Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden
Francisella tularensis, the causative agent of the zoonotic disease tularaemia, is highly contagious and potentially fatal for a wide range of wildlife species of the northern hemisphere, also humans. Although recognized as a pathogen for over 100 years, much still remains to be elucidated concerni...
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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_ | 1855570853019779072 |
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| author | Cavalli-Björkman Hellström, Sofia |
| author_browse | Cavalli-Björkman Hellström, Sofia |
| author_facet | Cavalli-Björkman Hellström, Sofia |
| author_sort | Cavalli-Björkman Hellström, Sofia |
| collection | Epsilon Archive for Student Projects |
| description | Francisella tularensis, the causative agent of the zoonotic disease tularaemia, is highly contagious and potentially fatal for a wide range of wildlife species of the northern
hemisphere, also humans. Although recognized as a pathogen for over 100 years, much still remains to be elucidated concerning the ecology and transmission of the bacterium, hence this literature overview aims at compiling data regarding the aquatic association and the role of
mosquitoes in transmission of Francisella tularensis subspecies holartica, the sole subspecies in Sweden. While a linkage between the bacterium and natural waters stands beyond dispute, there is no consensus in the literature concerning its potential as a reservoir. However, two
prevailing theories can be distinguished; one proposes the water association being mammaldependent and thus merely the result of contamination from semi-aquatic mammals living in
close vicinity to the water source. The other, quite contrary, suggests mammal-independence and hence that water, possibly in association with protozoa, serves as an environmental reservoir for the bacterium. Regarding transmission of the infection in Sweden, it is assumed
to be mediated by mosquitoes, yet their precise role and acquisition of bacteria is not well characterized. Again, two possibilities prevail. On the one hand, mosquitoes have been proposed to acquire the bacterium while feeding on infected animals and, on the other hand, already at their larval stages. Although no agreement is reached in literature, the involvement of larvae would inevitably bridge the gap between the aquatic and terrestrial cycle of the bacterium, especially when considering that mosquito invariably feed on protozoa as larvae in floodwater. Future determination of the natural reservoir of Francisella tularensis subspecies holarctica, as well as its relationship with mosquitoes, will shed new light upon its complex life cycle and thus significantly aid in prediction and prevention of new outbreaks. |
| format | M2 |
| id | RepoSLU5486 |
| 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 | RepoSLU54862013-04-24T12:32:55Z Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden Francisella tularansis holarctica : en bakteries underliga vatten- och myggassociation i Sverige Cavalli-Björkman Hellström, Sofia zoonosis tularaemia tularemia rabbit fever deer-fly fever Francisella tularensis subspecies holarctica transmission mosquito Francisella tularensis, the causative agent of the zoonotic disease tularaemia, is highly contagious and potentially fatal for a wide range of wildlife species of the northern hemisphere, also humans. Although recognized as a pathogen for over 100 years, much still remains to be elucidated concerning the ecology and transmission of the bacterium, hence this literature overview aims at compiling data regarding the aquatic association and the role of mosquitoes in transmission of Francisella tularensis subspecies holartica, the sole subspecies in Sweden. While a linkage between the bacterium and natural waters stands beyond dispute, there is no consensus in the literature concerning its potential as a reservoir. However, two prevailing theories can be distinguished; one proposes the water association being mammaldependent and thus merely the result of contamination from semi-aquatic mammals living in close vicinity to the water source. The other, quite contrary, suggests mammal-independence and hence that water, possibly in association with protozoa, serves as an environmental reservoir for the bacterium. Regarding transmission of the infection in Sweden, it is assumed to be mediated by mosquitoes, yet their precise role and acquisition of bacteria is not well characterized. Again, two possibilities prevail. On the one hand, mosquitoes have been proposed to acquire the bacterium while feeding on infected animals and, on the other hand, already at their larval stages. Although no agreement is reached in literature, the involvement of larvae would inevitably bridge the gap between the aquatic and terrestrial cycle of the bacterium, especially when considering that mosquito invariably feed on protozoa as larvae in floodwater. Future determination of the natural reservoir of Francisella tularensis subspecies holarctica, as well as its relationship with mosquitoes, will shed new light upon its complex life cycle and thus significantly aid in prediction and prevention of new outbreaks. Francisella tularensis, en zoonotisk bakterie spridd över norra halvklotet, ger upphov till den smittsamma och potentiellt dödliga pestsjukdomen tularemi. Bakterien upptäcktes för över 100 år sedan, men trots detta kvarstår flertalet kunskapsluckor angående dess komplexa livscykel, vilken involverar såväl land- och vattenlevande djur som flertalet vektorer. Syftet med denna litteraturöversikt är att undersöka möjligheten till en eventuell vattenassocierad reservoar för Francisella tularensis holarctica, den enda existerande underarten i Sverige, samt myggors roll som smittspridare. Att bakterien är starkt korrelerad till vattenmiljöer är sedan länge känt, dock råder idag ingen konsensus angående vattnets potential som reservoar för bakterien, istället tycks två huvudsakliga teorier föreligga: Bakteriens förekomst i vattendrag förklaras, å ena sidan, vara en följd av kontamination och således helt beroende av frekvent tillförsel från akvatiska däggdjur, medan den, å andra sidan, tycks indikera en självständig reservoar, oberoende av däggdjur men möjligtvis kopplad till protozoer. Båda teorierna har såväl styrkor som svagheter gällande att förklara Francisella tularensis holarcticas epidemiologi och ekologi, och det verkar därmed rimligt att anta att de båda är av vikt i naturen men under olika förutsättningar. Angående myggors betydelse för spridning av tularemi är de sedan länge ansedda de viktigaste vektorerna i Sverige, dock råder delade meningar om hur de infekteras. Traditionellt antas de uppta bakterien vid födosök hos smittade värddjur medan ny forskning pekar på möjlighet till infektion redan som mygglarver. En sådan inkorporering av bakterien i myggans tidiga vattenlevande livsstadier innebär onekligen en önskvärd sammanlänkning av patogenens akvatiska livscykel med dess terrestriska värddjur. Ett fastställande av Francisella tularensis holarcticas naturliga reservoar, eller reservoarer, samt en ökad förståelse för myggors roll som bärare och spridare av bakterien är av största vikt för att förutsäga och förhindra framtida epidemier och epizootier. SLU/Dept. of Biomedical Sciences and Veterinary Public Health (until 231231) 2013 M2 eng swe https://stud.epsilon.slu.se/5486/ |
| spellingShingle | zoonosis tularaemia tularemia rabbit fever deer-fly fever Francisella tularensis subspecies holarctica transmission mosquito Cavalli-Björkman Hellström, Sofia Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title | Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title_full | Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title_fullStr | Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title_full_unstemmed | Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title_short | Francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in Sweden |
| title_sort | francisella tularensis subspecies holarctica : the curious case of a water- and mosquito associated bacterium in sweden |
| topic | zoonosis tularaemia tularemia rabbit fever deer-fly fever Francisella tularensis subspecies holarctica transmission mosquito |