PREVENTIVE MEDICINE 307 



by every possible means, and in particular by facilitating the supply 

 of serum; that the production of immune herds by simultaneous 

 administration of serum and virus should be undertaken where pig 

 owners so desire, on premises selected as suitable and under careful 

 supervision and restrictions; that in order to control the spread of 

 the disease, the isolation of infected premises should be maintained 

 by restrictive regulations, but that such restrictions should allow 

 the introduction to infected premises of pigs to be treated immedi- 

 ately with serum." 



Stockman's conclusions in the final report (August, 1915) of the 

 Departmental Committee were as follows : 



1. That treatment with serum alone is of great value on infected 

 premises in saving the lives of those pigs which have escaped infec- 

 tion at the time of treatment. It follows from this that the sooner 

 the treatment is applied on such premises and the greater the efforts 

 made before its application to isolate the healthy pigs from those 

 which are ailing or doubtful, the better the results are likely to be. 



2. That immediately after treatment with serum it is advisable 

 to attempt to convert the passive immunity into active or lasting 

 immunity by allowing the healthy pigs which have been treated 

 to come into contact with those which are ailing. If the pigs 

 do not acquire active immunity, serious infection may re-assert 

 itself after the temporary protection derived from the serum alone 

 has passed off. The outbreak may thus be prolonged and the losses 

 will probably be increased. 



3. That, although it is possible that serum treatment exerts 

 some moderating influence on the course of the disease if applied 

 while a pig is in the earliest stages of infection, it has no curative 

 action when infection has gained a distinct start. 



4. That an affected piggery can be successfully restocked with 

 pigs provided the new animals are injected with serum on arrival, 

 and immediately afterwards brought into contact with the existing 

 infection. 



5. That in many cases the results obtained in the treatment 

 of young suckers were disappointing. (Vide infra.) 



It is advised that the dose of serum should not be less than 

 20 cc. Unfortunately it seems that owing to the variation in the 

 susceptibility of swine and of the virulence of the virus, the results 

 of vaccination in the field are irregular, some pigs showing very 

 severe reactions and centres of the disease being liable to become 

 established. This is particularly unfortunate, as the immunity 

 acquired by vaccination has been found to be both high and durable. 

 The method which appears to be attended with the least risk is 



