Review article

Ecology, host and vectors of Francisella tularensis

Vildana Semić ; Department of microbiology and parasitology, School of medicine, University of Rijeka, Rijeka, Croatia
Martin Brezovec ; Department of microbiology and parasitology, School of medicine, University of Rijeka, Rijeka, Croatia
Iva Lazarić ; Department of microbiology and parasitology, School of medicine, University of Rijeka, Rijeka, Croatia
Marina Šantić ; Department of microbiology and parasitology, School of medicine, University of Rijeka, Rijeka, Croatia

Abstract

Francisella tularensis is a gram-negative facultative intracellular bacterium that can cause a fatal disease, tularaemia, in human and animals. Francisella tularensis survives for months on very low temperatures, in water, mud or dead animals. If stored on –70° C or
lyophilized, virulence can be kept for years. It can also survive heating up to 42-65° C after food or water processing. Francisella tularensis is an intercellular parasite able to infect a great number of cell types while the macrophages are considered as the key cells for manifestation of the disease in humans. There are four subtypes of Francisella tularensis: tularensis (type A), holartica (type B), mediastatica and novicida. F. tularensis type A is found only in North America and is highly virulent. F. tularensis type B is less virulent for humans, and exists in North America and Europe. F. tuleransis subsp. holartica is less virulent, especially for humans, because its dissemination is slow and it causes a mild state of illness. F. tuleransis subsp. mediastatica has unique biochemical characteristics and is isolated only in Kazakhstan and Turkmenistan in central Asia, and shows virulence for organism similar to F. tuleransis type B. The primary reservoir of tularaemia are mammals like rabbits and other
rodents while the vector of disease are flies and mosquitoes. The bacteria can enter the organism by different routs of infection and the clinical symptoms of the disease depend on these entry.

Keywords

intracellular pathogen; tularaemia; zoonosis

Hrčak ID:

38811

URI

https://hrcak.srce.hr/38811

Publication date:

1.6.2009.

Article data in other languages: croatian

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