BUREAU OF ANIMAL INDUSTRY. 657 



streams they simply distribute the virus, allow it to multiply, and 

 all the other animals are thereby put in the way of becoming in- 

 fected. 



In many outbreaks the early cases do not succumb so rapidly. They 

 grow weaker, lie down much of the time, eat but little, and usually 

 have diarrhea. Most of such cases may linger for weeks, meanwhile 

 scattering the poison in the discharges. The disease may be recog- 

 nized in these cases as soon as they are observed to act suspiciously, 

 and there should be no delay in determining at once the nature of 

 the disease. When the animal has been opened the large intestine 

 should be carefully slit up and examined, beginning with the blind 

 or upper end. There will be seen roundish yellow or blackish spots, 

 having an irregular depressed, sometimes elevated, surface. These 

 are well shown in the Second Annual Report of this Bureau, p. 246, 

 or in the Annual Report of the Department for 1885, p. 522. These 

 spots correspond to dead portions of the mucous membrane, and they 

 are frequently seen from the outside as soon as the animal is opened. 

 Sometimes the membrane has been entirely destroyed. Its appear- 

 ance is well shown on Plates I and II of this report. These slow, 

 chronic cases are apt to spread the disease in the bowel discharges, 

 for in them the virus is chiefly located. 



Having determined the existence of the disease, it may not be pos- 

 sible to remove the healthy animals to uninfected quarters after the 

 sick ones have been taken away. Under such circumstances thorough 

 disinfection should be practiced at once. Among a large number of 

 substances tried in the laboratory only a few were found to meet the 

 requirements of rapidity of action combined with certainty and cheap- 

 ness. Carbolic acid seems to be useless, as it is expensive, and a con- 

 siderable quantity is required to destroy the germs. Thus experi- 

 ments in the laboratory have shown that to kill the virus in liquids 

 1 part carbolic acid in 100 parts of water is required, whereas 1 part 

 of mercuric chloride in 75,000 parts of water is sufficient. The best 

 disinfectant is therefore mercuric chloride, also called mercuric 

 bichloride and corrosive sublimate. As it is a violent poison to man 

 and animals, it should be very carefully handled. In order to make 

 a solution which is strong enough to act rapidly and with certainty, 

 1 part of the substance should be dissolved in 1,000 parts of water. 

 This is best accomplished by adding half an ounce to about four gal- 

 lons ol clear water, preferably rain-water. As a pound of corrosive 

 sublimate retails at about 70 cents, the cost of the disinfectant is very 

 small. This solution, which should be made in wooden or granite- 

 ware vessels at least half a day before use, should be applied by 

 means of a broom or brush to the flooring, sides, and covering of 

 pens in which diseased animals have staid. All utensils used about 

 the pens, as well as the troughs and other things containing food, 

 should be carefully vv^ashed with the solution and afterwards rinsed 

 thoroughly in pure water. Ten minutes' exposure to the disinfectant 

 solution is sufficient for all purposes. As the corrosive sublimate 

 solution attacks many metals, iron and tin utensils should be disin- 

 fected with boiling water instead of the mercuric chloride solution. 



The bowel discharges should be made innocuous by pouring upon 

 them corrosive sublimate solution or mixing them with powdered 

 chloride of lime. In general it may be stated that whatever has come 

 in contact with diseased animals or their discharges should first be 

 disinfected before healthy animals are brought in contact with them 

 In using the corrosive sublimate solution we must bear in mind that 

 42 AG— '86. 



