ANTHRAX 95 



from 15 to 20 miimtes then injected it as a protective agent. 

 Pasteur, however, was the first to prove that immunity could 

 be obtained by the use of cultures of attenuated bacteria. 

 Several methods of attenuating the specific organisms have 

 been proposed by Pasteur, Toussaint, Chaveau, Chamberland, 

 Arloing and others. 



Pasteur's method consists in inoculating the animal with 

 a small quantity of a culture which has been grown at a high 

 temperature — 42 to 43° C. — for several days. This deprives 

 the bacteria of their virulence. To strengthen the resistance, 

 the animals are again inoculated with a stronger virus. After 

 the two inoculations, they are said to be protected against the 

 most virulent anthrax ; but the immunity is of short duration, 

 Chamberland reported in 1894 that a total of 1,988,677 animals 

 had been treated by this method in France, and that the loss 

 from anthrax had diminished from 10 per cent, in sheep and 5 

 per cent, in cattle to less than i per cent. Cope, in his report 

 to the English Board of Agriculture, regards the conclusions 

 of Chamberland as somewhat fallacious, because in order to 

 prove that the animals inoculated received immunity, it should 

 be shown that they were subsequently exposed to the risks of 

 natural infection. The excellent work which has been done 

 bj' Neal and Chester, at the Delaware College Experiment 

 Station, has shown the possible efficiency of this method. Of 

 the 331 cows which they vaccinated against anthrax, two died 

 of the disease, giving a death rate of less than i per cent, and 

 this in a territory so saturated with the virus that it was prac- 

 tically impossible to keep cattle at all before its use. 



A more critical study of the reports on the use of this 

 vaccine shows that while success can not be denied, failures 

 must be admitted. It is reported both in England and 

 Germany that the Pasteur vaccine has not been a marked suc- 

 cess. In England, Klein, who tested the vaccine used in that 

 country, found that if the animals did not die from the effect 

 of the vaccine, they did when exposed to the disease. The 

 German veterinarians and agriculturahsts agree that the first 

 vaccine is mild and harmless, but that the second vaccine, 

 even in the hands of experts, is dangerous and often fatal. 



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