Mice were injected subcutaneously with Ozeki strain of Rickettsia orientalis under cold, moderate and hot thermal environment ; and their survival time after injection and the persistence of Rickettsiae in the blood and the organs of mice were observed.
The survival time of the injected mice under moderate and hot environment were above three months, on the contrary, that of the injected mice under cold were less than one month.
Rickettsia injected subcutaneously in mice caused uniformly splenomegaly and swelling of the inguinal lymphnodes.
The infectivity of the Rickettsia in the spleen and blood of mice after subcutaneous injection were assayed at intervals by intraperitoneal injection to normal mice and their LD
50 value and survival time, were measured.
The appearance of Rickettsiae in the spleen and blood of injected mice could be observed readily at an early stage of infection after injection.
The LD
50 value, which increased rapidly, showed maxirnum at 11-12th day after injection and then decreased gradually.
The Rickttsiae in the spleen showed greater LD
50 value than that in the blood throughout the observation period under each thermal environment.
The Rickettsiae in both the spleen and blood, showed smaller LD
50 value and longer survival time under hot environment than under moderate temperature environment. LD
50 value was greater and survival time was shorter under cold environment than under moderate environment.
The appearance of Rickettsiae in the brain, kidney, liver and lymphnodes after subcutaneous injection showed different pattern.
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