A Laboratory Method for the Diagnosis of Psittacosis in Man

Abstract

Since the pandemic of psittacosis in 1929 and 1930, instances of disease in human beings associated with parrots and parrakeets have continued to appear, either as isolated occurrences or as small localized epidemics. Frequently the patients have manifested unusual clinical pictures and have run courses not considered to be characteristic of psittacosis. Furthermore, at times the disease has occurred in people associated with birds which have apparently been in good health in this country for considerable periods of time and which until recently would have been considered “safe” in the sense of being free from psittacosis.

A reasonably safe laboratory method for the diagnosis of psittacosis in man is of importance. Our investigations, as well as similar experiences of others have indicated that serological tests are probably not suitable for the detection of psittacosis. Following Krum-wiede's observations, 1 our work 2 has shown that mice are highly susceptible to psittacosis and that the experimental disease in them can be easily recognized. We have found, furthermore, that this host can be used in a laboratory test for the diagnosis of psittacosis and when infected can be handled with relative safety and with a minimum of danger of accidental infection.

The method now used by us for the laboratory diagnosis of psittacosis in man is briefly as follows: The patient's sputum to which 20-50 volumes of meat infusion broth, pH 7.8, and a small amount of alundun have been added is thoroughly ground in a mortar. The emulsion is centrifuged for 10 minutes at a speed of 3000 R.P.M. Then the supernatant fluid is filtered through a Berkefeld V candle at a pressure of 15-30 cm. of mercury. Each of 6 mice receives intraperitoneally on 3 successive days 2 cc. of the filtrate.