2Q2 SPECIFIC MICRO-ORGANISMS 



at the same time diphtheria antitoxin. In this way virulent 

 diphtheria bacilli may be accurately detected. 



The very large number of examinations that have been made 

 by various boards of health have shown that the diphtheria 

 bacillus may persist in the throat for a long time occasionally 

 several weeks after the patient has apparently recovered; also 

 that diphtheria bacilli are occasionally found in the throat, 

 when there is an inflammatory condition without any pseudo- 

 membrane, and that they not only appear in an apparently 

 healthy throat, especially in hospital nurses and in children 

 who have been associated with cases of diphtheria, but also in 

 those who have had no traceable contact with diphtheria cases. 1 

 It has been found that bacilli sometimes occur in the throat, 

 which have all the morphological and cultural properties of the 

 diphtheria bacillus, but which are devoid of virulence when 

 tested upon animals. Such diphtheria bacilli have frequently 

 been called pseudodiphtheria bacilli. A bacillus closely resembling 

 the diphtheria bacillus, but without virulence, has been found 

 in xerosis of the conjunctiva. It is called the xerosis bacillus. 

 If not a transformed diphtheria bacillus, it is at least closely 

 related. The diphtheria bacillus is subject to wide variations 

 in morphology, so that, in dealing with unknown cultures where 

 the forms are not characteristic and injection into animals is 

 without result, it may be difficult to decide whether or not the 

 organisms are diphtheria bacilli. 



The disease is undoubtedly transmitted very largely by 

 immediate contact, especially with persons harboring the bacilli 

 but not seriously ill, and by fomites. Children in school or at 

 play readily transfer secretions of the mouth, and a cough or 

 sneeze may distribute such material over a wide area. 

 . Immunity to diphtheria was produced by Von Behring in 

 1890 by injecting the toxin into animals, the general method of 

 procedure being quite similar to that followed in the production 

 of tetanus antitoxin. The blood serum of the immunized animal 



1 Sholly: Journ. Infect. Dis., Vol. IV, 1907, pp. 337-346. 



