488 Diphtheria 



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 discharge 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 extra- 

 ordinary 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 observation must be ap- 

 parent to all readers, and serves as further evidence why 

 thorough isolation should be practised in connection with the 

 disease. 



Neumann f 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 McDaniel J have found it con- 

 venient to describe three chief types of the diphtheria 

 bacillus as it occurs in twenty-four-hour-old cultures on 

 Loffler'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 

 replaced by granular types when convalescence is established 

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



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



t "Centralbl. f. Bakt. u. Parasitenk.," Jan. 24, 1902, Bd. xxxi, 

 No. 2, p. 41. 



t "Trans. Assoc. Amer. Phys.," 1900. 



