PREDISPOSING CAUSES 121 



(22) Intestinal Parasites. — Due no doubt to the gross irregu- 

 larities practised in feeding, and the notoriously poor quahty of 

 food given to hogs on many farms, the hog is very prone to be- 

 come affected by intestinal parasites, and especially by worms. 

 The hog seems to be able to bear infestation by large numbers of 

 these worms without producing any very severe symptoms. 

 There can be no doubt, however, that the presence in the bowels 

 of these unnatural tenants cannot do otherwise than lower the 

 vitality of the animal and render them more susceptible to attack 

 by other diseases. 



Cholera is especially a disease of the bowels, and the inflamma- 

 tion of the mucous membrane lining the bowel by these parasites 

 undoubtedly makes it more easy for the virus of hog-cholera to 

 gain a foothold and start up the process of change that finally 

 results in formation of the typical ulcers of hog-cholera. 



I have repeatedly noted, on postmortem in hog-cholera out- 

 breaks, the presence of large numbers of worms in the bowels of 

 the dead animals. On the other hand, we find a large number of 

 animals with enormous numbers of worms who do not have 

 cholera. There is a wrong impression held by many farmers that 

 worms cause cholera. This is not true. The worms themselves 

 are not capable of causing cholera, and neither do I believe that 

 worms carry the infectious virus from one animal to another. 

 They do, however, undoubtedly lower the general health of the 

 animal, and especially do they tend to lower the vitality of the 

 bowels, and make them more susceptible to invasion by disease 

 germs of any kind. 



When, to the presence of worms, we have added the additional 

 factor of gross improprieties and irregularities in feeding, such as 

 feeding of decomposed swill, moldy grain, etc., it cannot be 

 otherwise than true that the hog so abused is especially inviting 

 to an attack by the cholera virus. It is in these debilitated animals 

 that the disease first gains its foothold in a community, and then, 

 by passage through the body of the living hog, the virus gains 

 increased power, and attacks more vigorous animals, and finally 

 becomes a widespread epidemic which sweeps away herd after 

 herd in its wake. 



(23) Disinfection of Premises. — When an outbreak of cholera 



