498 DISEASES OF CATTLE. 



ticks means a large total annual increase in the prices obtained for 

 southern cattle sold in northern markets. In addition to this, the 

 increase in prices of cattle sold locally in the South would represent 

 a large sum. This local increase has been found to amount to from 

 $3 to $15 a head in territory freed from ticks. An agricultural offi- 

 cial of one of the Southern States has reported that calves in the 

 tick-free area bring double the prices that can be obtained for similar 

 calves in the tick-infested region. 



Heretofore it has been impracticable to improve the quality of 

 southern cattle by introducing fine breeding animals from other sec- 

 tions, because such animals were liable to contract Texas fever and 

 die unless protected by inoculation. Furthermore, it is impossible 

 for animals to attain good growth and to thrive when they are 

 heavily infested with ticks. With the eradication of the ticks, how- 

 ever, the southern farmers are enabled to introduce good breeding 

 animals and to improve the grade of their stock. 



Tliere is no longer any doubt that it is entirely practicable to 

 exterminate the ticks throughout the entire region, and the accom- 

 plishment of this result will be of tremendous economic advantage 

 not only to the South but to the whole country. The rate of progress 

 depends mainly on two factors — the amounts appropriated by the 

 Federal and State Governments, and the cooperation of the people. 



CHRONIC BACTERIAL DYSENTERY. 



Chronic bacterial dysentery is a chronic infectious disease of 

 bovines caused by an acid-fast bacillus simulating tlie tubercle 

 bacillus and characterized by marked diarrhea, anemia, and emacia- 

 tion, terminating in death. 



This disease was observed in the United States for the first time 

 by Pearson in Pennsylvania cattle, and later by Mohler in Virginia 

 cattle, and in an imported heifer from the island of Jersey at the 

 Athenia quarantine station of the Bureau of Animal' Industry . 



Pearson proposed the name chronic bacterial dysentery for 

 this affection, and it has also been termed Johne's disease, chronic 

 bacterial enteritis, chronic hypertrophic enteritis, and chronic bovine 

 pseudotuberculous enteritis by various European investigators. The 

 disease was first studied in 1895 by Johne and Frothingham in Dres- 

 den, but they were inclined to attribute to the avian tubercle bacillus 

 the cause of the peculiar lesions of enteritis which they observed. In 

 1904 Markus reported this disease in Holland, and subsequently it 

 was observed in Belgium, Switzerland, Denmark, and Great Britain. 



Cause. — The bacillus, which has been invariably demonstrated in 

 the intestinal lesions and mesenteric lymph glands in this disease, is 

 a rod about 2 to 3 microns long and 0.5 micron wide. It stains more 

 or less irregularly, like the tubercle bacillus, and moreover the simi- 



