IOWA ACADEMY OF SCIENCE 17 



high (now 3 months after vaccination) in our cases. Clinical evidence 

 seems to indicate that the immunity will last at least three years. Lab- 

 oratory tests indicate that the quantity of specific antibodies formed in 

 the body after vaccination is higher than that developed during the 

 course of an attack of typhoid fever and inasmuch as one attack of 

 typhoid fever apparently confers an immunity that lasts a lifetime, it 

 is quite probable that one vaccination (three doses) will be quite as 

 efficient for as long a time. 



At the present time antityphoid vaccination is practically limited to 

 the personel of the army. They are especially subject to the disease 

 by virtue of being frequently stationed in temporary quarters under 

 unsanitary conditions. In view, however, of the harmlessness of the 

 process and the valuable protection which it affords, vaccination against 

 typhoid fever may well be much more widely extended especially among 

 individuals liable to exposure to infection, as physicians and nurses or 

 those who do considerable traveling. When typhoid fever is prevalent 

 in a community it may well be applied to citizens in general. 



