90 DYSENTERY 



with necrosis of the intestinal epithelium and ulceration in the large 

 intestine. These effects are produced by both living and dead bacilli 

 of the Shiga type, also with filtered cultures. This shows that the 

 nature of the process is an intoxication rather than a pure infection. 

 Even one one-hundredth of a loop of a culture may induce these 

 symptoms and lesions in mice. Strange to say, the guinea-pig is 

 relatively resistant to this organism. From the researches of Gay we 

 learn that the horse shows marked elevation of temperature, with 

 prostration and labored breathing when treated with one-fourth the 

 minimum fatal dose for guinea-pigs. 



There has been much controversy concerning the nature of the 

 soluble toxin found in cultures of the Shiga bacillus. Some claim that 

 it is a true toxin, a secretion of the bacillary cells, while others con- 

 tend that it is an autolytic product, resulting from the cleavage of 

 the bacilli. Antitoxic sera in variety have been made and have been 

 used for both prevention and cure. Living and dead cultures have 

 been used in the preparation of the toxins, and, as happens when 

 bacterial cell substance is repeatedly injected, many animals die in the 

 process of immunization. There is no standard method of preparing 

 the antitoxin as there is for diphtheria. It follows that the antitoxic 

 sera are not of uniform value and there is still some doubt as to 

 whether their effects should be ascribed to bactericidal or antitoxic 

 properties. Gay has obtained a serum by treating horses with 

 Flexner's bacillus, and has treated cases of dysentery with good results, 

 but Escherich in Vienna did not find it so valuable. Numerous observ- 

 ers have reported great reduction in the mortality in cases of Shiga 

 infection by treatment with the specific antitoxin. 



All attempts to induce typical dysentery in ordinary laboratory ani- 

 mals by feeding with dysentery bacilli have failed. It is true that 

 massive doses may cause some intestinal inflammation with loose stools, 

 but many bacteria will bring about this result. In apes the disease 

 may be induced by feeding, and it is stated that dysentery is sometimes 

 epidemic among these animals. This is certainly true of confined 

 animals, one such epidemic having been observed in Paris, and another 

 in Manila. Subcutaneous injections of dead bacilli in man have been 

 used for vaccination purposes, but quite naturally the value of such 

 a procedure must remain undetermined until it is done on a large 



