Preventable Diseases. Woods Hutchinson
Take out both the lens and the iris and the choroid coat of the eye will reproduce both.
We are in the A, B, C class in powers of repair by comparison with the angleworm, the lobster, or the salamander. Yet we are not without gruesome echoes of this lost power of regeneration in that our whole brood of tumors, including the deadly cancer and sarcoma, are due to a strange resumption, on the part of some little knot of our body-cells, of the power of reproducing themselves or the organ in which they are situated, without any regard to the welfare of the rest of the body. Cancer is, in one sense, a throwing off of the allegiance to the body-state and a resumption of amphibian powers of independent growth on the part of certain groups of our body-cells—literally, a "rebellion of the cells."
These are but a handful of scores of instances that could be adduced, showing that the majority of the processes upon which we rely in combating disease and preserving life are the result of the hereditary experiences of our cells. Intelligent physicians are receding completely from that curiously warped and jaundiced view which led us to regard heredity chiefly as a factor in the production of disease. It was, perhaps, natural enough, since it was inevitably only its injurious, or, so to speak, malicious, effects which were brought to our attention to be corrected. But, just as in the growth of our ethnic religions it is Evil that is worshiped first as strongest and most aggressive, and the recognition of the greater power of good comes only at a later stage, so it has been in pathology.
Not only do we regard heredity as a comparatively small and steadily receding factor in the production of disease, but we fully and frankly recognize it as the strongest and most important single force in its prevention. All our processes of repair, all the reactions of the body against the attack of accident or of disease, are hereditary endowments, worked out with infinite pains and labor through tens of thousands of generations. The utmost that we can do with our drugs and remedies is to appeal to and rouse into action the great healing power of nature, the classic "Vis medicatrix Naturæ," an incarnation of our past experiences handed down by heredity. Enormously valuable and important as are the services to human welfare, health, and happiness which can be rendered by the destruction of the living external causes of disease and the prevention of contagion, our most permanent and substantial victories are won by appealing to and increasing this long-descended and hard-won power of individual resistance.
"But," says some one at once, "I thought there were a large number of hereditary diseases." Fifty years ago there were a score of such, twenty years ago the score had sunk to five or six. Now there is scarcely one left. There is no known disease which is directly inherited as such. There is scarcely even a disease in which we now regard heredity as playing a dominant or controlling part. Among the few diseases in which there is serious dispute as to this are tuberculosis, insanity, epilepsy, and cancer.
Then there are diseases which for a long time puzzled us as to the possibility of their inheritance, but which have now resolved themselves clearly into instances of the fact that a mother who happens to contract an acute infectious disease of any sort may communicate that disease to the unborn child. If this occurs at an early stage of development the child will naturally be promptly killed. In fact, this is the almost invariable result in smallpox and yellow fever. If, on the other hand, development be further advanced or the infection be of a milder character, like scarlet fever or syphilis, the child may be born suffering with the disease or with the virus in its blood, which will cause the disease to develop within a few days after birth. This, however, is clearly not inheritance at all, but direct infection. We no longer use the term hereditary syphilis but have substituted for it the word congenital, which simply means that a child is born with the disease.
There is no such thing as this disease extending "unto the third and fourth generation," like the wrath of Jehovah. One fact must, of course, be remembered, which has probably proved a source of confusion in the popular mind, and that is its extraordinary "long-windedness." It takes not merely two or three weeks or months to develop its complete drama, but anywhere from three to thirty years, so that it is possible for a child to be born with the taint in its blood and yet not exhibit to the non-expert eye any sign of the disease until its eighth, twelfth, or even fifteenth year.
The case of tuberculosis is almost equally clear-cut. In all the thousands of post-mortem examinations which have been held upon newborn children and upon mothers dying in or shortly after childbirth, the number of instances of the actual transference of the bacilli of tuberculosis from mother to child could be counted upon the fingers of two hands. It is one of the rarest of pathologic curiosities and, for practical purposes, may be entirely disregarded. When tuberculosis appears in several members of a family, in eight cases out of ten it is due to direct infection from parents or older children. This is strikingly brought out in the admirable work done by the Associated Dispensaries for Tuberculosis of the Charity Organization Society of New York.
One of the first steps in advance which they took was to establish in connection with every clinic for tuberculosis an attendant nurse, whose duty it was to visit the patients at their homes and advise and instruct them as to improvements in their methods of living, ventilation, food, and the prevention of infection.
It was not long before these intelligent women began to bring back reports of other cases in the same family. Now the procedure is regularly adopted, whenever a case presents itself, of rounding up the remainder of the family group for examination, with the astounding result that where a mother or father is tuberculous, from twenty to sixty per cent of the children will be found to be suffering from some form of the infection. Instances of three infected children out of five living in the same room with a tuberculous mother are actually on record.
No one can practice long in any of our great climatic health resorts for tuberculosis, like Colorado or the Pacific Slope, without coming across scores of painful and distressing instances of children of tuberculous parents dying suddenly in convulsions from tuberculous meningitis, or by a wasting diarrhœa from tuberculosis of the bowels, or from a violent attack of distention of the bowels due to tuberculous peritonitis. The favorite breeding-place of the tubercle bacillus is unfortunately in the home.
On the other hand, while the vast majority of cases of so-called hereditary tuberculosis are due to direct infection, and may be prevented by proper disposal of the sputum and other methods for avoiding contagion, there is probably a hereditary element in the spread of tuberculosis to this degree: that, inasmuch as all of us have been exposed to the attack and invasion of the tubercle bacillus, not merely scores, but hundreds of times, and have been able to resist or throw off that attack without apparent injury, the development of an invasion of the tubercle bacillus sufficiently extensive to endanger life is, in nine cases out of ten, in itself a proof of lowered resisting power on the part of the patient. This may be, and often is, only temporary, due to overwork, underfeeding, overconfinement, or that form of gradual suffocation which we politely term inadequate ventilation.
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