SPECIAL BACTERIOLOGY 
149 
through swallowing the bacilli either directly in food, 
water, ice, milk, vegetables, etc., or indirectly by soiling 
fingers with patient’s excreta, or using the same utensils, 
glassware, etc. 
The prophylactic measures, therefore, consist of thor¬ 
ough disinfection of stools, urine, bed linen, etc., as de¬ 
scribed in detail in the chapter on Practical Disinfection; 
since typhoid fever is essentially a “wat£r borne” dis¬ 
ease, communities should guard the purity of their 
water supply, most effectively by having a modern filtra¬ 
tion plant, and removing the source of contamination and 
sewage pollution; milk supply should be closely inspected 
and flies should be destroyed as they very often contami¬ 
nate our food—screening is necessary. 
During a typhoid epidemic drinking only boiled water 
is a wise precaution. The nurse attending a typhoid pa¬ 
tient should receive prophylactic typhoid vaccination, 
which is the best prevention. 
VI. Mechanism of Infection and Immunity 
Typhoid bacillus produces an endotoxin; the antibodies 
produced are bacteriolysins, precipitins and agglutinins, 
one attack usually renders a person immune to subse¬ 
quent attacks. 
As regards the agglutinins, a few words must be said 
here about this: 
The blood of most of normal individuals has slight 
agglutinating property, but this is enormously increased 
during and following the diseases or by artificial immuni¬ 
zation (vaccine). From the fact that the typhoid, para¬ 
typhoid and the colon bacilli are all closely related to 
each other both morphologically (all being Gram-nega¬ 
tive, motile, flagella-possessing bacilli) and in their reac- 
