The history of the treatment of itch is such a curious instance of the
blind acceptance of authority through many centuries, in the course
of which the true explanation lay close at hand, that it is worth
narrating briefly.
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.
Even with this evidence before them the doctors went on faithful to
their theory of humours. Linnæus supported the view of Bonomo and
Cestoni, but made the mistake of identifying the itch parasite with
the cheese mite. The great medical authorities of the eighteenth
century, such as Hoffmann and Boerhaave, still recommended general
treatment, and a long list of drugs might be compiled which were
supposed to be suitable in the treatment of itch. Among these, luckily,
some parasiticides were included, and, consequently, the disease did
get cured by these, but the wrong things got the credit. About the
end of the eighteenth century Hahnemann promulgated the theory that
the “psoric miasm” of which the itch eruption was the symptomatic
manifestation, was the cause of a large proportion of chronic diseases.
Some observers thought there were two kinds of itch, one caused by the
acarus, the other independent of it. Bolder theorists held that the
insect was the product of the disease. The dispute continued until
1834, in which year Francois Renucci, a native of Corsica, and at the
time assistant to the eminent surgeon d’Alibert at the Hôpital St.
Louis, Paris, undertook to extract the acarus in any genuine case of
itch. As a boy he had seen the poor women extract it in Corsica, as
Bonomo and Cestoni had seen others do it at Leghorn, though his learned
master at the hospital remained sceptical for some years. It was near
the middle of the nineteenth century before the parasitic character of
itch was universally acknowledged.