SPLENIC ENLARGEMENT AND INFARCTION IN CANARIES INFECTED WITH A VIRULENT STRAIN OF PLASMODIUM CATHEMERIUM1

Abstract

Data are given concerning 107 canaries infected with a virulent strain of P. cathemerium relative to (1) splenic enlargement, (2) splenic infarction, and (3) compensatory liver hyperplasia following splenic infarction. No correlation was found between either the number of parasites or the time of the infection and the size of the spleen. Several of the spleens measured exceeded the measurements which have been recorded in infections with other strains of P. cathemerium, the largest of these being 9 mm. wide X 25 mm. long. Splenic infarctions were observed in 47% of the birds examined. These occurred as early as the 3d day of the patent period and continued throughout the infection. The production of infarcts in the spleen seemed not to depend on the number of parasites present, nor upon the size of the spleen or the amount of inoculum. Large thrombi in the central vein of the spleen were always associated with the infarcts, and numerous smaller thrombi occurred in the arterioles and venules. It is felt that the parasites were not directly responsible for the obstruction of the blood vessels in every case, but that extensive hyperaemia slowed the blood current sufficiently to cause widespread stasis with resulting thrombosis. In every case where splenic infarcts occurred in a series of 17 birds, the liver was markedly more hyperplastic than in birds not showing splenic infarcts.