Preventable Diseases

by Woods Hutchinson

In a certain percentage of cases, however, it is due to a chronic lack of vigor and vitality; a lowering of the whole systemic tone, which may have existed from birth. In that case it is hardly to be expected that such an individual, becoming a parent, will be able to transmit to his or her offspring more vigor than he originally possessed. It is therefore probable that the children of a considerable percentage of tuberculous parents would not possess the same degree of resisting power against tuberculosis, or any other infection, as the average individual.

It is doubtful whether this factor of inherited lowered resistance plays any very important part in the propagation of tuberculosis, partly because it is comparatively seldom that consumptive marries consumptive, and such tendencies to lowered vigor and vitality as may be transmitted by one parent will be neutralized by the other; partly also because, by the superb and beneficent logic of nature, the pedigree of any disease is of the most mushroom and insignificant length, while the pedigree of health stretches back to the very dawn of time. In the struggle for dominance which takes place between the germ cells of the father and those of the mother, the chances are at least ten to one in favor of the old ancestral traits of vigor, of resisting power, and of survival. How deeply this idea is implanted in the convictions of the scientific world, the bitterly and widely debated biologic question whether acquired characters or peculiarities can under any circumstances be inherited clearly shows. Victory for the present rests with those who deny the possibility of such inheritance, and disease is emphatically an acquired character.

Truth here, as everywhere, probably lies between the extremes, and both biologists and the students of disease have arrived at practically the same working compromise, namely, that while no gross defect, such as a mutilation, nor definite disease factor, such as a germ, nor even a cancer, can possibly be inherited, yet, inasmuch as the two cells, which by their development form the new individual, are nourished by the blood of the maternal body, influences which affect the nutritiousness or healthfulness of that blood may unfavorably influence the development of the offspring.

Disease cannot be inherited any more than a mutilating defect, but the results of both, in so far as they affect the nutrition of the offspring in the process of formation, may be transmitted, though to a very much smaller extent than we formerly believed. In the case of tuberculosis, if the mother, during the months that she is building up the body and framework of a child, is in a state of reduced or lowered nutrition on account of consumption or any other disease, or has her tissues saturated with the toxins of this disease, it is hardly to be expected that the development of the child will proceed with the same perfection as it would under perfectly normal maternal surroundings.

However, even this influence is comparatively small; for one of the most marvelous things in nature is the perfection of the barrier which she has erected between the child before birth and any injurious conditions which may occur in the body of the mother. Here preference, so to speak, is given to the coming life, and whenever there is a contest for an adequate supply of nutrition, as, for instance, in cases of underfeeding or of famine, it is the mother who will suffer in her nutrition rather than the child. The unborn child, biologically considered, feeds upon the best she has to offer, rejecting all that is inferior, doing nothing and giving nothing in return.

How perfectly the coming generation is protected under the most unfavorable circumstances we have been given a striking object-lesson in one family of the lower animals. In the effective crusade against tuberculosis in dairy cattle waged by the sanitary authorities in Denmark, it was early discovered that the greatest practical obstacle to the extermination of tuberculosis in cattle was the enormous financial sacrifice involved in killing all animals infected. The disease was at that time particularly rife among the high-bred Jersey, Holstein, and other milking breeds. It was determined as a working compromise to test the truth of the modern belief that tuberculosis was transmitted only by direct infection, by permitting the more valuable cows to be saved alive for breeding purposes. They were isolated from the rest of the herd and given the best of care and feeding. The moment that their calves were born they were removed from them altogether and brought up on the milk of perfectly healthy cows. The milk of the infected cows was either destroyed or sterilized and used for feeding pigs.

The results were brilliantly successful. Scarcely one of the calves thus isolated developed tuberculosis in spite of their highly infected ancestry. And not only were they not inferior in vigor and perfection of type to the remainder of their breed, but some of them have since become prize-winners. The additional care and more abundant feeding that they received more than compensated for any problematic defect in their heredity.

As to the heredity of cancer, all that can be said is that the burden of proof rests upon those who assert it. It is really curious how widespread the belief is that cancer "runs in families," and how exceedingly slender is the basis of evidence for such a belief. There are so many things that we do not know about cancer that any positive statement of any kind would be unbecoming. It would be absurd to declare that a disease, of which the cause is still unknown, either is or is not inherited. And this is our position in regard to cancer. An overwhelming majority of the evidence so far indicates that it is not a parasite; if it were, of course, we could say positively that it is not inherited. Although we are getting a discouraging degree of familiarity with the process and clearly recognize that it consists chiefly in the sudden revolt or rebellion of some group of cells, a tendency which quite conceivably might be transmitted to future generations, yet it is highly improbable, on both biological and pathological grounds, that such is the case. If this rebellious tendency were transmitted we should at least have the right to expect that it would appear in the cells of the same organ or region of the body. It is a singular fact that in all the hundreds of cases in which cancer has appeared in the child of a cancerous parent it has almost invariably appeared in some different organ from that affected in the parent.

For instance, cancer of the lip in the father may be followed by cancer of the liver in the son or daughter, while cancer of the breast in the mother will be followed by cancer of the lip in a son. Further than this, the percentage of instances in which cancer appears in more than one member of a family is decidedly small, considering the frequency of the disease.

I took occasion to look into the matter carefully from a statistical point of view some ten or twelve years ago, and out of a collection of some fifty thousand cases of cancer less than six per cent were found to give any history of cancer in the family. And this, of course, simply means that some one of the relatives of the patient had at one time developed the disease.