Laboratory diagnosis of psittacosis.

Date:
1937
Catalogue details

Licence: Public Domain Mark

Credit: Laboratory diagnosis of psittacosis. Source: Wellcome Collection.

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    IO in mice will then be desirable and this should be done by injecting two or more fresh mice intraperitoneally with 0-5 ml. of a fairly thick emulsion of the spleen of each of the mice originally inoculated. Should such emulsions contain a bacterial infection (salmonella or pasteurella), filtration through Berkefeld V or gradocol membrane filters must first be done and the bacterial sterility of the filtrate determined. Such passage mice, if the psittacosis virus is present, ought to die with typical appearances within 15 days and further passages may reduce this period to three days. It must be borne in mind, however, that, in such passage experiments, there is always the risk of activating some other infection latent in the ~ mouse. In addition to the bacterial infections, the virus disease, ectromelia, is common in mouse stocks and may sunulate psittacosis in that it produces death with liver and spleen necrosis in which no bacterial infection can be found. Moreover, it is associated, like psittacosis, with cell-inclusions superficially like the psittacosis virus bodies, though those of ectromelia are found more in epithelial cells than in reticulo- endothelium, and do not reach full development in the liver and spleen cells. In ectromelia the staining reaction, both of inclusions and free virus particles, differs from that of the psittacosis virus bodies, being definitely acidophil (red in Mann’s method and with Giemsa) as contrasted with the basophil staining of the latter. The pathologist should be familiar with the appearances in both in order to make a confident report. It is established that the budgerigar (love-bird) is subject to psittacosis, not only in domesticated stocks in all countries where these have been examined, but also in its native wild state in Australia. Furthermore the budgerigar is more resistant to the disease under ordinary conditions than the tropical parrots and parrakeets and, instead of dying more or less rapidly when infected, as these birds do, may survive and harbour the virus while appearing in perfect health. Such birds carrying virus not only maintain the infection in aviaries, but are a constant danger to human beings who come in contact with them. Data as to the extent of psittacosis infection in budgerigar stocks in this country are somewhat scanty, though its existence has been amply proved in a_ few _ instances. Pathologists who have reason to suspect the budgerigar origin of a case of human psittacosis should, therefore, make as many observations as possible on the suspected stock. Should proof of infection be obtained by the laboratory examination of sick or dead birds, it would be useful to extend the investigation to the rest of the stock or as many as practicable, to determine in