Of the Nature of Contagion
That the Reasonableness of any Method, which shall be proposed to prevent the spreading of Contagious Diseases, may the better appear, it is necessary to premise somewhat in general concerning Contagion, and the Manner, by which it acts.
Contagion is propagated by three Causes, the Air; Diseased Persons; and Goods transported from infected Places.
We shall therefore first enquire what alteration of the Air it is, that makes it infectious; and then, by what Means it communicates its noxious Quality to other Bodies.
The ancientest and best Authors of Physick, who lived in a Country more exposed to these Calamities than ours, observed the Constitution of the Air, which preceded Pestilential Fevers, to be great Heats attended with much Rain and Southerly Winds1: And one of Them takes particular Notice, that no other than a moist and hot Temperament of the Air brings the Plague; and that the Duration of this Constitution is the Measure of the Violence of the Distemper2.
1. Vid. Hypocrat. Epidem. lib. 3.
2. Galen, de Temperament. lib. 1 cap. 4. & Comment. in Epid. l. 3.
The Natural History of several Countries confirms this Observation; in Africa particularly, if Showers fall during the sultry Heats of July and August, the Plague ensues thereupon, with which whosoever is infected hardly escapes*.
* Vide J. Leon. Histor. Afric. lib. 1.
It has besides been remarked in all Times, that the Stinks of stagnating Waters in hot Weather, putrid Exhalations from the Earth; and above all, the Corruption of dead Carcasses lying unburied, have occasioned infectious Diseases.
From hence it appears to be a Concurrence of Causes, that produces Diseases of this Kind; which must not only meet, but exert their Force together for a considerable time. And when this happens, their first Effect is a Degree of Stagnation in the Air, which is afterwards followed by Corruption and Putrefaction.
And upon this account it is, that those Countries are chiefly liable to these Calamites, where not only the Heats are very great, and the Weather continues long in the same State; but the Winds (the Use of which is by Motion to purify the Air) do not shift and change so often as they do in Northern Climates.
Indeed Plagues seem to be of the Growth of the Eastern and Southern Parts of the World, and to be transmitted from them into colder Climates by the Way of Commerce. Nor do I think, that in this Island particularly there, is any one Instance of a Pestilential Disease among us of great Consequences which we did not receive from other Infected Places.
This I the rather mention, because it is a common Opinion, and propagated by Authors of great Name, that we are usually visited with the Plague once in 30 or 40 Years; which is a mere Fancy without any Foundation either in Reason or Experience: and therefore People ought to be delivered from the Subjection to such vain Fears.
On the contrary, though we have had several Strokes of this kind, yet there are Instances of bad Contagions from abroad being brought over to us, which have proved less malignant here by our Air not being disposed to receive such Impressions.
The Sweating Sickness, called the Sudor Anglicus and Febris Ephemera Britannica, because it was commonly thought to have taken its Rise here, was most probably of a foreign Original, and no other than a Plague abated in its Violence by the mild Temperament of our Climate.
For, we learn from Histories, that the first time this was felt here, which was in the Year 1485, it began in the Army, with which King Henry VII. came from France, and landed in Wales*; and it was then thought to have been brought into France from the famous Siege of Rhodes by the Turks 3 or 4 Years before. And of the four Returns, which this has made since that Time; two, viz. those in the Years 1517, and 1528, may very justly be suspected to have been owing to the Pestilence, which at those Times raged in Italy, particularly at Florence and Naples†. And the others were very probably from a Turkish Infection.
* Vid, Caium de Febre Ephemera Britannica.
† Vid. Rondinelli Contagio in Firenze, & Sum monte Histor di Napoli.
I call this Distemper a Plague with lessened Force, because the Symptoms of it were of that kind, though in a less Degree; as great Faintness and Inquietudes, inward Burning, Pain in the Head, a Delirium, &c. All which were accompanied with profuse Sweats, and the Disease lasted but 24 hours. And though for want of Care, and due Management many died of it; yet as a learned and wise Historian* observes, It appeared rather to be a surprize of Nature than obstinate to Remedies, for if the Patient was kept warm with temperate Cordials, he commonly recovered.
* Lord Verulam’s History of Henry VII.
And I cannot but take Notice, as a Confirmation of what I have been advancing, that we had here the same kind of Fever in the Year 1713, about the Month of September, which was called the Dunkirk Fever, as being brought by our Soldiers from that Place; where it was indeed a Malignant Disease attended with a Diarrhoea, Vomiting, &c. and probably had its Original from the Pestilential Distemper, which some time before broke out at Dantzick and Hamburgh: But with us was much more mild, beginning only with a Pain in the Head, and by very easy Means went off in large Sweats, after a Day’s Confinement.
There being in every Air a greater Disposition to Contagion at one Time than another, we have indeed sometimes felt this Calamity with greater Fury; as particularly the said time in the Year 1665; when it continued in this City about ten Months, and swept away by computation 97 306 Persons: But it was generally allowed, that the Contagion came by Cotton imported from Turkey*; and the long Duration of it, I believe, may justly be charged upon the unhappy Management of infected Houfes, which was then directed by publick Authority, as I shall shew anon.
* Vide Hodges de Peste.
And the History of the most terrible of all the Plagues, that ever were in these Parts of the World, which was that in the Year 1349, gives a manifest Proof from whence all Europe may trace the Origine of these Evils, viz. from Asia: for† This taking its Rise in China in the Year 1346, advanced through the East Indies to Syria, Turkey, Ægypt, Greece, Africa, &c. In 1347 some Ships from the Levant carried it to Sicily, Pisa, Genoa, &c. In 1348 it got into Savoy, Provence, Dauphiny, Catalonia, Castile, &c. In 1349 it seized England, Scotland, Ireland, and Flanders; and in the next place Germany, Hungary, and Denmark, and in all these Countries made most incredible Havock.
† Vid. Histor. Florent. di Matteo Villani.
But to return to the Consideration of the Air, which we left in a putrid State: It is to be observed, that Putrefaction is a kind of Fermentation, and that all Bodies in a Ferment emit a volatile active Spirit, of Power to agitate, and put into intestine Motions, that is, to change the Nature of other Fluids into which it insinuates it self.
From A short discourse concerning pestilential contagion, and the methods to be used to prevent it by Richard Mead, M.D., London, 1720.