INFLUENCE OF DISEASE UPON MILK 123 
ities all cases of typhoid fever and other infectious dis- 
cases occurring in their own families and among their 
employees or in the families of the latter. 
PARATYPHOID FEVER 
Paratyphoid fever is also transmitted by milk, but 
less frequently than typhoid fever. The milk may be 
infected directly with the paratyphus bacilli by contact 
with persons affected with the disease or indirectly by 
polluted water being used to wash the milk vessels, uten- 
sils, and bottles. Water may be contaminated by fecal 
matter from infected persons. 
DIPHTHERIA 
A number of milk-borne epidemics of diphtheria are 
on record, although this disease has been less frequently 
disseminated by milk than typhoid fever. The diph- 
theria bacilli are present in the oral cavity and on the 
nasal mucous membrane of persons affected with the 
disease and may persist in these locations for months 
after the patient has apparently recovered. Persons 
who have attended diphtheria patients may also carry 
the bacilli. Infected persons may infect the milk directly 
or indirectly. In the beginning of some cases of diph- 
theria, the throat is apparently normal or only slightly 
affected. These cases and cases of chronic nasal diph- 
theria are most difficult to diagnose from clinical symp- 
toms. Because of the occurrence of cases of this type 
and the continuance of the bacilli in some individuals 
after the subsidence of clinical symptoms, it is not possible 
to guard entirely against the occasional infection of milk 
by the diphtheria bacillus. But the danger will be greatly 
reduced if prompt attention is given to all cases of sore 
