280 



cent, of the corpuscles are infected, or in severe cases 

 as many as ten per cent. Besides typical pear-shaped 

 parasites, round and amoeboid forms occur. Free 

 parasites also are not uncommon in severe cases. 

 Cattle shewing emaciation, staring coat, etc., often 

 shew parasites scantily. 



Post-mortem. The tissues are oedematous and 

 icteric. The spleen and liver are much enlarged. The 

 kidneys are oedematous and haemorrhagic. The 

 lymphatic glands are oedematous and haemorrhagic 

 as in other forms of piroplasma affection. The serous 

 membranes of various organs shew petechiae. The 

 kidneys may have fifty per cent, upwards of red cells 

 infected. Parasites are also numerous in the capil- 

 laries of the heart, choroid plexuses, pia mater and 

 brain. 



Culture. Miyajima states that by adding a little 

 defibrinated blood to ordinary bouillon kept at 20 

 to 30 C., trypanosomes develop, and further, that 

 these give rise to piroplasmosis on injection. 



Transmission. (i) Is easily effected by intravenous 

 or subcutaneous inoculation ; the blood of recovered 

 animals is also infective. 



(2) The following ticks are known to be carriers. 

 The adult takes infection, the larva gives infection : 



M. annulatus (vide p. 324), in America, Africa, etc. 



M. australis, in Australia. 



/. ricinus (= reduvius), in Europe. 



P. boms. According to some observers this 

 European form differs from P. bigeminum : (i) The 

 parasites are plumper ; (2) The pears are smaller ; 

 (3) The disease is more benign. 



Development in the Tick (Koch). The parasites 

 leave the red cell and become rather long and club- 

 shaped (Fig. 91). At the clubbed end there is a large 



