The figures of the foundling hospital show the real danger of unprotected cows' milk.
The conclusion from these studies is inevitable, namely, that in children, in addition to the large number of deaths which occur from bovine infection, there are many cases of infection resulting in deformities, necessitating operations more or less severe in character and which frequently leave the patient disfigured permanently.
It must be plain to all, from these recent developments, that too much has been made of the slight differences in cultural characteristics, in morphology, and in virulence which have been observed in some cases in comparing the human and the bovine bacilli. The observations were interesting, and it was important that they be followed up until their significance was made entirely clear, but it was an almost unpardonable error, from a sanitary point of view, to promulgate sweeping generalizations calculated to arrest and abolish important measures for preventing human tuberculosis before the soundness of these generalizations had been established by a thorough course of experimentation.
When Koch said in the British Congress on Tuberculosis that he should estimate the extent of infection by the milk and flesh of tuberculous cattle and the butter made of their milk as hardly greater than that of hereditary transmission, and that he therefore did not deem it advisable to take any measures against it, he went far beyond what was justified by any experiments or observations which he reported, and he did a great deal of harm, which will be manifested for years to come, to those who endeavor to guard the human race from the dangers of animal tuberculosis. The researches which have been alluded to make these dangers more definite and certain than they have appeared before, and sanitarians should therefore most earnestly endeavor to counteract the erroneous and harmful impression which was made by Koch's address at London and his subsequent address at the International Conference on Tuberculosis at Berlin.
VACCINIA OR COWPOX.
Variola of cattle, more correctly vaccinia, is a contagious disease of cattle which manifests its presence through an elevation of temperature, a shrinkage in milk production, and by the appearance of characteristic, pustular eruptions, especially upon the teats and udders of dairy cows. Although this is a contagious disease, strictly speaking, it is so universally harmless and benign in its course that it is robbed of the terrors which usually accompany all spreading diseases, and is allowed to enter a herd of cattle, run its course, and disappear without exciting any particular notice.
The contagion of cowpox does not travel through the air from animal to animal, but is transfused only by actual contact of the contagious principle with the skin of some susceptible animal. It may be carried in this manner, not alone from cattle to cattle, but horses, sheep, goats, and man may readily contract the disease whenever suitable conditions attend their inoculation.
An identical disease frequently appears upon horses, attacking their heels, and thence extending upward along the leg, producing, as it progresses, inflammation and swelling of the skin, followed later by pustules, which soon rupture, discharging a sticky, disagreeable secretion. Other parts of the body are frequently affected in like manner, especially in the region of the head, where the eruptions may appear upon lips and nostrils, or upon the mucous surfaces of the nasal cavities, mouth, or eyes.
Variola of the horse is readily transmitted to cattle, if both are cared for by the same attendant, and, conversely, variola of cattle may be carried from the cow to the horse on the hands of a person who has been milking a cow affected with the disease.
The method of vaccination with material derived from the eruptions of cowpox as a safeguard against the ravages of smallpox in members of the human family is well known. The immunity which such vaccination confers upon the human subject has led many writers to assert that cowpox is simply a modified form of smallpox, whose harmless attack upon the human system is owing to a certain attenuation derived during its passages through the system of the cow or horse. The results of numerous experiments which have been carried out for the purpose of determining the relationship existing between variola of the human and bovine families seem to show, however, that although possessing many similar characteristics, they are nevertheless distinct, and that in spite of repeated inoculations from cattle to man, and vice versa, no transformation in the real character of the disease ever takes place.