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| __NOTOC__
| | #REDIRECT [[Bacillus anthracis]] |
| {{Anthrax}}
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| {{CMG}}; {{AE}} {{JS}}
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| ==Overview==
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| The causative agent of anthrax is [[B. anthracis]], a nonmotile, [[Gram-positive]], [[aerobic]] or facultatively anaerobic, [[endospore]]-forming, [[rod]]-shaped [[bacterium]]. The [[spores]] of [[B. anthracis]], which can remain dormant in the environment for decades, are the [[infectious]] form, but vegetative [[B. anthracis]] rarely causes disease.<ref>{{Cite journal | author = [[Sean V. Shadomy]] & [[Theresa L. Smith]] | title = Zoonosis update. Anthrax | journal = [[Journal of the American Veterinary Medical Association]] | volume = 233 | issue = 1 | pages = 63–72 | year = 2008 | month = July | doi = 10.2460/javma.233.1.63 | pmid = 18593313}}</ref> The [[natural reservoir]]s of [[Bacillus anthracis]] includes humans, mammals, herbivores, reptiles, and birds.
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| ==Taxonomy==
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| [[Bacterium|Bacteria]]; [[Archaebacteria]]; [[Firmicutes]]; [[Bacilli]]; [[Bacillales]]; [[Bacillaceae]]; [[Bacillus]]; anthracis; Bacillus anthracis
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| ==Biology==
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| {| style="float: right;"
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| | [[File:AnthraxCauses2.png|200px|thumb|none| Photomicrograph depicting a number of Gram-positive, endospore-forming Bacillus anthracis bacteria<SMALL>Courtesy: ''[http://phil.cdc.gov/phil/home.asp Public Health Image Library (PHIL), Centers for Disease Control and Prevention (CDC)]''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| | [[File:AnthraxCauses1.jpg|200px|thumb|none| Scanning electron micrograph (SEM) depicted spores from the Sterne strain of Bacillus anthracis bacteria<SMALL>Courtesy: ''[http://phil.cdc.gov/phil/home.asp Public Health Image Library (PHIL), Centers for Disease Control and Prevention (CDC)]''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| |}
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| [[B. anthracis]], the causative agent of [[anthrax]], is a nonmotile, [[Gram-positive]], [[aerobic]] or facultatively [[anaerobic]], [[endospore]]-forming, [[rod]]-shaped [[bacterium]] approximately 4 μm by 1 μm, although under the microscope it frequently appears in chains of [[cells]]. Like other [[Bacillus]], [[Bacillus anthracis]] is saprophyte, being able to live in vegetations, air, water and soil.<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| These [[bacterial]] [[cells]] may occur isolated, form groups of 2 or more [[cells]] in the body, or long chains in cultures.<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref> In [[blood smear]]s, smears of tissues or lesion fluid from diagnostic specimens, these chains are two to a few cells in length. In smears made from [[in vitro]] cultures, they can appear as endless strings of [[cells]] - responsible for the characteristic tackiness of the colonies and for the flocculating nature of broth cultures. Cell cultures appear as a large, grey and curled structure, resembling a "medusa head".<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| [[B. anthracis]] have a characteristic square-ended appearance, traditionally associated with its vegetative state, although this may not always be very clear. In the presence of [[oxygen]], mostly at 32 - 35 ºC, and towards the end of the exponential phase of growth, one ellipsoidal [[spore]] (approximately 2 μm by 1 μm in size) is formed in each [[cell]].<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref><ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| The [[spores]] of [[B. anthracis]], which can remain dormant in the environment for decades, being resistant to heat and disinfectants, are the [[infectious]] form, but vegetative [[B. anthracis]] rarely causes disease.<ref>{{Cite journal | author = [[Sean V. Shadomy]] & [[Theresa L. Smith]] | title = Zoonosis update. Anthrax | journal = [[Journal of the American Veterinary Medical Association]] | volume = 233 | issue = 1 | pages = 63–72 | year = 2008 | month = July | doi = 10.2460/javma.233.1.63 | pmid = 18593313}}</ref><ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| In the absence of [[oxygen]] and under a high partial pressure of Co2, in the presence of [[bicarbonate]], the vegetative [[cell]] secretes its [[polypeptide]] [[capsule]], and it is one of the two established [[in vivo]] [[virulence factor]]s of [[B. anthracis]]. The [[capsule]] is also a primary [[diagnostic]] aid.<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref> Protective [[antigen]] (PA) and [[edema]] factor (EF) combine to form [[edema]] toxin (ET) and PA and lethal factor (LF) combine to form lethal toxin (LT).<ref>{{Cite journal | author = [[Mahtab Moayeri]] & [[Stephen H. Leppla]] | title = The roles of anthrax toxin in pathogenesis | journal = [[Current opinion in microbiology]] | volume = 7 | issue = 1 | pages = 19–24 | year = 2004 | month = February | doi = 10.1016/j.mib.2003.12.001 | pmid = 15036135}}</ref><ref name=CDC>{{cite web | title = Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults | url = http://wwwnc.cdc.gov/eid/article/20/2/13-0687_article }}</ref>
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| ==Origin==
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| [[Anthrax]] is thought to have originated in Egypt and Mesopotamia. Many scholars think that in Moses’ time, during the 10 plagues of Egypt, [[anthrax]] may have caused what was known as the fifth [[plague]], described as a sickness affecting horses, cattle, sheep, camels and oxen.
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| ==Tropism==
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| After entering the body (through the [[skin]], [[lungs]], [[gastrointestinal tract]] or by [[injection]]) [[B. anthracis]] [[spores]] are believed to germinate locally or be transported by [[phagocytic cells]] to the [[lymphatics]] and regional [[lymph nodes]], where they germinate.<ref name=CDC>{{cite web | title = Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults | url = http://wwwnc.cdc.gov/eid/article/20/2/13-0687_article }}</ref><ref name="Ross1957">{{cite journal|last1=Ross|first1=Joan M.|title=The pathogenesis of anthrax following the administration of spores by the respiratory route|journal=The Journal of Pathology and Bacteriology|volume=73|issue=2|year=1957|pages=485–494|issn=0368-3494|doi=10.1002/path.1700730219}}</ref> Protective [[antigen]] (PA) and [[edema]] factor (EF) combine to form [[edema]] toxin (ET) and PA and lethal factor (LF) combine to form lethal toxin (LT). After binding to cell surface receptors, the PA portion of the complexes facilitates translocation of the [[toxins]] to the [[cytosol]], in which EF and LF exert their toxic effects.<ref name="Moayeri2004">{{cite journal|last1=Moayeri|first1=M|title=The roles of anthrax toxin in pathogenesis|journal=Current Opinion in Microbiology|volume=7|issue=1|year=2004|pages=19–24|issn=13695274|doi=10.1016/j.mib.2003.12.001}}</ref><ref name=CDC>{{cite web | title = Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults | url = http://wwwnc.cdc.gov/eid/article/20/2/13-0687_article }}</ref>
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| ==Natural Reservoir==
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| [[Natural reservoir]]s of [[Bacillus anthracis]] includes:<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref><ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref><ref name=CDC>{{cite web | title = Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults | url = http://wwwnc.cdc.gov/eid/article/20/2/13-0687_article }}</ref>
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| * Humans
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| * Mammals
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| * Herbivores
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| * Reptiles
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| * Birds
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| ==References==
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| {{reflist|2}}
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