The house fly is now regarded as one of the important means of spreading typhoid fever, indeed it is often called the "typhoid fly." The infectious material deposited in an open vault may serve as a source from which the fly carries the organisms to milk and other foods in the house or elsewhere. The protection of vaults and the screening of every place where human food is handled or prepared is the only protection.
It should be emphasized that in the case of the tubercle organism, no growth ever occurs in milk, but with the typhoid bacillus growth is possible. It thus needs but the contamination of the milk with the smallest particle of material containing them to seed the milk. By the time it is consumed it may contain myriads of the disease-producing organisms.
Diphtheria. This is a highly infectious disease, affecting children primarily and is characterized by the formation of membranous exudates in the throat and air passages, which are teeming with the causal organism, the diphtheria bacillus. This organism is capable of forming highly toxic products, and it is to the effect of these poisons that its fatal result is generally due. The organism is thrown out from the body, in the main, through the mouth, the surroundings of the patient being infected directly from the air, and indirectly, by contact with polluted hands, lips, etc. Thus, the germ deposited from the lips of a case of the disease, on the common drinking cup, slate, lead pencils, toys, and the like, may easily pass from child to child. Not infrequently, the causal organism persists in the throat long after all evidence of membranous growth has subsided, and so the child itself may act as a "bacillus carrier."
Not so many epidemics of diphtheria as of typhoid have been traced to milk, but the evidence is sufficient to indict milk as a disseminator of contagion. In several cases, the diphtheria germ has actually been isolated from infected milk supplies. Actual growth of the diphtheria germ is said to take place in raw milk more rapidly than in sterilized.
Scarlet fever. While the germ of scarlet fever has not yet been isolated, and therefore its life history in relation to milk cannot be depicted so accurately, yet milk-borne epidemics of this disease are sufficiently abundant to leave no doubt but that this food medium may sometimes serve as a means of disseminating such troubles. Infection of the milk doubtless comes in the case of this disease from direct contact with a person suffering from the malady.
Cholera. While this disease is of no practical importance in America, owing to its relative infrequency, yet outbreaks of cholera have been traced to milk, in spite of the fact that the causal organism is more sensitive to the action of acids than most disease-producing bacteria. In several outbreaks in India, milk has been the medium through which the disease was spread. Generally, infection of the milk has been traced to the use of polluted water.
Children's diseases. An exceedingly high mortality exists among infants and young children in the more congested centers, especially during the summer months. In the main, the cause of these troubles is due to intestinal disturbances, and unquestionably, the character of the food enters largely into the problem. As milk constitutes such a large proportion of the diet of the young, and is so susceptible to bacterial invasion, it would appear probable that much of the trouble of this character is due to the condition of this food supply. This is rendered more probable when it is remembered that bottle-fed infants suffer a much higher mortality than breast-fed children, due probably to the fact that the lengthened period between the time the milk is drawn and consumed permits of abundant bacterial growth. Much carelessness also prevails among the poor in cities, relative to the care of utensils used in feeding children. Nursing bottles often serve to infect the milk. Where milk is pasteurized, or properly heated, it has been found that the mortality rate has been greatly reduced, thus indicating that the condition of the milk was directly responsible for the death rate. In fact, the mortality from these indefinite intestinal troubles probably exceeds that from all of the specific infectious diseases combined. Improved care in handling this sensitive food supply will do much to better conditions in this direction.
Ptomaine poisoning. Acute poisoning affecting adults as well as children, not infrequently occurs from the use of foods of various kinds. Cases of poisoning arising from the use of shell fish, canned meats, ice cream, cheese, and other dairy products, are from time to time reported. These troubles are due to the production of toxic compounds, in the main, probably caused by bacterial decompositions. Often such troubles may affect a number of persons, as at banquets and such gatherings, thereby giving the semblance of an epidemic. While such troubles are doubtless to be ascribed to bacterial activity, they are not transmissible from person to person.
In the case of troubles arising from ice cream and such confections, the probable cause is due to the storage of milk or cream under refrigerator conditions, where germ growth can go on in the product, and yet the temperature be sufficiently low to prevent the usual acid fermentations.