In short, our motto may be said to be, "Take care of the patient, and the disease will take care of itself."
Though pneumonia is one of our most serious and most fatal of diseases, yet it is one over whose cause, spread, and cure we are obtaining greater and greater control every day, and which certainly should, within the next decade, yield to our attack, as tuberculosis and typhoid are already beginning to do.
CHAPTER IX
THE NATURAL HISTORY OF TYPHOID FEVER
Why should not a disease have a natural history, as well as an individual? At first sight, this might appear like a reversion to the old, crude theory of disease as a demonic obsession, or invasion by an evil spirit, of which traces still remain in such expressions as, "She was seized with a convulsion," "He was strong enough to throw off the illness," "He was attacked by a fever," etc. But apart entirely from such conceptions, which were perfectly natural in the infancy of the race, while clearly recognizing that disease is simply a perverted state of nutrition or well-being in the body of the patient, a disturbance of balance, so to say, yet it is equally true that it has a birth, an ancestry, a life-course, and a natural termination, or death.
This recognition of the natural causation and development of disease has been one of the greatest triumphs, not merely of pathology, but of intelligence and rationalism. It has done more to diminish that dread of the unknown which hangs like a black pall of terror over the mind of the savage and the semi-civilized mind than any other one advance. It contributes enormously to our courage, our hopefulness, and our power of protection in more ways than one: first of all, by revealing to us the external cause of disease, usually some careless, dirty, or bad habit on the part of an individual or of the community, and thus enabling us to limit its spread and even exterminate it; secondly, by assuring us that nearly all diseases, excepting a few of the most obstinate and serious, have not only a definite beginning, but a definite end, are, in fact, if left to themselves, self-limited, either by the exhaustion and loss of virulence of their cause, or by the resisting power of the body.
All infectious diseases, and many others, tend to run a definite course of so many days, or so many weeks, within certain limits, and at least ninety per cent of them tend to terminate in recovery. It is a most serious and fatal disease which has a death-rate of more than twenty per cent. Typhoid, pneumonia, diphtheria, and yellow fever all fall below this, smallpox barely reaches it, and only the bubonic plague, cholera, and lockjaw rise habitually above it. The recognition of this fact has enormously increased the efficiency of the medical profession in dealing with disease, by putting us on the track of imitating the methods which the body itself uses for destroying, or checking the spread of, invading germs and leading us to trust nature and try to work with her instead of against her. Our antitoxins and anti-serums, which are our brightest hope in therapeutics at present, are simply antidotes which are formed in the blood of some healthy, vigorous animal against the bacillus whose virulence we wish to neutralize, such as that of diphtheria or septicemia.
Diphtheria antitoxin, for instance, the first and best known triumph of the new medicine, is the antidotal substance formed in the blood of a horse in response to a succession of increasing doses of the bacilli of diphtheria. Similar antidotal substances are formed in the blood in all other non-fatal cases of infectious diseases, such as typhoid, pneumonia, blood-poisoning, etc.; and the point at which they have accumulated in sufficient amounts to neutralize the poison of the invading germs, forms the crisis, or "turn" of the disease. So that when we speak of a disease "running its course," we mean continuing for such length of time as the body needs to produce anti-bodies in sufficient amounts to check it.
The principal obstacle to the securing of antitoxins like that of diphtheria for all our infectious diseases is, that their germs form their poison so slowly that it is difficult to collect it in sufficient amounts to produce a strong concentrated antitoxin in the animal into which it is injected. But the overcoming of this difficulty is probably only a question of time.