840 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



Symptomatic anthrax is a very old disease and until recent years has 

 been confused with true anthrax. This disease is widely distributed, 

 affecting practically all countries and climates. 



It is enzootic, never spreading widely or rapidly, and is often found 

 in certain infected valleys and in relatively small areas. Young cattle, 

 generally under two years of age, are most commonly affected, but 

 sheep and goats are susceptible to this infection. 



This disease is infectious by inoculation, perhaps also by in- 

 gestion, and usually acute. Subcutaneous and muscular tissues are 

 especially affected. Its most prominent and characteristic feature is 

 swelling, affecting most frequently, the front or hind quarters, and 

 not extending below the knee or hock. As a rule, the bacillus of symp- 

 tomatic anthrax produces a very acute disease with severe constitu- 

 tional disturbances, and early death. 



The bacillus of symptomatic anthrax has been clearly demonstrated 

 to be the specific cause of blackleg. The period of incubation in the 

 natural disease is uncertain. Under artificial inoculation this period 

 varies from two to three days and is occasionally as short as one day. 



This bacillus produces in culture a very active toxin. This toxin 

 is quite resistant to heat. That the bacillus of symptomatic anthrax 

 stimulates the production of antibodies and that the injury is done by 

 toxins, is shown by the fact that immunity against virulent culture may 

 be produced by treatment with presumably sterile filtrates of virulent 

 cultures. 



The bacillus of symptomatic anthrax is rarely found in the general 

 blood before death; but is abundant in the affected muscle and over- 

 lying subcutaneous tissue. It also occurs in great numbers in the bile 

 and intestinal contents. 



Mucous membranes become congested and then very dark. There 

 is a high fever. Local swellings occur which are at first sensitive and 

 later insensitive and gaseous. There is usually developed a very 

 marked swelling of a front or hind quarter or of the neck, with rapid 

 formation of gas. The serous membranes, particularly the pleura and 

 peritoneum, develop severe inflammation with haemorrhages and 

 infiltrations and corresponding exudation in the cavities. General 

 decomposition is rapid and the swelling may show a slight acetone 

 odor. The local subcutaneous tissues are infiltrated, haemorrhagic or 

 gaseous. The local lymph glands are swollen and haemorrhagic or 



