Apr. 8, 1918 



Sources of Hog-Cholera Infection 



117 



Table VIII. — Results of experiment V on the contagiousness of hog cholera {igi6) 

 lAll pigs were exposed for 48-hour periods by association -with cholera-sick pigs iioi, 1102, and 1103] 



This experiment serves to corroborate Experiments I to IV, and 

 shows very clearly that cholera-infected pigs may transmit the disease 

 by contact prior to the appearance of visible symptoms. This is un- 

 doubtedly one of the reasons why the disease spreads so rapidly through- 

 out a susceptible herd, once the infection has been established. 



Experiment I indicated that the blood and urine of an inoculated 

 pig were infectious 24 hours after inoculation and that the blood, urine, 

 and feces were all infectious after 48 hours; yet in Experiment V the 

 disease was not transferred by contact exposure during that period. It 

 is an interesting and perhaps significant fact that the time at which 

 contagiousness develops as shown by Experiment V coincides with the 

 appearance of the infection in the eye and nose secretions. The num- 

 ber of experiments here recorded are only sufficient to permit the sugges- 

 tion that perhaps the eye and nose secretions play a very important 

 role in the dissemination of hog cholera. 



Experiments VI, VII, VIII, and IX were carried out with a view to 

 determining whether hog cholera may be transmitted by contact in the 

 later or more advanced stages of the disease, as well as in the early 

 stages. 



Experiment VI. — This experiment was designed to afford a compari- 

 son between contact infection alone and combined pen infection and 

 contact infection. 



