CONTROL OF BACILLARY WHITE DIARRHCEA, 



1921-1922. 



BY G. E. GAGE AND O. S. FLIXT. 



NATURE OF BACTERIUM PULLORUM INFECTION. 



It has been conclusively proved that white diarrhoea is an ovarian infection. 

 Chicks which survive frequently become permanent bacillus carriers, with the ovar}- 

 the important seat of infection. Eggs from such (Carriers often harbor the disease 

 organism in the yolk, and chicks that develop in infected eggs may in turn become in- 

 fected and have the disease at time of hatching. The organism of the disease may be 

 transmitted to normal chicks through infected droppings, thus producing an epidemic, 

 and completing the cycle of infection. 



Since it has been definitely proved that Bacterium pulloruyn is the causative factor 

 in this disease, and that eggs may gain infection from infected ovaries, the infected 

 individual must be sought and eliminated from the breeding flock. This is the only 

 real basis for improvement. The macroscopic agglutination test has aided in this 

 direction, and the results of our control tests to-day depend upon the application of it 

 to the work of epidemiology in the field. The test itself depends on the principle that 

 in the blood serum of infected hens is a substance produced as a reaction against 

 Bacterium pullorttm, the organism causing bacillary white diarrhoea, known as an 

 agglutinin. Under laboratory manipulation this agglutinin causes the bacteria of 

 bacillary white diarrhoea to clump together and precipitate in the bottom of the test 

 tube as rolled up or clumped masses of the organism. This process is known as ag- 

 glutination. This agglutination reaction may be seen with the unaided eye; hence, 

 the whole process is known as the "macroscopic agglutination test," in order to differ- 

 entiate it from those other agglutination tests in which the microscope must be used 

 to see the agglutination. When, after proper laboratory manipulation, no agglutinin 

 is found in the blood, the bird is considered free from the infection of bacillary white 

 diarrhoea. 



CM 



CO 



