Larval exposure to Francisella tularensisLVS affects fitness of the mosquito Culex quinquefasciatus
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Francisella tularensis is an environmental bacterium capable of infecting a wide spectrum of species from mammals and birds to reptiles. It has been demonstrated that F. tularensis can invade and survive within protozoa, but an association with aquatic insects has not been thoroughly investigated. We examined the interaction of F. tularensis LVS biofilms and Culex quinquefasciatus larvae to determine the effects on larvae and adults. Our results demonstrate that F. tularensis LVS can form and persist as biofilms in natural water and that the mosquito larvae of C. quinquefasciatus readily feed on biofilm and planktonic forms of F. tularensis LVS. Larvae raised in both bacteria-only cultures suffered significant delays in pupation. Adults resulting from larvae continuously exposed to the bacteria had significantly reduced wing lengths in males and fecundity of both sexes. The bacteria may be exerting these effects through localization and persistence within the midgut and Malpighian tubule cells of the larvae. The study of oral acquisition of pathogens by insect larvae can significantly contribute to the study of environmental persistence of pathogens. We show that oral uptake of F. tularensis LVS by C. quinquefasciatus larvae results in not only larval effects but also has effects on adult mosquitoes. These effects are important in understanding both the ecology of tularemia as well as bacterial interactions with aquatic invertebrates.Keywords:
Culex quinquefasciatus
Tularemia
This practical guide gives some starting points to manage biological safety issues with Francisella tularensis.
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Abstract Tularemia in the United States was examined by reviewing 106 Francisella tularensis isolates, mostly from Nebraska, collected during 1998–2012: 48% of Nebraska cases were cat-associated; 7/8 human cases were caused by subtype A.I. A vaccine is needed to reduce feline-associated tularemia, and cat owners should protect against bites/scratches and limit their pet's outdoor access.
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Immunogenic properties of cell wall (CW) preparations of Francisella tularensis four subspecies are investigated. It is shown that the preparations from F. tularensis urea lysates are not toxic for experimental animals. Besides, CW of F. tularensis А-61 subsp. mediasiatica and F. tularensis B-399 A-Cole subsp. tularensis possess immunogenic activity in experimental tularemia caused by F. tularensis 306 subsp. holarctica.
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Francisella tularensis is the causative agent of tularemia. This emerging zoonosis shows several clinical manifestations complicating its diagnosis. The chapter focus on the characteristics of this bacterium, the several forms of the disease, its diagnosis and molecular epidemiology.
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Abstract Tularemia is a zoonosis, a disease of animals transmissible to humans, and is caused by the facultative intracellular bacterium Francisella tularensis. F. tularensis is considered a potential agent of biological warfare and bioterrorism and as such has been rated among the top 6 category A agents. Formerly, F. tularensis was included among agents developed and used by state‐sponsored bioweapons programs. In fact, F. tularensis is one of the most infectious pathogenic bacteria known, requiring inoculation or inhalation of as few as 10 organisms to cause human infection. At present there are four recognized subspecies of F. tularensis: tularensis, holarctica, mediasiatica, and novicida. The natural reservoirs of F. tularensis still await complete delineation. Little is known about the virulence mechanisms of F. tularensis. In a bioterrorism scenario, respiratory tularemia (acquired through inhalation) is judged to be the greatest threat. Natural outbreaks of human respiratory type A or type B tularemia have repeatedly been recorded in farmers and landscape workers illustrating the potential of effective F. tularensis transmission by dry aerosols. The clinical expression of tularemia largely depends on the route of entrance of the infectious agent and the prognosis in tularemia is highly dependent on the causative subspecies of F. tularensis. There is currently no licensed and widely available tularemia vaccine. Tularemia warrants antibiotic treatment and is not transmitted from person to person. Currently, there is a reawakened interest in tularemia and a rapid development of new diagnostics, prophylactics and therapies.
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F. tularensis is a gram negative, highly infectious, facultative intracellular bacterium that causes fulminating disease tularemia. The genus Francisella includes four organisms: F. tularensis subsp. tularensis (type A), F. tularensis subsp. holarctica (type B), F. tularensis subsp. mediasiatica and Francisella subsp. novicida. The ability of F. tularensis to envade and proliferate within cells was shown to be of great relevance for the development of tularemia. F. tularensis is able to survive and replicate within various cell types but macrophages are the key cells in pathogenesis of tularemia.
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Francisella tularensis, the causative agent of tularemia, is a HHS Tier 1 select agent. Tularemia is the most commonly reported human and animal infection caused by a bacterial select agent in the ...
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An alternative to streptomycin for treatment of possible tularemia would be useful on occasions when a patient develops a perplexing pneumonia that does not respond to initial treatment. In geographic areas where tularemia is endemic, an antimicrobial drug that is bactericidal for Francisella tularensis and is also effective against a spectrum of common pulmonary pathogens, including the Enterobacteriaceae and most strains of Pseudomonas aeruginosa, would be desirable. The purposes of this report are (1) to describe observations regarding the in vitro susceptibility of Francisella tularensis to streptomycin, kanamycin, and gentamicin; (2) to describe in vivo efficacy of these drugs in mouse tularemia; (3) to describe the results in 10 patients with tularemia treated with gentamicin. Gentamicin was bactericidal for Francisella tularensis in vitro, was effective in mouse tularemia when given in large doses, and was effective in humans when given in the standard recommended dose.
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Abstract Tularemia is a zoonosis, a disease of animals transmissible to humans, and is caused by the facultative intracellular bacterium Francisella tularensis. F. tularensis is considered a potential agent of biological warfare and bioterrorism and as such has been rated among the top 6 category A agents (see also “Category Agents A‐C”). Formerly, F. tularensis was included among agents developed and used by state‐sponsored bioweapons programs. F. tularensis is one of the most infectious pathogenic bacteria known, requiring inoculation or inhalation of as few as 10 organisms to cause human infection. At present there are four recognized subspecies of F. tularensis : tularensis, holarctica, mediasiatica, and novicida, although only tularensis and holoarctica consistently cause disease in humans. Complete identification of all the natural reservoirs of F. tularensis has probably not yet occurred. Ongoing research continues to delineate the virulence mechanisms of F. tularensis . In a bioterrorism scenario, respiratory tularemia (acquired through inhalation) is judged to be the greatest threat. Natural outbreaks of human respiratory type A or type B tularemia have repeatedly been recorded in farmers and landscape workers illustrating the potential of effective F. tularensis transmission by dry aerosols. The clinical expression of tularemia largely depends on the route of entrance of the infectious agent and the prognosis in tularemia is highly dependent on the causative subspecies of F. tularensis . There is currently no licensed and widely available tularemia vaccine. Tularemia warrants antibiotic treatment and is not transmitted from person to person. Currently, there is renewed interest in tularemia and development of new diagnostics, prophylactics and therapies.
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Francisella
Biological Warfare
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Survey of <i>Francisella tularensis</i> in Wild Animals in Japan in Areas Where Tularemia is Endemic
Samples taken from 428 wild animals and 126 ticks, collected from a tularemia-endemic area in Japan between 2005 and 2013, were analyzed for the presence of Francisella tularensis. F. tularensis was isolated from a Japanese hare carcass whereas the samples from live animals and ticks were negative for F. tularensis by real-time PCR. Our results suggest that F. tularensis is still present in Japan although its prevalence is considerably low even in areas where tularemia is endemic.
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Francisella
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