78 VACCINE AND SERUM THEEAPY 



This is quite a common disease, and occurs gener- 

 ally throughout, and is usually prevalent in, the 

 infected region in summer. Mortality from this 

 disease is as high as 80 per cent. Some of the acute 

 cases recover completely ; the chronic cases nearly 

 all end fatally. 



Po'ojjJiylaxis and Treatment. — One attack of the 

 disease confers immunity. 



1. Protective inoculation with attenuated cultures. 

 (Pasteur's method). Pasteur showed in his experi- 

 ments that the passage of erysipelas virus through 

 the body of rabbits increases its virulence for those 

 animals. On the other hand, it reduces it for pigs, 

 so that the inoculation of such virus in the latter 

 animals causes only a slight febrile disease. Virus 

 attenuated up to a certain degree retains this degree 

 of virulence, even if transferred from the rabbit blood 

 to a suitable artificial medium, and if further culti- 

 vated at body temperature. A bouillon culture attenu- 

 ated by the above method produces the vaccine, which 

 is injected subcutaneously into young pigs in the form 

 of a weaker and stronger modification. The efficacy of 

 Pasteur's protective inoculation has been positively 

 established. 



Dose : 0*12 c.c. of the weaker vaccine is given sub- 

 cutaneously, and twelve days later 0*12 c.c. of the 

 stronger is given. In pure-bred pigs the above 

 method of vaccination is sometimes attended with 

 serious affections, but in the coarser breeds the 

 results have been highly satisfactory. 



