Apr. 8, 1918 



Sources of Hog-Cholera Infection 



125 



Table XII — Record of reovered pig lojo — Continued. 



1916. 

 November 26. 

 November 2 7 . 

 November 28. 

 November 29. 

 November 30. 

 December i . . 

 December 2 . . 

 December 3 . . 

 December 4. . 

 December 5. . 



Tempera- 

 ture. 



103. O 



103.4 

 102. 8 

 102. 8 



102. o 

 loi. 9 



103. I 



Ate feed. 

 Normal. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



SyxQptoms. 



From the above record it will be seen that hog 1070 had a typical 

 and well-marked case of hog cholera, the temperature going as high as 

 107°. On December 4, eight days after the animal was recorded as 

 normal, two suceptible pigs, Nos. 11 96 and 1197, were placed in the pen 

 with hog 1070. In this experiment the pen was not disinfected; nor was 

 the recovered pig washed and disinfected as in the first two experiments. 

 The three pigs were kept together from December 5 to 27, a period of 22 

 days, during which time they remained well. 



All three pigs were injected with virus on December 27 to test their 

 immunity. Hog 1070 remained well. Pigs 11 96 and 11 97 became sick 

 on January i, 191 7, developed the usual symptoms of hog cholera, and 

 were killed for virus on January 9, each showing well-marked hemorrhagic 

 lesions of hog cholera at autopsy. 



In the four experiments which have just been described, recovered 

 pigs which had suffered from typical attacks of hog cholera were tested 

 by exposure with susceptible pigs and also by the withdrawal of blood 

 and the inoculation of susceptible pigs to determine whether they har- 

 bored the virus within their bodies and could act as carriers of the dis- 

 ease. In all four experiments the results were entirely negative. 



These experiments do not, of course, show that recovered pigs may 

 not at times be carriers of hog cholera; yet, on the contrary, they do 

 prove that all recovered pigs are not carriers. When these results are 

 considered with those of experiments I to VI, we may conclude, that 

 although hogs which have been infected with cholera are dangerous so 

 long as they show any symptoms of cholera, they may lose the power 

 to convey the disease to others, once they have made a good lecovery. 



PIGEONS AS CARRIERS OF HOG CHOLERA 



The belief that birds play an important part in the dissemination of 

 hog cholera is based largely upon practical observations, such as an 

 outbreak of cholera on a farm frequented by pigeons that are known to 



