1 62 BACTERIA IN MILK. 
Tuberculosis. This subject will be considered in a separate 
chapter. 
Typhoid Fever. Typhoid fever is produced by a well-known 
bacterium primarily inhabiting the human intestine (Fig. 40). 
Inasmuch as the cow is not subject to typhoid fever, milk, when 
freshly drawn, will never contain typhoid bacilli. This disease, 
therefore, bears quite a different relation to dairy matters from 
tuberculosis. Milk, if infected with tuberculosis bacilli, contains 
them when freshly drawn, and secondary infection is 
a matter of no significance. But fresh milk never 
contains typhoid bacilli, and if they are present in the 
milk, they come wholly from secondary contamination. 
FIG. 40. The chief sources of these secondary contaminations 
bacillus^ ( are: I - Direct contact with persons who have or are 
recovering from the disease. It is well known that 
patients may, after recovery from this disease, carry around the living 
bacilli for a long time; "bacillus carriers" they are called. In other 
cases the patient may be so slightly sick with the disease as to keep 
about his work, having what is called "walking typhoid." If people 
from either of these classes are employed in the dairy, they will be 
pretty sure to infect with typhoid fever germs whatever dairy utensils 
they handle. 2. Patients who are sick enough to be confined in 
bed eliminate large numbers of bacilli in their excretion, and this, 
together with clothing soiled by it, may be carelessly handled by 
some one who is employed in the dairy. The chance of milk infec- 
tion from such persons is, then, very great, and no one who has 
anything to do with the care of a typhoid fever patient should be 
allowed to have any contact with the dairy. 3. Infected water is 
a common source of contamination. This does not mean that 
the milk is necessarily watered; but milk may become infected 
by simply allowing the cans to stand in impure water while they are 
cooling or by rinsing the cans in such water after they have been 
washed. There are also other secondary sources. That the danger 
from these sources is real and not imaginary, may be judged from 
the fact that already at least three hundred typhoid epidemics have 
been traced to milk. 
