It may cause different types of zoonotic infection of tularemia including glandular, oculoglandular, ulceroglandular, oropharyngeal (gastrointestinal), respiratory (pneumonic), and typhoidal forms (1-4).
Francisella genus includes two species of Fracisella tularensis (F.tularensis) and F.philomiragia. Besides, F.tularensis involves four subspecies (ssp.) of tularensis (type A), novicida, holarctica (type B) and mediasiatica. However, the classification of F.tularensis ssp. novicida and F.novicida is variable in different sources (2-6).
Transmission of tularemia is achieved via direct contact with insect vectors, infected animals, ingesting contaminated food or water, and inhalation of aerosolized bacteria …show more content…
The most severe form of tularemia is caused by F.tularensis subspecies (ssp.) tularensis. With ignorance of bacterial entrance, the lethal dosage of F.tularensis ssp. tularensis is about 10 cells and the rate of mortality in untreated situation is up to 35%. Thus, this subspecies is recognized as an important case regarding to bioterrorism concern. The centers for infectious diseases control and prevention (CDC) have classified the life threatening bacterium of F.tularensis ssp. tularensis in category A (2, 3, 6, 9, 11, 12).
In accordance with previous studies, the intracellular life cycle of Francisella within a host cell begins by entrance into the phagocytes and continues via bioactivities and replication. The host cells consist of alveolar and dendritic cells, fibroblasts, hepatocytes, macrophages and polymorphonuclear leukocytes (neutrophils) (2,