Multiplication of Mycobacterium tuberculosis and Mycobacterium bovis in Microtus agrestis (field vole)

The multiplication of bacteria is examined by quantitative culture from the organs of two groups of field voles injected intraperitoneally with a large dose of M. tuberculosis or a small dose of M. bovis and killed at intervals during a period of up to 3 months after the injection. M. tuberculosis given in a dose of 7 X 10(5) viable units did not multiply, or multiplied only to a small extent. None of the animals in the group died from tuberculosis and the macroscopical lesions found at autopsy were insignificant. In contrast, a dose of 14 viable units of M. bovis provoked generalized tuberculosis running a rapid, fatal course. The bacteria multiplied almost uninhibited throughout the course of the infection.