If there is any doubt as to the cause of the existence of these tunnels, a diagnosis can easily be verified by extracting the mite. With the point of a needle, held almost parallel to the skin, the tunnel can be slit open, and when the point has reached the inner end the mite is very apt to seize it with its suckers, and can be so withdrawn, and, if not, it can easily be picked out. It can then be examined in a drop of diluted glycerine under a microscope.
I am no doctor, hence I venture to refer my readers to the article on Scabies in the ‘Encyclopaedia Medica,’ by Dr. G. Pernet, and to quote the following paragraphs from Dr. H. Radcliffe Crocker’s ‘Diseases of the Skin,’ third edition, vol. ii.:—
Symptoms of Pathology.—The clinical picture of scabies is made up of two elements: the burrows, or cuniculi, and the attendant inflammation excited directly by the Acarus scabiei[13]; and, indirectly, the lesions produced by scratching, and the modifying influences of pressure, friction, &c. The result is a great multiformity of lesions, which, combined with their distribution, is in itself suggestive of the nature of the disease, and enables a practised eye to detect a well-marked case at a glance.
When the skin is first penetrated by the acarus, inflammation is often set up, and a papule, vesicle, or pustule is the consequence. These papules or small vesicles, individually indistinguishable from eczema vesicles, are the most common form of eruption; but the inflammatory symptoms are absent in many burrows. The tract extends and forms a sinuous, irregular, or rarely straight line, which in very clean people is white, but, as a rule, is brownish or blackish from dirt being entangled in the slightly roughened epidermis; the length of these burrows is generally from an eighth to half an inch, but occasionally much longer—Hebra having noticed one four inches long. When a pustule is formed, part of the burrow lies in the roof, but the acarus is always well beyond the pustule or vesicle; or, if there is none, lies at the far end, and with a lens may often be discerned as a white speck in the epidermis. The degree and number of inflammatory lesions vary much; there may be no inflammation at all about many burrows, or the whole hand—especially in children—may be covered by pustules, vesicles, or papules; and, indeed, a pustular eruption on the hands is always strongly suggestive of scabies; there is, however, no grouping or arrangement of any of the eruptions, as in eczema, the lesions being scattered about irregularly. It must be remembered that burrows are not always present, from various causes. If the disease is recent it may not have got beyond the papular or vesicular stage; while in washerwomen, bricklayers, or others whose hands are constantly soaked in water or alkaline fluids, or who have to scrub their hands violently, the burrows become destroyed. The eruptions due to scratching have already been described in the descriptions of the ‘scratched skin,’ and comprise excoriations, erythema in parallel lines, eczema, impetiginous or so-called ecthymatous eruptions and wheals, and the inflammatory scab-topped papules often left after the subsidence of the wheals—especially in children. In carmen, cobblers, tailors, and others who sit on hard boards for hours together, pustular and scabbed eruptions, situated over the ischial tuberosities, are so abundant and constant as to be practically diagnostic of scabies in such people. Similar eruptions may be seen where there is friction from trusses, belts, &c.
Treatment.—I use in private practice, after the preliminary soaking and scrubbing, naphthol 15 parts, cret. prep. 10 parts, sap. mollis 50 parts, adipis 100 parts, as recommended by Kaposi, well rubbed in. For infants it can be used half-strength, and I omit the soft-soap. I can speak of it in the highest praise. It is effectual, has no smell, and is not liable to irritate the skin, as sulphur does. It is, however, too expensive for public practice. Nephritis has occurred from its over-use, but I have never seen any bad symptoms. Another remedy less likely to irritate the skin than sulphur is balsam of Peru, of which the vapour alone is said to be fatal to the acari. The balsam is rubbed in for twenty minutes every night; a night-shirt impregnated with the drug is worn, and in the morning an ordinary soap-and-water bath is taken.
Colonel Allcock says that the best treatment for the itch ‘consists in the free use of soap and hot water and the liberal application of sulphur ointment, continued for several days. Some prefer baths of potassa sulphurata (1 ounce of the salt to 4 gallons of water). Clothing and bedding should be fumigated with sulphur or baked.’
Endo-parasitic Mites
Certain little mites whose appearance is as repellent as their name—for they are known as Nephrophages sanguinarius—were recorded by two Japanese observers twenty years ago as coming away in the urine of a Japanese patient who was suffering from various bladder troubles. As the mites were in all cases dead, the Japanese doctors thought that they must have been endo-parasites of the kidney. They were found day after day for a week or more, and they were found also in the water with which the bladder had been washed out, but always dead. It is, of course, possible that the Japanese doctors were right in their surmise, but the best that can be said for the case is that it is ‘not proven.’
Fig. 40.—Nephrophages sanguinarius (enlarged). Male, ventral surface. Female, dorsal aspect. (After Miyake and Seriba.)