Tularemia

Abstract

Francisella tularensis is the etiological agent of tularemia, a serious and occasionally fatal disease of humans and animals. In humans, ulceroglandular tularemia is the most common form of the disease and is usually a consequence of a bite from an arthropod vector which has previously fed on an infected animal. The pneumonic form of the disease occurs rarely but is the likely form of the disease should this bacterium be used as a bioterrorism agent. The diagnosis of disease is not straightforward. F. tularensis is difficult to culture, and the handling of this bacterium poses a significant risk of infection to laboratory personnel. Enzyme-linked immunosorbent assay- and PCR-based methods have been used to detect bacteria in clinical samples, but these methods have not been adequately evaluated for the diagnosis of pneumonic tularemia. Little is known about the virulence mechanisms of F. tularensis, though there is a large body of evidence indicating that it is an intracellular pathogen, surviving mainly in macrophages. An unlicensed live attenuated vaccine is available, which does appear to offer protection against ulceroglandular and pneumonic tularemia. Although an improved vaccine against tularemia is highly desirable, attempts to devise such a vaccine have been limited by the inability to construct defined allelic replacement mutants and by the lack of information on the mechanisms of virulence of F. tularensis. In the absence of a licensed vaccine, aminoglycoside antibiotics play a key role in the prevention and treatment of tularemia

Histologic and molecular diagnosis of tularemia: a potential bioterrorism agent endemic to North America

“…1 It has been found in every state in America except Hawaii (with Arkansas, South Dakota, Missouri, and Oklahoma considered major endemic areas), as well as in Scandinavia, Asia, and Canada. 1,3,4 Although the number of cases in the United States has declined since the mid-1900 s, many authorities think that tularemia is both markedly under-recognized and under-reported. 1,[3][4][5][6]16 Tularemia affects over 250 mammalian species including humans, and has also been found in invertebrates, water, mud, and feces.…”

“…1,3,4 Although the number of cases in the United States has declined since the mid-1900 s, many authorities think that tularemia is both markedly under-recognized and under-reported. 1,[3][4][5][6]16 Tularemia affects over 250 mammalian species including humans, and has also been found in invertebrates, water, mud, and feces. 1,3,17,25 Exposure from animals occurs primarily through skinning and dressing game, but ingesting contaminated meat and animal bites may also cause disease.…”

“…[1][2][3][4][5][6] This zoonotic bacterium is associated with arthropod vectors, and both wild and domestic animals (particularly cats that have eaten infected rodents or rabbits); transmission through water contaminated by infected rodents has also occurred. 2,7 Most human infections are acquired from arthropod bites, exposure to infected animals from skinning and dressing game, or inhalation of contaminated dust, dirt, and lawn clippings.…”

“…Due to the fastidious nature of this slow-growing organism, and more importantly the high risk of inhalational infection to laboratory personnel, culture techniques are difficult to perform and often avoided. 3,14 Serologic studies (including ELISA and agglutination assays) are the most common methods employed for diagnosis, but antibody is not usually detectable until the second week of the disease, and crossreactivity with other organisms remains an issue. 1,2,10,[14][15][16] Immunohistochemical studies, fluorescent antigen testing, and immunoelectron microscopy have also been used to detect FT, but these methods have very limited availability.…”

Development of novel plasmid vectors and a promoter trap system in Francisella tularensis compatible with the pFLN10 based plasmids

“…Francisella tularensis is a Gram-negative γ-Prote-obacteria that has been classified as a category A pathogen by the Centers for Disease control (Ellis et al, 2002). Little is known about the virulence factors required or pathogenicity of this important bio-defense species (Oyston et al, 2004).…”