Psittacosis I. Experimentally Induced Infections in Parrots

The widespread outbreak of psittacosis in man in 1929-30 led to renewed interest in the disease which quickly resulted in the discovery of the facts that the causative agent is not Nocard's bacillus but a filterable virus (1) and that the incidence of laboratory infections is high. Because of these facts it became imperative that further work on the nature of the etiological agent and the mode of spread of the infection be undertaken. Krumwiede and his coworkers (2) were among the first to show that the inciting agent of psittacosis is capable of passing filters and that mice are susceptible to the disease. Due to his ill health, however, and because of the development of psittacosis in several of his assistants, investigations so admirably begun by him had to be discontinued and two strains of the virus with which he was working were given to us for further study. The purpose of this paper and the three that follow is to present in detail investigations, already described in preliminary papers (3-5), concerning psittacosis experimentally produced in parrots, mice, rabbits, guinea pigs, and monkeys. Special attention has been paid to the mode of spread of the disease and to the pathological changes induced, depending upon the host and upon the portal of entry of the virus.