840 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



disease. The immunity is not an absolute one, however, for blood 

 taken from such recovered animals is often infective; the parasite > 

 probably exists in them in a latent form through the establishment of 

 a tolerance on the part of the host. 



There is no specific treatment for babesiosis. Some of the aniline 

 drugs, used in the treatment of trypanosomiasis, such as trypan-blue, 

 are of some value. 



Many districts are kept free from red water by not allowing cattle 

 coming from infected districts to enter them. Where it exists, the dis- 

 ease is controlled by destroying the ticks on cattle with poisonous 



A B C D E 



H 



K 



Fig. 180. — Babesia bigemina: Various stages of development in red blood cells. 

 A, young parasite; B, a twin-form; C-E, a multiple division; F-K, large pear-shaped 

 forms. (After Doflein.) 



washes and by occasionally plowing, or burning over, the pastures in 

 order to destroy ticks which have dropped to the ground. In the 

 United States, cattle on some farms are kept free from ticks, and conse- 

 quently from red water, by a manoeuvre which takes advantage of the 

 way in which the tick transmits the disease. The adult tick remains 

 upon her host until she is ready to deposit her eggs; she then drops off, 

 lays her eggs and dies. The young ticks, hatched from these eggs, 

 attach themselves to new hosts and it is through their bites that the 

 disease is transmitted. Therefore, since the disease is transmitted by 



