522 PATHOGENIC MICROORGANISMS 



proteid nature of toxins in general and has succeeded in producing 

 diphtheria toxin by growing the organism upon a medium entirely free 

 from albuminous bodies. Uschinsky believes that the protein reactions 

 observed by other workers may be due to ingredients of the precipitates 

 other than the toxin. It is not impossible, however, that the organ- 

 isms may have produced proteid substances by synthesis from the 

 simpler substances in Uschinsky's medium. The production of toxin 

 from such a medium, therefore, is not a conclusive argument against the 

 proteid nature of toxins. Accurate chemical isolation and analysis of 

 diphtheria toxin have not yet been accomplished. 



Diphtheria toxin is destroyed, 1 when in the fluid form, by tempera- 

 tures of 58 to 60 C. In the dry state, it may resist a temperature 

 of 70 C. and over, without noticeable change. Light and the free access 

 of air produce rapid deterioration. Sealed, protected from light, and 

 kept at almost freezing point, the toxin remains stable for very long 

 periods. Electrical currents passed through toxic broth have little or 

 no effect upon it. 



Transmission. Diphtheria is transmitted from one individual to 

 another directly or indirectly by contact or droplet infection as in 

 coughing, sneezing, etc. It has been found that many individuals may 

 retain virulent diphtheria bacilli in -nose and throat for long periods 

 after recovery from the disease. These are the so-called "diphtheria 

 carriers." 



The problem of diphtheria carriers has become one of considerable 

 importance and has been given special prominence of recent years by 

 the studies of Von Scholly, Moss, and Nuttall and Graham Smith. 

 Anderson, Goldberger and Hachtel 2 studied 4,093 healthy people in 

 the city of Detroit, and found that 0.928% harbor bacilli identical 

 morphologically with the Klebs-Loeffler bacillus. This figure is rather 

 lower than those of some other investigators, but would indicate, as 

 the writers stated, that there were from 5,000 to 6,000 diphtheria car- 

 riers in the city of Detroit. 



Of 19 cultures isolated from 19 of the carriers, only 2 were virulent, 

 which would indicate that only 0.097% of the people examined carried 

 organisms capable of producing disease. An interesting further point 

 is that the bacillus Hoffm'anni was present in at least 41.9% of over 2,000 

 individuals examined, and that 47 cultures, morphologically identified 



1 Roux et Yersin, loc. cit. 



2 Goldberger, Williams and Hachtel, Bull. No. 101, of the Hygienic Laboratories, 

 of the U. S. Public Health Service. 



