Piroplasmosis of Horses. 785 



Occurrence. The disease appears to occur frequently in 

 Italy and Eussia, in localities with forest and marshy pastures. 

 Native horses as a rule become affected only when young, while 

 animals brought from uninfected territories into infected 

 localities are affected at all ages, and almost exclusively in the 

 warm season (in Eussia it is w^rongiy termed "Spring dis- 

 ease"). The disease occurs also frequently in Africa and India. 



In Germany only one case has been diagnosed by Zieniann in Oldenburg, while 

 in Sweden Brickmann attributed a disease of horses to an infection with piro- 

 plasnia.— In Italy Baruehello & Pricolo, also Mori are inclined to identify piro- 

 plasmosis with catarrhal influenza, while Perrucci connects it with i)urpura hemor- 

 rhagica. This supposition is based principally on the similarity of the symptoms 

 and evidently does not apply to other localities. — In Eussia the disease was observed 

 in various localities after the demonstration of piroplasma in horses by Michailof 

 (1902), also by Bielitzer, Marzinowski, Feinschmidt, Michin and Yak'imoff, espe- 

 ciaH,y frequently, however, in southern Eussia (here, also, in donkeys), causing 

 sometimes losses up to. o09(. 



It is widely spread in Africa, where it has been diagnosed and carefully studied 

 in the south by Theiler, in the German protectorates by Koch, also by Eoger 

 as well as by Lafargue, Lussault & Savary in Algeria, by Plot in Egypt, by Dupuy 

 & Pierre in the Sudan and in Senegambia, by Thiroux in Madagascar. Lingard & 

 Jinnings, Axe and Williams reported on its occurrence in India. 



Etiology. The Piroplasma equi (Babesia equi) is a small 

 blood parasite resembling the Piroplasma parvum. It is 0.5-2.5 '^ 

 in size, of coccus, ring, spindle, rod or also pear shape. In the 

 red blood corpuscles it is present singly, in pairs, or in fours 

 in rosette form, which latter probably originated by direct 

 division of the single individuals. In the blood plasma they 

 are found only singly. By the Giemsa stain a clump of chromatin 

 granules and sometimes also a second chromatin granule 

 (Blepharoplast?) may be in their body. 



Marzinowski & Bielitzer observed in the intestinal contents of ticks which 

 previously had sucked blood from infected horses, transitory forms similar to those 

 described by Koch in piroplasma of cattle, and by Christophers and Kleine in 

 piroplasma of dogs. They are also inclined to consider oval and worm-shajied 

 bodies with large granular cytoplasm and small nucleus as one form, and those 

 with a still smaller nucleus and paler cytoplasm, as other sexual forms from which 

 new, worm-like actively motile forms (Ookinetes ?) develop, which occur in great 

 numbers in the saliva of the ticks with which the eggs are moistened. The demon 

 stration of parasites in the egg of the ticks was not successful, but various stages 

 of development, especially the worm forms, were found in the larvae in consider- 

 able numbers. 



Marzinowski also reported successful cultivation experiments in blood con- 

 taining 10% sodium citrate solution, in which the parasites passed through similar 

 stages of development as in the intestines of ticks. Their multiplication was only 

 moderate, and they died in the third generation. 



Theiler succeeded in producing by subcutaneous or intra- 

 venous inoculations of blood of immune horses a febrile affec- 

 tion in mules and donkeys which developed after an incubation of 

 5 to 9 days, and in the course of which the parasites appeared in 

 the blood. The first attack was followed by a second one, during 

 which the number of the red blood corpuscles diminished to one 

 third, and which frequently resulted in death. The disease was 

 likewise reproduced in horses with the blood of immune mules 



