424 Diphtheria 



large clubbed forms characteristic of the true diphtheria organism. 

 The chief points of difference between the bacilli are that the pseudo- 

 diphtheria bacillus, when grown upon blood-serum, is short and 

 stains uniformly; that cultures grown in bouillon develop more 

 rapidly at a temperature of from 20 to 22C. than those of the 

 true bacillus; and that the pseudo-bacillus is not pathogenic for 

 animals. 



Contagion. The diphtheria bacilli, being always present in the 

 throats of patients suffering from diphtheria, constitute the element 

 of contagion. 



The results obtained by Biggs, Park, and Beebe in New York 

 are of great interest. Bacteriologic examinations conducted in 

 connection with the Health Department of New York City show 

 that virulent diphtheria bacilli may be found in the throats of 

 convalescents from diphtheria as long as five weeks after the dis- 

 charge of the membrane and the commencement of recovery, and 

 that they exist not only in the throats of the patients themselves, 

 but also in those of their caretakers, who, while not themselves 

 infected, may be the means of conveying the disease germs from 

 the sick-room to the outer world. Still more extraordinary are the 

 observations of Hewlett and Nolen,* that the bacilli remained in 

 the throats of patients seven, nine, and in one case twenty-three 

 weeks after convalescence. The hygienic importance of this ob- 

 servation must be apparent to all readers, and serves as further 

 evidence why thorough isolation should be practised in connection 

 with the disease. 



Neumann! found that virulent diphtheria bacilli may occur in 

 the nose with the production of what seems to be a simple rhinitis 

 as well as a pseudo-membranous rhinitis. Such cases, not being 

 segregated, may easily serve to spread the contagion of the disease. 



Wesbrook, and Wilson and McDanielJ have found it convenient 

 to describe three chief types of the diphtheria bacillus as it occurs 

 in twenty-four-hour-old cultures on LofHer's blood-serum, sent to 

 the laboratory for diagnosis. The classification places all types in 

 three general groups: (a) granular, (b) barred, and (c) solid or 

 evenly staining forms. Each group is subdivided into types based 

 on the 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; (b) 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 re- 



* "Brit. Med. Jour.," Feb. i, 1896. 



f "Centralbl. f. Bakt. u. Parasitenk.," Jan. 24, 1902, Bd. xxxi, No. 2, p. 41. 



j "Trans. Assoc. Amer. Phys.," 1900; Trans. Amer. Public Health Asso., 1900. 



