396 INFECTION AND IMMUNITY. 



The reaction varies in severity with the amount 

 of serum used but individual variation and differ- 

 ences in the serum are the most important factors. 

 The reaction following a second injection v. Pir- 

 quet and Schick divide into (a) immediate, 

 appearing after a few hours, or (b) delayed, 

 appearing after a few days or a week. The symp- 

 toms are similar to those following a primary 

 injection but are more likely to be severe and may 

 be accompanied by vomiting, convulsions, collapse 

 and,, rarely, death. 



The abnormal reactions following a second 

 injection are more likely to appear when the 

 patient has had a reaction after the primary injec- 

 tion; secondly, when large amounts of serum have 

 been given in the primary injection; and thirdly, 

 with a history of asthma (especially in asthma in 

 which the attacks are brought on by proximity to 

 horses) or hay fever. 



It has been suggested that, in cases necessitating 

 second injections of antitoxin, a small amount, 

 1 c.c. or less, be given as a test dose to be followed 

 by the necessary therapeutic dose twenty-four 

 hours later. 



It is important to be sure that the antitoxin is 

 not injected into the vein because of the fact that 

 anaphylactic symptoms are produced as much 

 more readily by intravenous injections. This can 

 be avoided by preliminary aspiration just before 

 injection to see that blood does not enter the 

 syringe. 



Eosenau and Anderson have demonstrated the 

 presence of anaphylactin in the blood of men who 

 have been injected with antitoxic horse serum. 



