The results of the foregoing experiments show that the
typhus virus, found in the blood of guinea pigs during the height of typical experimental
typhus fever, does not survive at 37 degrees C. in anaerobic media for as long a period as in the same media under aerobic conditions. In media from which
oxygen is excluded, the viability period is 24 to 48 hours; in the same media having no barrier to atmospheric
oxygen, the period is usually 5 days, in one instance, 3 days. The dead virus fails to induce not only the typical experimental disease but also an immunity to further
injections of
typhus virus. That the death of the virus is due to exclusion of
oxygen from the medium, rather than to a change in the hydrogen ion concentration therein is inferred from the fact that media with varying hydrogen ion concentrations, such as broth (pH 7.4), horse serum (pH 7.8), and human ascitic fluid (pH 8.0) have the same comparative effect on the virus, when under aerobic and anaerobic conditions. That is, in all, the anaerobic state causes a shortening of the viability period of the
typhus virus. In the Smith-Noguchi tissue, ascitic fluid, sealed medium in which bacteria resembling Plotz' bacilli grow luxuriantly and remain viable for several weeks, the
typhus virus does not increase in virulence, and even dies after 24 hours. This evidence supports the conclusion previously presented that the Bacillus typhi exanthematici of Plotz is not identical with the active agent of
typhus virus.