CHANNELS OF INFECTION 345 



appear to retain bacilli in the throat for from two to nine weeks." ^ 

 After the ninth week, the number falls off very rapidly, but not 

 infrequently the bacillus remains in the throat for lOO days, and 

 it has been known to remain more than 200 days. This per- 

 sistence of diphtheria bacilli in the throat may play an 

 important part in determining the spread of the disease by 

 means of such cases which are supposed to be no longer 

 infective. " For it is now a matter of common experience that 

 so long as these diphtheria bacilli, even the less virulent forms, 

 remain in the crypts of the tonsils, etc, so long is the patient a 

 centre of infection, the diphtheria bacilli present resuming, under 

 favourable conditions, their more virulent form " (Woodhead). In 

 this way diphtheria bacilli can be readily transmitted by patients 

 who are apparently no longer suffering from the effects of the 

 disease, to those who have weak or ulcerated throats. In precisely 

 a similar manner, may the bacillus be conveyed to articles of attire 

 and articles of food, such as milk (as in outbreak at Leeds, 1903). 



Further, it has now been shown that in apparently healthy 

 persons who have not suffered from diphtheria, the B. diplitliericB 

 may be present Loffler found diphtheria bacilli in the throats of 

 4 out of 160 healthy children, and Park and Bee be found similar 

 virulent bacilli in 8 out of 330 " healthy " throats. Hewlett and 

 Murray found 1 5 per cent of the children in a general hospital had 

 diphtheria bacilli in their throats.- Kober ' examined diphtheria 

 cultures from two series of healthy persons. The first series com- 

 prised 128 individuals known to have been in recent contact with 

 patients suffering from diphtheria. The diphtheria bacillus was 

 found in the throat of 8 per cent of these. The second series 

 comprised 600 individuals who had not recently come into contact 

 with any diphtheria cases — from five of these a bacillus similar to 

 that of diphtheria was isolated. It was rather short with swollen 

 ends, and was not pathogenic to guinea-pigs. 



It is probable that, as a rule, "healthy" throats do not yield 

 the true B. dipht/ierice unless the persons have been in contact with 

 infected persons.* 



^ Report on the Bacteriological diagnosis and Antitoxic Serum Treatment of 

 cases admitted to the hospitals of the Metropolitan Asylums Board, 1895- 1896, ^7 

 Professor Sims Woodhead, Sect. 2, 1902, pp. 14, 28, 31. 



* Brit. Med. four.^ 1901, vol. i., p. 1474. 



^ Revue des Maladies de PEnfance, Juillet, 1900. 



* Since the above was written a paper on the distribution of the diphtheria 

 bacillus, by Graham-Smith, has appeared in the Jour, of Hygiene, 1903? PP- 

 216-257, which should be consulted. 



