Laboratory diagnosis of psittacosis.

Date:
1937
Catalogue details

Licence: Public Domain Mark

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

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    duration depends on the amount and virulence of the virus injected. Virulent material from parrots or parrakeets injected days; occasionally animals recover. Passage through a series of mice increases the virulence for this species of animal, pro- ducing death in two to three days when injected in adequate dose. The conditions found on post-mortem examination are of three main types : — (1) If death occurs in two to three days after inoculation there may be little abnormal to see with the naked eye; the spleen is usually normal in size and appearance, as is the liver though the latter may show. some mottling. Microscopically both these organs show small haemorrhages and necrotic foci. The virus particles are most abundant in endothelial cells of peritoneal exudate and especially of the spleen. These cells are packed with them and may show obvious signs of degeneration. | | (2) If death occurs in three to 15 days the abdominal cavity will be found full of thick fibrinous exudate; the intestines are matted together and the liver and spleen coated with a thick layer of fibrin easily stripped off. The fluid in the peritoneum and pericardium is in excess of the normal and is turbid with suspended fibrin flakes and endothelial cells. The virus particles are abundant in these cells, especially those from the perihepatic, peri- splenitic and pericardiac exudates; they are less numerous in the spleen. (3) If death occurs in 15 to 30 days turbid serous effusions in peritoneum, pleura and pericardium are con- spicuous. The liver and spleen may be enlarged and friable. Virus bodies, however, are usually scanty both in exudate and spleen pulp; the most favourable smears are those from the pericardium. In all three types lung lesions are exceptional. When they occur, they are usually in the form of an acute haemorrhagic oedema of the alveolar walls which, when extensive, may simulate lobar pneumonia; a true broncho-pneumonia, how- ever, is occasionally met with. The blood of the mouse at any stage is poor in virus, though endothelial cells in it may be found infected; this is in contrast to the blood of parrots, dead after natural or experimental infection, in which virus bodies are often abundant. | . ~ When the illness of inoculated mice is doubtful and death delayed, as not infrequently happens when the inoculum is poor in virus, as, for example, in much of the human material, it may be difficult to find typical virus bodies. Further passage