PIROPLASMOSIS 113 



ance that enables them to prevent the multiplication of 

 the parasites and to resist the effects of their presence. 

 Such animals, however, though in good health themselves, 

 are able to infect ticks. The non-recognition of the 

 practically universal infection of native cattle has in 

 several instances led directly to the destruction of im- 

 ported animals, as in the process of immunizing against 

 rinderpest virulent blood has been injected into newly 

 imported animals, which have then died from " red- 

 water/' 



Human Piroplasmosis. Several observers have de- 

 scribed piroplasmata in human blood ; so far, however, 

 without confirmation. 



A very fatal form of fever, occurring in the Rocky 

 Mountains and called locally spotted fever, was attributed 

 to the presence of a piroplasma in the blood, and infec- 

 tion was thought to be due to a tick (Dermocentor reticu- 

 laris). Subsequent observers have failed to find the 

 piroplasma, but confirm the opinion that it is a disease 

 carried by ticks which can be communicated to lower 

 animals. The disease occurs chiefly in the spring and 

 affects white races only ; it is more common in persons 

 under than over 40, and in males than females. 



The incubation is short, symptoms commencing two to 

 five days after the bite of a tick. The onset is gradual 

 and the general symptoms resemble those of typhus 

 fever, but are more severe, and a rash appears on the 

 second to the fifth day. The rash appears first on the 

 ankles or back, but soon becomes general. It is at first 

 vesicular, but later petechial, jaundice is usual and des- 

 quamation occurs in patients who survive. 



The mortality is very high, between 70 and 80 per 

 cent, of the patients dying, usually between the sixth and 

 eleventh days. In patients who survive recovery is 

 gradual, and commences about the end of the second 

 week. Quinine is said to be the only drug which does 

 good, and the avoidance of tick-bites is suggested as a 

 preventive. 

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