Intraperitoneal inoculation of Leptospira icterohaemorrhagiae (Mikawashima strain) was made in 3-week-old mice of ddN strain, it produced various of Jaundice and petechial bleeding mainly in the subcutaneous layer of the skin and in the lungs.
Histopathologic studies of these mice revealed following changes cloudy swelling, slight degeneration and necrosis of the hepatic cell in various places and the dissociation of the hepatic cell cord, necrosis characterized by degeneration and necrosis of tubular epithelial cells, vacuolation and hyaline degeneration at certain points of individual skeletal muscle fibers, and intraalveolar haemorrhage in the lung.
Leptospirae was demonstrated by Levaditi's or Dietrele's silver impregnation method in the liver, kidenys and skeletal muscle fibers.
The changes in the liver, kidneys and in the skeletal muscle, and petechial haemorrhage were observed to have developed in preicteric stage.