Supplement to the Studies on the Pathogenic Agent of "Izumi Fever" I: Chronic Infectious Course by the Pathogenic Agent of "Iznmi Fever"

It is well-known that the virus of "Izumi fever" is well preserved and even its serial passage is feasible by inoculation of the virus into the mouse. It is also inferred, however, that some alteration in virus multiplication or pathological changes will occur during the course of chronic infection. In order to study these points in the chronic infectious course, the author inoculated the virus into mice, killed them on the previously decided days, and studied the infectious aspect and infectious degree in detail by observation of the pathological findings. These observations were compared with those in chronic infectious course of infectious hepatitis, hereby a certain conclusion was obtained. The infection was well established and lasted for a long time by both of Yashiro and Mitsui strains. Two weeks after the inoculation of the virus, degeneration and necrosis of parenchymal cells and cell infiltration were observed in the liver, which suggested that these pathological changes had been occurring repeatedly. In the lung, septal interstitial pneumonitis and cell infiltration appeared. From these findings, Yashiro and Mitsui strains are concluded to be the virus of the same nature. These pathological findings are quite alike to those reported by Murakami et al. on the hepatitis virus; it appeared to be almost impossible to discriminate between these two sorts of viruses by the findings in chronic infectious course alone.