In complying with your wish that I should send you a letter exclusively upon the subject of the disease which has committed such afflicting ravages in our army, I shall confine myself principally to what concerns the nature of the disorder, feeling that a minute detail of the symptoms, and mode of treatment would not only be less interesting, but perhaps very tedious to you.
After all that I have been able to observe, with respect to this dreadful complaint, I think that, considering it as a malady of the West India colonies, it may be correctly regarded as the effect of climate, operating upon exotic bodies. It is the fever of the country—an endemial malady, which attacks those, most severely, whose general vigour, and whose firmness, or density of fibre offer the strongest resistance. To look for it in ships and vessels;—to strain the eye across the ocean, in order to fix its birth-place upon the opposite coast of the Atlantic, or to trace its descent from the shores of the Indian seas, would be to overlook the reality in search of a phantom! It needs no foreign parent: the earth is its mother: its father the sun.
When Europeans first take up their residence in the West Indies, it is usual for them, sooner or later after their arrival, to undergo an attack of fever; which in times of peace and tranquillity, when the “new-comers” are but few, is termed a “seasoning fever;” but in times of war, when, from great multitudes arriving at the same period, its destructive effects are more striking, is called a “yellow fever;” but, whether denominated “seasoning” or “yellow,” or marked by any other appellation, it is only the common bilious fever of hot climates: and it appears under an intermittent, a remittent, or a continued form, according to the soil and situation of the place; or the habit of body, and other circumstances of the person attacked. In negroes and creoles it is frequently an ague; in those who are in a degree acclimated a remittent; and in new-comers a continued, or, as it is commonly termed, a yellow fever; preserving, in each case, a distinct type throughout its course; while, in other instances of its attack upon Europeans, it shifts its form, and runs its progress with the utmost irregularity: in proof of which I may remark that it has happened to myself to receive newly arrived soldiers into the hospital, at the same time, with this seasoning malady, under all the varieties of its intermittent, remittent, and continued form: and notwithstanding each has been differently attacked, all of them have died, in the course of only a few days, with every symptom of the most malignant yellow fever.
Nature, in her fostering care, hath endowed the human frame with the power of accommodating itself to all the various climates upon the habitable regions of our globe; yet hath she more expressly adapted our organs to the particular climate in which she hath stationed us: so constituting the nice and delicate movements of the animal machine, that we cannot, without peril, expose ourselves to sudden or violent transitions.
To the inhabitants of different regions is given something of constitutional difference, which it would be difficult precisely to define: but it belongs to a certain original conformation, creating a difference of fibre or stamina, which more particularly befits the body for the specific region, in which it is designed to move: yet, while much is attributed to nature, it ought not to be forgotten that habit follows nature very closely, in her influence upon the human frame; and hence it is that by long residence, and similarity of pursuit, so near an approach to this specific and original structure may be acquired, as to promote healthy action, in a being removed to a foreign, and even to an ungenial climate: still, this is only the yielding of a body originally different; for the assimilation is never so complete as to be in all respects the same. The constitution of a negro from Africa, or the West Indies, never becomes entirely British, although he remain in England the greater number of his days: and however much an European, by long residence in the West Indies, be brought to resemble a creole, he can never acquire, precisely, the constitution of a native: some marks of original conformation will still exist, and something, even in his general appearance, to distinguish him.
Nor is this difference of organization confined to the human subject: other animal bodies, and also vegetables differ in their structure and external appearance, in different climates. The wool of sheep, removed from a northern region to the West Indies, becomes hair; and the almost tasteless potatoe of Europe assumes a strong saccharine flavour from tropical culture.
The influence of the atmosphere, not only in different climates, but under its various changes in the same climate, is, at all times, and in all countries, far greater than common opinion supposes: nor has the attention of medical men been sufficiently directed to this circumstance, although it is of great magnitude. Hypochondriacs, persons subject to rheumatism, or asthma, and those afflicted with painful thickenings of the cuticle (usually termed corns), become exquisitely sensible of the slightest variations in the state of the atmosphere; whence it may be concluded, that it cannot but operate, at all moments, with a powerful effect upon the tender fibres of our delicately organized vessels; and if, in our native region, the influence be so considerable, must it not be infinitely more important, upon the body being exposed to the stronger impressions of an unnatural climate,
Without entering more minutely into the subject, suffice it to remark, that there appears to be a certain gradation in the tone, or firmness of the animal fibre, as we proceed from the hotter through the more temperate regions; not following in exact mathematical proportion, but sufficiently manifest to form some standard for general observation; and, perhaps, to sanction the assumption that the density or laxity of the human fibre bears an intimate alliance with the temperature of the climate, with respect to heat or cold; although it may be influenced, likewise, by other circumstances; such as the dryness or moisture of the atmosphere, the state of the soil, the manner of clothing, and the habits pursued. In the colder regions towards the poles, the fibre is firmer, the circulation of the fluids slower, and the secretions are more languid; while in the warmer regions, near the equator, the fibre is lax, respiration quicker, the circulation more rapid, and the secretions are more copious, and more speedily performed. In order, therefore, to fit the constitution of a polar inhabitant for a tropical climate, or to accommodate the system of a tropical inhabitant to a polar atmosphere, it is needful that the change should be gradual, that the necessary density or laxity be induced, with as little risk as possible of disorganization, and consequent dissolution[15]. Not only do the inhabitants of cold climates suffer, on being transferred to the tropical regions—the negroes can as ill support the change to a northern atmosphere. They are frequently the victims of being brought to Europe: amidst the cold of our winter, all their energies seem to be destroyed, and their faculties benumbed: they seldom live to old age, but, commonly, sink into marasmus, or are cut off by early consumption.
Fever, excessive heat, violent passion, or any other cause which greatly, and suddenly hurries the circulation of the fluids, diminishes the tone and energy of the living animal fibre, and deprives it of that degree of firmness which is necessary to health; but, by gradually habituating the body to the change, a high degree of increased circulation, or a considerable diminution of the original density of fibre may be supported, without any consequent derangement of structure: the increased action of the vessels, the augmented velocity of the fluids, and the subsequent laxity of fibre, induced by great heat, or high fever, may be borne, provided they are not so sudden, nor so long continued, as to cause disorganization.
We have many familiar examples which testify the effect of original conformation, and the powerful influence of habit upon the animal body, with respect to its state of health or disease. If a person accustomed to live in the gloom of London should expose his face, for only a short time, to the full rays of the sun, at Brighton, the skin would be separated as if by the application of a blister; but if a hardy shepherd of the downs were to lie upon the hills, with his face open to the broad sun, throughout the day, not the smallest part of the cuticle would be disturbed.
A negro, to whom the climate is congenial, can run over the hills in the West Indies, for many hours in succession without suffering the slightest inconvenience: but if an European of more unyielding fibre, and only lately arrived within the tropics, were to follow him in such a course, it would be more than probable—it would be almost certain, that, within a few succeeding hours, a fever would complete the disorganization, and send him to the grave.
So the fluids of a racer may be hurried violently through his vessels, without any injury to the natural organization: but if an unpractised horse, of a different original conformation, were to be taken from the cart and made to gallop, with all possible speed, over a course of four or six miles, it is probable that from the increased impulse, and the resistance of his unaccommodating fibre, fever, disorganization, and death would speedily ensue.
In cold or temperate climates, bulls are baited, and hares hunted, in order that the sound texture of their fibres may be broken down, and the muscles made tender, by their dying in the fever of increased and violent circulation. This is a fact so well known to sportsmen, that a hunted hare is always preferred to one that has been shot, or taken by other means.
Epicures let their meat hang after it is killed, until the atmosphere has effected the same purpose, by a different process, and it be made tender by a decomposition, or partial putrefaction. But in the West Indies, it is common to see the animal alive in the market, and to have its joints smoking upon table the same day at dinner: it is slaughtered, dressed, and eaten, without the flesh growing cold; yet there is no complaint of the meat being hard or tough.
These remarks will serve to lead your attention more particularly to the subject of climate, and to the effects of habit and original conformation. Without attempting to enter more particularly into the various changes, which the febrile action produces in destroying life, or the specific mode in which these changes are effected, I may state a few other general circumstances, which will show the application, of what has been already said, to the subject in question, viz. the continued, or yellow fever.
Creoles and negroes are not subject to the fever in its continued, or most malignant form: when it invades them, it appears under a remittent or intermittent type. In these classes the original conformation, aided by a constant exposure to the heat and atmosphere of these regions, has established a due state of fibre, and given to the body a certain congeniality which empowers it to continue its healthy action, amidst all the circumstances of climate and situation.
Europeans, who have resided during a period of several years in the West Indies, are seldom attacked with the fever in its continued form; when it seizes them, it commonly assumes the type of a remittent. In persons of this class, the body, from long exposure to the climate, has become creolised, approaching to the conformation of the natives, by having the original firmness of fibre reduced to the appropriate standard for continuing the healthy action, under exposure to preternatural heat.
The strongest men—those of the most dense or rigid fibre are most subject to the high degrees of the continued, or yellow fever; and are most frequently, and most rapidly destroyed by it. Women, children, convalescents from former malady, and those who have been reduced by the use of mercurial remedies are less frequently the objects of its attack: and when it seizes them, it is usually milder, and less rapid in its progress. In these classes, the state of the animal fibre, either from original conformation, or from eventual circumstances, more nearly approaches to that of the creoles and natives.
In North America, the inhabitants, who constantly reside in the most southern states, are seldom attacked with the fever in its more violent, or continued form; while those of the north-east states are destroyed by it in great numbers: but, even in these districts, it is remarked that the fever more readily seizes strangers from Europe, or peasants from the interior provinces, than the natives of the towns, in which the disease prevails. These facts are striking, and they seem to admit of ready explanation. The inhabitants of the southern states, from being subject to constant heat, are acclimated, and, in constitution, approach nearly to the creoles or natives of the West Indies: but those residing in the more northern states, although exposed to a very high degree of heat during the summer, can never become creolised, on account of the intervening winter, which annually renews the predisposition, and creates a susceptibility of the disease; still, from living, during part of the year, in excessive heat, and remaining, at all times, in the atmosphere of their towns, the inhabitants of the place, where the disease prevails, are, in some degree, less susceptible of the most malignant form of the fever, than strangers from Europe, or peasants from the inland districts, whose more dense and rigid fibre renders them in a peculiar manner predisposed.
From these remarks, it appears that the presence of contagion is in no degree necessary to the production of this fever. Indeed its invasion is governed by circumstances very opposite to the known laws of contagion: for, in proportion as the body approaches the creole structure, so is it able to support the change of temperature, and to resist the fatal effects of the seasoning malady. If the constitution, either from natural organization, or from long residence, be assimilated to the climate, i. e. if it be reduced to the common standard of the creoles, there is nothing to apprehend from the disease: but if it be not, the fever will, assuredly, make its attack, without waiting for any such cause as contagion.
Moreover, if it can be ascertained, that certain classes of people are most liable to be attacked, and if it can be proved that there is a regular gradation, according as they have been more or less exposed to the influence of climate, it must be equally unnecessary and unphilosophical to call in the aid of a power, the application of whose laws it were impossible to reconcile with the appearances observed. No disease of known contagion is affected by the events which are, daily, seen to govern the progress of the yellow fever; if, therefore, contagion be regarded as the parent of this disease, it must be a contagion of a very uncommon and peculiar nature; for it is a circumstance, both singular and unprecedented, that an active and wide-spreading contagion, prevailing in any particular country, should, expressly, avoid the inhabitants of that country, and only lie in wait for strangers; and, further, that should these not chance to arrive, for many years, it would remain dormant throughout the whole period, and, again, rush forth with undiminished vigour, the very moment when strangers should appear! I think I might say, with the greatest correctness, that if no person from a colder climate, should visit the West India colonies for the space of five, ten, or any given number of years, no instance of the yellow fever, distinct from the bilious remittent fever of the country, would be known, during that period; yet, if a body of men, unaccustomed to the climate, should arrive from Europe, in the month of July or August immediately succeeding, a considerable proportion of them would be seized, and probably destroyed by this disease, before they had commemorated the first return of a new year: but, can it be supposed that a most subtile and active contagion would thus remain latent, for any specified term, amidst whole hosts of natives, and suddenly resume all its destructive powers, as soon as a body of more robust foreigners should come within its reach?
In England, the harvest-men and strangers, who go into the fens of Kent, or Lincolnshire in the autumn, are more readily attacked with the endemial fever of those counties, than the inhabitants, who constantly dwell in the atmosphere which causes it; yet we do not learn that, during the prevalence of any contagious malady in these districts, the contagion cautiously avoids the men of Kent or Lincolnshire, to lie in wait for strangers; nor, perhaps, will any physician venture to assert that the Kentish fever is produced by infection.
It would seem more probable that the contagion, common to any particular country, should seize the natives of that country. The plica Polonica shuns not the people of Poland; nor the sibbens those of Scotland: neither do the yaws spare the creoles, or the Africans. But what appears most surprising is, that this very extraordinary contagion should not attack the languid blacks of the West Indies; yet when it arrives in America, that it should seize the more robust negroes of the United States.
This is a fact, which is totally irreconcileable upon the principle of the disease proceeding from contagion. The negro of the West Indies, from always living in a high degree of heat, has no susceptibility: but the negro of America acquires a predisposition from the recurrent cold of the winter. The fibre of the one is relaxed, and yielding—of the other dense and resisting. In the same way it is explained why the inhabitants of Louisiana, Georgia, and the Carolinas, are less subject to the disease, than those of Virginia, Pennsylvania, and New York. Did the fever spread itself by contagion, we know of no cause why it should extend its ravages to the north instead of the south; why it should seize whites in preference to blacks; why a vigorous European rather than a languid creole; nor, why it should avoid the sable race of the West Indies, yet affect the negroes of North America.
It is not a law of contagion to make its attack upon the strongest people: more commonly it assails those of tender fibre. Were any given number of healthy men, and an equal number of children to be exposed, at the same time, to the influence of the contagion of small-pox, measles, or scarlatina, common observation informs us that the children would be found to be most susceptible of the impression, and attacked in the greatest number: but the very reverse of this would be the case if they were to be exposed, in a similar manner, to the cause producing the yellow fever—the men would be found to be most susceptible, and a greater proportion of them would fall victims to the disease.
Not only does this fever invade Europeans, newly arrived in the West Indies, in preference to creoles, negroes, and those who, by a long-continued residence, have become acclimated; but even among these unhappy Europeans, who happen to be susceptible, the most healthy and robust, and, in general, those who are the earliest subjected to great exertions, and the high degrees of temperature, are sooner seized, and more rapidly destroyed, than those of laxer fibre, or those who have the opportunity of becoming more gradually enured to the climate.
But the “New-comers,” if exposed to the yaws, the cra-cra, or any other disease of decided contagion, are not found to be more susceptible than the creoles, or the negroes: although, with regard to the bites of musquitoes and other insects, the difference of effect upon the Europeans, and the people of the climate, is as peculiarly marked, as it is with respect to the yellow fever. The small puncture made in the skin of a robust European by a musquito, or a sand-fly, frequently becomes inflamed, tumefies, breaks into a sore, spreads into a malignant ulcer, and, ultimately, robs the hardy son of the North of his life; while the languid creole, or the negro, quietly lets the insect bite, without apprehending any of this sad train of consequences.
Seeing that the fever can, unquestionably, originate without contagion, some contend that, in its passage through the body, it generates a matter, which is capable of producing the disease, by being diffused in the atmosphere, and that it, thus, becomes infectious. But even in this widest sense of the term, I cannot consider it to be either a contagious or infectious malady; for it does not appear that, by any inherent process, the living human body has the power of generating the pabulum necessary for the production or support of this fever; or that the disease, in its progress through the human frame, begets a poison, sui generis, which may be conveyed from one person to produce the disorder in another.
The contagious or infectious fever which proceeds from distempered human exhalations, is a distinct malady. The yellow fever has a different origin—is different in its symptoms, and requires a different mode of treatment. They both have their degrees, and the mild typhus, and typhus gravior of England are not more alike than the continued and the remittent fever of the West Indies. Perhaps the mild, and the confluent small-pox are more unlike: yet no one denies that either is small-pox; or doubts that both are derived from the same cause—the same specific virus.
If the medical attendants, and the (white) orderlies, who have been employed in the hospitals, have suffered from the fever; still, they have only suffered in common with the officers and soldiers, who have not been quartered near the hospitals; and, as their proportion of duty and fatigue has been unusually great, it were not to be expected that they could escape better than their comrades.
The following fact seems to militate strongly against the doctrine of the yellow fever being, originally, a contagious, or becoming, in the course of its progress, an infectious malady, viz. that, of the multitudes of black men and women, whom I have had occasion to see employed constantly in the hospitals, and who have executed all the menial duties about the sick, the dying, and the dead, I never knew even a single instance of either male or female taking the disease. Perhaps no person will contend that this would have happened if the hospitals had been equally crowded with patients in small-pox, measles, scarlet fever, the jail fever, or any complaint decidedly infectious[16].
The yellow fever prevails most commonly, and most extensively, at the decline of the wet season of the year, when the rains and the sun irregularly alternate, and cause unsettled weather: this is also the period when the bilious remittent, and the ague appear among the creoles and negroes. In the midst, or at the very height of the wet season, and during the finer dry season, the fever, in all its forms, is less prevalent: likewise in the dry and elevated parts of the country, which are open to the breeze, it is out of all proportion less frequent than in low damp situations in the valleys, and about the openings of the rivers. In North America it is principally, and almost exclusively a disease of the low and crowded towns, seated upon the borders of the rivers, and the bays of the sea; and is scarcely known in the inland and more lofty parts of the country.
The great favoring circumstances, therefore, appear to be a high degree of temperature, and a moist state of the atmosphere; to which may be added, perhaps, the ill-chosen site of the towns: but, from the particular season in which it spreads its ravages, and from all the concomitances, it is probable that some miasma, or unwholesome exhalation, may be regarded as the true pabulum of the disease.
At the middle period of the wet season the ditches and canals are full, and the brooks and rivulets fluent, so that the noxious exhalations are neither readily formed, nor easily taken up into the atmosphere: in the dry season, these deadly vapours are either chased away by the breeze, or rendered inert by the intense rays of the sun: but, during the intermediate period, at the decline of the wet season, every circumstance tends to favor their production, and to promote their diffusion and suspension in the surrounding air.
The fever is most readily generated in new colonies, where the land is only partially cleared of its wood, badly cultivated, and the half-drained soil left to exhale its noxious vapours into the atmosphere. In the older colonies, where the forests have been long cut down, the territory submitted to the labours of the planter, and its surface more opened to the breeze, it is found to be less prevalent. Examples of this are seen in the old islands of Barbadoes and Antigua, contrasted with those of Grenada and Trinidad. The former are well cleared, and universally tilled, and from locality as well as culture, freely exposed to the influence of the trade-wind: in these, the disease but seldom appears. The latter are not yet brought under general cultivation, but are partially covered with wood, and the atmosphere is damper, and less purified by the breeze: here, the fever frequently and fatally rages.
In new settlements, where the land is neither well cleared, nor drained; and particularly in the vicinity of the towns or habitations, which are commonly placed at the lowest, and most insalubrious spots, for the convenience of commerce, the dirty streams from the higher lands, and often the filth of rivers, or of bays and inlets of the ocean, together with decayed leaves, plants, and roots, and, in short, the whole exuviæ of the vegetable world collect, remain, and grow putrid; in such situations also, the very weeds, and coarser plants, become rank and exuberant, and, growing up only to decay, add to the fermenting mass, which, by holding the impure waters stagnant, accumulates and creates a noxious swamp: thus, is generated the hideous Python, who, though often subdued by the sun’s rays, again lifts up his deadly front, and can only be completely vanquished by the steady and persevering industry of man.
When the effect of climate and situation shall be fully understood, and duly estimated, the yellow fever may be no longer the scourge of our merchants, our planters, and our armies: yet, after the long and fatal experience the world has had, it is equally lamentable and surprising that men should blindly continue in error, with respect to the spots chosen for their towns and dwellings. Contrary to their better knowledge, they prefer the convenience of commerce to the more important advantages of health; and fix their habitations, as it were expressly, upon the most unhealthy points of the globe. In every nation, and almost every colony, striking examples might be selected of the strange folly and neglect with which a circumstance of such serious magnitude is regarded. Armies, perishing with fever, or dysentery, have been snatched from threatened destruction, by change of station; and countries, almost meriting the reproachful term pestilential, have been rendered salubrious by attentions to the soil: still, on the score of health, much remains to be done, by mankind fixing their residence where the atmosphere is least exposed to noxious exhalations. But, alas! commerce, and her seductive attendants, riches, dissipation, and luxury, deaden the loud calls of Hygeia, with her more virtuous train, ease, tranquillity, and happiness; hence it is to be feared that while man remains ambitious, and wealth is made the public road to honors and distinctions in society, health will continue to be only a secondary object of his consideration. It is in the province of the physician to expose this fatal error—to philosophy it belongs to remove it.
The fever of these regions seems, in many respects, to be governed by the same circumstances as the endemic fever of Kent and Lincolnshire, in England. When it attacks the natives of the country, it even assumes the same type and symptoms: and I much suspect that if it could happen that the temperature of these counties should continue as high as from 80° to 90° during the summer, and heavy rains should fall in July, the yellow fever would prevail in the months of August and September: but, while the general heat of the summer shall continue below 70°, there can be no fear of yellow fever being generated in England; and still less of its being imported: for this is just as improbable as that the Kentish fever should be carried off in a Scots trading vessel, and spread among the inhabitants of Edinburgh, whose rocks, and streams, and healthy mountains preclude its visitation.
In order to exhibit, in a more striking point of view, the similarity, or I might say the identity of the intermittent, the remittent, and the yellow fever of the West Indies, and to show that they are only different degrees of the same disease, I may briefly enumerate the more prominent points in which the resemblance is observed.
1. They run indiscriminately into each other—a quotidian, or a remittent, sometimes becoming a malignant yellow fever; and a yellow fever sometimes degenerating into a remittent, or an intermittent.
2. They are all connected with a derangement of the biliary system; and a common sequel of each, is a chronic affection of the liver.
3. They all prevail, most extensively, at the same period of the year; viz. the decline of the wet season.
4. A bilious vomiting is common to them all.
5. They are all, occasionally, attended with a yellowness of the skin, and the eyes.
6. In their relapses, and frequently in their first attack, they all bear a close alliance with the lunar periods.
7. The intermittent, the remittent, or the continued type; or, in other words, the milder, the intermediate, or the more malignant form is assumed, according to the state of vigour, the period of residence in the climate, and other circumstances of the subject attacked.
8. They all, occasionally, affect the same person various times.
With respect to the alleged novelty,—the recent production or importation of the yellow fever, it appears to be an error, which may be explained away, by the fact mentioned above; viz. that during a period of peace and tranquillity it is less frequent, and passes under the milder name of seasoning fever; but from recurring in a time of war, it creates new alarm, and consequently issues forth with a new appellation. Its existence is, no doubt, coeval with the discovery of the colonies; for it is mentioned by some of the oldest writers upon the subject of the West Indies, and is pointedly noticed by Père Labat, an author who himself experienced an attack of it in the year 1694. Were it fit to offer a conjecture with regard to its duration, I might suggest that, in all probability, it will continue to prevail, so long as the hope of riches shall impel the inhabitants of cold climates to pay their devotions to Plutus, by a pilgrimage to tropical fields; unless these fields shall be so improved, by tillage, as to deprive the fever of the aliment necessary for its support.