520 IOWA DEPARTMENT OF AGRICULTURE 



to stamp out, and are working on now. Hog cholera was reported back 

 in 1833, and it has spread ever since; but where in England it came 

 from, we don't know. We suppose that these specific diseases were created 

 at some stage of the world. But we do know now that we can't get hog 

 cholera in any other way except by the presence of the specific virus. 

 If you inoculate another hog with the blood of a sick hog, in almost 

 every case you get hog cholera; or if you associate a well hog with a 

 sick one you will get hog cholera. Of course, sick hogs may run on one 

 side of a barbed wire fence and well ones on the other, and the disease 

 not be communicated; but that is an exception to the rule. 



As to the means by which this disease spreads, we find that in order 

 to control hog cholera, it is extremely necessary to take precautions in 

 regard to the spread of the disease. The disease spreads by means of 

 the virus being conveyed in some way from place to place. The sick 

 hog is the most dangerous factor. A sick herd endangers nearby sur- 

 rounding herds because of the possibility of the virus being conveyed 

 from the sick herd to the other herds. The usual history of cholera 

 outbreaks is that the disease appears on certain farms; it spreads slowly 

 from one farm to the nearest farm, usually; then it spreads from that 

 herd to the next nearest herd. Sometimes, of course, it will not appear 

 in the herd nearest located to the one first attacked, but may occur in a 

 herd a little farther away; it depends upon circumstances. If your 

 neighbors live very close together, and go back and forth to each other's 

 hog yards, that is one way of carrying it. It usually extends along high- 

 ways or along the water course, but spreads slowly from the original 

 center of infection. 



Suppose the original center of infection is shown in the spring of the 

 year. It extends slowly during the early summer months, but along in 

 the fall, at the time when every farm contains quite a number of good- 

 sized hogs, they are extremely susceptible of cholera, and at the time 

 they eat green corn we have a lot of susceptible material. About this 

 time of year, cholera having gotten quite a good hold during the early 

 summer months, you begin to hear more about it. Some of you are 

 buying shoates from other farmers at this time; so it happens that hog 

 cholera and green corn appear about the same time of year. You can 

 of course make a hog sick by giving him green corn: you can set up 

 intestinal disorder; but I have never seen a large number of hogs made 

 sick or die on any farm where they have been fed on green corn without 

 being able to find that that herd had hog cholera. So I do not believe 

 it to be possible for you to take a herd of hogs and feed them on green 

 corn and make a large number of them sick with symptoms of hog cholera, 

 and show hog cholera on autopsy. So we ought not to lay much stress on 

 the fact that the way we feed our hogs has much to do with hog cholera. 

 You win find as you study this question that in many instances the best 

 cared-for herd has been kept in cleanly quarters, has had fresh water, 

 pasture and everything which ought to go to make a healthy herd, and 

 yet that herd is dying most rapidly with hog cholera. Some neighbor 

 of that man, who has filthy yards and hasn't exercised any care, may 

 have his herd free from hog cholera. The virus has in some manner 



