766 



Piroplasmosis of Cattle. 



rod and lancet forms are found rarely, and the presence of 

 more than two parasites in one blood corpuscle is also infre- 

 quent. 



The cultivation and propagation on artificial media has not yet 

 been successful with a certainty. 



AecoKling to Lignieres and Miyajima they are supposed to multiply in blood- 

 bouillon for a time, and here, according to the observations of the Japanese investi- 

 gator, forms containing flagellae similar to the trypanosomes are supposed to 

 appear after 3-4 days; the propagation reaches its height on the 10th to 14th day; 

 on the 45th day, however, the culture died (it is possible that they represented 

 mixed infections). 



According to Smith & Kilborne, as well as Laveran & Nicolle, their 

 propagation results by fission, or schizogony, while according to Theiler 's 

 former view, which was also accepted by Koch, the parasites assume, in 

 certain stages of development, rod- and ring-shapes, and then appear 

 similar to the causative factor of African horse fever (Fig. 131). Such 

 forms are usually found in the blood of cattle that are immune against 

 Texas fever, and they also appear in the blood of calves, which have 

 been infected with the blood from such cattle, during or after the second 

 reaction. Recently, however, these forms were described by Theiler as 

 a new variety, (Piroplasma mutans), (see p. 782). 



Fig. 130. Piroplasma bigemi- 

 num. Spherical and pear 

 shapes. Cattle blood; stained 

 with methylene blue. 



Fig. 131. Piroplasma bigemi- 

 num. Kod and ring shapes. Blood 

 of a cow in a stage of commencing 

 convalescence; stained after Lav- 



Koch examined material from ticks which sucked themselves full 

 of blood from affected animals, and found that, after leaving the blood 

 corpuscles, the parasites become elongated to club shape in the intestines 

 of the ticks and develop lancet-like projections, which may be slowly 

 drawn in and extended (morning star shapes). Later the extensions 

 become shorter, and diminish in number, whereupon the parasites change 

 into round or pear-shaped bodies. Such bodies are found, also, in the 

 eggs of infected ticks, but as they are 3-4 times the size of the piroplasma 

 in the blood of cattle, it is possible that between the two there are 

 still other transitory forms. (Kleine observed star forms also in dog 

 piroplasma, which he placed in strong salt solution. Hartman, however, 

 considered them as manifestations of degeneration.) 



