Some general remarks and new observations on psittacosis and ornithosis.

Complement-fixation tests of sera from patients with mild or obscure respiratory infections have shown that psittacosis is more prevalent in man than the occasional dramatic outbreaks had hitherto led one to suppose. In this paper, the author discusses the epidemiology of the disease in humans with special reference to the various sources of infection, which are now known to include a number of non-psittacine birds-particularly, turkeys, ducks and pigeons.After reviewing the distribution of human infection, describing the methods of diagnosing the infection in man and birds, and outlining briefly the mechanism of immunity, the author proceeds to the question of therapy with tetracycline compounds, which have proved effective for the treatment of human psittacosis provided that they are administered soon enough and over a sufficiently long period. He then deals with the public health aspects of the disease and with the problem of control, pointing out the many difficulties involved. Addition of tetracycline compounds to the feed has been successful in eradicating the infection from a few parakeet-breeding aviaries, but the results with parrots, pigeons and turkeys have been less promising; it is hoped, nevertheless, that a suitable chemotherapeutic method can be developed.Finally, the author reviews briefly the known instances of infection of mammals other than man with viruses of the psittacosis group.