47 Diphtheria 



shape and size of the bacilli. A study of variations in the 

 sequence of types in series of cultures derived from clinical 

 cases of diphtheria shows that (a) granular types are usually 

 the most predominant forms at the outset of the disease; 

 (6) the granular types usually give place wholly or in part 

 to barred and solid types shortly before the disappearance 

 of diphtheria-like organisms; (c) solid types, by many 

 observers called "pseudo-diphtheria bacilli," may cause 

 severe clinical diphtheria. Solid types may sometimes be 

 replaced by granular types when convalescence is established 

 and just before the throat is cleared of diphtheria-like bacilli. 



From these data the writers conclude that it is not safe 

 to base an opinion regarding the maintenance of quarantine 

 upon the bacterioscopic findings independently of the clinical 

 history of the case. 



The occurrence of true diphtheria bacilli in the throats 

 of healthy persons has been a stumbling-block to many 

 practitioners uninformed upon bacteriologic subjects, who 

 fail to account for its presence and also fail to realize how 

 rare its appearance under such circumstances really is. 



Park * found virulent diphtheria bacilli in about i per 

 cent, of the healthy throats examined in New York city, 

 but diphtheria was prevalent in the city at the time, and 

 no doubt most of the persons in whose throats they existed 

 had been in contact with cases of diphtheria. He very 

 properly concludes that the members of a household in 

 which a case of diphtheria exists, though they have not 

 the disease, should be regarded as possible sources of 

 danger, until cultures made from their throats show that 

 the bacilli have disappeared. 



In connection with the contagiousness of diphtheria the 

 recent experiments of Reyes are interesting. He has 

 demonstrated that in absolutely dry air diphtheria bacilli 

 die in a few hours. Under ordinary conditions their vitality, 

 when dried on paper, silk, etc., continues for but a few days, 

 though sometimes they can live for several weeks. In sand 

 exposed to a dry atmosphere the bacilli die in five days 

 in the light ; in sixteen to eighteen days in the dark. When 

 the sand is exposed to a moist atmosphere, the duration 

 of their vitality is doubled. In fine earth they remained 



* "Report on Bacteriological Investigations and Diagnosis of Diph- 

 theria, from May 4, 1893, to May 4, 1894," "Scientific Bulletin No. i," 

 Health Department, city of New York. 



