i8 2 SOME MINUTE ANIMAL PARASITES 



In contrast with piroplasmosis, Coast fever in 

 cattle, due to Theileria parva, is not characterized by 

 "redwater," nor can the disease be experimentally 

 communicated by the inoculation of infected blood. 

 On relatively few occasions, animals recover from 

 attacks of Coast fever. When this occurs, the cattle 

 are incapable of infecting ticks that may feed upon 

 them, and thus do not spread the disease. Cattle 

 which are immune to piroplasmosis are susceptible 

 to East Coast fever. 



The method of infection of cattle and dogs in 

 Nature assumes great importance, for success in 

 combating these fevers lies in destroying the inter- 

 mediaries. Cattle, horses, and dogs all become 

 infected by the agency of ticks which have previously 

 fed on infected animals, or have been born infected. 



The redwater of cattle is transmitted chiefly by 

 Bob'philus annulatus, B. australis, B. decolor atus, and 

 Ixodes ricinm. Other ticks transmit it occasionally, 

 while still more are under grave suspicion. Coast 

 fever is due to the attacks of Rhipicephalus appendicu- 

 latus and R. simu$. Sheep infested by R. bursa die 

 of redwater. Canine piroplasmosis is transmitted 

 by Hamaphysatis leachi in South Africa, and by 

 R. sanguineus in India, where the former tick is un- 

 known. The biliary fevers, fatal to horses, are 

 passed from horse to horse by the bites of the ticks, 

 Rhipicephalus evertsi and Dermacentor reticulatus. 



In order to understand the remarkable way in which 

 outbreaks occur, it is necessary to know the life- 

 histories of the transmitting ticks. Boophilus annulatus 

 is one of the most destructive to cattle, and its life- 



