NOX-SPORING BACILLI 233 



shows that danger is chiefly to be feared when pollution is 

 recent. In soil and faecal matter, however, duration of 

 vitality is more prolonged (five months in privy refuse, 

 and fourteen days after being spread on ground), but no 

 genuine multiplication proved. This suggests one mode 

 of pollution of surface water and surface wells after rains, 

 by the washing of dormant bacilli into the same, and to the 

 danger of using human excrement for manuring vegetable 

 gardens, and fields near water sources (Lincoln, 1905). 

 Air-borne infection is rare. Sewer air is not regarded as 

 an actual cause so much as a predisposing one. 



Pathogenicity. For man : enteric fever, typhoid fever, 

 abdominal typhus (German), la fievre typhoide (French). 

 For animals : do not multiply, and same effects by 

 injection of dead bacilli, as that due to endotoxins. 

 Chimpanzees have been infected by food, and have 

 shown characteristic lesions. Intraperitoneal injections 

 produce a short acute illness with pyrexia, etc., but non- 

 specific. 



Specificity has not been absolutely proved according to 

 Koch's postulates. In enteric fever the bacilli are present 

 in the blood, the bowel, the urine, the sputum and the 

 rose spots. Toxins are intracellular. 



Immunity usually follows one attack, and is due to 

 bactericidal and bacteriolytic bodies. 



Active Immunization is accomplished in animals by a 

 first injection of I c.c. of a broth culture heated for ten 

 minutes at 60 C., followed in five or six days by a larger 

 dose, and so on, until finally living cultures are injected in 

 considerable doses without serious consequences. 



Wright's vaccination against typhoid has been used 

 extensively in the British army. He uses a strain of 

 bacillus standardized by passage through guinea-pigs, and 

 sterilizes the culture by heating to 60 C. for five minutes. 

 The first injection is of an amount of bacilli fatal to 100 

 grm. of guinea-pig, or alternatively, 750 to 1000 million 

 of dead bacilli. The second injection given eleven days 

 later should be double the first. The first dose is followed 

 by tenderness and swelling locally and at the adjacent 

 lymphatic glands, and some pyrexia, all of which usually 

 subside in twenty-four to forty-eight hours. The method 



