60 THE PRINCIPLES OF IMMUNOLOGY 



500 units of tetanus antitoxin every ten days for four doses. It was 

 further recommended that the serum be given subcutaneously not 

 more than seven days and not less than two days before any oper- 

 ative procedure upon an old wound. If haste is necessary the serum 

 may be given intramuscularly twelve hours before operation. Ob- 

 viously this suggests the possibility that organisms may remain 

 dormant in wounds, to become active at a later period ; it is further be- 

 lieved that the antitoxin is probably eliminated in about ten days, 

 and the later doses of immune serum are given in order to neutral- 

 ize any toxin that might be produced subsequently. 



Golla tabulated the following cases not receiving prophylactic 

 doses of antitoxin: 



Incubation period Cases Mortality 



i- 7 days 17 (32.7 per cent.) 82.5 per cent. 



8-14 days 24 (46.2 per cent.) 79.0 per cent. 



15-21 days 6 (11.5 per cent.) 54.0 per cent. 



Over 21 days ' 5(9-6 per cent.) 



This shows that the commonest incubation period is eight to 

 fourteen days, and also illustrates the fact that the shorter the incu- 

 bation period the more serious is the disease. In another series of 

 patients who had received prophylactic treatment with serum, the 

 following data were collected ; 



Incubation period Cases Mortality 



i- 7 days 61 (22.6 per cent.) 75.5 per cent 



8-14 days 93 (34.6 per cent.) 70.0 per cent. 



15-21 days 33 (12.2 per cent.) 60.8 per cent. 



21-30 days 19 (7.05 per cent.) 62.8 per cent. 



30-40 days 14 ( 5.2 per cent.) 57.0 per cent. 



40-50 days 9 ( 3.3 per cent.) 33.4 per cent. 



50-60 days 18 ( 6.7 per cent.) 27.7 per cent. 



Over 60 days 22 ( 8.2 per cent.) 40.8 per cent. 



In the Franco-Prussian War only 5.7 per cent, exhibited an in- 

 cubation period of more than twenty-one days, whereas, according 

 to Golla, in the last war 30.54 per cent, showed an incubation period 

 of more than twenty-one days. In summary it may be stated that 

 the introduction of prophylactic injections of the tetanus antitoxin 

 not only reduces the incidence of the disease, but also lengthens 

 the incubation period, and therefore reduces the mortality. The 

 delay in incubation usually leads to more moderate symptoms as 

 well as reduces mortality, and oftentimes the cases exhibit tetanic 

 spasms in only one extremity. 



Treatment of Tetanus with Serum. When the disease has de- 

 veloped, treatment must be prosecuted vigorously. In the earlier 

 years of its employment subcutaneous, intramuscular, and intra- 

 venous administration was practised, but arguing from the nature of 

 the disease it was soon suggested that intrathecal injections be given. 

 This suggestion was followed by experimental and clinical investi- 

 gation, and in the hands of the majority of workers the method has 

 been found to have great value. Park and Nicoll injected twice the 



