Delayed type hypersensitivity reaction in the pathogenesis and formation of immunity in tularemia infections in mice

As a result of our studies, strain differences in the sensitivity of CBA and BALB/c mice to partially attenuated Francisella tularensis strain have been revealed. Relationship between the increased migration of lymphocytes to the liver and lymphoid organs and the intensive development of cell-mediated immunity reactions has been shown. An important role of local reactions (the skin at the site of the inoculation of F. tularessis + a regional lymph node) in the development of the pathological process and the formation of immunity to tularemia infection has been noted. A high level of resistance to F. tularensis strain used for inoculation in BALB/c mice seems to be greatly due to the fact that in these mice more intensive cell-mediated immunity reactions develop at the early stages of infection, than in CBA mice.     

Field investigations of tularemia in Norway

Abstract In Norway, tularemia is a common disease in small rodent and hare populations, where large outbreaks can be observed. In humans, the yearly number of cases is low, usually less than ten, with peaks up to 44 recorded in recent years. Serological investigations on hunters and healthy school children nevertheless indicate, with up to 4.7% positivity in the latter group, that Francisella tularensis low-grade infection is widespread. F. tularensis in co-culture with amoebae, e.g. Achantamoeba castellanii , may grow after internalization and kill the amoeba. As with Legionella, Francisella virulence may be enhanced after protozoan ingestion. This suggests a mechanism that can explain the pattern of dissemination and infection in our region.