ Snow noticed how cases had clustered in a specific London borough and persuaded the local council to remove the handle of the Broad street water pump, which halted the epidemic. archive.org/details/b28985… ph.ucla.edu/epi/snow/snowc… blog.rtwilson.com/john-snows-cho… pic.twitter.com/3xdiorlCCP

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Prof. Jose-Luis Jimenez @jljcolorado

30/ However, cholera was already in decline. The Board of Health refused to accept contaminated water, stating: “we see no reason to adopt this belief [that cholera was water-borne]” and dismissing Snow's conclusions as mere “suggestions" google.com/books/edition/…

Prof. Jose-Luis Jimenez @jljcolorado

31/ The Board of Health had strong incentives for rejecting water as the source of cholera. To remove the sources of the miasma (filth), they had spearheaded the effort to build sewers that dumped raw sewage into the Thames, the source of much of London's drinking water...

Prof. Jose-Luis Jimenez @jljcolorado

32/ ...thus effectively helping the spread of cholera. They had much to lose by admitting cholera transmitted through water [Technology has advanced, but human nature has changed less. @WHO has avoided saying LOUD & CLEAR that #COVIDisAirborne, as their denials helped it spread]

Prof. Jose-Luis Jimenez @jljcolorado

@WHO 33/ Also around 1850, Ignaz Semmelweis in Vienna showed that handwashing greatly reduced deaths by childbed fever in a maternity clinic. en.wikipedia.org/wiki/Ignaz_Sem… pic.twitter.com/gKEPlZW7Hc

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Prof. Jose-Luis Jimenez @jljcolorado

34/ These are some of Semmelweis' data, which would seem worth following up on: However, his ideas conflicted with established medical and scientific beliefs that STILL described diseases as due to an imbalance of humors triggered by a miasma in the air. doi.org/10.1556/650.20… pic.twitter.com/VeH5WsWsql

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Prof. Jose-Luis Jimenez @jljcolorado

35/ However, he was dismissed from his hospital and harassed by Vienna medical community, forced to move to Budapest. There he broke down, was interned and beaten by the guards, and ultimately died from an infected wound Like Snow, he died years before his theories were accepted

Prof. Jose-Luis Jimenez @jljcolorado

36/ Ironically, Semmelweis' name lives on not only for advances of hand sanitation, but also in “Semmelweis reflex,” which describes the reflex-like tendency to reject new knowledge or evidence when it contradicts established beliefs, norms, or paradigms en.wikipedia.org/wiki/Semmelwei…

Prof. Jose-Luis Jimenez @jljcolorado

37/ That is especially ironic, as the chief deniers of airborne transmission (John Conly -- chairman of key IPC @WHO committee, Dr. Seto, @DidierPittet, @CollignonPeter) are handwashing experts... ... following Semmelweis' scientific advances, while forgetting about the reflex

Prof. Jose-Luis Jimenez @jljcolorado

38/ The 2nd half of the 19th Century is a period of rapid progress on disease transmission. Pasteur and Koch proposed the GERM THEORY of disease. Microscopic germs enter the body and are the cause of many diseases. en.wikipedia.org/wiki/Germ_theo… worldcat.org/title/memoire-… pic.twitter.com/F90A0yjclt

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Prof. Jose-Luis Jimenez @jljcolorado

39/ Germ theory was NOT accepted overnight. E.g. experiments by others in which water containing organic matter was boiled in a vessel, but microorganisms still appeared (later shown to be an imperfect seal or insufficient boiling) created controversy: doi.org/10.1093/jhmas/…