The secret life of Bacillus anthracis
Bacillus anthracis is the causative agent of anthrax, a serious and globally distributed zoonosis affecting a wide range of wild and domestic animals, invariably also humans. However, although known to humans since biblical times, much remains to be elucidated concerning the ecology and transmissio...
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| Formato: | M2 |
| Lenguaje: | Inglés sueco |
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SLU/Dept. of Biomedical Sciences and Veterinary Public Health (until 231231)
2013
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| Materias: |
| _version_ | 1855570853194891264 |
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| author | Cavalli-Björkman Hellström, Anna |
| author_browse | Cavalli-Björkman Hellström, Anna |
| author_facet | Cavalli-Björkman Hellström, Anna |
| author_sort | Cavalli-Björkman Hellström, Anna |
| collection | Epsilon Archive for Student Projects |
| description | Bacillus anthracis is the causative agent of anthrax, a serious and globally distributed zoonosis affecting a wide range of wild and domestic animals, invariably also humans.
However, although known to humans since biblical times, much remains to be elucidated concerning the ecology and transmission of this bacterium. Of particular interest is the Bacillus anthracis spore, the uptake of which is the predominant way to contract anthrax and which is legendary for its resilience in the environment and thus crucial for persistence and spread of the disease. Hence, the aim of this study is to review the natural transmission of
Bacillus anthracis and investigate potential means by which soil persisting Bacillus anthracis spores reach concentrations sufficient to infect susceptible hosts. When reviewing the literature, three different theories can be distinguished. Firstly, “the incubator area” hypothesis suggests that favourable soil factors, possibly in association with amoebas, may constitute an environment supporting repeated spore-bacterium-spore cycling, thus increasing the local amount of spores. Secondly, water runoff from heavy rains or flooding has been proposed to collect spores and dispose them in closely restricted sites, thus creating “concentrator areas” with locally high amounts of spores. Lastly, the outermost layer of the
spore, the exosporium, is proposed to tie spores to the environment where they were first shed and hence maintain infectious spore concentrations at a particular site. Considering that these theories all have their agreements and disagreements with the ecology and epidemiology of
anthrax, it is reasonable to assume that all three exert an impact on spore concentrations, possibly at different degrees at various sites and regions. Howsoever, the ecology of Bacillus anthracis requires further research to fully understand the mechanism responsible for transmission and spread of anthrax. Only then can efficient methods for eradication of the disease from contaminated fields, and hence reducing the risk of future epidemics, be developed. |
| format | M2 |
| id | RepoSLU5487 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2013 |
| publishDateSort | 2013 |
| publisher | SLU/Dept. of Biomedical Sciences and Veterinary Public Health (until 231231) |
| publisherStr | SLU/Dept. of Biomedical Sciences and Veterinary Public Health (until 231231) |
| record_format | eprints |
| spelling | RepoSLU54872013-04-24T13:01:50Z The secret life of Bacillus anthracis Bacillus anthracis hemliga liv Cavalli-Björkman Hellström, Anna zoonosis anthrax Bacillus anthracis sporulation spore transmission soil Bacillus anthracis is the causative agent of anthrax, a serious and globally distributed zoonosis affecting a wide range of wild and domestic animals, invariably also humans. However, although known to humans since biblical times, much remains to be elucidated concerning the ecology and transmission of this bacterium. Of particular interest is the Bacillus anthracis spore, the uptake of which is the predominant way to contract anthrax and which is legendary for its resilience in the environment and thus crucial for persistence and spread of the disease. Hence, the aim of this study is to review the natural transmission of Bacillus anthracis and investigate potential means by which soil persisting Bacillus anthracis spores reach concentrations sufficient to infect susceptible hosts. When reviewing the literature, three different theories can be distinguished. Firstly, “the incubator area” hypothesis suggests that favourable soil factors, possibly in association with amoebas, may constitute an environment supporting repeated spore-bacterium-spore cycling, thus increasing the local amount of spores. Secondly, water runoff from heavy rains or flooding has been proposed to collect spores and dispose them in closely restricted sites, thus creating “concentrator areas” with locally high amounts of spores. Lastly, the outermost layer of the spore, the exosporium, is proposed to tie spores to the environment where they were first shed and hence maintain infectious spore concentrations at a particular site. Considering that these theories all have their agreements and disagreements with the ecology and epidemiology of anthrax, it is reasonable to assume that all three exert an impact on spore concentrations, possibly at different degrees at various sites and regions. Howsoever, the ecology of Bacillus anthracis requires further research to fully understand the mechanism responsible for transmission and spread of anthrax. Only then can efficient methods for eradication of the disease from contaminated fields, and hence reducing the risk of future epidemics, be developed. Bacillus anthracis är en zoonotisk bakterie som orsakar den allvarliga och globalt förekommande sjukdomen anthrax, eller mjältbrand. Trots att både agens och sjukdom är välbekanta sedan antikens dagar och har varit i fokus för gedigen forskning i över 150 år, kvarstår häpnadsväckande många frågetecken. Av särskilt intresse är Bacillus anthracis alternerande livscykel mellan vegetativ, replikerande cell och metaboliskt vilande, men fortfarande infektiös, spor. Då sporerna har en närmast legendarisk motståndskraft mot yttre omgivningsfaktorer kan de kvarstå i miljön under mycket lång tid, och således upprätthålla ett infektiöst fokus av Bacillus anthracis i jordmånen, från vilket nya mottagliga individer kan infekteras. Då anthrax är en sjukdom som huvudsakligen smittar via sporer och har en hög infektionsdos är syftet med denna litteraturöversikt följaktligen att utröna hur infektiösa nivåer av sporer bildas och bibehållas i omgivningen, samt undersöka möjliga spridningsvägar för nämnda sporer. I litteraturen framträder tre huvudsakliga teorier angående hur sporer koncentreras: För det första, i den så kallade ”incubator area”-hypotesen föreslås Bacillus anthracis sporer uppnå höga antal genom att självständigt, eller möjligtvis via amöbor, germinera, replikera och re-sporulera i miljön, dvs. utanför ett värddjur, under förutsättning att yttre faktorer är gynnsamma. Ett ytterligare alternativ förs fram i ”concentrator area”-teorin där Bacillus anthracis sporer tros följa med avrinningsvatten efter skyfall eller översvämningar för att ackumuleras i låglänta områden där höga lokala sporkoncentrationer således upprättas. Slutligen framförs möjligheten att Bacillus anthracis sporernas yttersta hölje, exosporium, binder sporerna till jordpartiklar och följaktligen kvarhålls de på det ställe där de först hamnar efter bildning. Under beaktande att alla tre teorier uppvisar både enigheter och motstridigheter med Bacillus anthracis epidemiologi och ekologi, är det rimligt att anta att de alla, var och en på sitt sätt, bidrar till att etablera och bibehålla infektiösa spormängder, troligtvis av varierande grad i olika miljöer och regioner. Dock kvarstår mycket forskning för att fullt kunna kartlägga Bacillus anthracis komplexa ekologi och därmed möjliggöra utvecklingen av effektiva metoder för sanering av sporkontaminerade områden och således förebygga framtida anthrax epidemier. SLU/Dept. of Biomedical Sciences and Veterinary Public Health (until 231231) 2013 M2 eng swe https://stud.epsilon.slu.se/5487/ |
| spellingShingle | zoonosis anthrax Bacillus anthracis sporulation spore transmission soil Cavalli-Björkman Hellström, Anna The secret life of Bacillus anthracis |
| title | The secret life of Bacillus anthracis |
| title_full | The secret life of Bacillus anthracis |
| title_fullStr | The secret life of Bacillus anthracis |
| title_full_unstemmed | The secret life of Bacillus anthracis |
| title_short | The secret life of Bacillus anthracis |
| title_sort | secret life of bacillus anthracis |
| topic | zoonosis anthrax Bacillus anthracis sporulation spore transmission soil |