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

40/ However, by the late 1880s, miasma theory was waning in popularity, and in 1888, the Institut Pasteur was created in Paris, reflecting the ascendancy of germ theory. pasteur.fr/en/institut-pa…

Prof. Jose-Luis Jimenez @jljcolorado

41/ Florence Nightingale did accept the new ideas of germ theory, in fact before many physicians did. E.g. in 1882, she wrote: books.google.com/books?id=dDDcy… pic.twitter.com/hH20EeG3R7

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Prof. Jose-Luis Jimenez @jljcolorado

42/ Initial results on plant pathogens in 1890s & the identification of bacteriophage in 1917 paved the way for recognition of viruses. A “golden era” followed, with the identification of the actual microorganisms that cause many infectious diseases. doi.org/10.1002/bies.2…

Prof. Jose-Luis Jimenez @jljcolorado

43/ The discovery and identification of the organisms causing different diseases did NOT, however, eliminate the great difficulty in conclusively determining the mode by which they transferred from one person to another. Malaria was still thought to go through the air in 1880

Prof. Jose-Luis Jimenez @jljcolorado

44/ French physician Charles Laveran identified the pathogen responsible for malaria in 1880 (got Nobel Prize in 1907), but the manner of transmission was still thought to be through the air. doi.org/10.1186/1475-2… en.wikipedia.org/wiki/Charles_L… pic.twitter.com/cvV0IjmIUP

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Prof. Jose-Luis Jimenez @jljcolorado

45/ American physician A. King proposed that malaria was transmitted by mosquitos, but encountered general skepticism In 1883, he presented a list of 19 facts supporting m. as vector of malaria [Reminds me of 10 scientific reasons for #COVIDisAirborne] en.wikipedia.org/wiki/Albert_Fr… pic.twitter.com/H90hN5GKkZ

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Prof. Jose-Luis Jimenez @jljcolorado

46/ In 1898 British surgeon R. Ross provided definitive evidence: - confirming the presence of the malarial parasites in mosquitoes - demonstrating transmission of bird malaria by mosquitoes World Mosquito day commemorates him doi.org/10.1186/1475-2… en.wikipedia.org/wiki/Ronald_Ro… pic.twitter.com/5kNarWcBI4

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Prof. Jose-Luis Jimenez @jljcolorado

47/ Looking back at period 1850-1900, belief on transmission of many diseases through AIR was still strong But cholera, malaria, puerperal fever had been shown to transmit OTHERWISE It was a fluid time. It was debated if air was actually important onlinelibrary.wiley.com/doi/10.1111/in… pic.twitter.com/iEbulA9Iy0

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Prof. Jose-Luis Jimenez @jljcolorado

48/ In the 1890s, Carl Flügge in Germany set out to disprove the then-dominant transmission theory for tuberculosis, one of the major infectious diseases of the time. Most experts believed that tuberculosis was transmitted when dust of dried sputum that had landed on floors... pic.twitter.com/N62DMszCs7

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Prof. Jose-Luis Jimenez @jljcolorado

49/ ...blankets, bowls, & other objects was dispersed into air. In contrast, Flügge thought that it was not DRIED secretions from sick that caused infection, but rather FRESH secretions that ppl were exposed to IN AIR BEFORE they reached the ground doi.org/10.1098/rsfs.2… pic.twitter.com/Wt4Baw4nRY

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Prof. Jose-Luis Jimenez @jljcolorado

50/ Some contemporaries of Flügge such as Cornet argued that tuberculosis was transmitted only through large droplets, which were easily visible to the naked eye. Perhaps because droplets were more CONVENIENT and airborne disease VERY INCONVENIENT? google.com/books/edition/… pic.twitter.com/zL3ll57mRg

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Prof. Jose-Luis Jimenez @jljcolorado

51/ However, although term “Flügge's droplets” has been used to describe ONLY those large particles that fell to the ground quickly near the infected person and that were assumed to dominate transmission, that does NOT accurately capture Flügge's results journals.sagepub.com/doi/10.1177/00…

Prof. Jose-Luis Jimenez @jljcolorado

52/ Rather, Flügge and collaborators used the term “droplet” to refer to fresh particles of ALL SIZES, including AEROSOLS for which the researchers waited 5 hours to settle from the air on their collection plates. doi.org/10.1098/rsfs.2…

Prof. Jose-Luis Jimenez @jljcolorado

53/ In 1905, microbiologist M.H. Gordon was commissioned to study the atmospheric hygiene of the UK House of Commons after an epidemic of influenza among members He famously performed the following experiment: after gargling with a broth culture of Serratia marcescens...

Prof. Jose-Luis Jimenez @jljcolorado

54/ ... he loudly recited passages from Shakespeare in an empty House to an audience of agar plates. Although growth of colonies was more numerous on plates near the speaker, cultures were apparent on some plates over 21 m away. bmj.com/content/4/5686…

Prof. Jose-Luis Jimenez @jljcolorado

55/ However, experimental progress in early 1900s was hampered by the limitations of the experimental techniques available at the time. In particular high-quality measurements of large droplets & aerosols would only be routinely available decades later. onlinelibrary.wiley.com/doi/10.1111/in…

Prof. Jose-Luis Jimenez @jljcolorado

56/ We get to the CRITICAL POINT of this history. Throughout most of human history, the dominant belief was transmission of many diseases through the air. The last half of the 19th Century proves otherwise for major diseases. Strong debate ensues: "is air major or minor?" pic.twitter.com/Lgf01zCoxJ

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Prof. Jose-Luis Jimenez @jljcolorado

57/ Charles V. Chapin was a prominent American epidemiologist. He worked only a couple of decades after Germ Theory was accepted, during a period of intense research on pathogens & their transmission. en.wikipedia.org/wiki/Charles_V… pic.twitter.com/LiPiKkd3FM

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Prof. Jose-Luis Jimenez @jljcolorado

58/ The period when Chapin's worked on disease transmission was a fluid one, following a major paradigm shift, in which it was easier to change the dominant scientific discourse than during normal times [See e.g. Kuhn en.wikipedia.org/wiki/The_Struc…]

Prof. Jose-Luis Jimenez @jljcolorado

59/ He summarized the evidence of transmission of different diseases in his 1910 seminal book, “The Sources and Modes of Infection.” [A must read if you are interested in this subject, esp. chapter on airborne transmission] play.google.com/store/books/de… pic.twitter.com/vx5th72Gd1

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Prof. Jose-Luis Jimenez @jljcolorado

60/ Chapin conceptualized “contact infection,” infection by germs that did NOT come from the environment, but from other PEOPLE through DIRECT CONTACT OR CLOSE PROXIMITY. play.google.com/books/reader?i… pic.twitter.com/KDEXpTErm9

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Prof. Jose-Luis Jimenez @jljcolorado

61/ Chapin believed contact was main mode of transmission of many diseases But he encountered resistance: “I have sometimes been told I lay too much emphasis on contact infection [although] until recently very little attention has been paid to it.” play.google.com/books/reader?i…

Prof. Jose-Luis Jimenez @jljcolorado

62/ Chapin also reviewed the possibility of airborne infection, which he conceived especially as infections from afar. Lingering belief on air infection was making it difficult to promote contact infection: play.google.com/books/reader?i… pic.twitter.com/rHjy0VsX3d

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Prof. Jose-Luis Jimenez @jljcolorado

63/ Chapin realized that airborne infection may explain infection in close proximity (CP). However, he argued that ease of infection in CP was better explained by “spray-borne” droplets, large visible droplets considered by Cornet Same as @WHO's droplets: twitter.com/WHO/status/124…

World Health Organization (WHO) @WHO

Watch this short animation to learn more about #COVID19, how it spreads and how to protect yourself against it. #coronavirus pic.twitter.com/FdfJCiTLry

2020-03-29 22:41:44

Prof. Jose-Luis Jimenez @jljcolorado

64/ This is the key. The evidence was insufficient, but Chapin turned absence of evidence into evidence of absence, and stated that airborne disease was almost impossible, and that "mouth spray" (large droplets) are only effective at short distances. onlinelibrary.wiley.com/doi/10.1111/in… pic.twitter.com/C8BosgRSng

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