Experimental splenectomy in ceratin protozoan infections: with especial refernece to feline piroplasmosis

Abstract

1. The role of the spleen in immunity in general has been briefly discussed. The effect of experimental splenectomy on infections, particularly those due to protozoa has been considered and the relevant literature reviewed.2. Experimental feline piroplasmosis, an infection of the domestic cat by Babesia felis Davis, had been studied in eleven cats. It has been shown to follow a uniform benign course, in which at most one per cent of the red blood -cells become parasitized, and to be without any apparent ill-effects on the host.3. Extirpation of the spleen either prior to infection or subsequently has been shown to modify the course of feline piroplasmosis most profoundly. Details of observations on the course of infection in eleven spleenless cats have been submitted, and the following conclusions drawn. A rapid multiplication of the parasites resulting in more than fifty per cent of the red cells becoming parasitized, accompanied by a severe megaloblastic anaemia occurred in all cases. Haemoglobinuria was an inconstant feature. Death ensued in more than half the cases studied. Recovery appeared to be associated with a relatively high leucocyte count. The morbid anatomy of the fatal cases has been described: the chief features were cloudy swelling and fatty degeneration in the liver and kidney and an erythroblastic reaction of the marrow in the long bones.4. It has been shown that a diet of raw sheep's spleen failed to modify the severity of piroplasmosis in spleenless cats.5. Attempted "blocade" by means of intra-venous infections of India ink exercised no apparent influence on the course of the infection in normal cats.6. An unsuccessful attempt to infect spleenless cats with Babesia fells by feeding with infected blood has been described.7. Trypanosoma brucei and Tnypanosoma rhodesiense infections have been studied in normal and in spleenless cats : the infections apparently followed similar courses in both series.8. Jerboas infected with Haemogregarina balfouri were splenectomized, but no significant modification of the degree of infection was found to occur.9. Splenectomy of gerbils in which a small percentage of the red blood -cells contained Grahamella bodies did not materially affect the relative number of affected cells, nor did it result in any appreciable variation in the red cell-counts.