Part 5 (1/2)
In this respect there is a marked difference between an epidemic and an endemic affection; for when an epidemic disease attacks a city or town we do not discover that the central parts are more exempt than others; indeed, it is rather the contrary; for the most crowded parts of towns and cities are those, if not exactly in the centre, which would be comprised in a s.p.a.ce nearer to the centre than the circ.u.mference; and it has been in those parts generally where the epidemic influences seem to have exercised the most potent sway. One would more naturally suppose, that a city surrounded by {99} paludal miasm, and not itself being capable of generating the poison, should be more affected at the circ.u.mference, from the simple fact that the paludal germs, which rise in the air, are suspended in the fogs and dews of the atmosphere. These, unless widely dispersed by the winds, would remain within a comparatively confined s.p.a.ce; and those situations nearest to them would be most subject to their influence. Besides, it has been shewn, that a small wood or hill, or even a wall, has been sufficient to cut off or obstruct the paludal miasm.
Without enumerating all the known endemic diseases, two or three may be alluded to for our present purpose; viz. that of shewing that endemic and epidemic diseases have a similar origin.[39]
It is well known that under certain favouring conditions an endemic may become a malignant and pestilential disease; that Yellow Fever, which is always endemic in the west, Cholera in the east, and the Plague in the south of Europe and north of Africa, every few years takes on an epidemic form, and desolates considerable tracts of country.[39]
The Pestilence which raged in the summer and autumn of 1804 in Spain, commenced at Malaga, and remained for a considerable time confined to its {100} boundaries, in consequence of the measures of precaution that were used, in preventing all communication between the inhabitants of the infected city and those living in the surrounding country. It was only in consequence of persons escaping through the cordon, and pa.s.sing into the interior of the country, that the disease spread, and extended its ravages to distant places.
It appears to be quite clear, that this disease may properly be considered in the first instance of endemic origin; but the tendencies, atmospheric and otherwise, were such as to favour its multiplication in other districts than that in which it first came into active existence. From this we may infer, that the seeds of the disease were dormant, and only became roused into vital activity by fortuitous circ.u.mstances. Dr. Rush states, that the endemic disorders of Pennsylvania were converted, by clearing the soil, to bilious and malignant remittents, and to destructive epidemics. Dr. Copland says, it has been observed, especially in warm climates, and in hot seasons in temperate countries, that when the air has been long undisturbed by high winds and thunder-storms, and at the same time hot and moist, endemic diseases have a.s.sumed a very severe and even epidemic character.
Dr. Robertson also confirms this view. ”Endemic diseases, in cases of neglect and preposterous management, are found to become more malignant even in the most temperate climates; and to {101} generate a matter in their course, capable of producing a particular disease in any circ.u.mstances. _Indeed the origin of every_ contagious fever unattended with eruptions, with the exception of Plague, must commence in this way.”
Why Dr. Robertson should except eruptive Fevers and Plague I cannot understand, for they must have had a commencement; and their many points of similarity indicate, if not an identical, an a.n.a.logous source to other endemic fevers.
It will doubtless be generally acknowledged that endemic and epidemic diseases depend upon some unknown agents, having their source in malarious districts, and being capable of a.s.suming either a contagious or non-contagious character, according to circ.u.mstances.
If, therefore, we find that under any conditions an endemic affection becomes capable of being propagated by contagion, the same law will hold with regard to it as to the Plague; that the power of reproduction in this matter is evidence of life, according to the doctrine laid down in the earlier part of this work. But whether or not infection be admitted, a matter generated in a malarious district, if confined in its effects to that district alone, would not necessarily imply an inorganic nature of the poison; for it is difficult to understand how inorganic poison, prevailing generally over a certain tract of country, could select particular individuals for its victims. If chloroform, chlorine, carbonic acid, sulphuretted hydrogen, or even spores of poisonous fungi, (as {102} supposed by Mitch.e.l.l, which, as he regards their effects, would act in a similar manner to inorganic compounds) were the agents, all persons would suffer more or less, and the majority be similarly affected. We do not find that uniformity of symptoms, which attend upon the exhibition of poisons in the ordinary acceptation of the term, poisoning. This subject shall be more particularly considered, when treating of the influence of organic germs on animals and plants.
The history of the Eclair steamer is particularly interesting, as shewing the extraordinary tenacity with which the germs of disease attach themselves to vessels, which we may call floating houses.
The crew of the Eclair contracted Yellow Fever on the coast of Africa, and a number of them died. The remainder, sick and well, landed at Bona Vista, one of the Cape de Verde Islands, and the vessel underwent a process of was.h.i.+ng, whitewas.h.i.+ng, and fumigating. Nevertheless, on the return of the s.h.i.+p's company, the disease broke out again with equal intensity, and the vessel was ordered home. Sixty-five out of 146 officers and men, who composed the crew, died of the disease before reaching Portsmouth, and twenty-three were sick at the time of arrival.
Eight days after the Eclair left Bona Vista, a Portuguese soldier who had mixed with her crew died in the fort which had been occupied by them. Other soldiers then fell sick, and the fort was abandoned. The fever still spread.
From the 20th September, when the first soldier {103} was attacked, to the first week in December, the fever continued to rage, and at that period it had found its way into almost all the country villages. The fever was believed to be the genuine black vomit fever; it proved contagious almost without exception to the nurses of the sick.
This is an abstract of Mr. Rendell's letter to Lord Aberdeen, Mr. Rendell being British Consul at Bona Vista.
Now at the time the fever broke out in the island the weather was extraordinarily hot, and much rain had fallen, and the town itself was badly drained and in a filthy state; can it be imagined then that the seeds of a disease liable to a.s.sume a pestilential character should lie dormant or be annihilated under circ.u.mstances the most favourable for their development, especially when we know that endemic diseases may a.s.sume a malignant character?
This is just one of many cases which confirm our opinion in this respect, that plants and diseases are not long in making their appearance where the soil and atmosphere are congenial.
The tenacity with which the disease attached itself to the Eclair is sufficiently explained in the absence of due ventilation; in fact, that in the first instance there was no ventilation at all in the hold of the s.h.i.+p.
This also the more readily affords a clue to the disaster through all its stages, first in the contraction of the disease as an endemical affection in the vessel; secondly, in the multiplication of the {104} germs in the damp ill-ventilated hold, in a warm climate; and thirdly, the persistence and entire localization of the disease to the vessel when it arrived in the climate of the British sh.o.r.es; while, fourth and lastly, in the unusually hot and damp island of Bona Vista, the seeds of the disease were sown, and, as we might expect, multiplied indefinitely.
The consecutive attacks of the crew of the Eclair shew that here a noxious gas or a vaporized inorganic poison could not have been the cause of the disease, for as I have before said, in this case the attacks should have been simultaneous; we find, on the contrary, that as the depressing effects of the melancholy condition of the crew was almost hourly undermining the health of the stoutest of them they as surely became the victims. The Kroomen, or natives on board the s.h.i.+p had not suffered, shewing that they were inured to the miasm, or were dest.i.tute of that condition of blood which would be favourable to a propagation of the materies of the disease.
The Eclair we learn had left Bona Vista eight days when the first victim breathed his last; this would give perhaps three or four days for the incubation of the disease in the patient, or supposing he had not contracted the germs of the disease before the crew of the Eclair left the fort, some local favouring conditions were the means of keeping the germs in a fertilizing state, for it is clear from this spot the infection spread as from a centre or focus. {105} Such instances as these might be multiplied to extend the length of the enquiry, but, I think, to little advantage. The chief facts to be gathered are that an endemic affection became epidemic and pestilential, contrary to its usual mode, for the Portuguese official physician, on being consulted by the Governor of the Island as to the safety of landing the contaminated crew, said, ”No danger at all; I have often brought sick men on sh.o.r.e coming in vessels from the African coast, and I never knew any ill effects to arise.” Putting the most reasonable construction on this emphatic and straightforward language, we may presume that ordinary, remittent, and yellow fever had been commonly imported into the island, for it is not to be supposed but that both forms of disease must have existed among those sick men who had ”_often been landed_,” under the sanction of the Portuguese physician.
To take another instance; intermittent fever or ague, is a disease known among almost all nations of the world, but it usually occurs in the endemic form only. It is universally supposed to depend entirely upon marsh effluvia, and we are accustomed to consider it as attaching only to low lying countries;[40] but this is not always the case, for disease in {106} this respect, like vegetation, may be found in various lat.i.tudes, to accommodate itself at varying alt.i.tudes, to the temperature and climatic relations, so as to appear indigenous. But though our prejudices are in favour of a simple miasmatic source of ague, as its sole cause, there are some who believe in its infectious nature. M. Sigaud, in his work on the Climate and Diseases of Brazil, speaks of Epidemics of _grave intermittent Fever_, and Dr. Copland says, that the epidemic prevalence of ague is a better established fact than its infection, and has been admitted by most writers.[41] We have, therefore, but to go one step further to arrive at infection, after having found that an endemic disease under peculiar circ.u.mstances, though but rarely, becomes {107} epidemic. The number of persons attacked by ague in a malarious district, in proportion to the population, is not so great as might be expected, considering that they are always subject by night and day, more or less, to respire the air containing the germs of intermittent fever; we might, therefore, deny the paludal source of the affection, as reasonably as deny infection, if we found that occasionally, persons, though subject to all the usual influences, yet escaped all injurious consequences.
There are grades and varieties of infectious diseases, from the most inveterate to the most mild and doubtful; but that all, without exception, which can in any way be traced to a specific generating and organic cause, may a.s.sume an exalted infectious character, and that the most inveterate, on the contrary, may more resemble the mild and doubtfully infectious forms, is a conviction that must be forced on all who pursue this enquiry with unbia.s.sed interest.
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CHAPTER III.
THE REASONABLENESS OF THE APPLICATION OF THE FACTS TO THE INFERENCE.
SECTION I.
THE CHEMICAL THEORY OF EPIDEMICS UNTENABLE.