The Common Nature of Epidemics, and their relation to climate and civilization

by Southwood Smith

It is stated by Dr Thomas Lesslie Gregson, who was at Alexandria during the prevalence of the great plague of 1836, on duty there as surgeon-in-chief to the Naval, Military, and Civil Hospital, that cattle were attacked with decided symptoms of plague some time before the disease broke out among the human species. “Before the disease broke out,” he says, “a number of the Pacha’s oxen were seized with a malady, of which above one hundred died in a few days. I was sent to investigate and report on this epidemic. On examination I found gastroenterite in the most intense degree; so much so, that I have found extensive gangrene in oxen that have only been observed ill twelve hours. They had also large buboes. This I reported plague, and caused them to be interred deeply.”

Quarantine is based on the assumption that epidemic diseases depend upon a specific contagion; but the question of contagion has no necessary connection with that of quarantine. The real question is whether quarantine can prevent the extension of epidemic diseases, whatever may be their nature, whether contagious or not. If it can, it is valuable beyond price; if it cannot, it is a barbarous encumbrance, interrupting commerce, obstructing international intercourse, periling life, and wasting, and worse than wasting, large sums of the public money.

But if the power of protecting the country from the introduction and spread of disease, whether contagious or otherwise, claimed by quarantine, be really possessed by it, this must be proved by other considerations than those which establish the contagiousness of disease; it is a mere matter of evidence and experience, and consequently the disputed point of contagion should be placed entirely out of view in this discussion, and the whole question should be argued on the broad ground whether or not quarantine is a public security, or is capable of affording practically any useful result.

There is indeed one point of view in which it may be proper, and even necessary, to consider the question of contagion with relation to that of quarantine. Assuming the existence of contagion, if it can be proved that quarantine, instead of affording any protection against contagion, absolutely fosters it, then the stronger the proof of contagion the more decisive the argument presented by it against quarantine; and it will be shown hereafter that this is the true and the only relation in which contagion stands to this question.

There is no more reason why the controversy on contagion should complicate the question of quarantine than why it should continue to encumber the general subject of the removable causes of disease, from which efforts have long been made to disentangle it.

The discussion whether epidemic diseases arise and spread from contagion or from common or specific poisons generated in the localities in which these pestilences first break out, has nothing whatever to do with quarantine, the sole inquiry with reference to this question being whether, however epidemic diseases arise, quarantine can prevent their introduction into a country or arrest their progress when there.

Few will question that the progress of the opinion of observers in Europe during the last half-century has been steadily towards a material modification, if not an entire abandonment, of the doctrine of contagion with reference to the majority of epidemic diseases, taking the word contagion in its strict sense, that is, the communicability of disease exclusively by contact: direct, that is, with the body or breath of an infected person; or indirect, with something which an infected person has touched.

Cholera may be taken as an example of the diseases of the epidemic class. When cholera first invaded Europe in 1831,[^[26]] the belief in its contagious nature was almost universal, and in this country in particular there was scarcely a medical man who did not entertain this conviction; but as in India, where this disease is known, the belief in its contagious nature is universally abandoned, so in Europe it gradually diminished in proportion as opportunities of observing the disease increased; and now in Russia, Poland, Prussia, France, Belgium, and England, the contrary view, with few exceptions, is maintained.

[26]. See note p. 61.

There has been much confusion of terms in respect to the use of the words contagion and non-contagion. Professional men have avowed their belief of the contagiousness of typhus, and stated that they had experienced it in their own persons. When asked for the evidence on which the belief was founded, they have usually related some circumstances showing, not the contagiousness, but the infectiousness of the disease. Contagion is a term applicable to a different set of circumstances. According to the hypothesis of contagion, no matter how pure the air, no matter what the condition of the fever ward, if the physician only feels the pulse of the patient, or touches him with the sleeve of his coat, though he may not catch the disease himself, he may communicate it by a shake of the hand to the next friend he meets; or that friend, without catching it himself, may give it to another; or if the physician wash and fumigate his hand, but neglect the cuff of his coat, he may still convey the deadly poison to every patient whose pulse he feels during the day. If this were so, the track of a general practitioner who attended one patient labouring under a specific epidemic disease would be marked by the seizure of the rest of his patients; if it were true of cholera and typhus, the members of the General Board of Health must have fallen by these diseases, who from morning until night received inspectors that came from places where these epidemics were rife; and if any disease of common occurrence really possessed such powers of communication and diffusion, it is difficult to conceive how it is that the human race has not been long since extinguished.[^[27]] To assume the method of propagation by touch, whether by the person or of infected articles, and to overlook that by the corruption of the air, is at once to increase the real danger, from exposure to noxious effluvia, and to divert attention from the true means of remedy and prevention. It is not in human power to take from any disease the property of contagion, if this property really belongs to it; but it is in our power to guard against and prevent the effects of any contagion, however intense; and it is equally in our power to avoid communicating to common disease an infectious character, and aggravating it into pestilence.