SERUM DISEASE 609 



to the horse serum itself, for, as was early shown by Johannessan, 1 

 Bokay, 2 and others, they may manifest themselves after the injection 

 of sterile normal horse serum. The serum, moreover, of certain horses 

 appears to be more likely than that of others to cause these symptoms, 

 thus accounting for the fact that one lot of antitoxin will cause a higher 

 percentage of serum sickness than will another. A concentrated serum 

 is not so likely to produce serum sickness as whole serum, owing partly 

 to the fact that smaller doses of it are given. According to Rolleston and 

 Ker, the frequency of serum sickness is, as a rule, in direct proportion to 

 the amount of serum given, and in inverse ratio to the severity of the 

 attack; in other words, we may expect to encounter it most often in 

 mild and moderately severe cases that have received very liberal dosages 

 of serum. 



The Nature of Serum Disease. Serum sickness is regarded as a 

 true anaphy lactic phenomenon. We are prone to call the severe, fatal, 

 and rare instances of death following serum injection examples of anaphy- 

 laxis, and to regard serum sickness as a different condition. Both are 

 fundamentally the same, except that in the first instance the body-cells 

 are for some unknown reason unduly and highly anaphy lactic. Fortu- 

 nately, this undue hyper sensitiveness is frequently foreshadowed by the 

 asthmatic or hay-fever-like attacks which the susceptible person may exhibit 

 when he enters stables or is otherwise around horses. It goes without saying 

 that horse serum should never be given to such persons. 



While serum sickness is usually due to horse serum for the reason 

 that the horse is so commonly employed in the preparation of various 

 curative serums, the serum of the ox, rabbit, and other animals may in- 

 duce the same train of symptoms in addition, in some instances, to 

 producing a direct toxic effect. 



An immediate reaction rarely follows the first injection of serum un- 

 less the patient is one of those unfortunate but rare persons who in some 

 manner have been rendered highly sensitive to horse protein. In the ma- 

 jority of instances symptoms do not develop for from eight to twelve 

 days, during which time the antibody is being produced. When antibody 

 formation has reached a certain point, it reacts upon any of the horse 

 serum that may persist in the cells or circulation, producing the anaphy- 

 lactic reaction. If the dose of serum has been small, antibody forma- 



1 Deutsch. med.Wchnschr., 1895, 21, 855. 



2 Jahresb. f. Kindesh., 1897, xliv, 133. 

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