THE TYPHOID BACILLUS 269 



bacilli very similar to typhoid bacilli in the soil in a region where no 

 typhoid fever was known to exist. 



Communicability. The bacilli may reach the mouth by means of 

 infected fingers or articles of various kinds, or by the ingestion of 

 infected food, milk, water, etc., or by more obscure ways, such as the 

 eating of raw oysters and clams or the contamination of food by flies 

 and other insects, or by inhalation through the mouth. Of the greatest 

 importance, however, is the production of infection by contaminated 

 drinking-water or milk. In a very large number of cases indirect proof 

 of this mode of infection has been afforded by finding that the water 

 had been contaminated with urine or feces from a case of typhoid. In 

 a few instances the proof has been direct namely, by finding typhoid 

 bacilli in the water. Examples of infection from water and milk have 

 frequently come under our direct observation. The following instances 

 may be cited : A large force of workmen obtained their drinking-water 

 from a well near where they were working. Typhoid fever broke out 

 and continued to spread until the well was filled up. Investigation 

 showed that some of the sick, in the early stages of their disease, 

 repeatedly infected the soil surrounding the well with their urine and 

 feces. Another example occurred in which typhoid fever broke out 

 along the course of a creek after a spring freshet. It was found that, 

 far up near the source of the creek, typhoid feces had been thrown on 

 one of its banks and had then been washed into the stream. 



In the late epidemic at Ithaca some 1500 cases developed among 

 those using the infected water supply of the town. The students and 

 towns-people not drinking the infected supply escaped. 



An instance of milk infection secondary to water infection was in 

 the case of a milk dealer whose son came home suffering from typhoid 

 fever. The feces were thrown into a small stream which ran into a 

 pond from which the milk cans were washed. A very alarming epidemic 

 of typhoid developed, which was confined to the nouses and asylums 

 supplied with this milk. During the Spanish-American war not only 

 water infection but food infection was noticed, as in the case of a regi- 

 ment where certain companies were badly infected, while others nearly 

 escaped. Each company had its separate kitchen and food supply, and 

 much of the infection could be traced to the food, the contamination 

 coming through the flies. Several epidemics have been traced to 

 oysters. 



Individual Susceptibility. In this, as in all infectious diseases, 

 individual susceptibility plays an important role in the production of 

 infection. Without a suitable soil upon which to grow, the seed cannot 

 thrive. There must in many be some disturbance of the digestion, 

 excesses in drinking, etc., or a general weakening of the power of resist- 

 ance of the individual, caused by bad food, exposure to heat, over- 

 exertion, etc., as with soldiers and prisoners, for example, to bring 

 about the conditions suitable for the production of typhoid fever. 



The supposition that the breathing of noxious gases predisposes to 

 the disease, though possibly true to a certain extent, as some animal 



