THE DIPHTHERIA BACILLUS 403 



picture of diphtheria poisoning. Guinea-pig B should live because 

 the diphtheria toxin is neutralized by the antitoxin. 



The diagnosis of diphtheria by serological methods is not practical. 



Dissemination and Prophylaxis. Diphtheria bacilli are spread chiefly 

 by contact or by carriers. Occasionally milk appears to be a vehicle 

 of transmission. As a prophylactic agent for destroying diphtheria 

 bacilli, antitoxin is one of the greatest blessings which bacteriology has 

 conferred on medicine. Diphtheria antitoxin is used in two ways : (a) 

 prophylactically ; (6) curatively. If diphtheria breaks out in a house- 

 hold or a hospital, those in contact with the patient should receive pro- 

 phylactic doses of antitoxin: that is, from 500 to 1500 units of antitoxin 

 repeated after fourteen days or until all danger is over, provided 

 the Schick test is faintly or markedly positive. (See Schick test.) 

 Curatively, from 3000 to 15,000 units, or in severe cases 20,000 units, 

 or even more, are used. In severe and desperate cases the antitoxin 

 should be introduced intravenously, preferably using antitoxin pre- 

 pared without preservatives for this purpose. Antitoxin must be 

 used early. If it is used early the mortality is reduced more than 50 

 per cent. If the serum is used within the first twenty-four hours, 

 the prognosis is favorable in at least 95 per cent, of the cases. The 

 general death rate prior to the introduction of antitoxin was from 

 25 to 33 per cent.; since the use of antitoxin it varies from 3 to 14 per 

 cent. 



In a certain proportion of cases of diphtheria treated with anti- 

 toxin, usually from eight to fourteen days after the administration 

 of antitoxin, rashes and painful joints develop, together with fever, 

 angioneurotic edema, swollen lymph glands, and albuminuria. This 

 is the so-called serum disease, which is usually particularly severe in 

 asthmatics, in whom there occasionally develops a true bronchial 

 spasm with respiratory embarrassment. In a few cases, less than one 

 in ten thousand, sudden death may occur within five to fifteen minutes 

 after the injection. At autopsy there is usually found a persistent 

 thymus. These are cases of status lymphaticus. This sudden death 

 is not due to the antitoxin, but to the proteins in the horse serum in 

 which the antitoxin is contained. 1 If there is reason to suspect that 

 the administration of antitoxin will result seriously, a few drops (not 

 more than a quarter of a cubic centimeter) should be injected, and 



1 It should be remembered in this connection that man is less susceptible than a 

 guinea-pig to serum diseases, and, furthermore, it ordinarily takes about 5 c.c. of horse 

 serum to bring about the anaphylactic reaction in sensitized guinea-pigs. Proportion- 

 ately, it would take 200 c.c. to induce the same symptoms in man. 



