SERUM DISEASE. 91 



serum and another type which follows the second and subsequent 

 injections of serum. 



Serum disease following the first injection of serum mani- 

 fests itself after an incubation period of eight to twelve days, 

 and is largely independent of the amount of serum injected. Of 

 the symptoms of this disease, fever is the most constant, lasting 

 usually during the entire course of the disease. The height of 

 fever, however, is not an indicator of the disease, but from the 

 curve of the temperature a prognosis can be made, because the 

 temperature drops by lysis. Together with fever there is usually 

 an exanthema, appearing most frequently as an urticaria. This 

 appears first about the point of injection, later it is distributed 

 symmetrically and usually itches severely. At times there is swell- 

 ing of the glands, especially of the glands found in the region in- 

 jected. The symptoms of pain in the glands are of prognostic 

 value, in as much as the pain usually disappears or abates before 

 the size of the gland decreases. During the period of incuba- 

 tion the leucocytes are increased in number, but during the height 

 of the disease the number of leucocytes is markedly diminished. 

 Joint pains are found in a small percentage of the cases of serum 

 disease. The metacarpal, hand and knee joints, are most fre- 

 quently effected. Usually these pains do not last long. In cer- 

 tain cases there is edema, but albuminuria is seldom or never 

 present. The mucous membrane is seldom effected, which dis- 

 tinguishes the condition from scarlet fever and measles. The 

 disease is further distinguished from measles by the absence of 

 Koplick spots, coryza, conjunctivitis and increased efflores- 

 cence about the point of injection. From scarlet fever the con- 

 dition is distinguished by its non-communicability by contact, and 

 absence of scaling, nephritis and angina. 



The disease following the second and subsequent injections 

 of serum varies somewhat with the interval between injections. 

 If an injection of serum is made from twelve to forty days 

 after a preceding one, the incubation period is very short, the 

 disease appearing at times in less than one hour after injec- 

 tion. If the interval between injections is from forty days to 

 six months, there may be an immediate reaction, or else an im- 

 mediate reaction with another reaction six to eight days later. 

 If the interval between injections is over six months there is usu- 



