Abstract
Krumweide and his coworkers, 1 Rivers and Berry, 2 and Bedson 3 have shown that mice are readily infected by intraperitoneal inoculations of the virus of psittacosis derived from birds or from man. Not only is the disease in mice less dangerous to the laboratory workers but the animal is inexpensive and reacts fairly uniformly to the virus. On account of the existence of latent infections parrakeets cannot be used for diagnostic work. The Japanese ricebird is quite expensive although excellent for the study of the elementary bodies and other related problems. In the course of an epidemiologic investigation of psittacosis in aviaries and in connection with diagnostic studies on human infections over 3,500 mice have been injected intraperitoneally with organ suspensions, blood or sputum specimens. The presence of a potent virus is indicated by illness and by typical anatomical lesions and death of the animals in from 4 to 30 days. However, a number of mice may show no signs of disease and yet harbor the virus in the spleen and liver many months after the inoculation of the suspected tissue emulsion or sputum. The following observations selected at random may illustrate this statement.
On January 12th 2 ricebirds and 4 mice were inoculated with emulsions of the spleen and liver of a dead parrakeet which exhibited the anatomical lesions of psittacosis. The ricebirds died on the 7th day with typical findings. The 4 mice remained well and when sacrificed on the 132nd day presented enlarged spleens. Subinoculations into mice caused fatal infections on the 9th and 10th day. The virus was easily propagated in series.
Mice injected with the enlarged spleens or nasal mucosa of several parrakeets failed to sicken.
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