606 VETERINARY HYGIENE 



tion period of the disease, viz., 10 to 12 days should elapse 

 before moving them. The affected animals should remain 

 where they are, and those that recover subsequently kept 

 by themselves, for if they get tick infected they can convey 

 the disease to others. The affected portion of the farm should 

 be closed for at least a year. 



Protective inoculation may be practised in this disease. 

 For this purpose the blood of an animal that has passed 

 through an undoubted attack of Red Water is taken ; but 

 care must be observed that at least two months after recovery 

 should elapse before the blood is used for inoculation or 

 Red Water may be produced. As much as 100 c.c. of de- 

 fibrinated blood is employed, the object being to produce a 

 mild form of the disease ; the blood is injected subcu- 

 taneously. Immunity is not obtained until about 21 days 

 after inoculation, so that cattle should not be exposed to 

 infection before that time has elapsed. 



Closely related to Texas Fever is the disease East Coast 

 Fever or Rhodesian lied Water ; it is, however, due to a 

 distinctive parasite, and has many features quite different 

 from Texas Fever, the chief one being that it is non- 

 inoculable. Dr. Koch observed the disease first in German 

 East Africa in 1897, and like subsequent observers mistook 

 it for a severe form of Texas Fever. 



The disease is transmitted entirely by ticks and in no 

 other way (see p. 417). It is this fact which renders the 

 future control of the disease such a difficult matter, as 

 protective inoculation, if not entirely impossible, is at 

 present outside the range of practical prophylaxis, as the 

 length of time required (5 months) is so great, that all the 

 animals would be dead on an infected farm before they 

 could obtain immunity. 



The incubation period, like that of Texas Fever, is about 

 12 days, and the fever period about 13 days. 



No other animal than bovines is affected; the disease 

 cannot be communicated to sheep, goats, or horses. The 

 mortality is not less than 95 per cent., and once the disease 

 has got into a district it is safe to assume all but 5 per 



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