Intempestivis pluviisque, et solibus icta.”
(De Rerum Nat. vi, 1100.)
Silius Italicus appears to refer an epidemical fever to the same cause. (xiv.)
In his work, on the ‘Varieties of Fever,’ Galen expresses his opinion on this subject very fully. He remarks that an atmosphere of a hot constitution, such as generally prevails at the time of the rising of the dog-star, having been inhaled by the heart, increases the heat in it, from which it is diffused all over the system, and enkindles a febrile affection. In pestilential constitutions, he adds, it is principally by the respiration that the disease is contracted, although sometimes it may arise from the fluids of the body being disposed to putrescency, which is increased by the condition of the atmosphere; but for the most part epidemical complaints derive their origin from the atmosphere being tainted with putrid exhalations. The putridity of the atmosphere may be occasioned either by a multitude of dead bodies which have not been burnt, as is apt to happen in wars, or it may arise from the exhalations of certain marshes or lakes in the summer season, or sometimes the inordinate heat of the atmosphere may give rise to them, as happened in the case of the Athenian plague, according to the testimony of Thucydides. And here we must digress to remark, that Homer evidently ascribes the plague which attacked the Grecian army to the great heat of the sun. See the Commentary of Eustathius on the beginning of the Iliad; Ammianus Marcellinus (xix); Heraclides Ponticus (Allegor); and Macrobius (Saturn. vii, 5.) Galen, however, inculcates that the constitution of the atmosphere alone is not sufficient to produce disease without a peculiar disposition of the body to admit it; for that, otherwise, all without exception would be seized with the prevailing epidemic. This leads him to give directions to correct the intemperament of the body when it is such as disposes it to be readily affected by the constitution of the atmosphere. His directions are similar to those of our author. Besides the causes of epidemical diseases which we have mentioned, he states that unwholesome food and drink may sometimes, though rarely, give rise to them. Of this he relates a striking instance. (De Rebus boni et mali Succi, c. i.) He remarks that the most common epidemical diseases are pestilential fevers. We shall have occasion to state his opinion of them in [the next Section].
Of the Greek authors posterior to Galen, Oribasius and Aëtius give the same account of epidemical diseases as our author; and the others either do not treat of them at all, or class them with the subject of our next Section.
Avenzoar has given us an elaborate treatise on epidemical complaints. (iii.) The first cause of them which he mentions is a humid and warm state of the atmosphere, such as that to which Hippocrates ascribed the pestilence which afflicted Thasus in his time. (Epid. iii.) The other causes enumerated by him are the effluvia from dead bodies, stagnant air, the miasmata from stagnant and corrupted waters, and unwholesome food. (iii, 3, 1.)
On the origin of epidemical diseases, especially the pestilence, see, in particular, Haly Abbas (Theor. v, 11.) The principal causes of the change of the atmosphere to a pestilential state, according to Haly, are the nature of the country and the season of the year. The former cause operates owing to the putrid effluvia arising from corrupted fruit, pot-herbs, &c., or the miasmata from marshes, cloacæ, or dead bodies, whether of men or cattle. It was from such causes, he remarks, that the plague of Athens derived its origin. The nature of the season, as it produces diseases in the vegetable, so does it also in the animal creation. As epidemical complaints, he mentions ephemerals, cynanche, smallpox, acute fevers, and other fatal diseases.
Avicenna’s account of the origin of pestilential and epidemic diseases is taken almost entirely from Galen; he therefore enumerates as causes of them, a humid and warm state of the atmosphere, the stagnant air of caverns, the miasmata of lakes and marshes, and the effluvia from dead bodies. (iv, i, 4.) Alsaharavius enumerates exactly the same causes. (32.) Rhases’ account is mostly taken from Hippocrates and Galen. (Contin. xxx.)
The historian Ammianus Marcellinus gives an ingenious disquisition on the origin of these diseases; but the distinction which he endeavours to establish in the following passage is not acknowledged by the medical authors in general: “Prima species luis Pandemus appellatur, quæ efficit in aridioribus locis agentes caloribus crebris interpellari; secunda, Epidemus quæ tempore ingruens acies hebetat luminum, et concitat periculosos humores; tertia, Lœmodes, quæ itidem temporaria est, sed volucri velocitate letabilis.” (xix, 4.) The causes of these complaints, as enumerated by him, are excessive heat, cold, drought, or moisture, effluvia from putrid bodies, and exhalations from the earth.
According to Diodorus Siculus, the causes which gave rise to the pestilential epidemic which attacked the Carthaginian army in Sicily were the marshy nature of the country in which they were encamped, the bodies of the dead lying unburied, and the excessive heat of the season. (xiv.) He ascribes the plague of Athens to similar causes. (xii. 58.)