1842 



THE DYSENTERIES 



a short bacillus, not decolourized by Gram, not clotting milk, not 

 producing gas in any sugar media. There was at first some differ- 

 ence of opinion as regards motility, but Kruse's statement that the 

 bacillus was always non-motile has been proved to be correct. 

 Kruse was also the first observer to state that there was more 

 than one variety of dysenteric bacilli. 



In 1900 Flexner reported that he had isolated a moderately 

 motile bacillus from cases of dysentery in Manila identical with 

 Shiga's bacillus, and producing a severe muco-hsemorrhagic diarrhoea 

 in a human being who was the victim of an accidental laboratory 

 infection. This bacillus was later demonstrated to be non-motile, 

 and 10 differ in several respects from Shiga's bacillus, notably in 

 fermenting certain sugar media, and could be distinguished there- 

 from by the different biological tests. These results have been 

 frequently confirmed by observers in different parts of the world. 

 Strong isolated a bacillus slightly different from that of Flexner, 

 also from cases in Manila. 



In 1903 Hiss and Russell separated a bacillus which closely 

 resembles Flexner's bacillus, but fails to ferment maltose. This 

 bacillus is often called the Y bacillus. In 1904 Castellani isolated 

 a bacillus from cases in Ceylon which he named the ' par ady sent eric 

 bacillus,' and later he described the group of metadysentery bacilli. 

 Several other germs have been described by various authorities, 

 while Kruse, Flexner, Strong, Lucet, Conradi, and others have 

 made a detailed study of the pathogenesis of the disease. 



Climatology. — Bacillary dysentery is found all over the world, 

 in cold, temperate, and warm climates, but especially in the latter. 

 In temperate climates the germs probably cause a type of the in- 

 fantile diarrhoeas which are such potent factors in the infantile 

 mortality of those regions, while they are also responsible for the 

 endemic and epidemic cases so frequently met with in Europe and 

 America. 



In the tropics they are also extremely common, occurring more 

 frequently at the end of the dry and the beginning of the wet seasons. 

 In certain regions and at certain times the virulence of the com- 

 plaint appears to be increased, the reason of which is not at present 

 apparent. Probably it depends upon the greater possibility of 

 infection, owing to the drinking-water being highly contaminated 

 in warm weather, or perhaps to the presence of multitudes of flies. 

 The agency of these or other factors has not been completely 

 inquired into. Whatever the cause may be, it is well known that 

 at times the disease may spread in epidemic form over larger or 

 smaller areas. These epidemics may be institutional, urban, or 

 rural, or they may attack a district, a country, or a continent. 

 Thus, celebrated epidemics are known to have occurred in Europe 

 in 1538, 1717-19^ i779-83> and 1834-36. ; 



Dysentery is particularly prone to occur whenever sanitation 

 is defective, and hence is found prevalent in lunatic asylums and 

 in armies in times of active service, as is clearly shown by the present 



