BACILLUS TYPHOSUS. 435 



80 days when dried on clothing, and for 3 months 

 in typhoid feces. When in water or moist earth 

 which contain many saprophytes its life is short- 

 ened. It survives drying for many months, al- 

 though direct sunlight kills in the course of a few 

 hours. 



That the typhoid bacillus secretes a soluble 

 toxin, has not been satisfactorily demonstrated. It 

 contains, however, an endotoxin which may be 

 obtained in solution by the autolytic digestion of 

 cultures, by extracting ground-up bacilli or by 

 squeezing out the plasma under high pressure. Up 

 to the present time, immunization with none of 

 these preparations has resulted in the production 

 of an antitoxic serum of accepted value. 



Typhoid fever may become epidemic either Typhoid 



, , n T Epidemics. 



through a contaminated water and food supply or 

 by contact infection. When due to infected water 

 there is something characteristic about the explo- 

 sive-like suddenness with which dozens or even hun- 

 dreds are stricken within a short period. The watet 

 of streams, small lakes or reservoirs may become 

 infected from an ill-constructed out-house, or from 

 discharges which have been thrown on the ground 

 in their vicinity. Typhoid stools thrown on the 

 ground adjacent to wells have caused small epi- 

 demics. Fruit, vegetables and milk cans may be 

 infected by washing them with contaminated water, 

 and it is supposed that the disease may be acquired 

 from oysters which have lain in water contami- 

 nated with sewage. 



The importance of the so-called bacillus-carriers 

 as a source of epidemics of typhoid has been 

 recently emphasized by a great many observers. 



