Infection of Clethrionomys G. glareolus Schreb. (red mice) with Mycobacterium tuberculosis and Mycobacterium bovis injected subcutaneously.

Groups of red mice were injected with doses from 10 mg to 10(-8) mg semidried culture of a strain of M. tuberculosis and with doses from 10(-1) to 10(-8) mg of a strain of M. bovis. Some animals were killed about 1 1/2 and 3 months after injection and the remainder lived until death occurred spontaneously. The number of tubercle bacilli in the organs was evaluated by microscopy of smears, in some cases by quantitative culture. Among the mice injected with M. tuberculosis in doses of up to about 2 million viable units, not one case of death occurred which could be attributed to tuberculosis. The autopsy findings consisted exclusively of lesions at the site of injection and in the regional lymph glands. Quantitative culture showed growth of a few viable units in the lymph glands, spleen or lungs, but no sign of progressive infection. Out of 10 mice injected with a giant dose of 3 X 10(7) viable units, only two died of tuberculosis. M. bovis provoked fatal tuberculosis in all animals injected with doses from 6.9 million to 7 viable units. Severe caseous lesions developed at the site of injection, in the lymph glands, in the lung, and often also in liver and spleen. The number of bacteria in the organs was enormous, particulary in the spontaneously dead animals. The survival times, which were dependent on dosage, varied from 51 to 159 days.