PIROPLASMOSIS 273 



minute protozoal parasites causing them live and 

 multiply in the red blood corpuscles of the animals. 

 This "malaria" in animals is known as piroplas- 

 mosis, but the parasites differ in each of the hosts 

 named. The parasite for instance which oc'curs 

 in cattle is not capable of producing infection in 

 sheep, horses and dogs, and vice versa. Whereas 

 malaria is conveyed by the bites of infected mos- 

 quitoes piroplasmosis is conveyed by infected ticks. 



Piroplasmosis causes a heavy mortality in 

 animals; it may entirely destroy large herds of 

 cattle, and before the discovery of the remedy 

 referred to it was impossible to keep dogs in many 

 parts of Africa. Piroplasmosis or red-water, as it 

 is frequently called, is a scourge of all the great 

 cattle-raising areas of the world. Trypan-blue con- 

 stitutes the only drug hitherto found of practical 

 use in the treatment of piroplasmosis ; it has been 

 successfully used for some years in the treatment 

 of dogs, horses and cattle. The curative effects in 

 the dog are impressive to witness an animal with 

 high fever and almost dying will show marked out- 

 ward signs of recovery within an hour or two. In 

 untreated dogs the mortality is almost 100 % ; in 

 dogs receiving early treatment the recovery is prac- 

 tically about 90 %. 



Ehrlich, finding the dyes ineffective in the treat- 

 ment of trypanosomiasis, experimented with other 

 compounds, notably with those containing arsenic, 

 a substance which has long been used in medicine 



18 



