CHAPTER XXXIV. 



BLOOD DISEASES. 



IXODIC AN.EMIA— TEXAS FEVEE, &a 



Later studies of this disease have brought to light that it 

 assumes two forms : an acute fatal type, as seen in America in the 

 hot summer months, and a mild, rather prolonged, usually non- 

 fatal form, recognised by an examination of the blood, which 

 must reveal the micro-parasite in the red corpuscles and plasma. 

 This form is seen in the autumn when the heat of summer has 

 passed away, also during October and November, and, rarely, in 

 the first week of December. It is stated that the difference 

 between the acute and mild type is accounted for by the fact 

 that during a stage of its life — the small stage — the Texas fever 

 parasite circulates in the blood in a condition differing from 

 that observed in acute cases ; that in the latter it rapidly 

 destroys the blood corpuscles, giving rise to hoemoglobinuria, — 

 red water, — whereas in the mild form the destruction of the 

 corpuscles is much more prolonged, and not associated with 

 hajmoglobin in the urine. 



It has also been observed that in certain cases when an animal 

 has recovered from the acute attack, and the number of red 

 corpuscles has nearly reached the normal number, they again 

 diminish, and many of them contain the parasite in its small 

 stage. The reason for the recurrence of this disease is not 

 clearly defined, — whether these second attaclzs are merely re- 

 lapses or reinfections. As already stated, the symptoms of the 

 mild form are indefinite, and may be confused with a variety of 

 mild diseases, but the acute foiim is manifested suddenly in the 

 hot summer months, and simultaneously in all animals of a herd 

 which have been exposed to the same infection together. 



The fever, chai'acterised by a temperature of from 105° to 

 108° r., precedes outward symptoms for several days, the animals 



