Chicken- Cholera 565 



Lesions. — The autopsy shows that when the bacilli are introduced subcuta- 

 neously a true septicemia results, with the formation of a hemorrhagic exudate 

 and gelatinous infiltration at the seat of inoculation. The liver and spleen are 

 enlarged; circumscribed, hemorrhagic, and infiltrated areas occur in the lungs; 

 the intestines show an intense inflammation with red and swollen mucosa, and 

 occasional ulcers following small hemorrhages. Pericarditis is frequent. The 

 bacilli are found in all the organs. If, on the other hand, the disease has been 

 produced by feeding, the bacilli are chiefly to be found in the intestine. Pasteur 

 found that when pigeons were inoculated, into the pectoral muscles, if death did 

 not come on rapidly, portions of the muscle {sequestra) underwent degeneration 

 and appeared anemic, indurated, and of a yellowish color. 



Immunity. — Pasteur* discovered that when cultures are allowed to remain 

 undisturbed for several months, their virulence becomes greatly lessened, and 

 new cultures transplanted from them are also attenuated. If chickens be inocu- 

 lated with such attenuated cultures, no other change occurs than a local inflam- 



Fig. 234. — Bacillus of chicken-cholera, from the heart's blood of a pigeon. 

 X 1000 (Frankel and Pfeiffer). 



matory reaction that soon disappears and leaves the birds protected against 

 future infection with virulent bacilli. From these observations Pasteur worked 

 out a system of protective vaccination in which the fowls are first inoculated with 

 attenuated, then with more active, and finally with virulent, cultures, with re- 

 sulting protection and immunity. 



Use has been made of this bacillus to kill rabbits in Australia, where they are 

 pests. It is estimated that two gallons of bouillon culture will destroy 20,000 

 rabbits, irrespective of infection by contagion. 



The baciUus of chicken-cholera may be identical with organisms found in 

 various epidemic diseases of larger animals, and, indeed, no little confusion has 

 arisen from the description of what is now pretty generally accepted to be the 

 same organism as the bacillus of rabbit septicemia (Koch), Bacillus cuniculicida 



* An interesting account of Pasteur's experiments upon chicken-cholera can 

 be found in the "Life of Pasteur," by Vallery-Radot, translated by Mrs. R. S. 

 Devonshire, igog. Popular Edition, New York, Doubleday, Page and Co. 



