DEPARTMENT OF VETERINARY SCIENCE AND ANIMAL PATHOLOGY 



CONTROL OF BACILLARY WHITE DIARRHOEA, 



1923-1924 



BY G. E. GAGE AND 0. S. FLINT. 



During the last few years, and especially over the past two years, the Massa- 

 chusetts Agricultural Experiment Station, through its Department of Veterinary 

 Science and Animal Pathology, has endeavored to secure effective control of 

 bacillary white diarrhoea of poultry. This work is now centered around the effort 

 to establish "disease-free flocks" from which day-old chicks and hatching eggs 

 may be obtained. The macroscopic agglutination test has been used as a con- 

 trolling agent; and methods instituted have brought about improvement in the 

 poultry industry in Massachusetts. 



NATURE OF THE INFECTION 



Bacillary white diarrhoea is infectious, and Salmonella pullora^ is the causative 

 agent. Chicks which survive the infection may become permanent carriers, with 

 the ovary as the important seat of infection. Groups of chicks may be infected 

 by the organism of the disease being transmitted to normal chicks through in- 

 fected droppings. The ultimate source of this infection is the hen. The infective 

 droppings come from chicks hatched from eggs, the yolks of which are infected. 

 Eggs thus contaminated with Salmonella pullora are from diseased ovaries of hens, 

 thus establishing them as disease carriers. Chicks which develop in these infec- 

 tive eggs may become infected, and have the disease at time of hatching. 



The problem is to locate the disease carriers and eliminate them from the breed- 

 ing flock. To locate such carriers in any breeding flock, it is essential to find 

 proof of the infection. This is accomplished by finding either the organism 

 Salmonella pullora itself, or evidence of antibodies (agglutinins) elaborated in 

 the blood of the infected hen. The macroscopic agglutination test is our most 

 expeditious method for making this determination; and the application of it, 

 as a means of identifying the carriers, has aided greatly in controlling the disease. 



The macroscopic agglutination test is based on the principle that in the blood 

 serum of infected hens a substance, known as an agglutinin, is produced as a re- 

 action against Salmonella pullora, the organism causing bacillary white diarrhoea. 

 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 

 differentiate 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. 



SERVICE RENDERED UNDER THE POULTRY DISEASE ELIMINATION LAW 

 FOR THE SEASON ENDING AUGUST 1, 1924 



During the present season, 1923-24, 59,635 breeding birds have been examined 

 for bacillary white diarrhoea by the macroscopic agglutination test. The follow- 

 ing tables show the geographical distribution according to breeds, the location of 

 reactors, the amount of infection among various breeds tested, and the number of 

 flocks, and of breeding birds in those flocks, having certain limits of infection. 



1 According to classification of the Society of American Bacte^iologists, recently published. 

 Bacterium pullorum is now named Salmonella pullora, which is being accepted throughout 

 this country as the standard name. 



