144 APPLIED BACTERIOLOGY 



be caused by a specific pathogenic organism, we must look 

 for the cause of every case in the specific contagion given 

 off by a previous case, and as the virus appears to be air- 

 borne (in this country) only for very short distances, if at 

 all, its chief means of propagation must be either through 

 the organism becoming endemic on the soil in close 

 proximity to the patient's abode, or through its finding its 

 way into water or milk, or adhering to articles of food, 

 such as vegetables or shell-fish. 



More than once carbon filters have been found to be 

 contaminated with typhoid, and thus become a veritable 

 poison-bottle. It seems at least probable that the typhoid 

 bacillus may, like the vibrio of cholera, become endemic for 

 a considerable period of time, since the bacilli will live in 

 the faeces, and may even thrive on the surface of the soil. 

 This is borne out by the recurrence of cases of enteric 

 fever close to previous cases, and is well illustrated by the 

 maps contained in the Local Government Board reports, 

 which show recent cases marked by red dots, while cases of 

 the previous year are marked in black. In those cases 

 where enteric fever has been communicated from patient 

 to nurse, it is probable that the infection has been carried 

 by particles of undisinfected excreta becoming dried, and 

 thus forming part of the floating dust of the atmosphere, or 

 still more directly through particles of excreta coming into 

 contact with the hands, and thus being conveyed directly 

 into the system. It still seems to be an open question as 

 to whether the lower animals are capable of transmitting 

 typhoid fever to human beings ; some observers think that 

 cows, for example, are capable of suffering from and trans- 

 mitting typhoid fever ; if this be so, it is surprising that they 

 do not more often suffer from it, as it is a comparatively rare 

 thing not to find a herd drinking from water constantly 

 polluted with their own and other animals' excreta. 



