Effects of environmental thermal factors on experimental infection in mice with Ozeki strain of Rickettsia orientalis were examined.
The infectivity of the rickettsiae whice passaged through cold acclimatized mice and moderate temperature acclimatiged mice were assayed for their LD
50 value and survival time for mice by intraperitoneal injection ; the rickettsiae passaged through cold acclimatized mice showed greater LD
50 value and shorter survival time.
After intraperitoneal injection with same same dosage of rickettsiae three groups of mice were exposed to cold, moderate and hot environment and the difference in susceptibility between them was studied ; cold-exposed group showed greater LD
50 value and shorter survival time than moderate-temperture-exposed group, and hot-exposed group showed smaller LD
50 value and shorter survival time than moderate-temperature-exposed group.
The susceptibility for rickettsiae infection of mice acclimatized to the thermal environment, to which mice were exposed after injection, was observed and compared with that of non-acclimatized mice.
While in non-acclimatized mice the group exposed to cold environment showed greater LD
50 value and shorter survival time than the group exposed to moderate temparature, in acclimatized mice the cold-exposed group showed slightly greater LD
50 value than moderate-temperature-exposed group, but survival time of the former group was not always shorter than the latter This results suggest the effect of acclimatization on the susceptibility of mice.
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