460 SEROTHERAPY 



be stated in terms of the United States standard unit, which has been 

 established by the United States Public Health Service and is kept at 

 Washington under special conditions to prevent deterioration. This unit 

 is almost exactly the same as the German unit or normal serum of Ehrlich. 

 It is approximately the amount of antitoxin which will neutralize 100 times 

 the minimum lethal dose of toxin for a standard 250 Gm. guinea-pig. 



Diphtheria antitoxin has the power of combining with, and hence 

 neutralizing, the toxin formed by the growth of the diphtheria bacillus. 

 If present in the blood-stream in large amounts it not only will combine 

 with the free toxin, but may also, by its superior attraction, dissociate 

 some of the toxin from the tissue cells with which it has already entered 

 into combination. 



The prime object in the administration of the antitoxin, however, 

 should be to give it early enough to nullify the toxin as fast as the latter 

 is produced. The characteristic and usual effects of diphtheria antitoxins 

 appear within twenty-four hours and consist of an amelioration of the 

 general symptoms and halting of the growth of the membrane, the edges 

 of which begin to loosen themselves from the mucous membrane. If 

 enough antitoxin has been given in the first dose, and if this dose was 

 given early enough, this action goes on to complete recovery. If as 

 much as seventy-two hours elapse from the onset of the disease to the 

 injection of the antitoxin, the remedy is not so efficient. Paralyses and 

 cardiac complications cannot be prevented by late administration even 

 though the primary symptoms be checked. The remedy is therefore 

 most useful as a prophylactic. Some harm has been done as soon as clin- 

 ical diphtheria is recognizable, and the antitoxin should be immediately 

 given to prevent more injury to the organism. At the same time, no case 

 is hopeless. The higher incidence of paralysis since antitoxin was in- 

 troduced is probably due to the recovery of the severely affected patients, 

 who formerly would have died. 



The .rashes, edema, and joint symptoms which sometimes follow the 

 injection of the antitoxin (or of any foreign serum), though very distress- 

 ing, have no serious effects and are to be disregarded in the presence of 

 actual diphtheria. Cases of immediate anaphylactic shock are exceedingly 

 rare and the possibility of their occurrence is not to be compared with the 

 danger in withholding antitoxin. If, however, the patient has been sub- 

 ject to attacks of asthma when exposed to horse emanations or if hyper- 

 susceptibility to horse-serum is, for any other reason, suspected, a pre- 

 liminary dose of 0.2 mil of the antitoxic serum may be given, followed in 

 an hour by the same dose if no untoward symptoms have occurred, and 

 doubled in successive hours until the necessary amount has been given. 

 This protects against acute anaphylactic collapse, but not against the later 

 manifestations of serum disease. 



For the average case of diphtheria the curative dose is 10,000 units, 



