Preventable Diseases

by Woods Hutchinson

The situation is, however, far from being as serious and alarming as it might appear, simply from this bald statement of statistics. First of all, because the forging ahead of pneumonia has been due in greater degree to the falling behind of tuberculosis than to any actual advance on its part. The death-rate of tuberculosis within the last thirty years has diminished between thirty and forty per cent; and pneumonia at its worst has never yet equaled the old fatality of tuberculosis. Furthermore, all who have carefully studied the subject are convinced that much of this apparent increase is due to more accurate and careful diagnosis. Up to ten years or so ago it was generally believed that pneumonia was rare in young children. Now, however, that we make the diagnosis with a microscope, we discover that a large percentage of the cases of capillary bronchitis, broncho-pneumonia, and acute congestion of the lung in children are due to the presence of the pneumococcus. Similarly, at the other end of the line, deaths that were put down to bronchitis, asthma, heart failure, yes, even to old age, have now been shown on bacteriological examination to be due to this ubiquitous imp of malevolence; so that, on the whole, all that we are probably justified in saying is that pneumonia is not decreasing under civilization. This is not to be wondered at, inasmuch as the inevitable crowding and congestion which accompanies civilization, especially in its derivative sense of "citification," tends to foster it in every way, both by multiplying the opportunities for infection and lowering the resisting power of the crowded masses.

Moreover, it was only in the last ten years, yes, within the last five years, that we fairly grasped the real method and nature of the spread of the disease, and recognized the means that must be adopted against it. And as all of these factors are matters which are not only absolutely within our own control, but are included in that programme of general betterment of human comfort and vigor to which the truest intelligence and philanthropy of the nation are now being directed, the outlook for the future, instead of being gloomy, is distinctly encouraging.

Our chief difficulty in discovering the cause of pneumonia lay in the swarm of applicants for the honor. Almost every self-respecting bacteriologist seemed to think it his duty to discover at least one, and the abundance and variety of germs constantly or accidentally present in the human saliva made it so difficult positively to isolate the real criminal that, although it was identified and described as long ago as 1884 by Fraenkel, the validity of its claim was not generally recognized and established until nearly ten years later.

It is a tiny, inoffensive-looking little organism, of an oval or lance-head shape, which, after masquerading under as many aliases as a confidence man, has finally come to be called the pneumococcus, for short, or "lung germ." Though by those who are more precise it is still known as the Diplococcus pneumoniæ or Diplococcus lanceolatus, from its faculty of usually appearing in pairs, and from its lance-like shape. Its conduct abounds in "ways that are dark and tricks that are vain," whose elucidation throws a flood of light upon a number of interesting problems in the spread of disease.

First of all, it literally fulfills the prognostic of Scripture, that "a man's foes shall be they of his own household," for its chosen abiding place and normal habitat is no less intimate a place than the human mouth. Outside of this warm and sheltering fold it perishes quickly, as cold, sunlight, and dryness are alike fatal to it.

We could hardly believe the evidence of our senses when studies of the saliva of perfectly healthy individuals showed this deadly little bacillus to be present in considerable numbers in from fifteen to forty-five per cent of the cases examined. Why, then, does not every one develop pneumonia? The answer to this strikes the keynote of our modern knowledge of infectious disease, namely, that while an invading germ is necessary, a certain breaking down of the body defenses and a lowering of the vital resistance are equally necessary. These invaders lie in wait at the very gates of the citadel, below the muzzles of our guns, as it were, waiting for some slackening of discipline or of watchfulness to rush in and put the fortress to sack. Nowhere is this more strikingly true than in pneumonia. It is emphatically a disease where, in the language of the brilliant pathologist-philosopher Moxon, "While it is most important to know what kind of a disease the patient has got, it is even more important to know what kind of a patient the disease has got."

The death-rate in pneumonia is an almost mathematically accurate deduction from the age, vigor, and nutrition of the patient attacked. No other disease has such a brutal and inveterate habit of killing the weaklings. The half-stifled baby in the tenement, the underfed, overworked laboring man, the old man with rigid arteries and stiffening muscles or waning life vigor, the chronic sufferer from malnutrition, alcoholism, Bright's disease, heart disease—these are its chosen victims.

Another interesting feature about the pneumococcus is its vitality outside of the body. If the saliva in which it is contained be kept moist, and not exposed to the direct sunlight and in a fairly warm place, it may survive as long as two weeks. If dried, but kept in the dark, it will survive four hours. If exposed to sunlight, or even diffuse daylight, it dies within an hour. In other words, under the conditions of dampness and darkness which often prevail in crowded tenements it may remain alive and malignant for weeks; in decently lighted and ventilated rooms, less than two hours. This explains why, in private practice and under civilized conditions, epidemics of this admittedly infectious disease are rare; while in jails, overcrowded barracks, prison ships, and winter camps of armies in the field they are by no means uncommon. This is vividly supported by the fact brought out in our later investigations of the sputum of slum-dwellers, carried out by city boards of health, that the percentage of individuals harboring the pneumococcus steadily increases all through the winter months, from ten per cent in December to forty-five, fifty, and even sixty per cent in February and March. The old proverb, "When want comes in at the door, Love flies out at the window," might be revised to read, "When sunlight comes in at the window the pneumococcus flies 'up the flue.'"

Authorities are still divided as to the meaning and even the precise frequency of the occurrence of the pneumococcus in the healthy human mouth. Some hold that its presence is due to recent infection which has either been unable to gain entrance to the system or is preparing its attack; others, that it is a survival from some previous mild attack of the disease, and the body tissues having acquired immunity against it, it remains in them as a harmless parasite, as is now well known to be the case with the germs of several of our infectious diseases—for instance, typhoid—for months and even years afterward. Others hold the highly suggestive view that it is a normal inhabitant of the healthy mouth, which can become injurious to the body, or pathogenic, only under certain depressed or disturbed conditions of the latter. In defense of this last it may be pointed out that dental bacteriologists have now already isolated and described some thirty different forms of organisms which inhabit the mouth and teeth; and the pneumococcus may well be one of these. Further, that a number of our most dangerous disease germs, like the typhoid bacillus, the bacillus of tuberculosis, and the bacillus of diphtheria, have almost perfect "doubles," law-abiding relatives, so to speak, among the germs that normally inhabit our throats, our intestines, or our immediate surroundings. The ultimate foundation question of the science of bacteriology is, How did the disease germs become disease germs? But the question is still unanswered.

However, fortunately, here, as in other human affairs, imperfect as our knowledge is, it is sufficient to serve as a guide for practical conduct. Widely present as the pneumococcus is, we know well that it is powerless for harm except in unhealthful surroundings. There is another interesting feature of its life history which is of practical importance, and that is, like many other bacilli it is increased in virulence and infectiousness by passing through the body of a patient. Flushed with victory over a weakened subject, it acquires courage to attack a stronger. This is the reason why, in those comparatively infrequent instances in which pneumonia runs through a family, it is the strongest and most vigorous members of the family who are the last to be attacked. It also explains one of the paradoxes of this disease, that, while emphatically a disease of overcrowding and foul air, and attacking chiefly weakened individuals, it is a veritable scourge of camps, whether mining or military. When once three or four cases of pneumonia have occurred in a mining camp, even though this consist almost exclusively of vigorous men, most of them in the prime of life, it acquires a virulence like that of a pestilence, so that, while ordinarily not more than fifteen to twenty per cent of those attacked die, death-rates of forty, fifty, and even seventy per cent are by no means uncommon in mining camps. The fury and swiftness of this "miners' pneumonia" is equally incredible. Strong, vigorous men are taken with a chill while working in their sluicing ditches, are delirious before night, and die within forty-eight hours. So widely known are these facts, and so dreaded is the disease throughout the Far West and in mountain regions generally, that there is a widespread belief that pneumonia at high altitudes is particularly deadly.