Abstract
Packchanian 1 studied the susceptibility of 32 species and subspecies of rodents to virulent strains of Leptospira icterohemorrhagiae and concluded that certain species of American deer-mice, genus Peromyscus, are suitable as susceptible small laboratory animals for experimental studies of icterohemorrhagic spirochetosis and for the diagnosis of Weil's disease. He did not, however, include hamsters in his studies. Larson 2 reported that white mice (Mus musculus) are extremely sensitive to L.icterohemorrhagiae. He emphasized that young animals be employed. The mortality rate approximates 100% in 3-week-old mice, but falls rapidly as age increases. At this time we wish to report on the susceptibility of Syrian hamsters to L. canicola and L. icterohemorrhagiae.
The Syrian hamsters were obtained originally from H. C. Schaefer, Research Department of Ralston Purina Co., St. Louis. The strain of L. canicola was obtained from Dr. Karl F. Meyer, George Williams Hooper Foundation, San Francisco. It was isolated from dog blood by culture methods. The strain of L. icterohemorrhagiae was obtained from Dr. Ruth E. Miller, Woman's Medical College of Pennsylvania, Philadelphia. It was isolated from rats in Philadelphia. The culture medium was Schüffner's modification of Verwoort's medium, as described by Meyer, Stewart-Anderson, and Eddie. 3
L. icterohemorrhagiae: 0.5 ml of cultures which had been incubated approximately one week at room temperature, when injected subcutaneously into hamsters 3 to 5 weeks old, produced death in 5 to 8 days. Cultures made from the heart's blood 24 hours after the injection remained sterile, but those made 48 and 72 hours after the injection were positive for leptospira. Animals not over 5 weeks old should be used if it is desired to produce death of the animals with typical sign of icterus.
L. canicola: 0.5 ml of cultures which had been incubated approximately one week at room temperature, when injected subcutaneously into hamsters 3 to 5 weeks old failed to bring about death of the animals.
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