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insuring that all of the animals become infected and thus develop 

 an active immunity under the protection of the serum. 



The owner of a large pig ranch close to the Berkeley serum 

 plant, who purchases all his serum there, absolutely refuses to 

 use their virus, but prefers to develop his own virus as described. 

 A week or ten days after birth all pigs are given a dose of pro- 

 tective serum alone ; then at weaning time, when large numbers 

 of pigs are to be actively immunized the owner brings to his place 

 a sufficient number of young hogs, 100-125 lbs. apiece, from some 

 part of the State where hog cholera is known not to exist, and 

 which consequently are highly susceptible to the disease. These 

 pigs are tested for tuberculosis and are then turned out on the 

 premises, their temperatures being taken every day so as to know 

 when they become infected and when is the best time to kill them 

 to obtain the most effective virus. With this and the serum pur- 

 chased from the Berkeley plant, all the weanlings are then treated, 

 and, it is said, with highly satisfactory results. It should be men- 

 tioned that the owner in question raises ten to fifteen thousand 

 pigs annually and feeds swill exclusively. Bvit as he does not 

 boil his swill there is a constant danger of reinfection, necessitat- 

 ing the continued use of serum. It was suggested that the disease 

 could easily be stamped out and reinfection by means of the 

 swill prevented through boiling, but it was held that the cost of 

 boiling would equal the cost of treatment, and that there were so 

 many other sources of infection from the cholera infected neigh- 

 borhood, and which it would be almost impossible to guard 

 against, the present method had been found the most econo- 

 mic. This undoubtedly is true, and will continue so until the 

 disease has been brought under better control, but it is equally 

 certain that the continued use of virus will postpone eradication 

 almost indefinitely or until a breed of swine with natural inherited 

 immunity has been evolved. 



In the meantime I can see no serious objections to the Berke- 

 ley method being tried here by pig raisers who believe they have 

 the infection on their premises, if proper precautions are taken, 

 and conscientiously adhered to against the spread of the disease. 

 Immune pigs are easily obtained here, and if such pigs develop 

 cholera when exposed on the suspected premises their blood 

 should furnish an ideal virus for just that place. But to introduce 

 virus here from abroad I am even more strongly opposed to than 

 before my visit to California. There is absolutely no call for it 

 with the small amount of mild infection which may possibly 

 still be here, as there will always be grave danger of serious 

 losses from inoculation cholera and its subsequent escape to 

 hitherto uninfected districts. 



If the above suggestion is acted on by any of the local hog 

 raisers, the following precautions, as laid down by federal and 

 state authorities, should be adhered to and only on i)rcmiscs 

 where thorough sanitation can be maintained and where the 



