Editing Infection (section)

==Germ theory of disease==
{{Main|Germ theory of disease}}
In [[Classical antiquity|Antiquity]], the [[Ancient Greece|Greek]] historian [[Thucydides]] ({{circa|460}} – {{circa|400 BCE}}) was the first person to write, in his account of the [[plague of Athens]], that diseases could spread from an infected person to others.<ref>{{Cite web |title=Annals of medical history. v.1 1917. |url=https://hdl.handle.net/2027/mdp.39015016778261?urlappend=%3Bseq=28 |access-date=2023-11-17 |website=HathiTrust |page=14 | hdl=2027/mdp.39015016778261?urlappend=%3Bseq=28 |language=en |archive-date=2023-11-17 |archive-url=https://web.archive.org/web/20231117122937/https://babel.hathitrust.org/cgi/imgsrv/html?id=mdp.39015016778261&seq=31 |url-status=live }}</ref><ref>{{Cite book |last1=Thucydides |url=http://archive.org/details/pelocrawleyr00thucuoft |title=History of the Peloponnesian War, done into English by Richard Crawley |last2=Crawley |first2=Richard |date=1914 |publisher=London Dent |others=Robarts - University of Toronto |pages=131–132}}</ref> In his ''On the Different Types of Fever'' ({{circa|175 AD}}), the Greco-Roman physician [[Galen]] speculated that plagues were spread by "certain seeds of plague", which were present in the air.<ref>{{Cite journal |last=Nutton |first=V |date=January 1983 |title=The seeds of disease: an explanation of contagion and infection from the Greeks to the Renaissance. |journal=Medical History |volume=27 |issue=1 |pages=1–34 |doi=10.1017/s0025727300042241 |issn=0025-7273 |pmc=1139262 |pmid=6339840 }}</ref> In the [[Sushruta Samhita]], the ancient Indian physician [[Sushruta]] theorized: "Leprosy, fever, consumption, diseases of the eye, and other infectious diseases spread from one person to another by sexual union, physical contact, eating together, sleeping together, sitting together, and the use of same clothes, garlands and pastes."<ref>{{Cite journal|last1=Rastogi|first1=Nalin|last2=Rastogi|first2=R|date=1985-01-01|title=Leprosy in ancient India|url=https://www.researchgate.net/publication/16797371|journal=International Journal of Leprosy and Other Mycobacterial Diseases|volume=52|issue=4|pages=541–43|pmid=6399073}}</ref><ref>{{Cite book|last1=Susruta|url=http://archive.org/details/englishtranslati00susruoft|title=An English translation of the Sushruta samhita, based on original Sanskrit text. Edited and published by Kaviraj Kunja Lal Bhishagratna. With a full and comprehensive introd., translation of different readings, notes, comparative views, index, glossary and plates|last2=Bhishagratna|first2=Kunja Lal|date=1907–1916|publisher=Calcutta|others=Gerstein – University of Toronto}}</ref> This book has been dated to about the sixth century BC.<ref>{{Cite book|last=Hoernle|first=A. F. Rudolf (August Friedrich Rudolf)|url=http://archive.org/details/studiesinmedicin01hoeruoft|title=Studies in the medicine of ancient India|date=1907|publisher=Oxford : At the Clarendon Press|others=Gerstein – University of Toronto}}</ref>

A basic form of contagion theory was proposed by [[Ancient Iranian medicine|Persian]] physician [[Ibn Sina]] (known as Avicenna in Europe) in ''[[The Canon of Medicine]]'' (1025), which later became the most authoritative medical textbook in Europe up until the 16th century. In Book IV of the ''Canon'', Ibn Sina discussed [[epidemics]], outlining the classical [[miasma theory]] and attempting to blend it with his own early contagion theory. He mentioned that people can transmit disease to others by breath, noted contagion with [[tuberculosis]], and discussed the transmission of disease through water and dirt.<ref>{{cite book |last1=Byrne |first1=Joseph Patrick |title=Encyclopedia of the Black Death |date=2012 |publisher=[[ABC-CLIO]] |isbn=978-1598842531 |page=29 |url=https://books.google.com/books?id=5KtDfvlSrDAC&pg=PA29}}</ref> The concept of invisible contagion was later discussed by several [[medicine in the medieval Islamic world|Islamic scholars]] in the [[Ayyubid Sultanate]] who referred to them as ''[[najasat]]'' ("impure substances"). The [[fiqh]] scholar [[Ibn al-Haj al-Abdari]] ({{circa|1250}}–1336), while discussing [[Islamic dietary laws|Islamic diet]] and [[Islamic hygienical jurisprudence|hygiene]], gave warnings about how contagion can contaminate water, food, and garments, and could spread through the water supply, and may have implied contagion to be unseen particles.<ref>{{cite book |last1=Reid |first1=Megan H. |title=Law and Piety in Medieval Islam |date=2013 |publisher=[[Cambridge University Press]] |isbn=978-1107067110 |pages=106, 114, 189–90 |url=https://books.google.com/books?id=5fJ4AAAAQBAJ}}</ref>

When the [[Black Death]] [[bubonic plague]] reached [[Al-Andalus]] in the 14th century, the Arab physicians Ibn Khatima ({{circa|1369}}) and [[Ibn al-Khatib]] (1313–1374) hypothesised that infectious diseases were caused by "minute bodies" and described how they can be transmitted through garments, vessels and earrings.<ref>{{cite journal |last1=Majeed |first1=Azeem |title=How Islam changed medicine |journal=[[BMJ]] |date=22 December 2005 |volume=331 |issue=7531 |pages=1486–87 |doi=10.1136/bmj.331.7531.1486 |pmid=16373721 |pmc=1322233 |issn=0959-8138}}</ref> Ideas of contagion became more popular in Europe during the [[Renaissance]], particularly through the writing of the Italian physician [[Girolamo Fracastoro]].<ref>{{cite journal | author = Beretta M | title = The revival of Lucretian atomism and contagious diseases during the renaissance | journal = Medicina Nei Secoli | volume = 15 | issue = 2 | pages = 129–54 | year = 2003 | pmid = 15309812 }}</ref> [[Anton van Leeuwenhoek]] (1632–1723) advanced the science of [[microscopy]] by being the first to observe microorganisms, allowing for easy visualization of bacteria.

In the mid-19th century [[John Snow (physician)|John Snow]] and [[William Budd]] did important work demonstrating the contagiousness of typhoid and cholera through contaminated water. Both are credited with decreasing epidemics of cholera in their towns by implementing measures to prevent contamination of water.<ref>{{cite journal | author = Moorhead Robert | date = November 2002 | title = William Budd and typhoid fever | journal = J R Soc Med | volume = 95 | issue = 11| pages = 561–64 | pmc=1279260 | pmid=12411628 | doi=10.1177/014107680209501115}}</ref> [[Louis Pasteur]] proved beyond doubt that certain diseases are caused by infectious agents, and developed a vaccine for [[rabies]]. [[Robert Koch]] provided the study of infectious diseases with a scientific basis known as [[Koch's postulates]]. [[Edward Jenner]], [[Jonas Salk]] and [[Albert Sabin]] developed effective vaccines for [[smallpox]] and [[polio]], which would later result in the [[eradication of infectious diseases|eradication]] and near-eradication of these diseases, respectively. [[Alexander Fleming]] discovered the world's first [[antibiotic]], [[penicillin]], which Florey and Chain then developed. [[Gerhard Domagk]] developed [[sulfonamide (medicine)|sulphonamides]], the first broad spectrum [[Chemical synthesis|synthetic]] antibacterial drugs.{{cn|date=April 2023}}

===Medical specialists===
The [[medicine|medical treatment]] of infectious diseases falls into the [[specialty (medicine)|medical field]] of [[infectious disease (medical specialty)|Infectious Disease]] and in some cases the study of propagation pertains to the field of [[Epidemiology]]. Generally, infections are initially diagnosed by [[primary care]] physicians or [[internal medicine]] specialists. For example, an "uncomplicated" [[pneumonia]] will generally be treated by the [[internist]] or the [[pulmology|pulmonologist]] (lung physician). The work of the infectious diseases specialist therefore entails working with both patients and general practitioners, as well as [[Research|laboratory scientists]], [[immunology|immunologists]], [[bacteriologist]]s and other specialists.<ref>{{Cite book |last=Evans |first=Alfred S. |chapter=Epidemiological Concepts |date=2009-05-29 |title=Bacterial Infections of Humans |pages=1–50 |doi=10.1007/978-0-387-09843-2_1 |pmc=7176254|isbn=978-0-387-09842-5 }}</ref>

An infectious disease team may be alerted when:{{cn|date=April 2023}}
* The disease has not been definitively diagnosed after an initial workup
* The patient is [[immunocompromised]] (for example, in [[AIDS]] or after [[chemotherapy]]);
* The [[infectious agent]] is of an uncommon nature (e.g. [[tropical disease]]s);
* The disease has not responded to first line [[antibiotic]]s;
* The disease might be dangerous to other patients, and the patient might have to be isolated