PATHOGENIC BACTERIA 135 



Similar Bacteria. The N eapolitanus bacillus of Emmerich, 

 or feces bacillus of Brieger, resembles the typhoid bacillus in 

 many ways, the colonies being the same and its structure 

 similar. But the growth on potato is very different; a thick, 

 yellow, pasty layer is formed thereon. 



The colon bacillus not only resembles the typhoid germ in 

 form, but also in some of the pathologic processes produced. 

 For points of resemblance and difference see Bacillus coli com- 

 munis. 



Typhoid Bacilli in Water. Although all evidence shows that 

 the water-supply is a frequent source of infection, very few 

 persons have ever isolated the typhoid bacillus from such an 

 infected source. The earlier reports show that no account 

 was taken of Bacillus coli, which is usually present in polluted 

 waters. (See Water Analysis.) 



Pathogenesis. Lower animals do not have enteric fever, 

 though their death has been caused by injection of the bacilli 

 into the veins of the ear. 



In man the bacillus has been found in the urine, blood, spu- 

 tum, milk, intestinal discharges, roseolar spots, and in various 

 organs, as spleen, liver, lymphatic glands, and intestinal villi. 



It is found in secretions several days after the attack has sub- 

 sided. It is found only in this disease, and regularly. 



Typhoid Carriers. Some individuals retain a culture of 

 the bacilli in the gall-bladder for years, and manufacture, or 

 at least expel, true virulent bacilli through the feces continually. 

 Such persons have infected other individuals without suffering 

 any inconvenience themselves. Some forms of chronic inflam- 

 mation, as cholecystitis and appendicitis, have been caused by 

 the typhoid bacillus. 



Way of Infection. The bacilli in the dejecta of the diseased 

 person find their way into drinking-water, milk, or dirty clothes, 

 and so into the alimentary tract of a person predisposed to the 

 disease. Flies act as conveyors by infecting food. The bacilli 

 enter the blood through the lymphatics, and so become lodged 

 in various organs. They are quite resistant, living for some 

 time in the soil and water, and are not affected, as other organ- 



