BACILLUS DYSENTERIC 127 



BACILLUS DYSENTERLffi. 



Dysentery occurs in two forms the bacillary type and the 

 amebic type. The former is caused by bacteria, while the 

 latter is a protozoon disease (see Chppter XIV). Bacillary 

 dysentery is an acute infectious disease, its chief lesion being 

 a violent inflammation of the lining of the large intestines. 

 The disease is caused by the Bacillus dysentericB or dysentery 

 bacillus. It is, however, better to say that a group of organ- 

 isms under this name gives rise to it because there are many 

 varieties with different chemical and se mm reactions, produc- 

 ing attacks of varying severity. Their general pathogenic 

 and etiological effects may be discussed together, however. 

 The usual ileocolitis of children is not due to the dysentery 

 bacillus, but some members of the dysentery group have been 

 found responsible for small epidemics of diarrhea among 

 children. 



In cholera the chief lesions are in the lower small intestine, 

 but otherwise the two diseases have many things in common. 



The bacilli enter probably only by the mouth in food and 

 drink infected with feces, handling by persons with soiled 

 hands or by flies, and pass through the alimentary tract to 

 their organ of predilection, the colon. Here they penetrate the 

 mucous lining to its deeper layers, causing violent irritation. 

 They may get deeper into the wall or even to the glands 

 draining the colon, but not into the blood. The inflammation 

 gives rise to diarrhea which passes from feculent to mucus, 

 to bloody mucus, and may be almost wholly blood. These 

 effects are due to the effort of the colonic wall to rid itself of 

 the poisons and the body seems to choose this method to free 

 itself of the intruder. This fact is further shown when we 

 inject susceptible small animals with the poisons, for a con- 

 gestion of the colon and diarrhea result, although no living 

 organisms are present. The poisons of the dysentery bacilli 

 are probably both extra- and intracellular, the latter being 

 more abundant. The toxic effect, therefore, is exerted by the 



