{{Short description|New or rapidly increasing disease}} {{cs1 config|name-list-style=vanc|display-authors=6}} {{About||the medical journal|Emerging Infectious Diseases}} [[File:Global Examples of Emerging and Re-Emerging Infectious Diseases.jpg|300px|thumb|When Anthony Fauci became director of the NIAID, he drew a map of the world for presentation at a congressional hearing that showed a single notable emerging infectious disease threat: HIV. Since then, he has continually updated the map, now showing the emergence of numerous infectious disease threats to illustrate the experiences of his years in office as well as highlighting certain infections that had emerged before HIV.<ref>{{cite journal | vauthors = Paules CI, Eisinger RW, Marston HD, Fauci AS | title = What Recent History Has Taught Us About Responding to Emerging Infectious Disease Threats | journal = Annals of Internal Medicine | volume = 167 | issue = 11 | pages = 805–811 | date = December 2017 | pmid = 29132162 | doi = 10.7326/M17-2496 | s2cid = 36800971 }}</ref>]]
An '''emerging infectious disease''' ('''EID''') refer to infectious diseases that have either newly appeared in a population or have existed but are rapidly increasing in incidence, geographic range, or severity due to factors such as environmental changes, antimicrobial resistance, and human-animal interactions.<ref name=NIOSH>{{cite web |title=Emerging Infectious Diseases - NIOSH Workplace Safety and Health Topic |url=https://www.cdc.gov/niosh/topics/emerginfectdiseases/default.html |website=www.cdc.gov |publisher=Centers for Disease Control and Prevention |archive-url=https://web.archive.org/web/20200418131812/https://www.cdc.gov/niosh/topics/emerginfectdiseases/default.html |archive-date=18 April 2020 |language=en-us |date=17 October 2018}}</ref><ref>{{Cite book|url=https://apps.who.int/iris/handle/10665/204722|hdl=10665/204722|isbn=9789290224587|title=A brief guide to emerging infectious diseases and zoonoses|year=2014|publisher=WHO Regional Office for South-East Asia}}</ref> The minority that are capable of developing efficient transmission between humans can become major public and global concerns as potential causes of epidemics or pandemics.<ref name=Woolhouse2005/> Their many impacts can be economic and societal, as well as clinical.<ref name=Morens2013>{{cite journal | vauthors = Morens DM, Fauci AS | title = Emerging infectious diseases: threats to human health and global stability | journal = PLOS Pathogens | volume = 9 | issue = 7 | article-number = e1003467 | date = 2013 | pmid = 23853589 | pmc = 3701702 | doi = 10.1371/journal.ppat.1003467 | author-link2 = Anthony Fauci | doi-access = free }}</ref> EIDs have been increasing steadily since at least 1940.<ref>{{cite journal | vauthors = Jones KE, Patel NG, Levy MA, Storeygard A, Balk D, Gittleman JL, Daszak P | title = Global trends in emerging infectious diseases | journal = Nature | volume = 451 | issue = 7181 | pages = 990–993 | date = February 2008 | pmid = 18288193 | pmc = 5960580 | doi = 10.1038/nature06536 | bibcode = 2008Natur.451..990J }}</ref>
For every decade since 1940, there has been a consistent increase in the number of EID events from wildlife-related zoonosis. Human activity is the primary driver of this increase, with loss of biodiversity a leading mechanism.<ref>{{cite journal | vauthors = Keesing F, Belden LK, Daszak P, Dobson A, Harvell CD, Holt RD, Hudson P, Jolles A, Jones KE, Mitchell CE, Myers SS, Bogich T, Ostfeld RS | title = Impacts of biodiversity on the emergence and transmission of infectious diseases | journal = Nature | volume = 468 | issue = 7324 | pages = 647–652 | date = December 2010 | pmid = 21124449 | pmc = 7094913 | doi = 10.1038/nature09575 | bibcode = 2010Natur.468..647K }}</ref>
Emerging infections account for at least 12% of all human pathogens.<ref>{{cite journal | vauthors = Taylor LH, Latham SM, Woolhouse ME | title = Risk factors for human disease emergence | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 356 | issue = 1411 | pages = 983–989 | date = July 2001 | pmid = 11516376 | pmc = 1088493 | doi = 10.1098/rstb.2001.0888 }}</ref> EIDs can be caused by newly identified microbes, including novel species or strains of virus<ref>{{cite journal | vauthors = Fauci AS | title = Emerging and reemerging infectious diseases: the perpetual challenge | journal = Academic Medicine | volume = 80 | issue = 12 | pages = 1079–1085 | date = December 2005 | pmid = 16306276 | doi = 10.1097/00001888-200512000-00002 | s2cid = 17293745 | doi-access = free }}</ref> (e.g. novel coronaviruses, ebolaviruses, HIV). Some EIDs evolve from a known pathogen, as occurs with new strains of influenza. EIDs may also result from spread of an existing disease to a new population in a different geographic region, as occurs with West Nile fever outbreaks. Some known diseases can also emerge in areas undergoing ecologic transformation (as in the case of Lyme disease<ref name=Kilpatrick2017>{{cite journal | vauthors = Kilpatrick AM, Dobson AD, Levi T, Salkeld DJ, Swei A, Ginsberg HS, Kjemtrup A, Padgett KA, Jensen PM, Fish D, Ogden NH, Diuk-Wasser MA | title = Lyme disease ecology in a changing world: consensus, uncertainty and critical gaps for improving control | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 372 | issue = 1722 | article-number = 20160117 | date = June 2017 | pmid = 28438910 | pmc = 5413869 | doi = 10.1098/rstb.2016.0117 }}</ref>). Others can experience a resurgence as a '''re-emerging infectious disease''', like tuberculosis<ref name=Porta2014>{{cite book | veditors = Porta M, Greenland S, Hernán M, dos Santos Silva I, Last JM |title=A Dictionary of Epidemiology |page=92 |url=https://books.google.com/books?id=4kZmAwAAQBAJ |year=2014 |publisher=Oxford University Press |isbn=978-0-19-997673-7}}</ref> (following drug resistance) or measles.<ref name=Fraser-bell2019>{{cite journal | vauthors = Fraser-Bell C |title=Global Re-emergence of Measles - 2019 update |journal=Global Biosecurity |date=2019 |volume=1 |issue=3 |doi=10.31646/gbio.43 |language=en |issn=2652-0036|doi-access=free }}</ref> Nosocomial (hospital-acquired) infections, such as methicillin-resistant ''Staphylococcus aureus'' are emerging in hospitals, and are extremely problematic in that they are resistant to many antibiotics.<ref name="auto">{{cite journal | vauthors = Witte W, Kresken M, Braulke C, Cuny C | title = Increasing incidence and widespread dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals in central Europe, with special reference to German hospitals | journal = Clinical Microbiology and Infection | volume = 3 | issue = 4 | pages = 414–422 | date = August 1997 | pmid = 11864151 | doi = 10.1111/j.1469-0691.1997.tb00277.x | doi-access = free }}</ref> Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics.
Many EID are zoonotic,<ref name=Woolhouse2005>{{cite journal | vauthors = Woolhouse ME, Gowtage-Sequeria S | title = Host range and emerging and reemerging pathogens | journal = Emerging Infectious Diseases | volume = 11 | issue = 12 | pages = 1842–1847 | date = December 2005 | pmid = 16485468 | pmc = 3367654 | doi = 10.3201/eid1112.050997 }}</ref> deriving from pathogens present in animals, with only occasional cross-species transmission into human populations.<ref name="ACAIM-WACEM COVID-19 Consensus Paper">{{cite web|title=The 2019–2020 Novel Coronavirus (Severe Acute Respiratory Syndrome Coronavirus 2) Pandemic: A Joint American College of Academic International Medicine‑World Academic Council of Emergency Medicine Multidisciplinary COVID-19 Working Group Consensus Paper|url=https://www.researchgate.net/publication/340903626|website=ResearchGate|access-date=May 16, 2020}}</ref> For instance, most emergent viruses are zoonotic<ref name=Woolhouse2005/> (whereas other novel viruses may have been circulating in the species without being recognized, as occurred with hepatitis C<ref name=Houghton2009>{{cite journal | vauthors = Houghton M | title = The long and winding road leading to the identification of the hepatitis C virus | journal = Journal of Hepatology | volume = 51 | issue = 5 | pages = 939–948 | date = November 2009 | pmid = 19781804 | doi = 10.1016/j.jhep.2009.08.004 | doi-access = free }}</ref>).
== History of the concept of emerging infectious diseases == The French doctor Charles Anglada (1809–1878) wrote a book in 1869 on extinct and new diseases.<ref>{{Cite book| vauthors = Anglada C |url=https://www.gutenberg.org/files/59140/59140-h/59140-h.htm|title=Étude sur les maladies éteintes et les maladies nouvelles, pour servir à l'histoire des évolutions séculaires de la pathologie|publisher=J.-B. Baillière et fils|year=1869|location=Paris}}</ref> He did not distinguish infectious diseases from others (he uses the terms reactive and affective diseases, to mean diseases with an external or internal cause, more or less meaning diseases with or without an observable external cause). He writes in the introduction:{{blockquote|A widely held opinion among physicians admits the invariability of pathologies. All the illnesses which have existed or which have an outbreak around us are categorized according to arrested and preconceived types, and must enter one way or the other into the frameworks established by the nosologists. History and observation protest wildly against this prejudice, and this is what they teach: Diseases which have disappeared and whose traces are confined to the archives of science, are followed by other diseases, unknown to the contemporary generation, and which come for the first time to assert their rights. In other words, there are ''extinct'' and ''new'' diseases.}}Charles Nicolle, laureate of the Nobel Prize in Physiology or Medicine elaborated the concept of emergence of diseases in his 1930 book ''Naissance, vie et mort des maladies infectieuses'' (Birth, Life and Death of Infectious Diseases), and later in ''Destin des maladies infectieuses'' (Fate of Infectious Diseases)<ref>{{Cite book| vauthors = Nicolle C |url=https://books.google.com/books?id=iQN9CAAAQBAJ|title=Destin des maladies infectieuses|publisher=Presses Électroniques de France|year=2013|isbn=979-10-223-0029-2|orig-year=1933}}</ref> published in 1933 which served as lecture notes for his teaching of a second year course at the Collège de France. In the introduction of the book he sets out the program of the lectures:{{blockquote|It is this historical existence, this ''destiny'' that will be the subject of our talks. I will have to answer, to the extent that our current knowledge allows, questions that you have asked yourself, that every thoughtful or simply curious mind asks: have the infectious diseases that we observe today always existed? Or have some of them appeared in the course of history? Can we assume that new ones will appear? Can we assume that some of these diseases will disappear? Have some of them already disappeared? Finally, what will become of humanity and domestic animals if, as a result of more and more frequent contacts between people, the number of infectious diseases continues to increase?}}The term emerging disease has been in use in scientific publications since the beginning of the 1960s at least<ref name="Ndow-2019">{{Cite book| vauthors = Ndow G, Ambe JR, Tomori O |title=Socio-cultural Dimensions of Emerging Infectious Diseases in Africa |chapter=Emerging Infectious Diseases: A Historical and Scientific Review |date=2019-03-20|pages=31–40|doi=10.1007/978-3-030-17474-3_3|pmc=7123112|isbn=978-3-030-17473-6}}</ref> and is used in the modern sense by David Sencer in his 1971 article "Emerging Diseases of Man and Animals"<ref>{{cite journal | vauthors = Sencer DJ | title = Emerging diseases of man and animals | journal = Annual Review of Microbiology | volume = 25 | issue = 1 | pages = 465–486 | date = October 1971 | pmid = 5005031 | doi = 10.1146/annurev.mi.25.100171.002341 }}</ref> where in the first sentence of the introduction he implicitly defines emerging diseases as "infectious diseases of man and animals currently emerging as public health problems" and as a consequence also includes re-emerging diseases:{{blockquote|Infectious diseases of man and animals currently emerging as public health problems include some old acquaintances and some that are new in respect to identity or concept.}}He also notes that some infectious agents are newly considered as diseases because of changing medical technologies:{{blockquote|But there are also many familiar organisms formerly considered nonpathogenic that are now associated with nosocomial infections, use of artificial kidneys, and the acceptance or rejection of organ transplants, for example.}}He concludes the introduction with a word of caution:{{blockquote|And so infectious disease, one of man's oldest enemies, survives as an adversary that calls forth our best efforts.}}However, to many people in the 1960s and 1970s the emergence of new diseases appeared as a marginal problem, as illustrated by the introduction to the 1962 edition of Natural History of Infectious Disease by Macfarlane Burnet:<ref>{{Cite book| vauthors = Burnet FM, White DO |title=Natural history of infectious disease|date=1962|publisher=University Press |edition=3rd|location=Cambridge [England]}}</ref>{{blockquote|to write about infectious disease is almost to write of something that has passed into history}}as well as the epilogue of the 1972 edition:<ref>{{Cite book| vauthors = Burnet FM, White DO |title=Natural history of infectious disease|date=1972|publisher=University Press |isbn=0-521-08389-3|edition=4th|location=Cambridge [England]|oclc=545868}}</ref>{{blockquote|On the basis of what has happened in the last thirty years, can we forecast any likely developments for the 1970s? If for the present we retain a basic optimism and assume no major catastrophes occur [...] the most likely forecast about the future of infectious disease is that it will be very dull. There may be some wholly unexpected emergence of a new and dangerous infectious disease, but nothing of the sort has marked the past fifty years.}}thumb|Throughout the 20th century until 1980, with the exception of the 1918 Spanish flu pandemic, the death rate from infectious diseases in the United States was steadily decreasing. However, because of the AIDS epidemic, the death rate from infectious diseases increased by 58% between 1980 and 1992. The concept gained more interest at the end of the 1980s as a reaction to the AIDS epidemic. On the side of epistemology, Mirko Grmek worked on the concept of emerging diseases while writing his book on the history of AIDS<ref>{{Cite book| vauthors = Grmek MD |title=Histoire du sida début et origine d'une pandémie actuelle|date=1995|publisher=Payot et Rivages |isbn=2-228-88908-3|edition=Nouv. édition revue et augmentée|location=[Paris]|oclc=708336637}}</ref> and later in 1993 published an article<ref>{{Cite journal| vauthors = Grmek M |date=1993|title=Le concept de maladie émergente|journal=History and Philosophy of the Life Sciences|volume=15|issue=3|pages=281–296|jstor=23331726}}</ref> about the concept of emerging disease as a more precise notion than the term "new disease" that was mostly used in France at that time to qualify AIDS among others.
Also under the shock of the emergence of AIDS, epidemiologists wanted to take a more active approach to anticipate and prevent the emergence of new diseases. Stephen S. Morse from The Rockefeller University in New York was chair and principal organizer of the NIAID/NIH Conference "Emerging Viruses: The Evolution of Viruses and Viral Diseases" held 1–3 May 1989 in Washington, DC. In the article summarizing the conference the authors write:<ref>{{cite journal | vauthors = Morse SS, Schluederberg A | title = From the National Institute of Allergy and Infectious Diseases, the Fogarty International Center of the National Institutes of Health, and the Rockefeller University. Emerging viruses: the evolution of viruses and viral diseases | journal = The Journal of Infectious Diseases | volume = 162 | issue = 1 | pages = 1–7 | date = July 1990 | pmid = 2113071 | doi = 10.1093/infdis/162.1.1 }}</ref>{{blockquote|Challenged by the sudden appearance of AIDS as a major public health crisis [...] jointly sponsored the conference "Emerging Viruses: The Evolution of Viruses and Viral Diseases" [...] It was convened to consider the mechanisms of viral emergence and possible strategies for anticipating, detecting, and preventing the emergence of new viral diseases in the future. }}They further note:{{blockquote|Surprisingly, most emergent viruses are zoonotic, with natural animal reservoirs a more frequent source of new viruses than is the sudden evolution of a new entity. The most frequent factor in emergence is human behavior that increases the probability of transfer of viruses from their endogenous animal hosts to man.}}In a 1991 paper<ref>{{cite journal | vauthors = Morse SS | title = Emerging viruses: defining the rules for viral traffic | journal = Perspectives in Biology and Medicine | volume = 34 | issue = 3 | pages = 387–409 | date = 1991 | pmid = 2067933 | doi = 10.1353/pbm.1991.0038 | s2cid = 46237193 }}</ref> Morse underlines how the emergence of new infectious diseases (of which the public became aware through the AIDS epidemic) is the opposite of the then generally expected ''retreat'' of these diseases:{{blockquote|The striking successes achieved with antibiotics, together with widespread application of vaccines for many previously feared viral diseases, made it appear to many physicians and the public that infectious diseases were retreating and would in time be fully conquered. Although this view was disputed by virologists and many specialists in infectious diseases, it had become a commonplace to suggest that infectious diseases were about to become a thing of the past [...].}}As a direct consequence of the 1989 conference on emerging viruses, the Institute Of Medicine convened in February 1991 the 19-member multidisciplinary Committee on Emerging Microbial Threats to Health, co-chaired by Joshua Lederberg and Robert Shope, to conduct an 18-month study. According to the report produced by the committee in 1992,<ref name="Institute-of-Medicine-(US)-Committee-on-Emerging-Microbial-Threats-to-Health-1992">{{Cite book| author = Institute of Medicine (US) Committee on Emerging Microbial Threats to Health |url = https://www.ncbi.nlm.nih.gov/books/NBK234855/ |title=Emerging Infections: Microbial Threats to Health in the United States|date=1992|publisher = National Academies Press (US)|isbn=978-0-309-04741-8| veditors = Lederberg J, Shope RE, Oaks SC |location=Washington (DC)|pmid=25121245}}</ref> its charge "was to identify significant emerging infectious diseases, determine what might be done to deal with them, and recommend how similar future threats might be confronted to lessen their impact on public health." The report recommended setting up a surveillance program to recognize emerging diseases and proposed methods of intervention in case an emergent disease was discovered.{{blockquote|A well-designed, well-implemented surveillance program can detect unusual clusters of disease, document the geographic and demographic spread of an outbreak, and estimate the magnitude of the problem. It can also help to describe the natural history of a disease, identify factors responsible for emergence, facilitate laboratory and epidemiological research, and assess the success of specific intervention efforts.}}The proposed interventions were based on the following: the U.S. public health system, research and training, vaccine and drug development, vector control, public education and behavioral change. A few years after the 1989 Emerging Viruses conference and the 1992 {{abbrlink|IOM|Institute of Medicine}} report, the Program for Monitoring Emerging Diseases (ProMED) was formed by a group of scientists as a follow-up in 1994<ref>{{cite journal | vauthors = Morse SS | title = Public Health Disease Surveillance Networks | journal = Microbiology Spectrum | volume = 2 | issue = 1 | article-number = OH-0002-2012 | date = February 2014 | pmid = 26082122 | doi = 10.1128/microbiolspec.OH-0002-2012 | isbn = 9781555818425 }}</ref> and the Centres for Disease Control (CDC) launched the ''Emerging Infectious Diseases'' journal in 1995.<ref name="Ndow-2019" />
A decade later the IOM convened the Committee on Emerging Microbial Threats to Health in the 21st Century which published its conclusions in 2003.<ref name="National-Academies-Press-2003">{{Cite book|url=https://www.ncbi.nlm.nih.gov/books/NBK221486/|title=Microbial threats to health : emergence, detection, and response|date=2003|publisher=National Academies Press| vauthors = Smolinski MS, Hamburg MA, Lederberg J | collaboration = Institute of Medicine (U.S.). Committee on Emerging Microbial Threats to Health in the 21st Century.|isbn=0-309-50730-8|location=Washington, D.C.|pmid=25057653 |oclc=53981415}}</ref>
In April 2000 the WHO organized a meeting on Global Outbreak Alert and Response,<ref>{{Cite journal|title=Global outbreak alert and response|location=Geneva, Switzerland|date=26–28 April 2000|hdl=10665/66750|language=en|website=WHO|url=https://www.who.int/csr/resources/publications/surveillance/whocdscsr2003.pdf?ua=1|access-date=10 September 2020 | vauthors = Organization WH }}</ref> which was the founding act of the Global Outbreak Alert and Response Network.
In 2014, the Western African Ebola virus epidemic demonstrated how ill-prepared the world was to handle such an epidemic. In response, the Coalition for Epidemic Preparedness Innovation was launched at the World Economic Forum in 2017 with the objective of accelerating the development of vaccines against emerging infectious diseases to be able to offer them to affected populations during outbreaks.<ref>{{cite web|title=A brief history of vaccines and how they changed the world|url=https://www.weforum.org/agenda/2020/04/how-vaccines-changed-the-world/|website=World Economic Forum|language=en|access-date=2020-04-30}}</ref> CEPI promotes the idea that a proactive approach is required to "create a world in which epidemics are no longer a threat to humanity".<ref>{{cite web|title=Creating a world in which epidemics are no longer a threat to humanity|url=https://www.who.int/immunization/sage/meetings/2019/april/1_CEPI_Summary_WHO_SAGE_Meeting_April.pdf|publisher=WHO|access-date=27 January 2021}}</ref>
==Classification== One way to classify emerging infections diseases is by time and how humans were involved in the emergence:<ref>{{cite journal | vauthors = Morens DM, Fauci AS | title = Emerging Pandemic Diseases: How We Got to COVID-19 | journal = Cell | volume = 182 | issue = 5 | pages = 1077–1092 | date = September 2020 | pmid = 32846157 | pmc = 7428724 | doi = 10.1016/j.cell.2020.08.021 }}</ref> * Newly emerging infectious diseases – diseases that were not previously described in humans, such as SARS-CoV-2 (COVID-19) and MERS * Re-emerging infectious diseases – diseases that have spread to new places or which previous treatments no longer control, such as methicillin-resistant ''Staphylococcus aureus'', tuberculosis (due to drug resistance, measles (due to declining vaccination rates), and cholera (due to climate-related factors) * Deliberately emerging infectious diseases – diseases created by humans for bioterrorism, such as bioterrorism-related agents like anthrax and smallpox * Accidentally emerging infectious diseases – diseases created or spread unintentionally by humans, such as vaccine-derived poliovirus
==Contributing factors== The 1992 {{abbrlink|IOM|Institute of Medicine}} report<ref name="Institute-of-Medicine-(US)-Committee-on-Emerging-Microbial-Threats-to-Health-1992" /> distinguished six factors contributing to emergence of new diseases (Microbial adaptation and change; Economic development and land use; Human demographics and behavior; International travel and commerce; Technology and industry; Breakdown of public health measures) which were extended to 13 factors in the 2003 report<ref name="National-Academies-Press-2003" /> (Chapter 3 of the report detailing each of them): * Microbial adaptation and change * Human susceptibility to infection * Climate and weather * Changing ecosystems * Human demographics and behavior * Economic development and land use * International travel and commerce * Technology and industry * Breakdown of public health measures * Poverty and social inequality * War and famine * Lack of political will * Intent to harm
Their classification serves as a basis for many others. The following table gives examples for different factors: {| class="wikitable" |+ !Factor of emergence !Example |- |Microbial adaption |Genetic drift and genetic shift in Influenza A |- |Changing human susceptibility |Mass immunocompromisation with HIV/AIDS |- |Climate change |Diseases transmitted by animal vectors such as mosquitoes (e.g. West Nile fever or dengue) are moving further from the tropics as the climate warms. By increasing the range of these animal vectors, the diseases are appearing in previously unaffected regions. |- |Changes in human demographics and travel facilitating rapid global spread |Globalization and travel facilitates the rapid spread of pathogens, ex SARS-related coronaviruses |- |Economic development |Use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance |- |War and famine |Clearing of animal habitats that increase the range of diseases such as ebola |- |Inadequate public health services | |- |Poverty and social inequality |Tuberculosis is primarily a problem in low-income areas |- |Bioterrorism |2001 Anthrax attacks |- |Land use |Dam construction and irrigation systems can encourage malaria and other mosquito-borne diseases <br>Use of indiscriminate pesticides in industrial farming reduces/eliminates biological controls (e.g. dragonflies, amphibians, insectivorous birds, spiders) of known disease vectors (e.g. mosquito, tick, biting midge). Deforestation and habitat destruction increase human exposure to zoonotic pathogens, Nipah virus which is linked to bat-to-human transmission. |- |Anti-vaccination or Vaccine hesitancy |Re-emergence of measles<ref name="Medical misinformation">{{cite journal | vauthors = Plaza M, Paladino L, Opara IN, Firstenberg MS, Wilson B, Papadimos TJ, Stawicki SP | title = The use of distributed consensus algorithms to curtail the spread of medical misinformation. | journal = International Journal of Academic Medicine | date = May 2019 | volume = 5 | issue = 2 | pages = 93–39 | doi = 10.4103/IJAM.IJAM_47_19 | doi-access = free }}</ref><ref>{{cite journal| vauthors = Patricia CR, Zulay JP, Carlos RL, Alejandra CM, Cristina JS, Josefina RV |date=2019|title=The Influence of Antivaccination Movements on the Re-emergence of Measles|journal=Journal of Pure and Applied Microbiology|volume=13|issue=1|pages=127–132|doi=10.22207/JPAM.13.1.13|doi-access=free}}</ref> |- |Wildlife trade |Has been linked to zoonotic emergence and spread of new infectious diseases in humans, including Nipah virus and COVID-19.<ref name="Smith2012">{{cite journal | vauthors = Smith KM, Anthony SJ, Switzer WM, Epstein JH, Seimon T, Jia H, Sanchez MD, Huynh TT, Galland GG, Shapiro SE, Sleeman JM, McAloose D, Stuchin M, Amato G, Kolokotronis SO, Lipkin WI, Karesh WB, Daszak P, Marano N | title = Zoonotic viruses associated with illegally imported wildlife products | journal = PLOS ONE | volume = 7 | issue = 1 | article-number = e29505 | date = 2012 | pmid = 22253731 | pmc = 3254615 | doi = 10.1371/journal.pone.0029505 | doi-access = free | bibcode = 2012PLoSO...729505S }}</ref><ref name="Smith2012a">{{cite book | vauthors = Smith KF, Schloegel LM, Rosen GE |title=New Directions in Conservation Medicine: Applied Cases of Ecological Health |publisher=Oxford University Press |year=2012 |isbn=978-0-19-990905-6 | veditors = Aguirre AA, Ostfeld R, Daszak P |editor-link=A. Alonso Aguirre |pages=151–163 |chapter=Wildlife Trade and the Spread of Disease |chapter-url=https://books.google.com/books?id=JnBpAgAAQBAJ&pg=PA151}}</ref> Crowded and unhygienic wet markets and wildlife farms have been implicated in animal-human transmission of emergent viruses, including novel coronaviruses and influenza viruses<ref name="Chan2013">{{cite journal | vauthors = Chan JF, To KK, Tse H, Jin DY, Yuen KY | title = Interspecies transmission and emergence of novel viruses: lessons from bats and birds | journal = Trends in Microbiology | volume = 21 | issue = 10 | pages = 544–555 | date = October 2013 | pmid = 23770275 | pmc = 7126491 | doi = 10.1016/j.tim.2013.05.005 }}</ref> Complex issues surrounding the commerce and consumption of bushmeat are also of particular concern.<ref name="LeBreton2012">{{cite book| vauthors = LeBreton M, Pike BL, Saylors KE, Le Doux Diffo J |chapter-url=https://books.google.com/books?id=JnBpAgAAQBAJ&pg=PA164|title=New Directions in Conservation Medicine: Applied Cases of Ecological Health |publisher=Oxford University Press|year=2012|isbn=978-0-19-990905-6| veditors = Aguirre AA, Ostfeld R, Daszak P |pages=164–178|chapter=Bushmeat and Infectious Disease Emergence }}</ref><ref name="Murray2015">{{cite book|title=Food Safety Risks from Wildlife|vauthors=Murray KA, Allen T, Loh E, et al|publisher=Springer|year=2015|isbn=978-3-319-24442-6|veditors=Russell MJ, Doyle MP|pages=31–57|chapter=Emerging Viral Zoonoses from Wildlife Associated with Animal-Based Food Systems: Risks and Opportunities|doi=10.1007/978-3-319-24442-6_2|s2cid=133576419}}</ref><ref name="Kurpiers2016">{{cite book|title=Problematic Wildlife: A Cross-Disciplinary Approach|vauthors=Kurpiers LA, Schulte-Herbrüggen B, Ejotre I, Reeder DM |publisher=Springer|year=2016|isbn=978-3-319-22246-2|editor=Angelici F|pages=31–57|chapter=Bushmeat and Emerging Infectious Diseases: Lessons from Africa|doi=10.1007/978-3-319-22246-2_24|s2cid=85916327}}</ref> |}
=== Climate change and environmental drivers === Climate change has emerged as a significant driver of emerging infectious diseases by altering ecosystems, vector distribution, and patterns of human–animal interaction. Rising global temperatures and changes in precipitation patterns expand the geographic range of vectors such as mosquitoes and ticks, facilitating the spread of diseases like dengue, malaria, Lyme disease, and West Nile virus into previously unaffected regions.<ref name="ipcc2023">'''Intergovernmental Panel on Climate Change.''' ''Climate Change 2023: Synthesis Report.'' IPCC, 2023. <nowiki>https://www.ipcc.ch/report/ar6/syr/</nowiki> </ref><ref name="lancetcountdown2023">'''Romanello M, Napoli CD, Green C, et al.''' The 2023 report of the Lancet Countdown on health and climate change: the imperative for a health-centred response in a world facing irreversible harms. ''Lancet.'' 2023 Dec 16;402(10419):2346–2394. doi:10.1016/S0140-6736(23)01859-7.</ref>
Environmental disruptions such as deforestation, biodiversity loss, and habitat fragmentation increase contact between humans and wildlife, raising the likelihood of zoonotic spillover events. Reduced biodiversity has been associated with increased transmission of certain pathogens, as ecological imbalance may favor reservoir species that carry infectious agents.<ref name="keesing2010">'''Keesing F, Belden L, Daszak P, et al.''' Impacts of biodiversity on the emergence and transmission of infectious diseases. ''Nature.'' 2010;468:647–652. doi:10.1038/nature09575.</ref>
Extreme weather events, including floods, droughts, and heatwaves, can further influence disease dynamics by disrupting infrastructure, displacing populations, and compromising sanitation systems. These conditions can lead to outbreaks of waterborne and vector-borne diseases, particularly in vulnerable populations.<ref name="who_climate_health">'''World Health Organization.''' Climate change and health. WHO, 2023. Available at: <nowiki>https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health</nowiki> (accessed March 22, 2026).</ref>
The interconnected impacts of climate, ecosystems, and human health are often described within a One Health framework, which emphasizes the integration of environmental, animal, and human health systems in understanding and mitigating emerging infectious diseases.<ref>Food and Agriculture Organization of the United Nations (FAO), United Nations Environment Programme (UNEP), World Health Organization (WHO), & World Organization for Animal Health (WOAH). (2022). ''One Health Joint Plan of Action (2022–2026): Working together for the health of humans, animals, plants and the environment''.</ref>
== Zoonotic diseases == Zoonotic diseases, originating from animal sources, pose a significant threat to human health. Proximity to wildlife, and climate change have created favorable conditions for the transmission of zoonotic diseases, leading to outbreaks such as Zika, Ebola, and COVID-19. Up to 75% of emerging infectious diseases are zoonotic, originating from viruses and other pathogens that are transmitted from animals to humans. Understanding the mechanisms of transmission, the role of wildlife trade, and the importance of surveillance and early detection is crucial for mitigating the impact of zoonotic diseases on human health. Surveillance efforts involving wastewater have been identified as valuable tools for detecting early warning signs of disease emergence and providing timely interventions.<ref name="Leifels-2022">{{cite journal |vauthors=Leifels M, Khalilur Rahman O, Sam IC, Cheng D, Chua FJ, Nainani D, Kim SY, Ng WJ, Kwok WC, Sirikanchana K, Wuertz S, Thompson J, Chan YF |date=2022-10-30 |title=The one health perspective to improve environmental surveillance of zoonotic viruses: lessons from COVID-19 and outlook beyond |journal=ISME Communications |volume=2 |issue=1 |page=107 |bibcode=2022ISMEC...2..107L |doi=10.1038/s43705-022-00191-8 |pmc=9618154 |pmid=36338866}}</ref><ref name="Health-Ecology-and-Disease-Transmission">{{Cite web|url=https://journalofethics.ama-assn.org/sites/joedb/files/2024-01/joe-2402_0.pdf|title=Health Ecology and Disease Transmission}}</ref>
==List==
=== NIAID list of Biodefense and Emerging Infectious Diseases === The U.S. National Institute of Allergy and Infectious Diseases (NIAID) maintains a list of Biodefense and Emerging Infectious Diseases. The list is categorized by biodefense risk, which is mostly based on biological warfare and bioterrorism considerations. As of 2004, it recognized the following emerging and re-emerging diseases.<ref>{{cite web|url=https://www.niaid.nih.gov/research/niaid-biodefense-pathogens |title=NIAID Emerging Infectious Diseases/ Pathogens | NIH: National Institute of Allergy and Infectious Diseases |publisher=Niaid.nih.gov |date=2018-07-26 |access-date=2020-05-24}}</ref>
{{columns-list|colwidth=30em| Newly recognized (since the 1980s): * Acanthamebiasis * Australian bat lyssavirus * ''Babesia'', atypical * ''Bartonella henselae'' * Coronaviruses, including SARS coronavirus * Ehrlichiosis * ''Encephalitozoon cuniculi'' * ''Encephalitozoon hellem'' * ''Enterocytozoon bieneusi'' * ''Helicobacter pylori'' * Hendra virus (equine morbilli virus) * Hepatitis C * Hepatitis E * Human herpesvirus 8 * Human herpesvirus 6 * Lyme borreliosis * Microsporidia * Parvovirus B19
Re-emerging: * ''Coccidioides immitis'' * Enterovirus 71 * Prion diseases * ''Streptococcus'', group A * ''Staphylococcus aureus''
Diseases with bioterrorism potential, CDC category A (most dangerous): * Anthrax * ''Clostridium botulinum'' * Tularemia * Smallpox and other pox viruses * Viral hemorrhagic fevers ** Arenaviruses: Lymphocytic choriomeningitis (LCM), Junin virus, Machupo virus, Guanarito virus, Lassa fever ** Bunyaviruses: Hantaviruses, Rift Valley Fever, Crimean-Congo hemorrhagic fever virus ** Flaviviruses: Dengue ** Filoviruses: Ebola, Marburg * ''Yersinia pestis''
Diseases with bioterrorism potential, CDC category B: * ''Brucella'' species (brucellosis) * ''Burkholderia pseudomallei'' (melioidosis) * ''Burkholderia mallei'' (glanders) * ''Coxiella burnetii'' (Q fever) * Epsilon toxin of ''Clostridium perfringens'' * Food-borne and Water-borne Pathogens ** Bacteria *** ''Campylobacter jejuni'' *** Diarrheagenic ''E. coli'' *** ''Listeria monocytogenes'' *** Pathogenic vibrios *** ''Salmonella'' *** ''Shigella'' species *** ''Yersinia enterocolitica'' ** Protozoa *** ''Cryptosporidium parvum'' *** ''Cyclospora cayetanensis'' *** ''Entamoeba histolytica'' *** ''Giardia lamblia'' *** ''Toxoplasma'' ** Fungi *** Microsporidia ** Viruses: *** Caliciviruses *** Hepatitis A * Mosquito-borne encephalitis viruses ** California encephalitis ** Eastern equine encephalitis (EEE) ** Japanese encephalitis virus (JE) ** Kyasanur Forest virus ** LaCrosse virus (LACV) ** Venezuelan equine encephalitis (VEE) ** Western equine encephalitis (WEE) ** West Nile virus (WNV) ** Yellow fever * Ricin toxin (from ''Ricinus communis'') * Staphylococcal enterotoxin B * Typhus fever (''Rickettsia prowazekii'')
Diseases with bioterrorism potential, CDC category C (least dangerous): * Influenza * Multidrug-resistant tuberculosis (MDR-TB) * Nipah virus * Rabies * SARS coronavirus * Tick-borne encephalitis virus * Tick-borne hemorrhagic fever viruses * Other hantaviruses * Other rickettsias
Since 2004, NIAID has added to its biodefense emerging pathogen list:<ref name="NIAID-2018">{{cite web |title=NIAID Emerging Infectious Diseases/ Pathogens |url=https://www.niaid.nih.gov/research/niaid-biodefense-pathogens |website=www.niaid.nih.gov |publisher=NIH - National Institute of Allergy and Infectious Diseases |archive-url=https://web.archive.org/web/20200418140838/https://www.niaid.nih.gov/research/emerging-infectious-diseases-pathogens |archive-date=18 April 2020 |url-status=live |date=26 July 2018}}</ref> * ''Yersinia pestis'' (plague, category A) * Chapare virus (category A areanavirus) * Lujo (category A arenavirus) * ''Chlamydia psittaci'' (category B) * ''Naegleria fowleri'' (category B) * ''Balamuthia mandrillaris'' (category B) * St. Louis encephalitis virus (SLEV, category B) * Tick-borne hemorrhagic fever viruses (category C) ** Bunyaviruses: Severe Fever with Thrombocytopenia Syndrome virus (SFTSV), Heartland virus ** Flaviviruses: Omsk Hemorrhagic Fever virus, Alkhurma virus, Kyasanur Forest virus (reclassified from B to C) * Powassan virus (Deer Tick virus, category C) * Chikungunya virus (category B) * ''Coccidioides'' species (category C) * Human coronavirus HKU1 (category C) * Middle East respiratory syndrome coronavirus (category C) * Anaplasmosis * Aspergillus * BK virus * Bordetella pertussis * Borrelia miyamotoi * Clostridioides difficile * ''Cryptococcus gattii'' * ''Enterococcus faecium'' * ''Enterococcus faecalis'' * Enterovirus 68 * JC virus * Leptospirosis * Measles * Mucormycosis * Mumps virus * Poliovirus * Zika virus (category B)
NIAID also monitors antibiotic resistance, which can become an emerging threat for many pathogens. }}
=== WHO list of most important emerging infectious diseases === In December 2015, the World Health Organization held a workshop on prioritization of pathogens "for accelerated R&D for severe emerging diseases with potential to generate a public health emergency, and for which no, or insufficient, preventive and curative solutions exist."<ref>{{cite web|url=https://www.who.int/who-documents-detail/blueprint-for-r-d-preparedness-and-response-to-public-health-emergencies-due-to-highly-infectious-pathogens|title=Blueprint for R&D preparedness and response to public health emergencies due to highly infectious pathogens|website=www.who.int|language=en| archive-url=https://web.archive.org/web/20200428151749/https://www.who.int/who-documents-detail/blueprint-for-r-d-preparedness-and-response-to-public-health-emergencies-due-to-highly-infectious-pathogens | archive-date=28 April 2020}}</ref> The result was a list containing the following six diseases: * Crimean–Congo hemorrhagic fever * Filovirus diseases (Ebola virus disease and Marburg virus disease) * Highly pathogenic emerging Coronaviruses relevant to humans (MERS and SARS) * Lassa fever * Nipah virus infection * Rift Valley fever
These were selected based on the following measures:
# Human transmissibility (including population immunity, behavioural factors, etc.) # Severity or case fatality rate # Spillover potential # Evolutionary potential # Available countermeasures # Difficulty of detection or control # Public health context of the affected area(s) # Potential scope of outbreak (risk of international spread) # Potential societal impacts
=== Newly reported infectious diseases === In 2007 Mark Woolhouse and Eleanor Gaunt established a list of 87 human pathogens first reported in the period between 1980 and 2005.<ref>{{cite journal | vauthors = Woolhouse M, Gaunt E | title = Ecological origins of novel human pathogens | journal = Critical Reviews in Microbiology | volume = 33 | issue = 4 | pages = 231–242 | date = January 2007 | pmid = 18033594 | doi = 10.1080/10408410701647560 | s2cid = 19213392 }}</ref> These were classified according to their types. {| class="wikitable" |+Numbers of pathogen species by taxonomic category ! !Number of species known in 2005 !Number of species reported from 1980 to 2005 |- |TOTAL |1399 |87 |- |Bacteria |541 |11 |- |Fungi |325 |13 |- |Helminths |285 |1 |- |Prions |2 |1 |- |Protozoa |57 |3 |- |Viruses |189 |58 |- |DNA viruses |36 |9 |- |RNA viruses |153 |49 |}
=== Major outbreaks === The following table summarizes the major outbreaks since 1998 caused by emerging or re-emerging infectious diseases.<ref>{{cite web|url=https://www.gov.uk/government/publications/emerging-infections-characteristics-epidemiology-and-global-distribution/emerging-infections-how-and-why-they-arise|title=Emerging infections: how and why they arise|date=27 February 2019}}</ref>
{{mw-datatable}} {| class="wikitable"sortable mw-datatable" style="text-align:left" |+ !Disease !Country or region !Year of start of outbreak |- |Ngari virus<ref>{{cite journal | vauthors = Gerrard SR, Li L, Barrett AD, Nichol ST | title = Ngari virus is a Bunyamwera virus reassortant that can be associated with large outbreaks of hemorrhagic fever in Africa | journal = Journal of Virology | volume = 78 | issue = 16 | pages = 8922–8926 | date = August 2004 | pmid = 15280501 | pmc = 479050 | doi = 10.1128/JVI.78.16.8922-8926.2004 }}</ref> |Kenya, Tanzania, Somalia |1998 |- |Nipah virus |Malaysia |1998 |- |West Nile virus |US |1999 |- |Itaya virus<ref>{{cite journal | vauthors = Hontz RD, Guevara C, Halsey ES, Silvas J, Santiago FW, Widen SG, Wood TG, Casanova W, Vasilakis N, Watts DM, Kochel TJ, Ebihara H, Aguilar PV | title = Itaya virus, a Novel Orthobunyavirus Associated with Human Febrile Illness, Peru | journal = Emerging Infectious Diseases | volume = 21 | issue = 5 | pages = 781–788 | date = May 2015 | pmid = 25898901 | pmc = 4412221 | doi = 10.3201/eid2105.141368 }}</ref> |Peru |1999 |- |Rift Valley fever |Saudi Arabia and Yemen |2000 |- |EBLV-2 |Scotland |2002 |- |SARS-CoV | |2002 |- |Influenza A virus subtype H7N2 | |2002 |- |Monkeypox |US |2003 |- |Chapare virus |Bolivia |2003 |- |Plague |Algeria |2003 |- |HTLV-3, HTLV-4 |Cameroon |2005 |- |Melaka virus |Malaysia |2006 |- |LuJo virus |southern Africa |2008 |- |Multi-drug resistant P. falciparum |South-East Asia |2008 |- |Candida auris | |2009 |- |Heartland virus |US |2009 |- |Bas-Congo virus |DRC |2009 |- |Lassa fever |Mali |2009 |- |Pandemic H1N1/09 virus |Global pandemic |2009 |- |Huaiyangshan banyangvirus | |2009 |- |Plague |Libya |2009 |- |Cholera |Haiti |2010 |- |Lassa fever |Ghana |2011 |- |Plasmodium cynomolgi<ref>{{Cite journal| vauthors = Law YH |date=2018-04-16|title=Rare human outbreak of monkey malaria detected in Malaysia|url=http://www.nature.com/articles/d41586-018-04121-4|journal=Nature|language=en|pages=d41586–018–04121–4|doi=10.1038/d41586-018-04121-4|issn=0028-0836|url-access=subscription}}</ref> |Malaysia |2011 |- |H3N2v | |2011 |- |MERS -CoV | |2012 |- |Mojiang paramyxovirus<ref>{{cite journal | vauthors = Wu Z, Yang L, Yang F, Ren X, Jiang J, Dong J, Sun L, Zhu Y, Zhou H, Jin Q | title = Novel Henipa-like virus, Mojiang Paramyxovirus, in rats, China, 2012 | journal = Emerging Infectious Diseases | volume = 20 | issue = 6 | pages = 1064–1066 | date = June 2014 | pmid = 24865545 | pmc = 4036791 | doi = 10.3201/eid2006.131022 }}</ref> | |2012 |- |H7N9 | |2013 |- |Sosuga pararubulavirus | |2013 |- |H10N8<ref>{{cite journal | vauthors = To KK, Tsang AK, Chan JF, Cheng VC, Chen H, Yuen KY | title = Emergence in China of human disease due to avian influenza A(H10N8)--cause for concern? | journal = The Journal of Infection | volume = 68 | issue = 3 | pages = 205–215 | date = March 2014 | pmid = 24406432 | doi = 10.1016/j.jinf.2013.12.014 | hdl = 10722/200735 | hdl-access = free }}</ref> | |2013 |- |Chikungunya |Caribbean |2013 |- |{{ill|Variegated Squirrel Bornavirus 1|de|Bunthörnchen-Bornavirus 1}} | |2013 |- |Colpodella sp. Heilongjiang<ref>{{cite journal | vauthors = Jiang JF, Jiang RR, Chang QC, Zheng YC, Jiang BG, Sun Y, Jia N, Wei R, Liu HB, Huo QB, Wang H, von Fricken ME, Cao WC | title = Potential novel tick-borne Colpodella species parasite infection in patient with neurological symptoms | journal = PLOS Neglected Tropical Diseases | volume = 12 | issue = 8 | article-number = e0006546 | date = August 2018 | pmid = 30071019 | pmc = 6071948 | doi = 10.1371/journal.pntd.0006546 | doi-access = free | veditors = Vinetz JM }}</ref> |China |2013 |- |Ebola virus disease<ref name="Kalra_2014">{{cite journal | vauthors = Kalra S, Kelkar D, Galwankar SC, Papadimos TJ, Stawicki SP, Arquilla B, Hoey BA, Sharpe RP, Sabol D, Jahre JA | title = The emergence of ebola as a global health security threat: from 'lessons learned' to coordinated multilateral containment efforts | journal = Journal of Global Infectious Diseases | volume = 6 | issue = 4 | pages = 164–177 | date = October 2014 | pmid = 25538455 | pmc = 4265832 | doi = 10.4103/0974-777X.145247 | doi-access = free }}</ref> |West Africa |2014 |- |H5N6 | |2014 |- |Lassa fever |Benin |2014 |- |Bourbon virus |US |2014 |- |Zika virus<ref>{{cite journal | vauthors = Sikka V, Chattu VK, Popli RK, Galwankar SC, Kelkar D, Sawicki SG, Stawicki SP, Papadimos TJ | title = The Emergence of Zika Virus as a Global Health Security Threat: A Review and a Consensus Statement of the INDUSEM Joint working Group (JWG) | journal = Journal of Global Infectious Diseases | volume = 8 | issue = 1 | pages = 3–15 | date = 11 February 2016 | pmid = 27013839 | pmc = 4785754 | doi = 10.4103/0974-777X.176140 | doi-access = free }}</ref> |Americas |2015 |- |Crimean–Congo hemorrhagic fever |Spain |2016 |- |Chikungunya |Pakistan |2016 |- |Lassa fever |Togo |2016 |- |Ntwetwe virus<ref>{{cite journal | vauthors = Edridge AW, Deijs M, Namazzi R, Cristella C, Jebbink MF, Maurer I, Kootstra NA, Buluma LR, van Woensel JB, de Jong MD, Idro R, Boele van Hensbroek M, van der Hoek L | title = Novel Orthobunyavirus Identified in the Cerebrospinal Fluid of a Ugandan Child With Severe Encephalopathy | journal = Clinical Infectious Diseases | volume = 68 | issue = 1 | pages = 139–142 | date = January 2019 | pmid = 29893821 | pmc = 6293039 | doi = 10.1093/cid/ciy486 }}</ref> |Uganda |2016 |- |Monkeypox |Nigeria |2017 |- |Yellow fever |Brazil |2017 |- |Rat hepatitis E virus<ref>{{cite journal | vauthors = Andonov A, Robbins M, Borlang J, Cao J, Hatchette T, Stueck A, Deschambault Y, Murnaghan K, Varga J, Johnston L | title = Rat Hepatitis E Virus Linked to Severe Acute Hepatitis in an Immunocompetent Patient | journal = The Journal of Infectious Diseases | volume = 220 | issue = 6 | pages = 951–955 | date = August 2019 | pmid = 30649379 | doi = 10.1093/infdis/jiz025 }}</ref> | |2017 |- |Guinea worm |Chad |2018 |- |Lyme disease | |2018 |- |H7N4 | |2018 |- |Monkeypox |Liberia, UK |2018 |- |Nipah virus |India |2018 |- |COVID-19<ref name="ACAIM-WACEM COVID-19 Consensus Paper"/> |Global pandemic |2019 |}
==Methicillin-resistant ''Staphylococcus aureus''== Methicillin-resistant ''Staphylococcus aureus'' (MRSA) evolved from methicillin-susceptible ''Staphylococcus aureus'' (MSSA), otherwise known as common ''S. aureus''. Many people are natural carriers of ''S. aureus'', without being affected in any way. Infections occur in healthcare settings (Healthcare acquired-MRSA) and in the community (Community acquired-MRSA), often leading to severe skin infections, pneumonia, and bloodstream infections. Community-acquired MRSA, is increasingly found in healthy individuals such as athletes, prisoners, and schoolchildren outside of hospital settings.<ref>{{cite journal | vauthors = Chambers HF, Deleo FR | title = Waves of resistance: Staphylococcus aureus in the antibiotic era | journal = Nature Reviews. Microbiology | volume = 7 | issue = 9 | pages = 629–641 | date = September 2009 | pmid = 19680247 | pmc = 2871281 | doi = 10.1038/nrmicro2200 }}</ref> MSSA was treatable with the antibiotic methicillin until it acquired the gene for antibiotic resistance.<ref name="auto"/> MRSA is a major public health threat due to its resistance to antibiotics.<ref>{{cite journal | vauthors = David MZ, Daum RS | title = Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic | journal = Clinical Microbiology Reviews | volume = 23 | issue = 3 | pages = 616–687 | date = July 2010 | pmid = 20610826 | pmc = 2901661 | doi = 10.1128/CMR.00081-09 }}</ref> Through genetic mapping of various strains of MRSA, scientists have found that MSSA acquired the mecA gene in the 1960s, which accounts for its pathogenicity, before this it had a predominantly commensal relationship with humans. It is theorized that when this ''S. aureus'' strain that had acquired the mecA gene was introduced into hospitals, it came into contact with other hospital bacteria that had already been exposed to high levels of antibiotics. When exposed to such high levels of antibiotics, the hospital bacteria suddenly found themselves in an environment that had a high level of selection for antibiotic resistance, and thus resistance to multiple antibiotics formed within these hospital populations. When ''S. aureus'' came into contact with these populations, the multiple genes that code for antibiotic resistance to different drugs were then acquired by MRSA, making it nearly impossible to control.<ref>{{cite journal | vauthors = Benson MA, Ohneck EA, Ryan C, Alonzo F, Smith H, Narechania A, Kolokotronis SO, Satola SW, Uhlemann AC, Sebra R, Deikus G, Shopsin B, Planet PJ, Torres VJ | title = Evolution of hypervirulence by a MRSA clone through acquisition of a transposable element | journal = Molecular Microbiology | volume = 93 | issue = 4 | pages = 664–681 | date = August 2014 | pmid = 24962815 | pmc = 4127135 | doi = 10.1111/mmi.12682 }}</ref> It is thought that MSSA acquired the resistance gene through the horizontal gene transfer, a method in which genetic information can be passed within a generation, and spread rapidly through its own population as was illustrated in multiple studies.<ref name=Krishnapillai1996>{{cite journal | vauthors = Krishnapillai V | year = 1996 | title = Horizontal gene transfer | journal = Journal of Genetics | volume = 75 | issue = 2| pages = 219–232 | doi = 10.1007/bf02931763 | s2cid = 5989957 }}</ref> Horizontal gene transfer speeds the process of genetic transfer since there is no need to wait an entire generation time for gene to be passed on.<ref name=Krishnapillai1996/> Since most antibiotics do not work on MRSA, physicians have to turn to alternative methods based in Darwinian medicine. Efforts to combat MRSA include improved tracking,<ref name=":0">{{cite journal | vauthors = Duerden B, Fry C, Johnson AP, Wilcox MH | title = The Control of Methicillin-Resistant Staphylococcus aureus Blood Stream Infections in England | journal = Open Forum Infectious Diseases | volume = 2 | issue = 2 | article-number = ofv035 | date = April 2015 | pmid = 26380336 | pmc = 4567090 | doi = 10.1093/ofid/ofv035 }}</ref> enhanced hospital hygiene protocols to reduce healthcare-associated infections,<ref>{{cite journal | vauthors = Otter JA, Yezli S, Salkeld JA, French GL | title = Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital settings | journal = American Journal of Infection Control | volume = 41 | issue = 5 Suppl | pages = S6-11 | date = May 2013 | pmid = 23622751 | doi = 10.1016/j.ajic.2012.12.004 }}</ref> and development of new antimicrobial agents and alternative therapies, such as bacteriophage therapy.<ref>{{cite journal | vauthors = Plumet L, Ahmad-Mansour N, Dunyach-Remy C, Kissa K, Sotto A, Lavigne JP, Costechareyre D, Molle V | title = Bacteriophage Therapy for ''Staphylococcus Aureus'' Infections: A Review of Animal Models, Treatments, and Clinical Trials | journal = Frontiers in Cellular and Infection Microbiology | volume = 12 | article-number = 907314 | date = 2022-06-17 | pmid = 35782148 | pmc = 9247187 | doi = 10.3389/fcimb.2022.907314 | doi-access = free }}</ref> However, prevention is the most preferred method of avoiding antibiotic resistance.<ref name=":0" />
==Scientific Advisory Group for Origins of Novel Pathogens== On 16 July 2021, the Director-General of WHO announced the formation of the Scientific Advisory Group for Origins of Novel Pathogens (SAGO),<ref name="WHO-20210716">{{cite news |author=Staff |title=WHO Director-General's opening remarks at the Member State Information Session on Origins |url=https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-member-state-information-session-on-origins |date=16 July 2021 |work=World Health Organization |access-date=27 September 2021 }}</ref><ref name="SCI-20210717">{{cite news | vauthors = Cohen J |title=With call for 'raw data' and lab audits, WHO chief pressures China on pandemic origin probe - A new team of scientists may replace agency group already probing the start of COVID-19 |url=https://www.science.org/news/2021/07/who-chief-sharpens-call-china-further-help-probe-origin-pandemic |date=17 July 2021 |work=Science |access-date=27 September 2021 }}</ref><ref name="SCI-20210825">{{cite news | vauthors = Kupferschmidt K |title=New WHO group aims to improve efforts to find pathogen origins - The World Health Organization's Maria Van Kerkhove on the hunt for COVID-19 origins and what's next |url=https://www.science.org/news/2021/08/new-who-group-aims-improve-efforts-find-pathogen-origins |date=25 August 2021 |work=Science |access-date=27 September 2021 }}</ref> which is to be a permanent advisory body of the organisation. The Group was formed with a broad objective to examine emerging infectious diseases, including COVID-19.<ref name="WHO-20210716" /><ref name="WHO-202100908">{{cite news |author=Staff |title=Deadline extension - call for experts to join the Scientific Advisory Group for the Origins of Novel Pathogens (SAGO). |url=https://www.who.int/news-room/articles-detail/who-scientific-advisory-group-for-the-origins-of-novel-pathogens-(sago) |date=8 September 2021 |work=World Health Organization |access-date=27 September 2021 }}</ref> The group's primary objective is to provide scientific guidance on identifying the origins of emerging pathogens, including SARS-CoV-2.<ref>{{Cite web |date=2021-10-13 |title=WHO establishes new scientific group to study COVID origins, prevent future pandemics {{!}} UN News |url=https://news.un.org/en/story/2021/10/1102992 |access-date=2025-03-17 |website=news.un.org |language=en}}</ref> The group has also recommended enhanced global surveillance systems.<ref>{{Cite web |title=WHO launches global framework for understanding the origins of new or re-emerging pathogens |url=https://www.who.int/news/item/04-09-2024-who-launches-global-framework-for-understanding-the-origins-of-new-or-re-emerging-pathogens |access-date=2025-03-17 |website=www.who.int |language=en}}</ref> According to the WHO Director-General, "SAGO will play a vital role in the next phase of studies into the origins of SARS-CoV-2, as well as the origins of future new pathogens."<ref name="WHO-20210716" /> <!--- Related References --- * https://www.bloomberg.com/news/articles/2021-08-25/embattled-who-virus-origins-team-says-window-closing-for-probe * https://www.scmp.com/news/china/politics/article/3146730/political-rows-hamper-covid-19-origins-hunt-more-china-research * https://www.statnews.com/2021/08/25/the-who-seeks-experts-to-investigate-the-origins-of-pathogens/ * https://www.telegraph.co.uk/global-health/science-and-disease/proposes-new-pandemic-origins-inquiry-team-amid-mounting-criticism/ * https://www.wsj.com/articles/covid-19-origin-researchers-warn-time-is-running-out-to-find-answers-11629903950 * https://www.wsj.com/articles/who-seeks-to-revive-stalled-inquiry-into-origins-of-covid-19-with-new-team-11632657603 * https://news.yahoo.com/window-rapidly-closing-gather-evidence-121852213.html --->
== See also == * Climate change and infectious diseases * Disease X * Epidemiological transition * Globalization and disease * Pandemic prevention
== References == {{Reflist|2}}
== Further reading == * {{cite book |author=Nathan Wolfe |title=The Viral Storm: The Dawn of a New Pandemic Age |isbn=978-1250012210 |year=2012 |publisher=St. Martin's Griffin}}
== External links == * [https://wwwnc.cdc.gov/eid/ Website] of ''Emerging Infectious Diseases'', an open-access, peer-review journal published by the Centers for Disease Control and Prevention (CDC)
{{Concepts in infectious disease}} {{Authority control}}
Category:Infectious diseases Category:Microbial population biology Category:Infectious diseases by mode of transmission