Editing Anthrax (section)

=== Bacteria ===
[[Image:Bacillus anthracis Gram.jpg|thumb|[[Photomicrograph]] of a [[Gram stain]] of the bacterium ''Bacillus anthracis'', the cause of the anthrax disease]]
{{Main|Bacillus anthracis}}
''Bacillus anthracis'' is a rod-shaped, [[Gram-positive]], facultative anaerobe<ref>{{cite journal | vauthors = Koehler TM | title = Bacillus anthracis physiology and genetics | journal = Molecular Aspects of Medicine | volume = 30 | issue = 6 | pages = 386–396 | date = December 2009 | pmid = 19654018 | pmc = 2784286 | doi = 10.1016/j.mam.2009.07.004 }}</ref> bacterium about 1 by 9&nbsp;μm in size.<ref name=CDC2015Bas /> It was shown to cause disease by [[Robert Koch]] in 1876 when he took a blood sample from an infected cow, isolated the bacteria, and put them into a mouse.<ref name="pages 277-310">{{cite journal | vauthors = Koch R |title=Untersuchungen über Bakterien: V. Die Ätiologie der Milzbrand-Krankheit, begründet auf die Entwicklungsgeschichte des ''Bacillus anthracis'' |journal=Beiträge zur Biologie der Pflanzen |volume=2 |issue=2 |pages=277–310 |year=1876 |url=http://edoc.rki.de/documents/rk/508-5-26/PDF/5-26.pdf |url-status=live |archive-url=https://web.archive.org/web/20110718171133/http://edoc.rki.de/documents/rk/508-5-26/PDF/5-26.pdf |archive-date=18 July 2011 }} [Investigations into bacteria: V. The etiology of anthrax, based on the ontogenesis of ''Bacillus anthracis''], Cohns</ref> The bacterium normally rests in spore form in the soil, and can survive for decades in this state. Herbivores are often infected while grazing, especially when eating rough, irritant, or spiky vegetation; the vegetation has been hypothesized to cause wounds within the gastrointestinal tract, permitting entry of the bacterial spores into the tissues. Once ingested or placed in an open wound, the bacteria begin multiplying inside the animal or human and typically kill the host within a few days or weeks. The spores germinate at the site of entry into the tissues and then spread by the circulation to the lymphatics, where the bacteria multiply.<ref name="Widdicombe">{{cite journal | vauthors = Hughes R, May AJ, Widdicombe JG | title = The role of the lymphatic system in the pathogenesis of anthrax | journal = British Journal of Experimental Pathology | volume = 37 | issue = 4 | pages = 343–49 | date = August 1956 | pmid = 13364144 | pmc = 2082573 }}</ref>

The production of two powerful exotoxins and lethal toxin by the bacteria causes death. Veterinarians can often tell a possible anthrax-induced death by its sudden occurrence and the dark, nonclotting blood that oozes from the body orifices. Most anthrax bacteria inside the body after death are outcompeted and destroyed by anaerobic bacteria within minutes to hours ''post mortem'', but anthrax vegetative bacteria that escape the body via oozing blood or opening the carcass may form hardy spores. These vegetative bacteria are not contagious.<ref name=Liu>{{cite journal | vauthors = Liu H, Bergman NH, Thomason B, Shallom S, Hazen A, Crossno J, Rasko DA, Ravel J, Read TD, Peterson SN, Yates J, Hanna PC | title = Formation and composition of the Bacillus anthracis endospore | journal = Journal of Bacteriology | volume = 186 | issue = 1 | pages = 164–78 | date = January 2004 | pmid = 14679236 | pmc = 303457 | doi = 10.1128/JB.186.1.164-178.2004 }}</ref> One spore forms per vegetative bacterium. The triggers for spore formation are not known, but oxygen tension and lack of nutrients may play roles. Once formed, these spores are very hard to eradicate.<ref>{{Citation |title=Disinfection, decontamination, fumigation, incineration |date=2008 |work=Anthrax in Humans and Animals. | edition = 4th |url= https://www.ncbi.nlm.nih.gov/books/NBK310477/ |access-date=2025-03-05 |publisher=World Health Organization |language=en}}</ref>

The infection of herbivores (and occasionally humans) by inhalation normally begins with inhaled spores being transported through the air passages into the tiny air sacs (alveoli) in the lungs. The spores are then picked up by scavenger cells ([[macrophage]]s) in the lungs and transported through small vessels ([[lymphatic system|lymphatics]]) to the [[lymph nodes]] in the central chest cavity ([[mediastinum]]). Damage caused by the anthrax spores and bacilli to the central chest cavity can cause chest pain and difficulty breathing. Once in the lymph nodes, the spores germinate into active bacilli that multiply and eventually burst the macrophages, releasing many more bacilli into the bloodstream to be transferred to the entire body. Once in the bloodstream, these bacilli release three proteins: [[Anthrax lethal factor endopeptidase|lethal factor]], edema factor, and protective antigen. The three are not toxic by themselves, but their combination is incredibly lethal to humans.<ref name=Pimental04>{{cite journal | vauthors = Pimental RA, Christensen KA, Krantz BA, Collier RJ | title = Anthrax toxin complexes: heptameric protective antigen can bind lethal factor and edema factor simultaneously | journal = Biochemical and Biophysical Research Communications | volume = 322 | issue = 1 | pages = 258–62 | date = September 2004 | pmid = 15313199 | doi = 10.1016/j.bbrc.2004.07.105 }}</ref> Protective antigen combines with these other two factors to form lethal toxin and edema toxin, respectively. These toxins are the primary agents of tissue destruction, bleeding, and death of the host. If antibiotics are administered too late, even if the antibiotics eradicate the bacteria, some hosts still die of toxemia because the toxins produced by the bacilli remain in their systems at lethal dose levels.<ref name="Sweeney">{{cite journal | vauthors = Sweeney DA, Hicks CW, Cui X, Li Y, Eichacker PQ | title = Anthrax infection | journal = American Journal of Respiratory and Critical Care Medicine | volume = 184 | issue = 12 | pages = 1333–41 | date = December 2011 | pmid = 21852539 | pmc = 3361358 | doi = 10.1164/rccm.201102-0209CI }}</ref>

<gallery>
File:Bacillus Anthracis.png|''Bacillus anthracis''
File:Anthrax color enhanced micrograph.JPG|Color-enhanced [[Scanning electron microscope|scanning electron micrograph]] shows [[spleen|splenic tissue]] from a [[monkey]] with inhalational anthrax; featured are rod-shaped [[bacilli]] (yellow) and an [[red blood cell|erythrocyte]] (red)
File:Gram Stain Anthrax.jpg|Gram-positive anthrax bacteria (purple rods) in [[cerebrospinal fluid]]: If present, a Gram-negative bacterial species would appear pink. (The other cells are [[white blood cell]]s.)
</gallery>