BUREAU OF ANIMAL INDUSTRY. 133 



virus. From January 1 to November 30, 1914, there was produced 

 at such plants 140,963,313 cubic centimeters of the serum, of which 

 2,812,003 cubic centimeters was pronounced worthless or contami- 

 nated and withheld from market as a result of the bureau's inspection. 



To procure men for inspection work in enforcing this law has 

 been one of the greatest difficulties of the work. The number of in- 

 spectors at the beginning of the fiscal year was 19; the number 

 employed at the end of the year was 42. These men were selected 

 from other lines of work in the bureau service because of their sup- 

 posed special fitness, and were given a careful course of training in 

 methods of inspection of virus and serum plants, as well as in methods 

 of serum production. 



The establishments licensed to produce anti-hog-cholera serum have 

 improved greatly during the fiscal year both in construction of plants 

 and in methods of operation. 



The outbreak of foot-and-mouth disease in the fall of 1914 was a 

 distinct menace to plants producing anti-hog-cholera serum and hog- 

 cholera virus. The serum and virus respectively consist of de- 

 fibrinated blood of immune hogs in the one case and of hogs sick 

 with hog cholera in the other. The virus of foot-and-mouth disease 

 in the case of hogs appears in the blood of the affected animal before 

 the characteristic lesions of this disease develop. Therefore it is 

 possible for an animal to be simultaneously affected with hog cholera 

 and foot-and-mouth disease. 



If a hog is killed for the production of virus at a time when the foot- 

 and-mouth disease infection is in its early stages, such blood might 

 convey the infection of foot-and-mouth disease. Apparently this 

 did occur in the fall of 1914, when a small lot of virus derived from 

 four pigs appeared to be infected. These pigs were slaughtered for 

 virus at a time when they showed no lesions of foot-and-mouth 

 disease. 



In August, 1915, as already stated (page 7), certain cases of foot- 

 and-mouth disease were produced by one lot of infected hog-cholera 

 serum, the infection of which with the virus of foot-and-mouth 

 disease was discovered only after prolonged tests. 



In view of this danger strict requirements were made of licensed 

 hog-cholera serum plants located in areas quarantined against foot- 

 and-mouth disease. No new stock was allowed to be brought on the 

 premises. The disinfection of yards, pens, buildings, etc., was re- 

 quired, and the shipment of neither serum nor virus was permitted 

 until the Federal quarantine was lifted. In the case of plants lo- 

 cated in free areas, new stock was admitted only when originating 

 outside of quarantined areas and accompanied by certificate that the 

 farm of origin was free of foot-and-mouth disease. All incoming stock 

 was inspected, the premises disinfected as a precautionary measure, 

 and quarantine of the premises maintained by the owner. All serum 

 has to be tested on pigs which are inspected for foot-and-mouth dis- 

 ease, and all virus for simultaneous inoculation must have added to it 

 1 per cent of carbolic acid and must be held at the plant until it has 

 been found to be free of foot-and-mouth disease infection by a test 

 on calves. 



