A system of practical medicine. By American authors. Vol. 2

by Unknown

ETIOLOGY.—In the causation of this disease two distinct factors are recognized—the one atmospheric, the other dietetic.

The prevalence and severity of the summer diarrhoea correspond closely with the degree of atmospheric heat, as may be inferred from the foregoing statistics. In New York this disease begins in the month of May—earlier in some years than in others—in a few scattered cases, commonly of a mild type. Cases become more and more numerous and severe as the weather grows warmer until July and August, when the diarrhoea attains its maximum prevalence and severity. In these two months it is by far the most frequent and fatal of all the diseases in cities. In the middle of September new patients begin to be less common, and in the latter part of this month and subsequently new cases do not occur, unless under unusual circumstances which favor the development of this malady. In New York a considerable number of deaths of infants occur from the diarrhoea in October. October is not a hot month in our latitude—its average temperature is lower than that of May—and yet the mortality from this disease is considerably larger in the former than in the latter month. This fact, which seems to show that the prevalence of the summer diarrhoea does not correspond with the degree of atmospheric heat, is readily explained. The mortality in October, and indeed in the latter part of September, is not that of new cases, but is mainly of infants, as I have observed every year, who contract the disease in July or August or earlier, and linger in a state of emaciation and increasing weakness till they finally succumb, some even in cool weather.

The fact is therefore undisputed, and is universally admitted, that the summer season, stated in a general way, is the cause of this annually-recurring diarrhoeal epidemic, but it is not so easy to determine what are the exact causative conditions or agents which the summer weather brings into activity. That atmospheric heat does not in itself cause the diarrhoea is evident from the fact that in the rural districts there is the same intensity of heat as in the cities, and yet the summer complaint does not occur. The cause must be looked for in that state of the atmosphere engendered by heat where unsanitary conditions exist, as in large cities. Moreover, observations show that the noxious effluvia with which the air becomes polluted under such circumstances constitute or contain the morbific agent. Thus, in one of the institutions of this city a few years since, on May 10, which happened to be an unusually warm day for this month, an offensive odor was noticed in the wards, which was traced to a large manure-heap that was being upturned in an adjacent garden. On this day four young children were severely attacked by diarrhoea, and one died. Many other examples might be cited showing how the foul air of the city during the hot months, when animal and vegetable decomposition is most active, causes diarrhoea. Several years since, while serving as sanitary inspector for the Citizens' Association in one of the city districts, my attention was particularly called to one of the streets, in which a house-to-house visitation disclosed the fact that nearly every infant between two avenues had the diarrhoea, and usually in a severe form, not a few dying. This street was compactly built with wooden tenement-houses on each side, and contained a dense population, mainly foreign, poor, ignorant, and filthy in their habits. It had no sewer, and the refuse of the kitchens and bed-chambers was thrown into the street, where it accumulated in heaps. Water trickled down over the sidewalks from the houses into the gutters or was thrown out as slops, so that it kept up a constant moisture of the refuse matter which covered the street, and promoted the decay of the animal and vegetable substances which it contained. The air in the domicils and street under such conditions of impurity was necessarily foul in the extreme, and stifling during the hot days and nights of July and August; and it was evidently the important factor in producing the numerous and severe diarrhoeal cases which were in these domicils.

In another locality, occupied by tripe-dealers and a low class of butchers who carried on fat- and bone-boiling at night, the air was so foul after dark that the peculiar impurity which tainted it could be distinctly noticed in the mouth for a considerable time after a night visit. In the street where these nuisances existed and in adjacent streets the summer diarrhoea was very prevalent and destructive to human life. Murchison states that twenty out of twenty-five boys were affected with purging and vomiting from inhaling the effluvia from the contents of an old drain near their school-room. Physicians are familiar with a similar fact showing this purgative effect of impure air—that the atmosphere of a dissecting-room often causes diarrhoea in those otherwise healthy.

The exact nature of the deleterious agent or agents in foul air which cause the diarrhoea, whether they be gases or organisms, has not been fully determined; but at a recent meeting of the Berliner Med. Gesellschaft, A. Baginsky made a report on the bacilli of cholera infantum, which he states he has found both in the dejections and in the intestinal mucous membrane in the bodies of those who have perished with this disease. In the stools, along with numerous other organisms, Baginsky states that he found masses of zoögloea, and the same organisms he detected on the surface of the small intestines, and could trace their wanderings as far as the submucous tissue.¹ But it is evidently very difficult to determine whether such organisms sustain a causative relation to diarrhoea or spring into existence in consequence of the foul secretions and decomposing fecal matters which are present.

¹ Allegem. Wien. Mediz. Zeitung, Nov. 6, 1883.

The impurities in the air of a large city are very numerous. Among those of a gaseous nature are sulphurous acid, sulphuric acid, sulphuretted hydrogen; various gases of the carbon group, as carbonic acid, carburetted hydrogen, and carbonic oxide; gases of the nitrogen group, as the acetate, sulphide, and carbonate of ammonium, nitrous and nitric acids; and at times compounds of phosphorus and chlorine (Parkes). A theory deserving consideration is that certain gaseous impurities found in the air form purgative combinations. D. F. Lincoln, in his interesting paper on the atmosphere in the Cyclopædia of Medicine, writes in regard to sulphuretted hydrogen: "When in the air, freely exposed to the contact of oxygen, it becomes sulphuric acid. Sulphide of ammonium in the same circumstances becomes a sulphate, which, encountering common salt (chloride of sodium), produces sulphate of sodium and chloride of ammonium. The sulphates form a characteristic ingredient of the air in manufacturing districts." The sulphates, we know, are for the most part purgatives, but whether they or other chemical agents exist in the respired air in sufficient quantity to disturb the action of the intestines, even where atmospheric impurities are most abundant, is problematical and uncertain.

Again, the solid impurities in the air of a large city are very numerous, as any one may observe by viewing a sunbeam in a darkened room, which is made visible by the numerous particles floating in it. These particles consist largely of organic matter, which sometimes has been carried a long distance by the wind. The remarkable statement has been made that in the air of Berlin organic forms have been found of African production. Ehrenberg discovered fragments of insects of various kinds—rhizopods, tardigrades, polygastrica, etc.—which, existing in considerable quantity and inhaled in hot weather, when decomposition and fermentation are most active, may be deleterious to the system. Monads, bacteria, vibriones, amorphous dust containing spores which retain their vitality for months, are among the substances found in the air of cities. The well-known hazy appearance of the atmosphere resting over a large city like New York when viewed from a distance is due to the gaseous and solid impurities with which the air is so abundantly supplied—impurities which assume importance in pathological studies, since minute organisms are now believed to cause so many diseases the etiology of which has heretofore been obscure. With our present knowledge we must be content with the general statement that impure air is one of the two important factors which cause summer diarrhoea, without being able to state positively which of the elements in the air are most instrumental in causing this result. But the theory is plausible that minute organisms rather than chemical products are the chief cause. Henoch of Berlin, writing upon this subject, calls attention to the disease known as intestinal mycosis, its prominent symptom being a severe diarrhoea produced by eating diseased meat containing a fungus. He believes that "a portion of the fungus not destroyed by the gastric juice settles upon different parts of the intestine, and there produces its effects;" and he adds, "At present, however, we can regard the mykotic theory of cholera infantum only as a very probable hypothesis. There is no doubt that high atmospheric temperature increases the tendency to fermentation dyspepsias which is present in imperfectly-nourished children at all seasons, and causes them to appear not only epidemically, but also in an extremely acute form which is not frequent under ordinary circumstances. This would lead to the conclusion that, in addition to the heat, infectious germs are present, which, being developed in great masses by the former, enter the stomach with the food." The fungus theory of the causative relation of atmospheric heat to the diarrhoea of the summer season as thus explained by Henoch commands the readier assent since it comports with the well-known facts relating to the etiology of the summer complaint. This disease, as we have seen, is most prevalent and fatal under precisely those conditions of dense population, filthy domicils and streets, and atmospheric heat which are favorable for the development of low organisms.

In those portions of our cities which are occupied by the poor, more than anywhere else, those conditions prevail which render the atmosphere deleterious. One accustomed to the pure air of the country would scarcely believe how stifling and poisonous the atmosphere becomes during the hot summer days and close summer nights in and around the domicils in the poor quarters of the city. Among the causes of this foul air may be mentioned too dense a population, the occupancy of small rooms by large families, rigid economy and ceaseless endeavor to make ends meet, so that in the absorbing interest sanitary requirements are sadly neglected. Adults of such families, and children of both sexes as soon as they are old enough, engage in laborious and often filthy occupations. Many of them seldom bathe, and they often wear for days the same undergarments, foul with perspiration and dirt. The intemperate, vicious, and indolent, who always abound in the quarters of the city poor, are notoriously filthy in their habits and add to the insalubrity by their presence. Children old enough to be in the streets and adults away at their occupations escape to a great extent the evil effects of impure air, but the infantile population always suffer severely.

Every physician who has witnessed the summer diarrhoea of infants is aware of the fact that the mode of feeding has much to do with its occurrence. A large proportion of those who each summer fall victims to it would doubtless escape if the feeding were exactly proper. In New York City facts like the following are of common occurrence in the practice of all physicians: Infants under the age of eight months, if bottle-fed, nearly always contract diarrhoea, and usually of an obstinate character, during the summer months. The younger the infant, the less able is it to digest any other food than breast-milk, and the more liable is it therefore to suffer from diarrhoea if bottle-fed. In the institutions nearly every bottle-fed infant under the age of four or even six months dies in the hot months with symptoms of indigestion and intestinal catarrh, while the wet-nursed of the same ages remain well. Sudden weaning, the sudden substitution of cow's milk or any artificially-prepared food in place of breast-milk in hot weather, almost always produces diarrhoea, often of a severe and fatal nature. Feeding an infant in the hot months with indigestible and improper food, as fruits with seeds or the ordinary table-food prepared in such a way that it overtaxes the digestive function of the infant, causes diarrhoea, and not infrequently that severe form of it which will be described under the term cholera infantum. Many obstinate cases of the summer complaint begin to improve under change of diet, as by the substitution of one kind of milk for another or the return of the infant to the breast after it has been temporarily withdrawn from it. It is a common remark in the families of the city poor that the second summer is the period of greatest danger to infants. This increased liability of infants to contract diarrhoea in the second summer is due to the fact that most infants in their second year are table-fed, while in the first year they are wet-nursed. Such facts, with which all physicians are familiar, show how important the diet is as a factor in causing the summer complaint.