DISEASE GERMS IN MILK L177 
Diphtheria is produced by a well-known bacillus (Fig. 40). 
Here again there seems some doubt whether cows have the dis- 
ease. It is certain, however, that the milk may become second- 
arily infected through convalescent diphtheria patients working 
in the dairy and handling the milk. Some in- 
stances of diphtheria have been traced to such a ys) 
cause. 0 Le : 
Diarrheal Diseases—Besides the diseases 
mentioned, milk is responsible for a portion Of Bye 4o ont one 
those obscure diseases characterized by diarrheal cuphthersa bacter- 
troubles, which are especially prevalent in warm 
weather. Among these are cholera infantum, which is responsible 
for the death of so many children, and summer complaint, which 
is less serious. These troubles are not yet so well understood as 
the others we have mentioned. They do not appear to be caused 
by any single specific bacterium, but are probably due to the 
excessive multiplication of a number of certain kinds of bacteria 
in the milk. That they are due to milk bacteria is proved by the 
facts that (1) they occur most frequently at the seasons of the 
year when milk bacteria are most numerous; (2) they are more 
prevalent among infants fed upon cow’s milk than among breast- 
fed children. What kinds of bacteria are at fault in the production 
of these diseases we do not know. Quite a number of bacteria 
are found in milk which produce poisonous secretions and which 
may be agents in the production of these obscure diseases. For 
the purpose of our discussion it is sufficient to state that they are 
probably due to putrefactive bacteria, which are the bacteria 
of filth. Anything which increases the amount of filth in the milk 
will have a tendency to increase the amount of such troubles, and 
any advance in cleanliness will have an influence in the opposite 
direction. 
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