78 
HOUSEHOLD BACTERIOLOGY 
Point of 
Attack 
Method of 
Infection 
Precautions 
Outside of the body disease producing bacteria may 
remain alive under very varying circumstances, but as 
a rule they do not multiply as most of them require a 
temperature equal to that of the body. There are ex¬ 
ceptions, as, for example, the growth of the bacteria 
of typhoid fever in milk, and many others which 
reproduce in the laboratory under artificial conditions. 
The lower animals may serve as a breeding ground 
for some of the disease germs dangerous to man. 
For most of these germ diseases there is some spe¬ 
cial portion of the body which is more susceptible than 
any other. We associate pneumonia and usually tu¬ 
berculosis with the lungs, diphtheria with the throat, 
typhoid fever with certain parts of the intestines. From 
these most usual points of attack may be inferred the 
most common methods of infection. 
When the seat of the disease is some portion of the 
respiratory system—nostrils, throat or lungs—it is 
probable that dust entering with the inhaled air car¬ 
ried the germ, or it came by contact with the lips, as 
in kissing; when it is in the digestive tract, that food 
or drink was the vehicle; or when in the skin or outer 
tissues, that there was actual contact with the germ 
either as dust, dirt, or germ bearing material from a 
previous case of the disease, which gained entrance 
through some puncture or a break in the skin. 
When we remember that all such diseased condi¬ 
tions due to germs are infectious, we shall exercise 
great care in preventing contact with the diseased 
