SECTION II 

 DIAGNOSIS OF CERTAIN DISEASES 



DIPHTHERIA 



DIPHTHERIA is a local disease with general symptoms. The 

 local symptoms are due to the local action of the bacillus 

 which causes the disease, while the general symptoms are due 

 to the toxin or poison which it produces, and which is carried 

 in the blood-stream to the brain, heart, and other organs. Now 

 the local symptoms are comparatively unimportant, and it is to 

 the general symptoms caused by the toxin that diphtheria 

 owes the greater part of its high mortality. Diphtheria anti- 

 toxin neutralizes this toxin (much in the same way as an alkali 

 neutralizes an acid), and prevents it from harming the vital 

 structures; but it does not repair the harm that the toxin has 

 done. It is obvious, therefore, that we must not make our 

 diagnosis of diphtheria from the general symptoms if the anti- 

 toxin treatment is to do any good. The diagnosis is to be 

 made from the local symptoms, and this is what we can rarely 

 do by ordinary clinical methods at a stage sufficiently early to 

 get the full value of the antitoxin treatment. 



The practitioner has a choice of two methods. He may 

 inject all patients who suffer from 'sore throats which present 

 the slightest resemblance to those seen in diphtheria, or he 

 may employ bacteriological methods of diagnosis. The- 

 former method may be applicable in an epidemic of diphtheria, 

 but suspicious throats are common and antitoxin expensive. 

 In most cases it is necessary to have recourse to the second 

 method. 



Most sanitary authorities have now recognized that it is 

 their duty and privilege to provide for the bacterial investiga- 

 tion of supposed diphtheria free of charge to doctor and 

 patient, and supply outfits to be used for taking the material 

 and transmitting it to the laboratory. When the practitioner 



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