352 TEXAS FEVER 



provinces and in South Africa (Rhodesia Rotwasser*). It is 

 restricted, however, to those countries where the climate is not 

 sufficiently severe to destroy the cattle tick during the winter 

 season and where the animals are constantly infected. Cattle 

 (genus Bos) are the only animals which suffer from it. 



§ 267. Etiology. Texas fever is caused by a microor- 

 ganism belonging to the protozoa and named by Smith, the 

 discoverer, Pyrosoma bigeniinuni.'\ It is generally recognized 



*'rhe Rhodesian redwater or East African coast fever is according to 

 Stockman's report a very different disease from the tick fever in 

 America. The conclusions from Stockman's repprt are as follows : 



1. That the disease is caused by a special blood parasite — a piro- 

 plasma. 



2. That it is a disease peculiar to bovine animals. 



3. That it is only indirectly contagious ; that is to say, a sick 

 animal will not infect another susceptible animal by contact, however 

 intimate, or by any of the excretions or fluids of its body, as in the case 

 of rinderpest and like diseases. 



4. That the indirect agents of infections are the nymphal and adult 

 stages of the brown tick (Rhisicephalus Appendiculatus) and the black 

 tick (R. Simus?). The former however is the more important factor. 



5. That only those ticks which in one of their intermediate stages 

 have sucked on affected animals are capable of transmitting the disease 

 to other oxen. 



6. That the infecting agent does not pass through the egg of the 

 tick to the second generation, as was at first thought probable, by 

 reasoning from analogy with what takes place in the blue tick in case of 

 Texas fever. 



7. That the brown and black ticks existed in certain parts of the 

 Transvaal long before the disease was imported and that the said ticks 

 only become virulent after sucking sick animals recently introduced. 

 These species of ticks exist to-day on many farms that are perfectly 

 clean, and which will remain clean as long as sick animals are kept off 

 them. 



8. That the blue tick is not a carrier of the disease. 



9. That the proportion of recoveries from the disease is five per 

 cent, at the very most. 



fThe genus of the parasite has been changed to Piroplasma by Pat- 

 ton, to Apiosoma by Wandelleck, to Aatnbosporidies by Bonome, and 

 Porteus virulentissimus by Perroncito. Starcoyici has named the organ- 

 ism described by Babes as Hematococcus, Babesia bigeminum bovis. 



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