398 YETEEINAEY HYGIENE 



with disease, and a knowledge of the habits of animals. 

 This is why disinfection in the hands of a layman is as 

 incomplete as it is perfunctory, for the reason that the 

 word ' thoroughness ' is not understood. 



Take a very common example, the disinfection of premises 

 after an outbreak of swine fever, what are the special points 

 which here require attention in addition to the obvious one 

 of disinfecting the piggery ? The special points are the 

 disinfection of the entire ground to which the pigs have 

 had access ; the collection of all excreta, the filling in and 

 disinfection of puddles, the entire destruction of all manure 

 heaps and food which has been in contact ; the disinfection 

 of trees, posts, boulders, hurdles, ropes, nets, carts, or any- 

 thing else with which swine would commonly come in 

 contact, treating each and all of these as if they were as 

 infective as the animal itself. 



Such disinfection is thorough, and should leave the place 

 after sufficient time has elapsed as secure as before infec- 

 tion. It is not possible for a layman, unless carefully 

 trained, to carry out effectively such a system, which 

 though simple in itself depends for its effectiveness on 

 attention to detail. He does not realize how many 

 hundreds of disease organisms may comfortably occupy the 

 eye of a needle, and a splash with a lime-wash brush 

 according to his views meets the entire case. It is here 

 that disinfection commonly fails, it is seldom thorough. 



The extent to which disinfection is carried largely depends 

 on the character of the disease ; in the example selected of a 

 highly infectious form of fever in the pig, we know that the 

 poison is liberally distributed by means of the discharge 

 from the bowel. Where animals are at liberty to roam 

 the infected area may not only be considerable, but the 

 evacuations are means of distributing the poison over 

 substances and material that are not generally regarded 

 as having much to do with pigs. 



And this is where the expert comes in, he knows that the 

 chief danger from glanders, for example, lies in the nasal 

 discharge, and his experience tells him that the wall in 



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