ITCH-Infest. See ACARUS.
In speaking of the manner of finding these insects in the itch, Fabricius observes, that the failure of many who have sought for them has been owing to their having expected to meet with them in the larger vessels that contain a yellowish fluid like pus; in these, however, he tells us, he has never found them, but in those pustules only which are recent, and contain only a watery fluid. We must therefore, he observes, not expect to find them in the same proportionate number in patients who for many months have been afflicted with the disease, as in those in whom its appearance is recent, and where it is confined to the fingers or wrists. The cause of this difference with respect to the pustules, he conjectures, may be owing to the death of the insect after it has deposited its eggs.
A small transparent vesicle being found, a very minute white point, distinct from the surrounding fluid, may be discovered, and very often even without the assistance of a glass; this is the insect, which may be easily taken out on the point of a needle or penknife, and when placed on a green cloth may be seen much more distinctly, and observed to move.
The author remarks, that even before such a transparent vesicle is formed, we may often discover traces of the insect on the fingers or hands, in a reddish streak or furrow, which is occasioned by the acarus; and he adds, that it is even more usual to find it in these furrows than in the pustules themselves. He tells us, that a friend of his at Hanover (who had the itch in a slight degree, and to whose accurate inquiries with an excellent microscope he acknowledges himself much indebted) found several insects in such furrows. Two of the longest of the furrows were about an inch in extent. They seemed to be thoroughly dry, but exhibited here and there very minute shining and transparent spots. These spots, however, were not at all elevated above the surface of the skin; and although several of them were opened and examined, no insect was found in them. These furrows he has observed only on the hands and fingers, having in vain sought for them on the legs and other parts of the body, in his children, who had the itch in a high degree.