306 PUBLIC HEALTH BACTERIOLOGY 



Spores. Only produced in the presence of oxygen 

 (free), and hence not formed in blood of infected animals 

 while in the unopened vessels or tissues. For this reason 

 it is advised to cut into an animal dead of anthrax as 

 little as possible, and to be specially careful not to spill 

 the blood. The spores are very resistant, keeping for 

 twenty years. They are killed by dry heat at 140 C. 

 (248 F.) in 3 hours, and live steam at ioo C. in 5 to 10 

 minutes, or boiling water for 1 J hours. Their behaviour to 

 chemical disinfectants is variable, some strains resisting 

 1-20 carbolic acid for forty days, while others are destroyed 

 by the same solution in two days. Corrosive sublimate, 

 1-2000, kills most strains in 40 minutes. Direct sunlight 

 destroys anthrax spores within 6 to 12 hours. Creolin (10 

 per cent) kills anthrax bacilli in 10 to 20 minutes, but 

 anthrax spores can survive in a 60 per cent solution of 

 creohn. Freezing has little effect on their vitality. Spores 

 are formed best at 30 C, and by keeping the bacilli at 

 42 C. for eight days, the power of sporulation is lost, and 

 is only regained by passing the bacilli through a series of 

 animals. 



Anthrax spores are often used for testing the value of 

 " germicides." To do this, sterile silk threads are steeped 

 in an emulsion of an anthrax culture and are dried over 

 strong sulphuric acid in a desiccator. They are then 

 placed in a solution of the " germicide " for a certain time, 

 well washed with water, and laid on the surface of agar 

 medium or dropped into broth, and incubated to see if any 

 growth occurs. The culture used is first tested for spore 

 formation. 



Pathogenicity. For man : great. For animals : mainly 

 for cattle and sheep. In the German Empire in 1899, the 

 following cases were reported : 3678 cattle, 307 sheep, 

 282 horses, 61 swine, and 6 goats. 



In Great Britain, in the ten years 1896 to 1905, the 

 total reported " outbreaks " in animals were 6203, and the 

 number is increasing. In man, 512 cases were reported in 

 1901 to 1910, and of these 120 were fatal. Internal anthrax 

 is usually fatal. In the external form, head and neck cases 

 show a mortality of 85 per cent ; and hand and arm cases 

 12 per cent. 



