It is stated in some histories that the disease was known to the Chinese some thousands of years ago, and the name they gave it, Tchong-kiai, which means pustules formed by a worm, indicates that at least when that term was adopted they had some acquaintance with the character of the disease.
Some writers have supposed that certain of the uncleannesses alluded to in the Book of Leviticus have reference to this complaint; and it is quite possible that in old times it acquired a much more severe character than it ever has now, owing to neglect or improper treatment. Psora, in Greek, and the equivalent term Scabies, in Latin, are supposed to have at least included the itch, though in all probability those words comprehended a number of skin diseases which are now more exactly distinguished. Hippocrates mentions psora, and apparently treated it solely by the internal administration of diluents and purgatives. Aristotle mentions not only the disease but the insects found, he said, in the blisters. Celsus advocated the application of ointments composed of a miscellaneous lot of drugs, such as verdigris, myrrh, nitre, white lead, and sulphur. Galen hints at the danger of external applications which might drive the disease inwards. In Cicero, Horace, Juvenal, and other of the classical writers, the word scabies is used to indicate something unnatural; showing that it had come to be adopted metaphorically.
The Arab writers are much more explicit. Rhazes, Haly Abbas, and Avicenna are very definite in their descriptions of the nature of the complaint, and how it is transmitted from one person to another; but Avicenna’s mode of treatment was directed to the expulsion of the supposed vicious humours from the body by bleeding and purgatives, especially by a purgative called Hamech. At the same time he advised that the constitution should be reinforced by suitable diet and astringent medicines.
Avenzoar of Seville, a remarkable observer, who lived in the twelfth century, alludes to a malady of the skin, common among the people, and known as Soab. This, he says, is caused by a tiny insect, so small that it can scarcely be seen, which, hidden beneath the epidermis, escapes when a puncture has been made.
One would have supposed that the doctors were at that time on the eve of understanding the itch correctly, and in fact the writers of the next few centuries were at least quite clear about the acarus. Ambrose Paré, for example, who lived through the greater part of the sixteenth century, uses this language:—“Les cirons sont petits animaux cachés dans le cuir, sous lequel ils se trainent, rampent, et rongent petit par petit, excitant une facheuse demangeaison et gratelle;” and elsewhere “Ces cirons doivent se tirer avec espingles ou aiguilles.”
All this time, however, the complaint was regarded as a disturbance of the humours which had to be treated by suitable internal medicines. In a standard work, De Morbis Cutaneis, by Mercuriali, published at Venice in 1601, the author attributes the disease to perverted humours, and says it is contagious because the liquid containing the contagious principle is deposited on or in the skin.
This view, or something like it, continued to be the orthodox opinion at least up to the seventeenth century. Van Helmont’s personal experience of the itch is referred to in dealing with that eccentric genius who was converted from Galenism to Paracelsianism as a consequence of his cure; but he never got beyond the idea that the cause of the complaint was a specific ferment.
The earliest really scientific contribution to the study of this disorder may be credited to Thomas Mouffet, of London, who, in a treatise published in 1634, entitled Insectorum sive Minimorum Animalium Theatrum, showed not only that the animalculæ were constantly associated with the complaint, but made it clear that they were not to be found in the vesicles, but in the tunnels connected with these. For this was the stumbling block of most of the investigators. It had been so often stated that the parasites were to be found in the vesicles, that when they were not there the theory failed. Mouffet’s exposition ought to have led to a correct understanding of the cause of the complaint, but it was practically ignored.
About this time the microscope was invented, and in 1657 a German naturalist named Hauptmann published a rough drawing of the insect magnified. A better, but still imperfect, representation of it was given a few years later by Etmuller.
In 1687 a pharmacist of Leghorn, named Cestoni, induced a Dr. Bonomo of that city to join him in making a series of experiments to prove that the acarus was the cause of itch. They had both observed the women of the city extracting the insects from the hands of their children by the aid of needles, and the result of their research was a treatise in which the parasitic nature of the complaint was maintained, and the uselessness of internal remedies was insisted on. These intelligent Italians recommended sulphur or mercury ointment as the essential application.