Editing Epidemiology (section)

=== Modern era ===
{{See also|History of emerging infectious diseases}}
In the middle of the 16th century, a doctor from [[Verona]] named [[Girolamo Fracastoro]] was the first to propose a theory that the very small, unseeable, particles that cause disease were alive. They were considered to be able to spread by air, multiply by themselves and to be destroyable by fire. In this way he refuted [[Galen]]'s [[Miasma theory of disease|miasma theory]] (poison gas in sick people). In 1543 he wrote a book ''[[De contagione et contagiosis morbis]]'', in which he was the first to promote personal and environmental [[hygiene]] to prevent disease. The development of a sufficiently powerful microscope by [[Antonie van Leeuwenhoek]] in 1675 provided visual evidence of living particles consistent with a [[germ theory of disease]].{{citation needed|date=June 2022}}

During the [[Ming dynasty]], [[Wu Youke]] (1582–1652) developed the idea that some diseases were caused by transmissible agents, which he called ''Li Qi'' (戾气 or pestilential factors) when he observed various epidemics rage around him between 1641 and 1644.<ref>{{cite book |last1=Joseph |first1=P Byre |title=Encyclopedia of the Black Death |date=2012 |publisher=ABC-CLIO |isbn=978-1598842548 |page=76 |url=https://books.google.com/books?id=AppsDAKOW3QC&pg=PA76 |access-date=24 February 2019}}</ref> His book ''Wen Yi Lun'' (瘟疫论, Treatise on Pestilence/Treatise of Epidemic Diseases) can be regarded as the main etiological work that brought forward the concept.<ref>{{cite book |last1=Guobin |first1=Xu |last2=Yanhui |first2=Chen |last3=Lianhua |first3=Xu |title=Introduction to Chinese Culture: Cultural History, Arts, Festivals and Rituals |year= 2018 |publisher=Springer |isbn=978-9811081569 |page=70 |url=https://books.google.com/books?id=-KFTDwAAQBAJ&pg=PA70 |access-date=24 February 2019}}</ref> His concepts were still being considered in analysing SARS outbreak by WHO in 2004 in the context of traditional Chinese medicine.<ref>{{cite web |title=Report 1: Clinical research on treatment of SARS with integrated Traditional Chinese medicine and Western Medicine |work=SARS: Clinical Trials on Treatment Using a Combination of Traditional Chinese Medicine and Western Medicine |date=2004 |url=http://apps.who.int/medicinedocs/en/d/Js6170e/4.html#Js6170e.4 |publisher=World Health Organization |access-date=24 February 2019 |archive-url=https://web.archive.org/web/20180608111238/http://apps.who.int/medicinedocs/en/d/Js6170e/4.html |archive-date=8 June 2018}}</ref>

Another pioneer, [[Thomas Sydenham]] (1624–1689), was the first to distinguish the fevers of Londoners in the later 1600s. His theories on cures of fevers met with much resistance from traditional physicians at the time. He was not able to find the initial cause of the [[smallpox]] fever he researched and treated.<ref name="Merril, Ray M. 2010"/>

[[John Graunt]], a [[haberdasher]] and amateur statistician, published ''Natural and Political Observations ... upon the Bills of Mortality'' in 1662. In it, he analysed the mortality rolls in [[London]] before the [[Great Plague of London|Great Plague]], presented one of the first [[life tables]], and reported time trends for many diseases, new and old. He provided statistical evidence for many theories on disease, and also refuted some widespread ideas on them.{{citation needed|date=June 2022}}

[[File:Snow-cholera-map.jpg|thumb|350px|Original map by [[John Snow (physician)|John Snow]] showing the [[cluster (epidemiology)|clusters]] of cholera cases in the [[1854 Broad Street cholera outbreak|London epidemic of 1854]]]]
[[John Snow (physician)|John Snow]] is famous for his investigations into the causes of the 19th-century [[cholera]] epidemics, and is also known as the father of (modern) Epidemiology.<ref>{{cite journal |url-status=dead |url=http://www.ph.ucla.edu/epi/snow/fatherofepidemiology.html |title=Doctor John Snow Blames Water Pollution for Cholera Epidemic |first1=David |last1=Vachon |archive-url=https://web.archive.org/web/20111228050259/http://www.ph.ucla.edu/epi/snow/fatherofepidemiology.html |archive-date=28 December 2011 |website= UCLA Department of Epidemiology, School of Public Health |date=May–June 2005}}</ref><ref>"[https://www.npr.org/templates/story/story.php?storyId=3935461 John Snow, Father of Epidemiology]", NPR, ''Talk of the Nation''. 24 September 2004. {{Webarchive|url=https://web.archive.org/web/20170620140913/http://www.npr.org/templates/story/story.php?storyId=3935461 |date=20 June 2017 }}.</ref> He began with noticing the significantly higher death rates in two areas supplied by Southwark Company. His identification of the [[Broadwick Street|Broad Street]] pump as the cause of the Soho epidemic is considered the classic example of epidemiology. Snow used chlorine in an attempt to clean the water and removed the handle; this ended the outbreak. This has been perceived as a major event in the history of [[public health]] and regarded as the founding event of the science of epidemiology, having helped shape public health policies around the world.<ref>{{cite web|url=http://www.ph.ucla.edu/epi/snow/importance.html|title=Importance of Snow|website=Jonathan and Karin Fielding School of Public Health |url-status=dead |archive-url= https://web.archive.org/web/20210617195407/https://www.ph.ucla.edu/epi/snow/importance.html |archive-date= Jun 17, 2021 }}</ref><ref>{{cite web |url-status=dead |url=http://www.jsi.com/JSIInternet/About/snow.cfm |title=Dr. John Snow |archive-url=https://web.archive.org/web/20140616100942/http://www.jsi.com/JSIInternet/About/snow.cfm |archive-date=16 June 2014 |publisher= John Snow, Inc. and JSI Research & Training Institute, Inc.}}</ref> However, Snow's research and preventive measures to avoid further outbreaks were not fully accepted or put into practice until after his death due to the prevailing [[Miasma theory|Miasma Theory]] of the time, a model of disease in which poor air quality was blamed for illness. This was used to rationalize high rates of infection in impoverished areas instead of addressing the underlying issues of poor nutrition and sanitation, and was proven false by his work.<ref>{{Citation|last=Johnson, Steven|title=The ghost map : [the story of London's most terrifying epidemic – and how it changed science, cities, and the modern world]|url=http://worldcat.org/oclc/1062993385|oclc=1062993385|access-date=2020-09-16}}</ref>

Other pioneers include Danish physician [[Peter Anton Schleisner]], who in 1849 related his work on the prevention of the epidemic of [[neonatal tetanus]] on the [[Vestmanna Islands]] in [[Iceland]].<ref>{{cite journal |author1=Ólöf Garðarsdóttir |author2=Loftur Guttormsson |title=Public health measures against neonatal tetanus on the island of Vestmannaeyjar (Iceland) during the 19th century |journal=The History of the Family|volume=14 |issue=3 |date=25 August 2009 |pages=266–79 |doi=10.1016/j.hisfam.2009.08.004|s2cid=72505045 }}{{Verify source|date=April 2011}}</ref><!-- please check also Daniel E. Vaisey, "An Estimate of Neonatal Tetanus Mortality in Iceland, 1790–1839" European Journal of Population 13 (1997), 62, 67 as cited in Loftur Guttormsson and Ólöf Garðarsdóttir [http://www.ep.liu.se/ej/hygiea/ "The Development of Infant Mortality in Iceland 1800–1920"] (2002) Hygiea Internationalis 3(1) pp. 151–77 --> Another important pioneer was [[Hungary|Hungarian]] physician [[Ignaz Semmelweis]], who in 1847 brought down infant mortality at a Vienna hospital by instituting a disinfection procedure. His findings were published in 1850, but his work was ill-received by his colleagues, who discontinued the procedure. Disinfection did not become widely practiced until British surgeon [[Joseph Lister, 1st Baron Lister|Joseph Lister]], aided by his college, chemist [[Thomas Anderson (chemist)|Thomas Anderson]], was able to "discover" [[antiseptics]] in 1865 based on the earlier work of [[Louis Pasteur]].<ref>{{Cite web |last=Hollingham |first=Richard |date=2020-08-20 |title=The pioneering surgeons who cleaned up filthy hospitals |url=https://www.bbc.com/future/article/20200812-the-pioneering-surgeons-who-cleaned-up-filthy-hospitals |access-date=2025-03-11 |website=www.bbc.com |language=en-GB}}</ref>

In the early 20th century, mathematical methods were introduced into epidemiology by [[Ronald Ross]], [[Janet Lane-Claypon]], [[Anderson Gray McKendrick]], and others.<ref>[https://books.google.com/books?id=6DD1FKq6fFoC&q=mathematical+methods+were+introduced+into+epidemiology+20th+century+ross&pg=PA323 Statisticians of the centuries] {{Webarchive|url=https://web.archive.org/web/20220630015959/https://books.google.com/books?id=6DD1FKq6fFoC&pg=PA323#v=onepage&q=mathematical%20methods%20were%20introduced%20into%20epidemiology%2020th%20century%20ross |date=30 June 2022 }}. By C. C. Heyde, Eugene Senet</ref><ref>[http://statprob.com/encyclopedia/AndersonGrayMcKENDRICK.html Anderson Gray McKendrick] {{webarchive|url=https://web.archive.org/web/20110822114404/http://statprob.com/encyclopedia/AndersonGrayMcKENDRICK.html |date=22 August 2011 }}</ref><ref>{{cite web|url=https://oneweb.soton.ac.uk/node/201970|title=Homepage|publisher=Tel: +4423 8059 5000 Fax: +4423 8059 3131 University of Southampton University Road Southampton SO17 1BJ United Kingdom|website=University of Southampton}}{{Dead link|date=May 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite web |url=http://www.epidemiology.ch/history/papers/SPM%2047(6)%20359-65%20Paneth%20et%20al.%20_%20Part%202.pdf |title=Origins and early development of the case-control study |access-date=31 August 2013 |archive-url=https://web.archive.org/web/20170118055648/http://www.epidemiology.ch/history/papers/SPM%2047(6)%20359-65%20Paneth%20et%20al.%20_%20Part%202.pdf |archive-date=18 January 2017 |url-status=dead |df=dmy-all }}</ref> In a parallel development during the 1920s, German-Swiss pathologist [[Max Askanazy]] and others founded the International Society for Geographical Pathology to systematically investigate the geographical pathology of cancer and other non-infectious diseases across populations in different regions. After World War II, [[Richard Doll]] and other non-pathologists joined the field and advanced methods to study cancer, a disease with patterns and mode of occurrences that could not be suitably studied with the methods developed for epidemics of infectious diseases. Geography pathology eventually combined with infectious disease epidemiology to make the field that is epidemiology today.<ref name="cancer">{{cite journal |author=Mueller LM |title=Cancer in the tropics: geographical pathology and the formation of cancer epidemiology |journal=BioSocieties|pages=512–528 |year=2019  |volume=14 |issue=4 |doi=10.1057/s41292-019-00152-w|hdl=1721.1/128433 |s2cid=181518236 |hdl-access=free }}</ref>

Another breakthrough was the 1954 publication of the results of a [[British Doctors Study]], led by [[Richard Doll]] and [[Austin Bradford Hill]], which lent very strong statistical support to the link between [[tobacco smoking]] and [[lung cancer]].{{cn|date=November 2023}}

In the late 20th century, with the advancement of biomedical sciences, a number of molecular markers in blood, other biospecimens and environment were identified as predictors of development or risk of a certain disease. Epidemiology research to examine the relationship between these [[biomarker]]s analyzed at the molecular level and disease was broadly named "[[molecular epidemiology]]". Specifically, "[[genetic epidemiology]]" has been used for epidemiology of germline genetic variation and disease. Genetic variation is typically determined using DNA from peripheral blood leukocytes.{{citation needed|date=June 2022}}