PREVENTIVE MEDICINE 305 



sometimes carried to market when infected by swine fever, and 

 when straw is used in the cart, it may be thrown out and used by 

 others carrying pigs to healthy premises. Railway trucks or 

 vehicles used for carrying swine may be the means of infecting 

 healthy animals. It is important to note that in an outbreak many 

 adult pigs survive after having passed through a chronic attack, 

 and such pigs, which usually remain unthrifty, are often infectious. 

 Other animals may merely show a rise of temperature without 

 any clinical symptoms, but with a resulting powerful immunity. 



The Departmental Committee, inquiring into swine fever,* 

 concluded that : " The manure of pigs suffering from swine fever 

 is infective. That a period of 14 days may be regarded as sufficient 

 to bring about the disinfection of infective manure through natural 

 causes. That rats are not, as has been suggested, pathological 

 carriers of swine fever. That all available evidence suggests that 

 swine fever is not disseminated by external parasites. That while 

 persons, vehicles and animals which have been in contact with 

 infected pigs or premises may carry infective material mechanically 

 within the area of their movements, subject to the time limit 

 indicated above, the evidence leads the Committee to the conclusion, 

 that all wide dissemination of disease is due to the movement of 

 infected pigs. That a pig may become infective in three days 

 after it has itself contracted infection and before it has actually 

 exhibited clinical symptoms of disease, and a pig which has con- 

 tracted the disease may continue to be infective for a variable period 

 the extent of which has not yet been fully ascertained, but which 

 is often of considerable duration. That there would appear to be 

 cases in which healthy pigs that have not been visibly affected by 

 swine fever, and which on post-mortem examination show no evid- 

 ence of having suffered from swine fever, are infective and continue 

 to be so for a considerable time." 



Miessnerf states that : " The virus exhibits considerable resist- 

 ance to destructive agencies ; thus, serum containing virus can stand 

 being heated to from 45 to 46 C for 24 hours. The virus is also 

 resistant to drying and sunlight, but is destroyed by putrefaction 

 in 8 days." 



PREVENTIVE MEASURES. If swine fever is to be kept under 

 control and eventually eradicated, it is imperative that the pro- 

 visions of the swine fever Order be carried out. Magistrates 

 who fail to inflict a substantial penalty on offenders are a serious 

 hindrance to attempts to reduce the number of outbreaks. The 



* Final Report, Part IV., Cd, 8045. 



f Epizootics and their Control in War, 1917, Trans, by Liebold. 

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