MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 807 



within the first two weeks. The chicks become listless, and are inclined 

 to huddle together for warmth. There is loss of appetite, and emacia- 

 tion. The wings droop, the back seems to shorten and the abdomen 

 protrudes out of proportion, causing the chicks to look stilty. The 

 characteristic whitish discharge from the bowel may be absent from 

 individual chicks, but is usually noticeable in groups of any appreciable 

 size. 



Bacillary white diarrhoea may be transmitted to young chicks under 

 five days old through infected food and drinking water, as has been 

 demonstrated repeatedly. Furthermore, chicks are often infected with 

 Bad. pullorum before they are hatched. This is due to the fact that 

 the yolk of infected hens carries the specific organism in it from the time 

 of its formation in the ovary. Hence, the mother hen is the source of 

 infection, having retained within it the bacterium in question from the 

 time she was an infected chick, or having acquired it later in life through 

 contact with diseased fowls. In laying hens the infection is localized 

 in the ovary which becomes decidedly abnormal in appearance. The 

 partly developed ova are discolored, misshapen and of all degrees of 

 consistency. 



Ovarian infection may be determined by the macroscopic agglutina- 

 tion test which has proven itself very valuable and practicable in the 

 organized campaign against bacillary white diarrhoea that has been 

 conducted in the State of Connecticut for the past six years. This 

 method of diagnosis has been found to be much more valuable than the 

 bacteriological examination of eggs. 



Eradication of infected laying stock is the solution of the white 

 diarrhoea problem. Flocks which are at all doubtful, or which have 

 given a history of infection, should be tested, and the reacting fowls 

 eliminated. Better still, no eggs should be used for hatching which 

 have come from flocks that have shown an appreciable degree of infec- 

 tion, although reacting individuals have been removed. 



CHICKEN CHOLERA* 

 Bacterium cholera gallinarum 



The bacterium causing this disease was first noticed by Perroncito 

 and Toussaint; later, in 1880, it was described by Pasteur, and was the 



* Prepared by F. C. Harrison. 



