| 1. |
- Birdsell, Dawn N, et al.
(författare)
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Francisella tularensis subsp. tularensis group A.I, United States
- 2014
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Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 20:5, s. 861-865
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Tidskriftsartikel (refereegranskat)abstract
- We used whole-genome analysis and subsequent characterization of geographically diverse strains using new genetic signatures to identify distinct subgroups within Francisella tularensis subsp. tularensis group A.I: A.I.3, A.I.8, and A.I.12. These subgroups exhibit complex phylogeographic patterns within North America. The widest distribution was observed for A.I.12, which suggests an adaptive advantage.
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| 2. |
- Larsson, Pär, et al.
(författare)
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Canonical insertion-deletion markers for rapid DNA typing of Francisella tularensis
- 2007
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Ingår i: Emerging Infectious Diseases. - 1080-6040 .- 1080-6059. ; 13:11, s. 1725-1732
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Tidskriftsartikel (refereegranskat)abstract
- To develop effective and accurate typing of strains of Francisella tularensis, a potent human pathogen and a putative bioterrorist agent, we combined analysis of insertion-deletion (indel) markers with multiple-locus variable-number tandem repeat analysis (MLVA). From 5 representative F. tularensis genome sequences, 38 indel markers with canonical properties, i.e., capable of sorting strains into major genetic groups, were selected. To avoid markers with a propensity for homoplasy, we used only those indels with 2 allelic variants and devoid of substantial sequence repeats. MLVA included sequences with much diversity in copy number of tandem repeats. The combined procedure allowed subspecies division, delineation of clades A.I and A.II of subspecies tularensis, differentiation of Japanese strains from other strains of subspecies holarctica, and high-resolution strain typing. The procedure uses limited amounts of killed bacterial preparations and, because only 1 single analytic method is needed, is time- and cost-effective.
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| 3. |
- Lundström, Jan O., et al.
(författare)
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Transstadial Transmission of Francisella tularensis holarctica in Mosquitoes, Sweden
- 2011
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Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 17:5, s. 794-799
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, human cases of tularemia caused by Francisella tularensis holarctica are assumed to be transmitted by mosquitoes, but how mosquito vectors acquire and transmit the bacterium is not clear. To determine how transmission of this bacterium occurs, mosquito larvae were collected in an area where tularemia is endemic, brought to the laboratory, and reared to adults in their original pond water. Screening of adult mosquitoes by real-time PCR demonstrated F tularensis IpnA sequences in 14 of the 48 mosquito pools tested; IpnA sequences were demonstrated in 6 of 9 identified mosquito species. Further analysis confirmed the presence of F tularensis holarctica-specific 30-bp deletion region sequences (FtM19inDel) in water from breeding containers and in 3 mosquito species (Aedes sticticus, Ae. vexans, and Ae. punctor) known to take blood from humans. Our results suggest that the mosquitoes that transmit F tularensis holarctica during tularemia outbreaks acquire the bacterium already as larvae.
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| 4. |
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| 5. |
- Svensson, Kerstin, et al.
(författare)
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Landscape epidemiology of tularemia outbreaks in Sweden
- 2009
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Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 15:12, s. 1937-1947
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Tidskriftsartikel (refereegranskat)abstract
- Summer outbreaks of tularemia that occurred from 1995 through 2005 in 2 locations in Sweden affected 441 persons. We performed an epidemiologic investigation of these outbreaks using a novel strategy, involving high-resolution genotyping of Francisella tularensis isolates obtained from 136 patients (using 18 genetic markers developed from 6 F. tularensis genome sequences) and interviews with the patients. Strong spatial associations were found between F. tularensis subpopulations and the places of disease transmission; infection by some subpopulations occurred within areas as small as 2 km(2), indicating unidentified environmental point sources of tularemia. In both locations, disease clusters were associated with recreational areas beside water, and genetic subpopulations were present throughout the tularemia season and persisted over years. High-resolution genotyping in combination with patients' statements about geographic places of disease transmission provided valuable indications of likely sources of infection and the causal genotypes during these tularemia outbreaks.
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