Diagnosis

The diagnosis of scabies should not in most cases be difficult. The early vesicles on the hands are either to be found, or the patient may tell you that the affection commenced with small "watery pimples". Next, examine the penis, and you will rarely miss finding papules on the glans or papules or vesicles on the cutaneous surface. Rather good-sized isolated pustules about the wrists are commonly present, and in women you usually find an eczematous eruption around the nipple. If on inquiry you find that one or the other of the patient's associates is suffering from a similar trouble, and that he has slept with him or worn his clothes, you may be fully confident of the diagnosis.

The mere presence or the intensity of the itching cannot be relied on to establish the nature of the disease, as in several other affections intense pruritus is a marked feature and this is notably the case in ptheiriasis, produced by the pediculus corporis, or body louse. The papules or other lesions on the penis should not be mistaken for lesions of venereal origin.


To briefly sum up, then, the diagnostic points are:

1. A history of contagion.
2. The development of minute papulo-vesicles or vesicles, spreading on contiguous portions of the skin or on parts habitually handled by the patient (never in patches but in rather a scattered manner).
3. Itching, worse at night and becoming progressively worse as larger areas become invaded by the itch-mite.
4. Sites of predilection shown by the disease. They are the webs of the fingers, the front of the wrists, the anterior edges of the axillae, the mamma, the penis, the abdomen and groins, the toes and feet. Flexor surfaces are more involved than extensor.
5. That the face remains free from the disease, except in the case of infants at the breast.
6. That it has taken about three weeks for the disease to involve the whole surface.
7. That old cases show all the lesions that can possibly be produced by disease of the skin, expressed by the term multiformity of lesions.
8. Incidentally - numerous scratch-marks.
9. The itch-mite and its canaliculi.