CHICKEN CHOLERA. "67 



at the start than to keep them to multiply the contagious germs and infect the 

 grounds and remaining fowls." 



Tlie only practicable treatment, therefore, is preveniion; for the accomplishing 

 of which we quote the following rules deduced from Dr. Salmon's report by a 

 correspondent of the Scientific American; 



"Measures for prevention of fowl cholera should be based upon the following 

 facts : 



"1. 7%e virus is not diffusible.-^tha.t is, the disease germs are seldom if ever 

 taken up by the air and carried any considerable distance to produce the malady. 

 The virus remains in the fixed form, and is generally if not always taken into 

 the body with the food ; it is distributed over the grounds, feeding places, etc., 

 in the excrement of affected birds, and the food, drink, and gravel are thus con- 

 taminated. Healthy birds may be kept in coops within a few feet of the sick 

 ones for months without contracting the disease; but if the former are now 

 placed in the same inolosure with the latter, they sicken in a few days. 



"2. The virus must be carried upon the grounds freguenied by fowls before they 

 contract the disease. — It is not probable that this disease originates in any consid- 

 able number of cases in any other way than by contagion. There is a possibility 

 that it may originate in occasional instances by filthy surroundings, if closely con- 

 fined, or by feeding on decomposing substances ; but there are few facts to sup- 

 port such a conclusion. 



"It is thus brought upon farms either (1) with sick or infected fowls newly 

 acquired, (2) with the blood or parts of the bodies of dead birds carried on the 

 feet of people or brought by dogs or other animals, (3) with infected manure or 

 feathers, or (4) possibly by wild birds, animals (rabbits), or even insects that 

 have contracted the disease or have eaten the blood or bodies of affected birds 

 recently dead. The origin of the disease can generally be traced in country dis- 

 tricts where houses are a considerable distance apart, to recently acquired poul- 

 try. It'is only in districts more thickly peopled, and then in exceptional in- 

 . stances, that the germs are carried by wild birds or animals or by insects. 



"Forgrounds not already infected the following precautions should be observed : 



"1. Ifewly acquired birds to be isolated. — When cholera is raging in a locality, 

 all birds introduced from other flocks should be placed in an inclosure by them- 

 selves for at least three weeks,. until it is certain that they are free from the 

 disease. No fowl should be accepted from a place known to be infected, for at 

 least a year after the last known cases occur. 



"2. ■ PrecamtiUyns in regard to eggs. — ^All the eggs from a distance to be used for 

 hatching must be thoroughly cleaned of all particles of excrement adhering to' 

 them, and the water with which they are washed, as well as cloths or brushes 

 used, must be raised to the boiling )>oiht before being thrown upon grounds to ' 

 which poultry has access. The virus is always destroyed by a boiling tempera- 

 ture, or even by 140° F. if maintainedfor fifteen minutes. 



"3. Fowls not to wcmder upon adjoiming infected premises, — A stone wall is in 

 towns frequently the boundary line of an infected place, and though' fowls are 

 npon each side of it the contagion may not cross for years. In such cases it is a 

 matter of the greatest importance to prevent the healthy fowls from trespassing 

 upon the infected grounds. 



