Introduction to viruses: Difference between revisions

Revision as of 15:30, 28 January 2025

Revision as of 16:28, 28 January 2025

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[[File:SIV primates.jpg|right|400px|thumb|Left to right: the [[African green monkey]], source of [[Simian immunodeficiency virus|SIV]]; the [[sooty mangabey]], source of [[HIV-2]]; and the [[Common chimpanzee|chimpanzee]], source of [[HIV-1]]]]

[[File:Orgin and evolution of SARS.jpg|thumb|Origin and evolution of (A) SARS-CoV (B) MERS-CoV, and (C) SARS-CoV-2 in different hosts. All the viruses came from bats as coronavirus-related viruses before mutating and adapting to intermediate hosts and then to humans and causing the diseases [[SARS]], [[MERS]] and [[COVID-19]].(<small>Adapted from Ashour et al. (2020)</small> <ref name="pmid32143502">{{cite journal |vauthors=Ashour HM, Elkhatib WF, Rahman MM, Elshabrawy HA |title=Insights into the Recent 2019 Novel Coronavirus (SARS-CoV-2) in Light of Past Human Coronavirus Outbreaks |journal=Pathogens (Basel, Switzerland) |volume=9 |issue=3 |pages= 186|date=March 2020 |pmid=32143502 |doi=10.3390/pathogens9030186 |pmc=7157630 |doi-access=free }}</ref>)]]

Although viral [[pandemic]]s are rare events, HIV—which evolved from viruses found in monkeys and chimpanzees—has been pandemic since at least the 1980s.<ref name="pmid29460740">{{cite journal |vauthors=Eisinger RW, Fauci AS |title=Ending the HIV/AIDS Pandemic1 |journal=Emerging Infectious Diseases |volume=24 |issue=3 |pages=413–416 |date=March 2018 |pmid=29460740 |pmc=5823353 |doi=10.3201/eid2403.171797 }}</ref> During the 20th century there were four pandemics caused by influenza virus and those that occurred in 1918, 1957 and 1968 were severe.<ref name="pmid30180422">{{cite journal |vauthors=Qin Y, Zhao MJ, Tan YY, Li XQ, Zheng JD, Peng ZB, Feng LZ |title=[History of influenza pandemics in China during the past century] |language=zh |journal=Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi |volume=39 |issue=8 |pages=1028–1031 |date=August 2018 |pmid=30180422 |doi=10.3760/cma.j.issn.0254-6450.2018.08.003 |doi-broken-date=28 January 2025 }}</ref> Before its eradication, smallpox was a cause of pandemics for more than 3,000 years.<ref name="pmid26060873">{{cite journal |vauthors=Nishiyama Y, Matsukuma S, Matsumura T, Kanatani Y, Saito T |title=Preparedness for a smallpox pandemic in Japan: public health perspectives |journal=Disaster Medicine and Public Health Preparedness |volume=9 |issue=2 |pages=220–223 |date=April 2015 |pmid=26060873 |doi=10.1017/dmp.2014.157 |s2cid=37149836 }}</ref> Throughout history, human migration has aided the spread of pandemic infections; first by sea and in modern times also by air.<ref name="pmid30878442">{{cite journal |vauthors=Houghton F |title=Geography, global pandemics & air travel: Faster, fuller, further & more frequent |journal=Journal of Infection and Public Health |volume=12 |issue=3 |pages=448–449 |date=2019 |pmid=30878442 |doi=10.1016/j.jiph.2019.02.020 |pmc=7129534 }}</ref>

With the exception of smallpox, most pandemics are caused by newly evolved viruses. These [[Emergent virus|"emergent"]] viruses are usually mutants of less harmful viruses that have circulated previously either in humans or in other animals.<ref>{{Cite web|url=https://virologyj.biomedcentral.com/articles/sections/emerging-viruses|title=Virology Journal|website=Virology Journal}}</ref>