Preventable Diseases

by Woods Hutchinson

This clears the ground of a good many ancient misconceptions; for instance, that the chief cause of pneumonia is direct exposure to cold or a wetting, or the inhalation of raw, cold air. Few beliefs were more firmly fixed in the popular mind—and, for the matter of that, in the medical—up to fifteen or twenty years ago. It has found its way into literature; and the hero of the shipwreck in an icy gale or of weeks of wandering in the Frozen North, who must be offered up for artistic reasons as a sacrifice to the plot, invariably dies a victim of pneumonia, from his "frightful exposure," just as the victim of disappointed love dies of "a broken heart," or the man who sees the ambitions of years come crashing about his ears, or the woman who has lost all that makes life worth living, invariably develops "brain fever."

There is a physical basis for all of these standard catastrophes, but it is much slenderer than is usually supposed. For instance, almost every one can tell you how friends of theirs have "brought on congestion of the lungs," or pneumonia, by going without an overcoat on a winter day, or breaking through the ice when skating, or even by getting their feet wet and not changing their stockings; and this single dramatic instance has firmly convinced them that the chief cause of "lung fever" is a chill or a wetting. Yet when we come to tabulate long series of causes, rising into thousands, we find that the percentage in which even the patients themselves attribute the disease to exposure, or a chill, sinks to a surprisingly small amount. For instance, in the largest series collected with this point in mind, that of Musser and Norris, out of forty-two hundred cases only seventeen per cent gave a history of exposure and "catching cold"; and the smaller series range from ten to fifteen per cent. So that, even in the face of the returns, not more than one-fifth of all cases of pneumonia can reasonably be attributed to chill. And when we further remember that under this heading of exposure and "catching cold" are included many mere coincidences and the chilly sensations attending the beginning of those milder infections which we term "common colds," it is probable that even this small percentage could be reduced one-half. Indeed, most cautious investigators of the question have expressed themselves to this effect. This harmonizes with a number of obstinate facts which have long proved stumbling-blocks in the way of the theory of exposure as a cause of pneumonia. One of the classic ones was that, during Napoleon's frightful retreat from Moscow in the dead of winter, while his wretched soldiers died by thousands of frost-bite and starvation, exceedingly little pneumonia developed among them. Another was that, as we have already seen with colds, instead of being commoner and more frequent in the extreme Northern climate and on the borders of the Arctic Zone, pneumonia is almost unknown there. Of course, given the presence of the germ, prolonged exposure to cold may depress the vital powers sufficiently to permit an attack to develop.

Again, the ages at which pneumonia is both most common and most deadly, namely, under five and over sixty-five, are precisely those at which this feature of exposure to the weather plays the most insignificant part. Last and most conclusive of all, since definite statistics have begun to be kept upon a large scale, pneumonia has been found to be emphatically a disease of cities, instead of country districts. Even under the favorable conditions existing in the United States, for instance, the death-rate per hundred thousand living, according to the last census, was in the cities two hundred and thirty-three, and for the country districts one hundred and thirty-five,—in other words, nearly seventy per cent greater in city populations.

How, then, did the impression become so widely spread and so firmly rooted that pneumonia is chiefly due to exposure? Two things, I think, will explain most of this. One is, that the disease is most common in the winter-time, the other, that like all febrile diseases it most frequently begins with sensations of chilliness, varying all the way from a light shiver to a violent chill, or rigor. The savage, bone-freezing, teeth-rattling chill which ushers in an attack of pneumonia is one of the most striking characteristics of the disease, and occurs in twenty-five to fifty per cent of all cases.

Its chief occurrence in the winter-time is an equally well-known and undisputed fact, and it has been for centuries set down in medical works as one of the diseases chiefly due to changes in temperature, humidity, and directions of the wind. Years of research have been expended in order to trace the relations between the different factors in the weather and the occurrence of pneumonia, and volumes, yes, whole libraries, published, pointing out how each one of these factors, the temperature, humidity, direction of wind, barometric pressure, and electric tension, is in succession the principal cause of the spread of this plague. Many interesting coincidences were shown. But one thing always puzzled us, and that was, that the heaviest mortality usually occurred, not just at the beginning of winter, when the shock of the cold would be severest, nor even in the months of lowest temperature, like December or January, but in the late winter and the early spring. Throughout the greater part of the temperate zone the death-rate for pneumonia begins to rise in December, increases in January, goes higher still in February, reaching its climax in that month or in March. April is almost as bad, and the decline often doesn't fairly set in until May.

No better illustration could probably be given of the danger of drawing conclusions when you are not in possession of all the facts. One thing was entirely overlooked in all this speculation until about twenty years ago,—that pneumonia was due not simply to the depressing effects of cold, but to a specific germ, the pneumococcus of Fraenkel. This threw an entirely new light upon our elaborate weather-causation theories. And while these still hold the field by weight of authority and that mental inertia which we term conservatism, yet the more thoughtful physicians and pathologists are now coming to regard these factors as chiefly important according to the extent to which we are crowded together in often badly lighted and ill-ventilated houses and rooms, with the windows and doors shut to save fuel, thus affording a magnificent hothouse hatching-ground for such germs as may be present, and ideal facilities for their communication from one victim to another. At the same time, by this crowding and the cutting off of life and exercise in the open air which accompanies it, the resisting power of our bodies is lowered. And when these two processes have had an opportunity of progressing side by side for from two to three months; when, in other words, the soil has been carefully prepared, the seed sown, and the moist heat applied as in a forcing-house, then we suddenly reap the harvest. In other words, the heavy crop of pneumonia in January, February, and March is the logical result of the seed-sowing and forcing of the preceding two or three months.

The warmth of summer is even more depressing in its immediate effects than the cold of winter, but the heat carries with it one blessing, in that it drives us, willy-nilly, into the open air, day and night. And on looking at statistics we find precisely what might have been expected on this theory, that the death-rate for pneumonia is lowest in July and August.

It might be said in passing that, in spite of our vivid dread of sunstroke, of cholera, and of pestilence in hot weather, the hot months of the year in temperate climates are invariably the months of fewest diseases and fewest deaths. Our extraordinary dread of the summer heat has but slender rational physical basis. It may be but a subconscious after-vibration in our brain cells from the simoons, the choleras, and the pestilences of our tropical origin as a race. Open air, whether hot, cold, wet, dry, windy, or still, is our best friend, and house air our deadliest enemy.

If this view be well founded, then the advance of modern civilization would tend to furnish a more and more favorable soil for the spread of this disease. This, unfortunately, is about the conclusion to which we are being most unwillingly driven. Almost every other known infectious disease is diminishing, both in frequency and in fatality, under civilization. Pneumonia alone defies our onslaughts. In fact, if statistics are to be taken at their surface-value, we are facing the appalling situation of an apparently marked increase both in its prevalence and in its mortality. For a number of years past, ever since, in fact, accurate statistics began to be kept, pneumonia has been listed as the second heaviest cause of death, its only superior being tuberculosis.

About ten years ago it began to be noticed that the second competitor in the race of death was overtaking its leader, and this ghastly rivalry continued until about three years ago pneumonia forged ahead. In some great American cities it now occupies the bad eminence of the most fatal single disease on the death-lists.