INFLUENCE OF DISEASE UPON MILK 121 
TYPHOID FEVER 
Typhoid fever is more frequently spread by milk than 
any of the other infectious diseases of man except tuber- 
culosis. As a carrier of typhoid infection, milk is second 
only to water, although the cases caused by infected water 
greatly outnumber those resulting from infected milk. 
Milk may be infected with the Bacillus typhosus in sev- 
eral ways. The organisms may be introduced into milk 
when infected water is used to wash the milk vessels and 
utensils. Infected water may contaminate the milk when 
there is a leak in the milk cooler or when a can of milk 
is submerged in such water to cool. Water in open or 
thin-walled springs, surface wells, and in streams receiv- 
ing surface drainage may be readily infected by excre- 
tions from typhoid fever patients, convalescents, and 
chronic bacilli carriers. Milk bottles from houses where 
the disease exists may be a source of infection; one or 
two infected bottles may contaminate the water in which 
they are washed or rinsed, and this water will infect other 
bottles washed in it. A few bacilli introduced into a 
vessel or bottle by infected water will multiply rapidly 
when milk is placed in it, for the Bacillus typhosus grows 
abundantly in milk. Milk may be infected directly when 
the cows are milked or the milk or milk vessels are handled 
by persons affected with the disease, by convalescents, 
by chronic bacilli carriers, and by those attending typhoid 
fever patients. The greatest danger of direct infection 
is from those cases in which the disease is of such a mild 
type that it is not recognized, the so-called walking 
typhoid, and from chronic bacilli carriers, i.e., individuals 
who continue to excrete typhoid bacilli in the feces and 
urine after they have recovered from the disease. It is 
estimated that 2 to 4 per cent. of typhoid fever patients 
