Virus

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==Notable viruses==
 
==Notable viruses==
There are thousands of virus types of which we are aware and have studied, and millions more which we have yet to discover. However, there are (or have been) a few viruses that have particular relevance to RationalWiki.  
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There are thousands of virus types of which we are aware and have studied, and millions more which we have yet to discover.{{fact}} However, there are (or have been) a few viruses that have particular relevance to RationalWiki.  
  
 
===Smallpox===
 
===Smallpox===

Revision as of 05:56, 1 September 2014

A virus type, the bacteriophage.

A virus is an extremely small (the HIV virus, for example, is only a tenth of a micron in size[1]) infectious agent. A virus consists of a protein coating over a strand of RNA or DNA, which replicates itself by taking over a host cell of another life form, implanting its genetic information into it, and causing the cell to produce more viruses.[2] Often (but not always) this is done very rapidly until the cell bursts dispersing the new viruses.[3] They also play a part in maintaining genetic diversity through transfer of genetic material between cells.

There is a significant amount of debate about whether viruses are living organisms or not. While they do contain genetic material (i.e. the DNA or RNA), and evolve, like any other living organism, they also contain no cell structures (things like a cytoplasm, cell wall, nucleus, et cetera), and cannot reproduce independently.[4]

Viruses cause many infectious diseases, from things as non-threatening as the Common Cold, to being Bio-Safety Level 4 pathogens, such as the Ebola and Marburg viruses.[5] [6] [7]

There are also other virus-like infectious agents like viroids, which are just strands of RNA without the protein coating and cause plant diseases, and prions, which are just protein particles and can cause, for example, degenerative disorders of the central nervous system like mad cow disease.

While the ability of viruses to infect cells is generally bad for health, there are some possible interesting applications in science and technology, like using viruses to reduce cancer.[8]

Like all things related to medicine there is a lot of woo regarding viruses. Most commonly said woo questions whether viruses are linked to certain diseases, how effective vaccines are in preventing virus infection, or even whether viruses can cause infection at all.

Contents

Notable viruses

There are thousands of virus types of which we are aware and have studied, and millions more which we have yet to discover.[citation needed] However, there are (or have been) a few viruses that have particular relevance to RationalWiki.

Smallpox

Smallpox is caused by a virus known as Variola Major, a member of the family poxviridae or poxviruses. Smallpox is a disease that only affects humans and likely first arose in agricultural Mesopotamian populations, at around 5000 BCE.[9] It is a very infectious disease that can be spread by breathing in infected droplets of saliva[10] This, combined with an average mortality rate of about 30%[11], led to the disease killing several million people, with 300-500 million deaths observed in the 20th century alone.[12] It is notable in that it was the first infectious disease to be eradicated, due to a worldwide vaccination programme, with the last naturally occurring case being observed in Somalia, 1977.[11][13]

HIV/AIDS

The human immunodeficiency virus (HIV) is known to cause the condition known as acquired immunodeficiency syndrome (AIDS)[14][15][16] which it achieves by damaging, destroying, or impeding the functioning of various T-helper cells in the immune system, particularly CD4+ cells.[14][16][17] Not everyone believes this, however, which leads to HIV denialism, which is strongly connected with alternative medicine practitioners and vaccine denialism.

Influenza

The influenza virus is best known for its astounding variety of mutations, as well as routinely causing pandemics during the 20th century (most notably, the Spanish flu killed between 50 and 100 million [18]). It mutates very quickly, rendering influenza vaccines useless within a year,[19] but since there remains a need for them, vaccines are reformulated every year.

Gastroenteritis[wp] is sometimes called "stomach flu," but is unrelated to the influenza virus.

Ebola

The Ebola virus is known for its very short incubation period and its lethality, exhibiting a 90% death rate.[citation needed] Recently (1st August 2014), with 1300 infected in West Africa so far, there's no telling how much further it will spread.[citation needed]

See also

Footnotes

  1. http://www.straightdope.com/columns/read/1178/can-hiv-pass-through-the-pores-in-latex-condoms
  2. http://www.nsf.gov/news/overviews/biology/bio_q01.jsp
  3. http://www.diffen.com/difference/Bacteria_vs_Virus
  4. Rybicki, EP. The classification of organisms at the edge of life, or problems with virus systematics. S Afr J Sci. 1990;86:182–186.
  5. http://www.nhs.uk/Conditions/Cold-common/Pages/Introduction.aspx
  6. https://www.bcm.edu/departments/molecular-virology-and-microbiology/ebola
  7. http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/marburg/qa.htm
  8. http://www.sciencedaily.com/releases/2013/09/130909201048.htm
  9. http://www.britannica.com/EBchecked/topic/549405/smallpox/253294/History#ref895272
  10. http://www.niaid.nih.gov/topics/smallpox/pages/transmission.aspx
  11. 11.0 11.1 http://www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp
  12. http://www.sciencedaily.com/releases/2008/01/080131122956.htm
  13. In the mid 20th century, smallpox vaccination scars on the skin over the deltoid muscle were a common sight, more the rule than the exception.
  14. 14.0 14.1 http://www.avert.org/hiv-causes-aids.htm
  15. http://www.avert.org/hiv-causes-aids.htm
  16. 16.0 16.1 http://hivinsite.ucsf.edu/hiv?page=basics-00-03
  17. http://www.sciencemuseum.org.uk/whoami/findoutmore/yourbody/whatdoesyourimmunesystemdo/whatisaids/howdoeshivaffectthebody.aspx
  18. http://www.nap.edu/books/0309095042/html/60.html
  19. These changes happen often enough that your immune system can’t recognize the flu virus from year to year.
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