I06 FOWL CHOLERA 



Perroacito was among the first to describe the specific 

 cause of the disease. This was followed by the contributions 

 of Pasteur, who, in 1880, cultivated the bacterium in chicken 

 broth and showed that its virulence might be reduced to such 

 an extent that it could safely be used for vaccination. This 

 is the first case in which a virulent organism was successfully 

 modified in a laboratory and made to act as a vaccine. It was 

 the forerunner of the preparation of vaccines for a number of 

 diseases, more particularly for anthrax, black quarter, and 

 rabies. 



§ 87. Geographical distribution. Fowl cholera seems 

 to be widely distributed in Europe and it has been found in a 

 few localities in the United States and in Canada. In Ger- 

 many it is the cause of heavy losses among poultry. In 1903. 

 it is reported to have killed over 48,000 fowls and 23,000 geese 

 besides other poultry. 



§ 88. Etiology. Fowl cholera is caused by a specific 

 bacterium {Bacillus {bipolaris') avisepticus, Pasteurella avium') 

 which is not distinguishable morphologically or in its cultural 

 manifestations from the other members of the group of bacteria 

 of which Bad. septicemiae hemorrhagicae is the type. In this 

 group are the bacteria of rabbit septicemia, swine plague, and 

 Wildseuche. It is a small, slightly elongated organism with 

 rounded ends. In stained preparations from the tissues it 

 exhibits a pronounced polar stain. 



The period of incubation is placed by European writers at 

 from 18 to 48 hours. In the case of 40 fowls inoculated by 

 Salmon, it varied from 4 to 20 days, the average period being 

 8 days. Ward fed viscera of dead fowls to 10 healthy ones. 

 They died in from 24 hours to 6 days. 



§ 89. Symptoms. The symptoms described for this 

 disease in Europe differ somewhat from those reported by 

 Salmon. Usually the appetite is lessened. Occasionally they 

 continue to eat almost to the time of death. The earliest indi- 

 cation of the disease is a yellow coloration of the urates. In 



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