386 INVESTIGATION, ETC., OF MILK-BORNE EPIDEMICS 



the bacillus had infected 14 others.^ Hewlett and Murray 

 examined the throats of 385 children in a general hospital, 

 and found the pseudo-diphtheria bacillus in 92 (or 24 per cent), 

 and the Klebs-Loffler bacillus in 58 (or 15 per cent.).^ It has 

 been estimated that of all persons exposed to infection 

 of diphtheria about 33 per cent, get the bacillus in their 

 throats.^ From these facts the evidence of experience is not 

 surprising. Such evidence is twofold. In the first place it is 

 now accepted that the continuance of an epidemic of diphtheria, 

 particularly in isolated communities such as schools, depends 

 in large measure upon the bacilli carried in the apparently 

 healthy throats. This latter point has been well illustrated, and 

 the inestimable advantage of bacteriological examination in such 

 epidemics has been demonstrated, in the Poplar Union Schools at 

 Forest Gate in 1898- 1899 (Goadby)* ; the London Orphan Asylum 

 at Watford 1898,^ and in an outbreak at Cambridge, Chesterton, 

 and Colchester in 1900 and 1901 (Cobbett).*" So serviceable did 

 bacteriological diagnosis prove in the last-named outbreak that 

 Dr Cobbett concluded that " the principal means of combating 

 diphtheria are, after the isolation of persons actually sick, the 

 detection of persons who go about apparently in good health 

 carrying with them the diphtheria bacillus, and the isolation of 

 such persons and of convalescents from the disease until diph- 

 theria bacilli can no longer be cultivated from them." If actual 

 isolation is impossible such infectious persons should be warned 

 that they are a danger to others, and instructed to take certain 

 precautions. 



{b) The serum diag-nosis of typhoid fever is a second example 

 of the application of bacteriology to the investigation of epidemics. 

 An account of the method as generally used will be found below. 

 After five years' most careful investigation and experience 

 of this reaction, it is safe to assume that the test is generally 

 reliable. In 400 hospital cases the serum diagnosis was supported 



^ Jahrbuch fiir Kindeheilkunde, 1896, B. xiii., Heft i. 



2 Brit. Med. Jour., 1901, vol. i., p. 1474. 



^ Trans, of the Epidetntological Society of London, 1900, vol. xix., p. 94. 

 For further evidence on this subject see Jour, of Hygiene, 1903, vol. iii., pp. 

 217-223 (Graham-Smith). 



* Trans, of the Epidemiological Society of London, 1900, vol. xix., pp. 

 87-116. 



■' Ibid., pp. 1 17-122. 



" Jour, of Hygiene, 1901, vol. i., pp. 228-259 and 485-1499. See also vol. ii., 

 1902, pp. 170-194, and vol. iii., 1903, pp. 216-253 (Graham-Smith). 



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