SERUM TREATMENT OF DIPHTHERIA 705 



weeks. But patients frequently come under treatment comparatively 

 late in the disease, or the true nature of the condition may not be fully 

 diagnosed at first and treatment thus be delayed. Diphtheria is, there- 

 fore, still to be regarded as a dangerous infection, and while the proper 

 use of antitoxin constitutes the most important part of the treatment, 

 local applications, general constitutional measures, and the management 

 of the various conditions that may complicate the disease are all to be 

 considered. Here we will discuss only the serum treatment of the dis- 

 ease. 



Bearing in mind the pathology of diphtheria, serum treatment aims 

 to fulfil the following primary indications: 



1. To neutralize all free toxin circulating in the body fluids, and 

 also to neutralize, as much as possible, the toxin that has already united 

 with the tissue-cells. 



2. To cause the destruction or removal of the bacilli producing the 

 toxin as quickly as possible. 



3. To furnish the patient with sufficient excess of antitoxin to neu- 

 tralize the toxin as rapidly as it is produced until the virulent bacilli 

 disappear. 



Action of Diphtheria Antitoxin. Diphtheria antitoxin best fulfils 

 these requirements. In fact, there are no substitutes. In former days 

 the powerful and irritant caustics and germicides that were freely ap- 

 plied to the throat, instead of limiting the disease and destroying the 

 bacilli, probably actually encouraged its extension by excoriating and 

 depressing the resistance of the surrounding mucous membranes. 



1. The chief action of antitoxin is just what its name implies, namely, 

 a substance that neutralizes the toxin. This is regarded as a chemical 

 reaction analogous to the neutralization of an acid by an alkali. When 

 the Antitoxin molecule has united with the toxin molecule, it is believed 

 that the toxin is neutralized and that both are rendered inert. As the 

 result of experimental studies, however, we know that this union is not 

 always a firm one, and it is possible for the toxin to become dissociated 

 and attack body-cells or other molecules of antitoxin, thus explaining in 

 part the necessity for giving quite large doses of antitoxin doses that 

 are out of all proportion to what we would expect to be necessary, 

 when considered weight for weight between guinea-pig and man, to 

 effect complete neutralization of the toxin. 



It is reasonable to presume, and may be accepted as true, that a 

 stronger affinity exists between diphtheria toxin and antitoxin than be- 

 tween body-cells and toxin. Just as the union between this toxin and 

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