756 PASSIVE IMMUNIZATION SERUM THERAPY 



Nature of Diphtheria. In the great majority of cases diphtheria is 

 a local infection of some portion of the upper respiratory tract. The 

 bacilli are usually inhaled, find lodgment upon a mucous membrane, 

 and secrete a toxin that produces necrosis of the cells of the mucosa and 

 effectually resists phagocytosis of the bacilli. From this area of infec- 

 tion, which now becomes a prolific source of toxin production, the toxin 

 or poison is absorbed by the body-fluids, and the resulting toxemia is 

 chiefly responsible for most of the symptoms of the disease. 



Other microorganisms, such as staphylococci, pneumococci, and 

 streptococci, which may be unable to infect a healthy mucous membrane, 

 readily multiply in the necrotic tissue and add to the severity of the 

 local lesion, the lymphadenitis, and the toxemia. 



Rarely the diphtheria bacilli gain access to the blood-stream. The 

 severity and danger of diphtheria are dependent primarily upon the 

 strength and amount of toxin produced by the bacilli, and secondarily 

 upon the size and location of the primary lesion and the amount of anti- 

 toxin present in the patient's blood. A lesion in the larynx is far more 

 dangerous than one of equal size on a tonsil, because in the former the 

 edema and necrotic exudate obstruct the trachea and may produce 

 death by suffocation. On the other hand, the size of the local lesion alone 

 is not an indication of the severity of the infection, because virulent 

 bacilli in a small patch may produce more toxin than less virulent ones 

 in a larger area, and the degree of local tissue necrosis is not an absolute 

 indication of the toxicity of the soluble poison. Other things being 

 -equal, the patient who has most antitoxin, either naturally or acquired 

 as the result of a previous injection with antitoxin or of an attack of 

 diphtheria, will present least evidences of toxemia, although the bacilli 

 causing the infection may be most virulent. For example, the highly 

 virulent strain of diphtheria bacillus used extensively in the past eighteen 

 years in the production of antitoxin was isolated by Park and Williams 

 from the throat of a patient presenting no clinical symptoms other than 

 redness of the fauces and slight toxemia. 



The primary lesion of diphtheria is usually located in the throat 

 (tonsils, uvula, larynx), and frequently in the nose; more rarely the 

 ears, conjunctiva, vulva, prepuce, and wounds are the seats of primary 

 infection. 



. Treatment of Diphtheria. If, we were always certain of seeing our 

 patients on the first day of their illness, and if the disease could always 

 be diagnosed in this stage, the treatment of diphtheria would resolve 

 itself into an immediate dose of antitoxin and rest in bed for two or three 



