534 Major W. J. Tulloch. Serological Types of B. tetani in 



percentage incidence of the disease among men infected is higher, and the 

 death rate is also considerably higher. 



These facts are graphically shown in fig. 3. 



lo 20 ao ^o ao oo to 











u 







imm 1 





















U_B 

















. from Caoee 

 ..from Ind/i 

 Wounds 



'ferenh' 





m 























Fig. 3. — Tj'pes of B. tetani isolated from cases of the disease compared with those isolated 

 from " indifferent ■wounds," expressed as percentage of the total numbers isolated 

 from each source. 



If the figures of Table II be considered as an index pf the prevalence of 

 the various Types, it can be assumed that, of x wounded men, one falls a 

 victim to tetanus ; it then follows that the number of wounded men who 

 will have been infected with Type I bacilli before one case of the disease 

 occurs will be 15/100 x a;. Similarly, Type II will be 2/100 x a, and 

 Types III and IV 1/100 x:<;. This is indicated graphically in fig. 4. 



5 10 15 









I 









■ m 









- K 









Fig. 4. — Estimation of the number of men who must be infected with each type of the 

 bacillus in order to produce one case of the disease. 

 The columns indicate the numbers of infections x a'/IOO. 



