Editing Vibrio cholerae

{{Short description|Species of bacterium}}
{{Speciesbox
| image = Cholera bacteria SEM.jpg
| taxon = Vibrio cholerae
| authority = [[Filippo Pacini|Pacini]], 1854
}}

'''''Vibrio cholerae''''' is a species of [[Gram-negative bacteria|Gram-negative]], [[Facultative anaerobic organism|facultative anaerobe]] and [[Vibrio|comma-shaped]] [[bacteria]].<ref name="cdc.gov">{{cite web|title=Laboratory Methods for the Diagnosis of Vibrio cholerae|url=https://www.cdc.gov/cholera/pdf/laboratory-methods-for-the-diagnosis-of-vibrio-cholerae-chapter-6.pdf|access-date=29 October 2013|publisher=Centre for Disease Control|archive-date=4 January 2023|archive-url=https://web.archive.org/web/20230104132128/https://www.cdc.gov/cholera/pdf/laboratory-methods-for-the-diagnosis-of-vibrio-cholerae-chapter-6.pdf|url-status=live}}</ref> The bacteria naturally live in [[Brackish water|brackish]] or [[saltwater]] where they attach themselves easily to the [[chitin]]-containing shells of crabs, shrimp, and other shellfish. Some strains of ''V. cholerae'' are pathogenic to humans and cause a deadly disease called [[cholera]], which can be derived from the consumption of undercooked or raw marine life species or drinking contaminated water.<ref name="LutzErken20132">{{cite journal|last1=Lutz|first1=Carla|last2=Erken|first2=Martina|last3=Noorian|first3=Parisa|last4=Sun|first4=Shuyang|last5=McDougald|first5=Diane|year=2013|title=Environmental reservoirs and mechanisms of persistence of Vibrio cholerae|journal=Frontiers in Microbiology|volume=4|pages=375|doi=10.3389/fmicb.2013.00375|issn=1664-302X|pmc=3863721|pmid=24379807|doi-access=free}}</ref>

''V. cholerae'' was first described by [[Félix-Archimède Pouchet]] in 1849 as some kind of protozoa. [[Filippo Pacini]] correctly identified it as a bacterium and from him, the scientific name is adopted. The bacterium as the cause of cholera was discovered by [[Robert Koch]] in 1884. [[Sambhu Nath De]] isolated the [[cholera toxin]] and demonstrated the toxin as the cause of cholera in 1959.

The bacterium has a [[flagellum]] (a tail like structure) at one pole and several [[Pilus|pili]] throughout its cell surface. It undergoes respiratory and fermentative metabolism. Two [[serotype|serogroups]] called O1<ref>NCBI: [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=127906&lvl=3 Vibrio cholerae O1] {{Webarchive|url=https://web.archive.org/web/20220507163259/https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=127906&lvl=3 |date=2022-05-07 }} (serogroup)</ref> and O139<ref>NCBI: [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=45888&lvl=3 Vibrio cholerae O139] {{Webarchive|url=https://web.archive.org/web/20220507163258/https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=45888&lvl=3 |date=2022-05-07 }} (serogroup)</ref> are responsible for cholera outbreaks. Infection is mainly through drinking contaminated water or ingestion of food contaminated with faecal matter from an infected person, therefore is linked to sanitation and hygiene. When ingested, it invades the intestinal mucosa which can cause diarrhea and vomiting in a host within several hours to 2–3 days of ingestion. Ringers lactate and Oral rehydration solution combined with antibiotics such as [[Quinolone antibiotic|fluoroquinolones]] and [[tetracycline]]s are the common treatment methods in severe cases.

''V. cholerae'' has two circular chromosomes. One chromosomes produces the [[cholera toxin]] (CT), a [[protein]] that causes profuse, watery [[diarrhea]] (known as "rice-water stool").<ref name="Cholera">{{Cite journal|last1=Harris|first1=Jason B.|last2=LaRocque|first2=Regina C.|last3=Qadri|first3=Firdausi|last4=Ryan|first4=Edward T.|last5=Calderwood|first5=Stephen B.|date=2012|title=Cholera|journal=Lancet|volume=379|issue=9835|pages=2466–2476|doi=10.1016/S0140-6736(12)60436-X|pmc=3761070|pmid=22748592}}</ref> But the DNA does not directly code for the toxin as the genes for cholera toxin are carried by [[CTXφ bacteriophage|CTXphi]] (CTXφ), a [[Temperateness (virology)|temperate]] [[bacteriophage]] (virus). The virus only produces the toxin when inserted into the bacterial DNA. [[Quorum sensing]] in ''V. cholerae'' is well studied<ref>{{Cite journal |last1=Papenfort |first1=Kai |last2=Bassler |first2=Bonnie L. |date=2016-08-11 |title=Quorum sensing signal–response systems in Gram-negative bacteria |url=http://dx.doi.org/10.1038/nrmicro.2016.89 |journal=Nature Reviews Microbiology |volume=14 |issue=9 |pages=576–588 |doi=10.1038/nrmicro.2016.89 |pmid=27510864 |pmc=5056591 |issn=1740-1526 |access-date=2022-10-27 |archive-date=2023-07-02 |archive-url=https://web.archive.org/web/20230702065613/https://www.nature.com/articles/nrmicro.2016.89 |url-status=live }}</ref> and it activates host immune signaling and prolongs host survival, by limiting the bacterial intake of nutrients, such as [[tryptophan]], which further is converted to [[serotonin]].<ref name=":02">{{Cite journal |last1=Jugder |first1=Bat-Erdene |last2=Batista |first2=Juliana H. |last3=Gibson |first3=Jacob A. |last4=Cunningham |first4=Paul M. |last5=Asara |first5=John M. |last6=Watnick |first6=Paula I. |date=2022-09-20 |title=Vibrio cholerae high cell density quorum sensing activates the host intestinal innate immune response |journal=Cell Reports |language=en |volume=40 |issue=12 |pages=111368 |doi=10.1016/j.celrep.2022.111368 |pmid=36130487 |pmc=9534793 |s2cid=252413073 |issn=2211-1247}}</ref> As such, quorum sensing allows a [[Commensalism|commensal]] interaction between host and pathogenic bacteria.<ref name=":02" />

{{Further|Vibrio cholerae ToxT activated RNAs}}

== Discovery ==
=== Initial observations ===
During the [[1846–1860 cholera pandemic|third global pandemic of cholera (1846–1860)]], there was extensive scientific research to understand the etiology of the disease.<ref>{{Cite journal|last=Tognotti|first=Eugenia|date=2011|title=The dawn of medical microbiology: germ hunters and the discovery of the cause of cholera|journal=Journal of Medical Microbiology|volume=60|issue=Pt 4|pages=555–558|doi=10.1099/jmm.0.025700-0|pmid=21212146|doi-access=free}}</ref> The [[miasma theory]], which posited that infections spread through contaminated air, was no longer a satisfactory explanation. The English physician [[John Snow]] was the first to give convincing evidence in London in 1854 that cholera was spread from drinking water – a contagion, not miasma. Yet he could not identify the pathogens, which made most people still believe in the miasma origin.<ref name=":3">{{Cite journal|last1=Lippi|first1=D.|last2=Gotuzzo|first2=E.|date=2014|title=The greatest steps towards the discovery of Vibrio cholerae|journal=Clinical Microbiology and Infection|volume=20|issue=3|pages=191–195|doi=10.1111/1469-0691.12390|pmid=24191858|doi-access=free}}</ref>

''V. cholerae'' was first observed and recognized under microscope by the French zoologist [[Félix-Archimède Pouchet]]. In 1849, Pouchet examined the stool samples of four people having cholera.<ref name=":4">{{Cite book|last=Hugh|first=Rudolph|url=https://books.google.com/books?id=NP7AY38J1hcC|title=Public Health Service Publication|date=1965|publisher=U.S. Department of Health, Education, and Welfare, Public Health Service, Environmental Health Service, National Air Pollution Control Administration|pages=1–4|language=en|chapter=Nomenclature and taxonomy of Vibrio cholerae Pacini 1854 and Vibrio eltor Pribam 1933|access-date=2021-04-05|archive-date=2023-07-02|archive-url=https://web.archive.org/web/20230702065612/https://books.google.com/books?id=NP7AY38J1hcC|url-status=live}}</ref> His presentation before the [[French Academy of Sciences]] on 23 April was recorded as: "[Pouchet] could verify that there existed in these [cholera patients] dejecta an immense quantity of microscopic [[infusoria]]."  As summarised in the Gazette medicale de Paris (1849, p 327), in a letter read at the 23 April 1849 meeting of the [[Paris Academy of Sciences]], Pouchet announced that the organisms were ''[[infusoria]]'', a name then used for microscopic [[protists]], naming them as the '''Vibrio rugula'' of Mueller and Shrank', a species of [[protozoa]] described by Danish naturalist [[Otto Friedrich Müller]] in 1786.<ref>{{Cite book|last=Pollitzer|first=R.|chapter-url=https://books.google.com/books?id=zHNrAAAAMAAJ&q=bacillus+cholerae+trevisan+1884&pg=PA380|title=Proceedings of the Cholera Research Symposium, January 24-29, 1965, Honolulu, Hawaii|date=1965|publisher=U.S. Public Health Service|pages=380–387|language=en|chapter=Cholera advances in historical perspective|access-date=2021-04-20|archive-date=2023-07-02|archive-url=https://web.archive.org/web/20230702065612/https://books.google.com/books?id=zHNrAAAAMAAJ&q=bacillus+cholerae+trevisan+1884&pg=PA380|url-status=live}}</ref>

=== Identification of the bacterium ===
An Italian physician, [[Filippo Pacini]], while investigating cholera outbreak in Florence in the late 1854, identified the causative pathogen as a new type of bacterium. He performed autopsies of corpses and made meticulous microscopic examinations of the tissues and body fluids. From feces and [[intestinal mucosa]], he identified many comma-shaped bacilli.<ref>{{Cite web|title=Who first discovered cholera?|url=https://www.ph.ucla.edu/epi/snow/firstdiscoveredcholera.html|access-date=2021-04-04|website=www.ph.ucla.edu|archive-date=2021-04-17|archive-url=https://web.archive.org/web/20210417111245/http://www.ph.ucla.edu/epi/snow/firstdiscoveredcholera.html|url-status=live}}</ref><ref>{{Cite journal|last=Nardi|first=M. G.|date=1954|title=[Discovery of Vibrio cholerae by Filippo Pacini, of Pistoia, established in the initial phases of microbiological thought and judged after a century]|url=https://pubmed.ncbi.nlm.nih.gov/14355829|journal=Minerva Medica|volume=45|issue=102|pages=1024–1029|pmid=14355829|access-date=2021-04-04|archive-date=2022-10-05|archive-url=https://web.archive.org/web/20221005133108/https://pubmed.ncbi.nlm.nih.gov/14355829/|url-status=live}}</ref> Reporting his discovery before the Società Medico-Fisica Fiorentina (Medico-Physician Society of Florence) on 10 December, and published in the 12 December issue of the ''Gazzetta Medica Italiana'' (''Medical Gazette of Italy''), Pacini stated:{{blockquote|Le poche materie del vomito che ho potuto esaminare nel secondo e terzo caso di cholera ... e di più trovai degli ammassi granulosi appianati, simili a quelli che si formano alla superficie delle acque corrotte, quando sono per svilupparsi dei vibrioni; dei quali di fatto ne trovai alcuni del genere ''Bacterium'', mentre la massima parte, per la loro estrema piccolezza, erano stati eliminati con la decantazione del fluido. [From the few samples of vomit that I was able to examine in the second and third cases of cholera ... and in addition I found smoothed granular masses, similar to those which form on the surface of dirty waters, when they are about to develop vibrios; of which in fact I found some of the genus ''Bacterium'', while the greatest part, because of their extreme smallness, had been eliminated with the removal of the liquid.<ref>Fillipo Pacini (1854) [https://books.google.com/books?id=xdtQAAAAcAAJ&pg=PA397 "Osservazioni microscopiche e deduzioni patologiche sul cholera asiatico"] (Microscopic observations and pathological deductions on Asiatic cholera), ''Gazzetta Medica Italiana:  Toscana'', 2nd series, 4(50) :  397–401; 4(51): 405–412. Reprinted (more legibily) as a [https://books.google.com/books?id=F9s_AAAAcAAJ&pg=PA1 pamphlet.] {{Webarchive|url=https://web.archive.org/web/20231201205632/https://books.google.com/books?id=F9s_AAAAcAAJ&pg=PA1 |date=2023-12-01 }}</ref>]}}Pacini thus introduced the name ''vibrioni'' (Latin ''vībro'' means "to move rapidly to and fro, to shake, to agitate"). A [[Catalonia|Catalan]] physician Joaquim Balcells i Pascual also reported such bacterium around the same time.<ref>{{cite web|year=2018|editor=[[Real Academia de la Historia]]|title=Joaquín Balcells y Pasqual|url=http://dbe.rah.es/biografias/18541/joaquin-balcells-y-pasqual|archive-url=https://web.archive.org/web/20190708211444/http://dbe.rah.es/biografias/18541/joaquin-balcells-y-pasqual|archive-date=2019-07-08|access-date=2020-08-01|language=es}}</ref><ref>{{cite web|year=2015|editor=[[:ca:Col·legi Oficial de Metges de Barcelona|Col·legi Oficial de Metges de Barcelona]]|title=Joaquim Balcells i Pascual|url=http://www.galeriametges.cat/galeria-fitxa.php?icod=EGMM|archive-url=https://web.archive.org/web/20200801110910/http://www.galeriametges.cat/galeria-fitxa.php?icod=EGMM|archive-date=2020-08-01|access-date=2020-08-01|language=ca}}</ref> The discovery of the new bacterium was not regarded as medically important as the bacterium was not directly attributed to cholera. Pacini also stated that there was no reason to say that the bacterium caused the disease since he failed to create a pure culture and perform experiments, which was necessary 'to attribute the quality of contagion to cholera'.<ref name=":3" /> The miasma theory was still not ruled out.<ref>{{Cite journal|last1=Subba Rao|first1=M.|last2=Howard-Jones|first2=N.|date=1978|title=Original observations of Filippo Pacini on vibrio cholera|url=https://pubmed.ncbi.nlm.nih.gov/11613633|journal=Bulletin of the Indian Institute of History of Medicine|volume=8|issue=1–4|pages=32–38|pmid=11613633|access-date=2021-04-04|archive-date=2022-03-23|archive-url=https://web.archive.org/web/20220323195612/https://pubmed.ncbi.nlm.nih.gov/11613633/|url-status=live}}</ref>

=== Rediscovery ===
The medical importance and relationship between the bacterium and the cholera disease was discovered by German physician [[Robert Koch]]. In August 1883, Koch, with a team of German physicians, went to Alexandria, Egypt, to investigate the cholera epidemic there.<ref>{{Cite journal|last=Howard-Jones|first=N.|date=1984|title=Robert Koch and the cholera vibrio: a centenary|journal=British Medical Journal|volume=288|issue=6414|pages=379–381|doi=10.1136/bmj.288.6414.379|pmc=1444283|pmid=6419937}}</ref> Koch found that the intestinal mucosa of people who died of cholera always had the bacterium, yet he could not confirm if it was the causative agent. He moved to Calcutta (now Kolkata), India, where the epidemic was more severe. It was from here that he isolated the bacterium in a pure culture on 7 January 1884. He subsequently confirmed that the bacterium was a new species, and described it as "a little bent, like a comma."<ref name=":3" /> He reported his discovery to the German Secretary of State for the Interior on 2 February, and it was published in the ''Deutsche Medizinische Wochenschrift'' (''German Medical Weekly'').<ref>{{Cite journal|last=Robert|first=Koch|date=1884|title=Sechster Bericht der deutschen wissenschaftlichen Commission zur Erforschung der Cholera|url=https://www.scopus.com/record/display.uri?eid=2-s2.0-33748441571&txGid=8dfe522676542084e21a1178b5e3695a|journal=Deutsche Medizinische Wochenschrift|volume=10|pages=191–192}}</ref>

Although Koch was convinced that the bacterium was the cholera pathogen, he could not entirely procure critical evidence that the bacterium produced the symptoms in healthy subjects (an important element in what was later known as [[Koch's postulates]]). His experiment on animals using his pure bacteria culture did not lead to the appearance of the disease in any of the subjects, and he correctly deduced that animals are immune to the human pathogen. The bacterium was by then known as "the comma bacillus."<ref>{{Cite journal|last1=Nair|first1=G. Balakrish|last2=Narain|first2=Jai P.|date=2010|title=From endotoxin to exotoxin: De's rich legacy to cholera|journal=Bulletin of the World Health Organization|volume=88|issue=3|pages=237–240|doi=10.2471/BLT.09.072504|pmc=2828792|pmid=20428396}}</ref> It was only in 1959, in Calcutta, that Indian physician [[Sambhu Nath De]] isolated the cholera toxin and showed that it caused cholera in healthy subjects, hence fully proving the bacterium-cholera relationship.<ref>{{Cite journal|last=De|first=S. N.|date=1959|title=Enterotoxicity of bacteria-free culture-filtrate of Vibrio cholerae|url=https://pubmed.ncbi.nlm.nih.gov/13666809|journal=Nature|volume=183|issue=4674|pages=1533–1534|doi=10.1038/1831533a0|pmid=13666809|bibcode=1959Natur.183.1533D|s2cid=34139686|access-date=2021-04-04|archive-date=2021-05-26|archive-url=https://web.archive.org/web/20210526033610/https://pubmed.ncbi.nlm.nih.gov/13666809/|url-status=live}}</ref><ref>{{Cite journal|last1=Nair|first1=G. Balakrish|last2=Takeda|first2=Yoshifumi|date=2011|title=Dr Sambhu Nath De: unsung hero|journal=The Indian Journal of Medical Research|volume=133|issue=2 |pages=127|pmc=3089041|pmid=21415484}}</ref>

=== Taxonomy ===
Pacini had used the name "''vibrio cholera''", without proper [[Binomial nomenclature|binomial]] rendering, for the name of the bacterium.<ref>{{Cite web|last=|title=Taxonomy browser (Vibrio cholerae)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=info&id=666|access-date=2021-04-05|website=www.ncbi.nlm.nih.gov|archive-date=2020-09-20|archive-url=https://web.archive.org/web/20200920060115/https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=666|url-status=live}}</ref> Following Koch's description, a scientific name ''Bacillus comma'' was popularised. But an Italian bacteriologist Vittore Trevisan published in 1884 that Koch's bacterium was the same as that of Pacini's and introduced the name ''Bacillus cholerae.<ref>{{Cite journal|last1=Subba Rao|first1=M.|last2=Howard-Jones|first2=N.|date=1978|title=Original observations of Filippo Pacini on vibrio cholera|url=http://ccras.nic.in/sites/default/files/viewpdf/jimh/BIIHM_1978/32%20to%2038.pdf|journal=Bulletin of the Indian Institute of History of Medicine (Hyderabad)|volume=8|issue=1–4|pages=32–38|pmid=11613633|access-date=2021-04-05|archive-date=2022-07-07|archive-url=https://web.archive.org/web/20220707032600/http://www.ccras.nic.in/sites/default/files/viewpdf/jimh/BIIHM_1978/32%20to%2038.pdf|url-status=live}}</ref>'' A German physician [[Richard Friedrich Johannes Pfeiffer]] renamed it as ''Vibrio cholerae'' in 1896.<ref name=":4" /> The named was adopted by the [[Society of American Bacteriologists|Committee of the Society of American Bacteriologists on Characterization and Classification of Bacterial Types]] in 1920.<ref>{{Cite journal|last1=Winslow|first1=C. E.|last2=Broadhurst|first2=J.|last3=Buchanan|first3=R. E.|last4=Krumwiede|first4=C.|last5=Rogers|first5=L. A.|last6=Smith|first6=G. H.|date=1920|title=The Families and Genera of the Bacteria: Final Report of the Committee of the Society of American Bacteriologists on Characterization and Classification of Bacterial Types|journal=Journal of Bacteriology|volume=5|issue=3|pages=191–229|doi=10.1128/JB.5.3.191-229.1920|pmc=378870|pmid=16558872}}</ref> In 1964, Rudolph Hugh of the George Washington University School of Medicine proposed to use the genus ''Vibrio'' with the type species ''V. cholerae'' (Pacini 1854) as a permanent name of the bacterium, regardless of the same name for protozoa.<ref>{{Cite journal|last=Hugh|first=R.|date=1964|title=The Proposed Conservation of the Generic Name Vibrio Pacini 1854 and Designation of the Neotype Strain of Vibrio Cholerae Pacini 1854|journal=International Bulletin of Bacteriological Nomenclature and Taxonomy|language=en|volume=14|issue=2|pages=87–101|doi=10.1099/0096266X-14-2-87|doi-access=free}}</ref> It was accepted by the [[International Code of Nomenclature of Prokaryotes|Judicial Commission of the International Committee on Bacteriological Nomenclature]] in 1965,<ref>{{Cite journal|last=Judicial Commission of the International Committee on Bacteriological Nomenclature|date=1965|title=Opinion 31. Conservation of Vibrio Pacini 1854 as a Bacterial Generic Name, Conservation of Vibrio Cholerae Pacini 1854 as the Nomenclatural Type Species of the Bacterial Genus Vibrio, and Designation of Neotype Strain of Vibrio Cholerae Pacini|journal=International Bulletin of Bacteriological Nomenclature and Taxonomy|language=en|volume=15|issue=3|pages=185–186|doi=10.1099/00207713-15-3-185|doi-access=free}}</ref> and the [[International Association of Microbiological Societies]] in 1966.<ref>{{Cite journal|last=Feeley|first=J. C.|date=1966|title=Minutes of IAMS Subcommittee on Taxonomy of Vibrios|journal=International Journal of Systematic Bacteriology|language=en|volume=16|issue=2|pages=135–142|doi=10.1099/00207713-16-2-135|doi-access=free}}</ref>

== Characteristics ==
''V. cholerae'' is a highly motile, comma shaped, gram-negative rod. The active movement of ''V. cholerae'' inspired the genus name because "vibrio" in [[Latin]] means "to quiver".<ref name="MedNet">{{cite web | last = Stöppler, MD | first = Melissa | title = Medical Definition of Vibrio cholerae | work = MedTerms Dictionary | publisher = [[MedicineNet]] | url = https://www.medicinenet.com/vibrio_cholerae/definition.htm | access-date = 2021-06-03 | archive-date = 2021-06-03 | archive-url = https://web.archive.org/web/20210603135307/https://www.medicinenet.com/vibrio_cholerae/definition.htm | url-status = live }}</ref> Except for ''V. cholerae'' and ''V. mimicus'', all other vibrio species are [[Halophile|halophilic]]. Initial isolates are slightly curved, whereas they can appear as straight rods upon laboratory culturing. The bacterium has a [[flagellum]] at one cell pole as well as [[Pilus|pili]]. It tolerates alkaline media that kill most intestinal commensals, but they are sensitive to acid. It is an aerobe while all other Vibrios are facultative anaerobes, and can undergo respiratory and fermentative metabolism.<ref name="cdc.gov"/> It measures 0.3 μm in diameter and 1.3 μm in length<ref>{{cite web |title=New strains of Vibrio cholerae |url=https://www.mrc-lmb.cam.ac.uk/genomes/madanm/articles/cholera.htm |website=www.mrc-lmb.cam.ac.uk |access-date=26 June 2019 |archive-date=19 October 2016 |archive-url=https://web.archive.org/web/20161019171322/http://www.mrc-lmb.cam.ac.uk/genomes/madanm/articles/cholera.htm |url-status=dead }}</ref> with average swimming velocity of around 75.4 μm/sec.<ref>{{Cite journal |last1=Shigematsu |first1=M. |last2=Meno |first2=Y. |last3=Misumi |first3=H. |last4=Amako |first4=K. |year=1995 |title=The measurement of swimming velocity of Vibrio cholerae and Pseudomonas aeruginosa using the video tracking methods. |journal=Microbiol. Immunol. |volume=39 |issue=10 |pages=741–4 |pmid=8577263|doi=10.1111/j.1348-0421.1995.tb03260.x |s2cid=24759458 |doi-access=free }}</ref>

== Pathogenicity ==
[[File:Toxin2.jpg|thumb|584x584px|Cholera toxin interrupting regulation of adenyl cyclase inside the cell causing efflux of water and sodium into the intestinal lumen]]
''V. cholerae'' [[Pathogen#Pathogenicity|pathogenicity]] genes code for proteins directly or indirectly involved in the virulence of the bacteria. To adapt the host intestinal environment and to avoid being attacked by [[bile acid]]s and [[antimicrobial peptides]], ''V. cholera'' uses its [[Bacterial outer membrane vesicles|outer membrane vesicles]] (OMVs). Upon entry, the bacteria sheds its OMVs, containing all the membrane modifications that make it vulnerable for the host attack.<ref>{{Cite journal|last1=Jugder|first1=Bat-Erdene|last2=Watnick|first2=Paula I.|date=2020-02-12|title=Vibrio cholerae Sheds Its Coat to Make Itself Comfortable in the Gut|journal=Cell Host & Microbe|language=en|volume=27|issue=2|pages=161–163|doi=10.1016/j.chom.2020.01.017|issn=1931-3128|pmid=32053783|doi-access=free}}</ref>

During infection, ''V. cholerae'' secretes [[cholera toxin]] (CT), a [[protein]] that causes profuse, watery [[diarrhea]] (known as "rice-water stool").<ref name="ReferenceA"/><ref name="Cholera"/> This cholera toxin contains 5 B subunits that plays a role in attaching to the intestinal epithelial cells and 1 A subunit that plays a role in toxin activity''.'' Colonization of the small intestine also requires the toxin coregulated [[pilus]] (TCP), a thin, flexible, filamentous appendage on the surface of bacterial cells. Expression of both CT and TCP is mediated by [[Two-component regulatory system|two component systems]] (TCS), which typically consist of a membrane-bound [[histidine kinase]] and an intracellular response element.<ref name=":1">{{Cite journal|last1=Xi|first1=Daoyi|last2=Li|first2=Yujia|last3=Yan|first3=Junxiang|last4=Li|first4=Yuehua|last5=Wang|first5=Xiaochen|last6=Cao|first6=Boyang|title=Small RNA coaR contributes to intestinal colonization in Vibrio cholerae via the two-component system EnvZ/OmpR|journal=Environmental Microbiology|year=2020|volume=22|issue=10|language=en|pages=4231–4243|doi=10.1111/1462-2920.14906|pmid=31868254|issn=1462-2920|doi-access=|bibcode=2020EnvMi..22.4231X }}</ref> TCS enable bacteria to respond to changing environments.<ref name=":1" /> In ''V. cholerae'' several TCS have been identified to be important in colonization, biofilm production and virulence.<ref name=":1" /> Quorum regulatory small RNAs ([[Qrr RNA]]) have been identified as targets of ''V. cholerae'' TCS.<ref name=":1" /><ref name=":2">{{Cite journal| last1=Song|first1=Tianyan|last2=Mika| first2=Franziska|last3=Lindmark|first3=Barbro|last4=Liu|first4=Zhi| last5=Schild|first5=Stefan|last6=Bishop| first6=Anne|last7=Zhu|first7=Jun|last8=Camilli|first8=Andrew|last9=Johansson|first9=Jörgen|last10=Vogel|first10=Jörg|last11=Wai|first11=Sun Nyunt|date=2008|title=A new Vibrio cholerae sRNA modulates colonization and affects release of outer membrane vesicles|journal=Molecular Microbiology|language=en|volume=70|issue=1|pages=100–111|doi=10.1111/j.1365-2958.2008.06392.x|issn=1365-2958|pmc=2628432|pmid=18681937}}</ref><ref>{{Cite journal|last1=Bradley|first1=Evan S.|last2=Bodi|first2=Kip|last3=Ismail|first3=Ayman M.|last4=Camilli|first4=Andrew|date=2011-07-14|title=A Genome-Wide Approach to Discovery of Small RNAs Involved in Regulation of Virulence in Vibrio cholerae|journal=PLOS Pathogens|language=en|volume=7|issue=7|pages=e1002126|doi=10.1371/journal.ppat.1002126|issn=1553-7374|pmc=3136459|pmid=21779167 |doi-access=free }}</ref> Here, the small RNA (sRNA) molecules bind to mRNA to block translation or induce degradation of inhibitors of expression of virulence or colonization genes.<ref name=":1" /><ref name=":2" /> In ''V. cholerae'' the TCS [[EnvZ/OmpR two-component system|EnvZ/OmpR]] alters gene expression via the sRNA ''coaR'' in response to changes in [[Osmotic concentration|osmolarity]] and pH. An important target of ''coaR'' is ''tcpI'', which negatively regulates expression of the major subunit of the TCP encoding gene (''tcpA''). When ''tcpI'' is bound by ''coaR'' it is no longer able to repress expression ''tcpA'', leading to an increased colonization ability.<ref name=":1" /> Expression of ''coaR'' is upregulated by EnvZ/OmpR at a pH of 6,5, which is the normal pH of the intestinal lumen, but is low at higher pH values.<ref name=":1" /> ''V. cholerae''  in the intestinal lumen utilizes the TCP to attach to the intestinal mucosa, not invading the mucosa.<ref name=":1" /> After doing so it secretes cholerae toxin causing its symptoms. This then increases cyclic AMP or cAMP by binding (cholerae toxin) to adenylyl cyclase activating the GS pathway which leads to efflux of water and sodium into the intestinal lumen causing watery stools or rice watery stools.

''V. cholerae'' can cause syndromes ranging from asymptomatic to cholera gravis.<ref name="jones1984">{{cite journal|last1=Howard-Jones|first1=N|year=1984|title=Robert Koch and the cholera vibrio: a centenary|journal=BMJ|volume=288|issue=6414|pages=379–81|doi=10.1136/bmj.288.6414.379|pmc=1444283|pmid=6419937}}</ref> In [[Endemic (epidemiology)|endemic]] areas, 75% of cases are asymptomatic, 20% are mild to moderate, and 2–5% are severe forms such as cholera gravis.<ref name="jones1984" /> Symptoms include abrupt onset of watery [[diarrhea]] (a grey and cloudy liquid), occasional [[vomiting]], and abdominal cramps.<ref name="cdc.gov" /><ref name="jones1984" /> [[Dehydration]] ensues, with symptoms and signs such as thirst, dry mucous membranes, decreased skin turgor, sunken eyes, [[hypotension]], weak or absent [[radial pulse]], [[tachycardia]], [[tachypnea]], hoarse voice, [[oliguria]], cramps, [[kidney failure]], [[seizure]]s, [[somnolence]], coma, and death.<ref name="cdc.gov" /> Death due to dehydration can occur in a few hours to days in untreated children. The disease is also particularly dangerous for pregnant women and their fetuses during late pregnancy, as it may cause premature labor and fetal death.<ref name="jones1984" /><ref name="davis2003">{{cite journal|last1=Davis|first1=B|title=Filamentous phages linked to virulence of Vibrio cholerae|journal=Current Opinion in Microbiology|date=February 2003|volume=6|issue=1|pages=35–42|doi=10.1016/S1369-5274(02)00005-X|pmid=12615217|last2=Waldor|first2=M. K.}}</ref><ref name="boyd2002">{{cite journal|last=Boyd|first=EF|author2=Waldor, MK |title=Evolutionary and functional analyses of variants of the toxin-coregulated pilus protein TcpA from toxigenic Vibrio cholerae non-O1/non-O139 serogroup isolates.|journal=Microbiology|date=Jun 2002|volume=148|issue=Pt 6|pages=1655–66|pmid=12055286|doi=10.1099/00221287-148-6-1655|doi-access=free}}</ref> A study done by the Centers for Disease Control (CDC) in Haiti found that in pregnant women who contracted the disease, 16% of 900 women had fetal death. Risk factors for these deaths include: third trimester, younger maternal age, severe dehydration, and vomiting<ref>{{cite journal | author = Schillberg E., Ariti C., Bryson L., Delva-Senat R., Price D., GrandPierre , Lenglet A. | year = 2016 | title = Factors Related to Fetal Death in Pregnant Women with Cholera, Haiti, 2011–2014 | journal = Emerging Infectious Diseases | volume = 22 | issue = 1| pages = 124–127 | doi = 10.3201/eid2201.151078 | pmid = 26692252 | pmc = 4696702 | doi-access = free }}</ref> Dehydration poses the biggest health risk to pregnant women in countries that there are high rates of cholera.  In cases of cholera gravis involving severe dehydration, up to 60% of patients can die; however, less than 1% of cases treated with [[Management of dehydration|rehydration therapy]] are fatal. The disease typically lasts 4–6 days.<ref name="jones1984" /><ref name="miller2002">{{cite journal|last=Miller|first=Melissa B.|author2=Skorupski, Karen |author3=Lenz, Derrick H. |author4=Taylor, Ronald K. |author5= Bassler, Bonnie L. |title=Parallel Quorum Sensing Systems Converge to Regulate Virulence in Vibrio cholerae|journal=Cell|date=August 2002|volume=110|issue=3|pages=303–314|doi=10.1016/S0092-8674(02)00829-2|pmid=12176318|s2cid=696469|doi-access=free}}</ref> Worldwide, [[diarrhoeal disease]], caused by cholera and many other pathogens, is the second-leading cause of death for children under the age of 5 and at least 120,000 deaths are estimated to be caused by cholera each year.<ref name="nielsen2006">{{cite journal|last=Nielsen|first=Alex Toftgaard|author2=Dolganov, Nadia A. |author3=Otto, Glen |author4=Miller, Michael C. |author5=Wu, Cheng Yen |author6= Schoolnik, Gary K. |title=RpoS Controls the Vibrio cholerae Mucosal Escape Response|journal=PLOS Pathogens|year=2006|volume=2|issue=10|pages=e109|doi=10.1371/journal.ppat.0020109|pmid=17054394 |pmc=1617127 |doi-access=free }}</ref><ref name="faruque1998">{{cite journal|last=Faruque|first=SM|author2=Albert, MJ |author3=Mekalanos, JJ |title=Epidemiology, genetics, and ecology of toxigenic Vibrio cholerae.|journal=Microbiology and Molecular Biology Reviews|date=Dec 1998|volume=62|issue=4|pages=1301–14|doi=10.1128/MMBR.62.4.1301-1314.1998|pmid=9841673|pmc=98947}}</ref> In 2002, the WHO deemed that the case fatality ratio for cholera was about 3.95%.<ref name="jones1984" />

== Cholera illness and symptoms ==

{{main article|Cholera}}

[[File:Suspected Source of Cholera- Waste Water - Nigeria (16436898133).jpg|thumb|Children in Mpape community play in a waste water drainage area. This drainage was the suspected source of contamination of the well water that led to the cholera outbreak investigated by Nigeria FELTP residents in April 2014. Two samples collected from home wells around this drainage tested positive for ''Vibrio cholerae''.]]
''V. cholerae'' infects the intestine and causes diarrhea, the hallmark symptom of cholera. Infection can be spread by eating contaminated food or drinking contaminated water.<ref name="ReferenceA">{{Cite web|url=https://www.cdc.gov/cholera/illness.html|title=Illness & Symptoms {{!}} Cholera|date=2018-12-13|website=CDC|language=en-us|access-date=2019-11-12|archive-date=2019-11-12|archive-url=https://web.archive.org/web/20191112021632/https://www.cdc.gov/cholera/illness.html|url-status=live}}</ref> It also can spread through skin contact with contaminated human feces. Not all infection indicate symptoms, only about 1 in 10 people develop diarrhea. The major symptoms include: watery diarrhea, vomiting, rapid heart rate, loss of skin elasticity, low blood pressure, thirst, and muscle cramps.<ref name="ReferenceA"/> This illness can get serious as it can progress to kidney failure and possible coma. If diagnosed, it can be treated using medications.<ref name="ReferenceA"/>

== Disease occurrence ==
''V. cholerae'' has an endemic or epidemic occurrence. In countries where the disease has been for the past three years and the cases confirmed are local (within the confines of the country) transmission is considered to be "endemic."<ref>"Cholera." World Health Organization, World Health Organization, 17 Jan. 2019, www.who.int/news-room/fact-sheets/detail/cholera.</ref> Alternatively, an outbreak is declared when the occurrence of disease exceeds the normal occurrence for any given time or location.<ref name="searo.who.int">"World Health Organization, Disease Outbreaks." World Health Organization, World Health Organization, 8 Mar. 2016, www.searo.who.int/topics/disease_outbreaks/en/.</ref> Epidemics can last several days or over a span of years. Additionally, countries that have an occurrence of an epidemic can also be endemic.<ref name="searo.who.int"/> The longest standing ''V. cholerae'' epidemic was recorded in Yemen. Yemen had two outbreaks, the first occurred between September 2016 and April 2017, and the second began later in April 2017 and recently was considered to be resolved in 2019.<ref name="sciencedaily.com">"Mystery of Yemen Cholera Epidemic Solved." ScienceDaily, ScienceDaily, 2 Jan. 2019, www.sciencedaily.com/releases/2019/01/190102140745.htm.</ref> The epidemic in Yemen took over 2,500 lives and impacted over 1 million people of Yemen.<ref name="sciencedaily.com"/> More outbreaks have occurred in Africa, the Americas, and Haiti.

== Preventive measures ==
When visiting areas with epidemic cholera, the following precautions should be observed: drink and use bottled water; frequently wash hands with soap and safe water; use chemical toilets or bury feces if no restroom is available; do not defecate in any body of water and cook food thoroughly. Supplying proper, safe water is important.<ref>{{cite web|url=https://www.cdc.gov/cholera/preventionsteps.html|title=Five Basic Cholera Preventions|website=Center for Disease Control and Prevention|access-date=20 November 2019|archive-date=15 August 2019|archive-url=https://web.archive.org/web/20190815203323/https://www.cdc.gov/cholera/preventionsteps.html|url-status=live}}</ref> A precaution to take is to properly sanitize.<ref name="sciencedirect.com">{{cite book |doi=10.1016/B978-1-4557-4801-3.00216-2 |chapter=''Vibrio cholerae'' |title=Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases |author1=Matthew K. Waldor |author2=Edward T. Ryan |date=2015 |pages=2471–2479.e2 |isbn=9781455748013 }}</ref> Hand hygiene is an essential in areas where soap and water is not available. When there is no sanitation available for hand washing, scrub hands with ash or sand and rinse with clean water.<ref>"Five Basic Cholera Prevention Steps | Cholera | CDC." Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, www.cdc.gov/cholera/preventionsteps.html.</ref> A single dose [[cholera vaccine|vaccine]] is available for those traveling to an area where cholera is common.

There is a ''V. cholerae'' vaccine available to prevent disease spread. The vaccine is known as the, "oral cholera vaccine" (OCV). There are three types of OCV available for prevention: Dukoral®, Shanchol™, and Euvichol-Plus®. All three OCVs require two doses to be fully effective. Countries who are endemic or have an epidemic status are eligible to receive the vaccine based on several criteria: Risk of cholera, Severity of cholera, WASH conditions and capacity to improve, Healthcare conditions and capacity to improve, Capacity to implement OCV campaigns, Capacity to conduct M&E activities, Commitment at national and local level<ref name="who.int">"Oral Cholera Vaccines." World Health Organization, World Health Organization, 17 May 2018, www.who.int/cholera/vaccines/en/.</ref> Since May the start of the OCV program to May 2018 over 25 million vaccines have been distributed to countries who meet the above criteria.<ref name="who.int"/>

== Treatment ==
The basic, overall treatment for Cholera is re-hydration, to replace the fluids that have been lost. Those with mild dehydration can be treated orally with an [[Oral rehydration therapy|oral rehydration solution (ORS)]].<ref name="sciencedirect.com"/> When patients are severely dehydrated and unable to take in the proper amount of ORS, IV fluid treatment is generally pursued. Antibiotics are used in some cases, typically [[Quinolone antibiotic|fluoroquinolones]] and [[tetracycline]]s.<ref name="sciencedirect.com"/>

==Genome==
''V. cholerae'' (and [[Vibrionaceae]] in general)<ref name=Bruhn>{{cite journal |last1=Bruhn |first1=Matthias |last2=Schindler |first2=Daniel |last3=Kemter |first3=Franziska S. |last4=Wiley |first4=Michael R. |last5=Chase |first5=Kitty |last6=Koroleva |first6=Galina I. |last7=Palacios |first7=Gustavo |last8=Sozhamannan |first8=Shanmuga |last9=Waldminghaus |first9=Torsten |title=Functionality of Two Origins of Replication in Vibrio cholerae Strains With a Single Chromosome |journal=Frontiers in Microbiology |date=30 November 2018 |volume=9 |pages=2932 |doi=10.3389/fmicb.2018.02932|pmid=30559732 |pmc=6284228 |doi-access=free }}</ref> has two circular [[chromosomes]], together totalling 4 million [[base pairs]] of [[DNA]] sequence and 3,885 predicted [[genes]].<ref>{{cite journal |last1=Fraser |first1=Claire M. |last2=Heidelberg |first2=John F. |last3=Eisen |first3=Jonathan A. |last4=Nelson |first4=William C. |last5=Clayton |first5=Rebecca A. |last6=Gwinn |first6=Michelle L. |last7=Dodson |first7=Robert J. |last8=Haft |first8=Daniel H. |last9=Hickey |first9=Erin K. |title=DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae |journal=Nature |volume=406 |issue=6795 |pages=477–83 |year=2000 |pmid=10952301 |pmc=8288016 |doi=10.1038/35020000 |display-authors=8 |last10=Umayam |first10=L. |last11=Gill |first11=S.R. |last12=Nelson |first12=K.E. |last13=Read |first13=T.D. |last14=Tettelin |first14=H. |last15=Richardson |first15=D. |last16=Ermolaeva |first16=M.D. |last17=Vamathevan |first17=J. |last18=Bass |first18=S. |last19=Qin |first19=H. |last20=Dragoi |first20=I. |last21=Sellers |first21=P. |last22=McDonald |first22=L. |last23=Utterback |first23=T. |last24=Fleishmann |first24=R.D. |last25=Nierman |first25=W.C. |last26=White |first26=O. |last27=Salzberg |first27=S.L. |last28=Smith |first28=H.O. |last29=Colwell |first29=R.R. |last30=Mekalanos |first30=J.J. |bibcode=2000Natur.406..477H |s2cid=807509 |url=http://www.nature.com/nature/journal/v406/n6795/pdf/406477aa.pdf |doi-access=free |access-date=2018-04-20 |archive-date=2021-12-19 |archive-url=https://web.archive.org/web/20211219124913/https://www.nature.com/nature/journal/v406/n6795/pdf/406477aa.pdf |url-status=live }}</ref>  The genes for cholera toxin are carried by CTXphi (CTXφ), a [[temperateness (virology)|temperate]] [[bacteriophage]] inserted into the ''V. cholerae'' genome. CTXφ can transmit cholera toxin genes from one ''V. cholerae'' strain to another, one form of [[horizontal gene transfer]]. The genes for toxin coregulated pilus are coded by the Vibrio [[pathogenicity island]] (VPI), which is separate from the [[prophage]].<ref name="cdc.gov" />

The larger first chromosome is 3&nbsp;Mbp long with 2,770 [[open reading frame]]s (ORFs). It contains the crucial genes for toxicity, regulation of toxicity, and important cellular functions, such as [[Transcription (genetics)|transcription]] and [[Translation (biology)|translation]].<ref name=cdc.gov />

The second chromosome is 1&nbsp;Mbp long with 1115 ORFs. It is determined to be different from a [[plasmid]] or [[megaplasmid]] due to the inclusion of housekeeping and other essential genes in the genome, including essential genes for metabolism, heat-shock proteins, and [[MT-RNR2|16S rRNA]] genes, which are ribosomal subunit genes used to track evolutionary relationships between bacteria. Also relevant in determining if the [[replicon (genetics)|replicon]] is a chromosome is whether it represents a significant percentage of the genome, and chromosome 2 is 40% by size of the entire genome. And, unlike plasmids, chromosomes are not self-transmissible.<ref name="jones1984" /> However, the second chromosome may have once been a megaplasmid because it contains some genes usually found on plasmids,<ref name=cdc.gov /> including a P1 plastid-like [[origin of replication]].<ref name=Bruhn/>

===Bacteriophage CTXφ===
[[CTXφ bacteriophage|CTXφ]] (also called CTXphi) is a [[filamentous phage]] that contains the genes for [[cholera toxin]]. Infectious CTXφ particles are produced when ''V. cholerae'' infects humans. Phage particles are secreted from bacterial cells without [[lysis]]. When CTXφ infects ''V. cholerae'' cells, it integrates into specific sites on either chromosome. These sites often contain [[tandem array]]s of integrated CTXφ [[prophage]]. In addition to the ''ctxA'' and ''ctxB'' genes encoding cholera toxin, CTXφ contains eight genes involved in phage reproduction, packaging, secretion, integration, and regulation. The CTXφ genome is 6.9 kb long.<ref>{{cite journal |last1=McLeod |first1=S. M. |last2=Kimsey |first2=H. H. |last3=Davis |first3=B. M. |last4=Waldor |first4=M. K. |title=CTXφ and ''Vibrio cholerae'': exploring a newly recognized type of phage-host cell relationship |journal=Molecular Microbiology |volume=57 |issue=2 |pages=347–356 |year=2005 |pmid=15978069 |doi=10.1111/j.1365-2958.2005.04676.x |doi-access=free }}</ref>

==Ecology and epidemiology==
The main reservoirs of ''V. cholerae'' are aquatic sources such as [[river]]s, [[brackish water]]s, and [[estuaries]], often in association with [[copepods]] or other [[zooplankton]], [[shellfish]], and aquatic plants.<ref name="LutzErken2013">{{cite journal|last1=Lutz|first1=Carla|last2=Erken|first2=Martina|last3=Noorian|first3=Parisa|last4=Sun|first4=Shuyang|last5=McDougald|first5=Diane|title=Environmental reservoirs and mechanisms of persistence of Vibrio cholerae|journal=Frontiers in Microbiology|volume=4|pages=375|year=2013|issn=1664-302X|doi=10.3389/fmicb.2013.00375|pmid=24379807|pmc=3863721|doi-access=free}}</ref>

Cholera infections are most commonly acquired from drinking water in which ''V. cholerae'' is found naturally or into which it has been introduced from the feces of an infected person. Cholera is most likely to be found and spread in places with inadequate water treatment, poor sanitation, and inadequate hygiene. Other common vehicles include raw or undercooked fish and shellfish. Transmission from person to person is very unlikely, and casual contact with an infected person is not a risk for becoming ill.<ref name=":0">{{Cite web|url=https://www.cdc.gov/cholera/general/index.html|title=General Information {{!}} Cholera {{!}} CDC|date=2018-12-13|website=www.cdc.gov|language=en-us|access-date=2019-11-14|archive-date=2012-03-20|archive-url=https://web.archive.org/web/20120320171945/https://www.cdc.gov/cholera/general/index.html|url-status=live}}</ref>''V. cholerae'' thrives in an [[aquatic ecosystem|aquatic environment]], particularly in surface water. The primary connection between humans and pathogenic strains is through water, particularly in economically reduced areas that do not have good water purification systems.<ref name=faruque1998 />

Nonpathogenic strains are also present in water ecologies. The wide variety of pathogenic and nonpathogenic strains that co-exist in aquatic environments are thought to allow for so many genetic varieties. [[Gene transfer]] is fairly common amongst bacteria, and recombination of different ''V. cholerae'' genes can lead to new virulent strains.<ref name=faruque2002>{{cite journal|last=Faruque|first=SM|author2=Nair, GB |title=Molecular ecology of toxigenic Vibrio cholerae.|journal=Microbiology and Immunology|year=2002|volume=46|issue=2|pages=59–66|pmid=11939579|doi=10.1111/j.1348-0421.2002.tb02659.x|doi-access=}}</ref>

A symbiotic relationship between ''V. cholerae'' and ''Ruminococcus obeum'' has been determined.  ''R. obeum'' [[autoinducer]] represses the expression of several ''V. cholerae'' [[virulence factors]]. This inhibitory mechanism is likely to be present in other gut microbiota species which opens the way to mine the gut microbiota of members in specific communities which may utilize autoinducers or other mechanisms in order to restrict colonization by ''V. cholerae'' or other [[Gastroenteritis#Cause|enteropathogens]]. Autoinducers, specifically with ''V. cholerae,'' can develop biofilms and control virulence in response to extracellular quorum-sensing molecules. 

Outbreaks of Cholera cause an estimated 120,000 deaths annually worldwide. There has been roughly seven pandemics since 1817, the first. These pandemics first arose in the Indian subcontinent and spread.<ref name="faruque1998" />

==Diversity and evolution==
Two [[serotype|serogroups]] of ''V. cholerae'', O1 and O139, cause outbreaks of cholera.  O1 causes the majority of outbreaks, while O139 – first identified in [[Bangladesh]] in 1992 – is confined to Southeast Asia. Many other serogroups of ''V. cholerae'', with or without the cholera toxin gene (including the nontoxigenic strains of the O1 and O139 serogroups), can cause a cholera-like illness. Only toxigenic strains of serogroups O1 and O139 have caused widespread epidemics.

''V. cholerae'' O1 has two biotypes, classical and [[El Tor]], and each biotype has two distinct serotypes, Inaba and Ogawa. The symptoms of infection are indistinguishable, although more people infected with the El Tor biotype remain asymptomatic or have only a mild illness. In recent years, infections with the classical biotype of ''V. cholerae'' O1 have become rare and are limited to parts of Bangladesh and [[India]].<ref>{{cite journal |last1=Siddique |first1=A.K. |last2=Baqui |first2=A.H. |last3=Eusof |first3=A. |last4=Haider |first4=K. |last5=Hossain |first5=M.A. |last6=Bashir |first6=I. |last7=Zaman |first7=K. |title=Survival of classic cholera in Bangladesh |journal=The Lancet |volume=337 |issue=8750 |pages=1125–1127 |year=1991 |doi=10.1016/0140-6736(91)92789-5|pmid=1674016 |s2cid=33198972 }}</ref> Recently, new variant strains have been detected in several parts of Asia and Africa. Observations suggest these strains cause more severe cholera with higher case fatality rates.

==Natural genetic transformation==

''V. cholerae'' can be induced to become competent for [[transformation (genetics)|natural genetic transformation]] when grown on [[chitin]], a biopolymer that is abundant in aquatic habitats (e.g. from crustacean exoskeletons).<ref name=Meibom>{{cite journal |vauthors=Meibom KL, Blokesch M, Dolganov NA, Wu CY, Schoolnik GK |title=Chitin induces natural competence in Vibrio cholerae |journal=Science |volume=310 |issue=5755 |pages=1824–7 |year=2005 |pmid=16357262 |doi=10.1126/science.1120096 |bibcode=2005Sci...310.1824M |s2cid=31153549 }}</ref>  Natural genetic transformation is a sexual process involving DNA transfer from one bacterial cell to another through the intervening medium, and the integration of the donor sequence into the recipient genome by [[homologous recombination]]. Transformation competence in ''V. cholerae'' is stimulated by increasing cell density accompanied by nutrient limitation, a decline in growth rate, or stress.<ref name=Meibom />  The ''V. cholerae'' uptake machinery involves a [[natural competence|competence]]-induced [[pilus]], and a conserved DNA binding protein that acts as a ratchet to reel DNA into the cytoplasm.<ref name="pmid26614677">{{cite journal |vauthors=Matthey N, Blokesch M |title=The DNA-Uptake Process of Naturally Competent Vibrio cholerae |journal=Trends Microbiol. |volume=24 |issue=2 |pages=98–110 |year=2016 |pmid=26614677 |doi=10.1016/j.tim.2015.10.008 }}</ref><ref>{{cite web|last=quintdaily|date=3 August 2017|title=Vibrio Cholera Starts Spreading In India – QuintDaily|url=http://quintdaily.com/2017/08/vibrio-cholera-in-india/|access-date=3 August 2017|archive-date=18 September 2021|archive-url=https://web.archive.org/web/20210918132832/https://quintdaily.com/2017/08/vibrio-cholera-in-india/|url-status=live}}</ref> There are two models of genetic transformation, sex hypothesis and competent bacteria.<ref>{{Cite journal|last1=Johnsborg|first1=O|last2=Eldholm|first2=V|last3=Ha˚varstein|first3=L|title=Natural genetic transformation: prevalence, mechanisms and function|journal= Research in Microbiology|year=2007|volume=158|issue=10|pages=767–778|doi=10.1016/j.resmic.2007.09.004|pmid=17997281|doi-access=free}}</ref>

==Gallery==
<gallery class="center" widths="275" heights="225">
File:Vibrio diagram.png|Diagram of the bacterium, ''V. cholerae''
File:Vibrio cholerae on TCBS agar.jpg|Yellow colored (sucrose-fermenting) colonies of ''Vibrio cholerae'' on TCBS agar.
File:Vibrio cholerae.jpg|Transmission electron microscope image of ''Vibrio cholerae'' that has been negatively stained.
</gallery>

==See also==
{{Portal|Biology}}
* [[Drinking water]]
* [[Haiti cholera outbreak]]
* [[Cholera vaccine]]
{{clear}}

==References==
{{Reflist|30em}}

==External links==
{{Commons category}}
{{Wikispecies}}
* [https://www.nsf.gov/news/speeches/colwell/rc01_anatlesson/tsld024.htm Copepods and cholera in untreated water]
* [https://archive.today/20140223073625/http://cmr.jcvi.org/cgi-bin/CMR/GenomePage.cgi?org=gvc Vibrio cholerae El Tor N16961 Genome Page]
* [http://bacdive.dsmz.de/index.php?search=130763&submit=Search Type strain of ''Vibrio cholerae'' at Bac''Dive'' –  the Bacterial Diversity Metadatabase]

{{Cholera}}
{{Gram-negative bacterial diseases}}

{{Taxonbar|from=Q160821}}
{{Authority control}}

[[Category:Vibrionales]]
[[Category:Food microbiology]]
[[Category:Gram-negative bacteria]]
[[Category:Cholera]]
[[Category:Bacteria described in 1854]]
[[Category:Pathogenic bacteria]]