This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
This is a zooparasitic affection, due to the invasion of the skin by the Phthirius or Pediculus corporis. It is characterized by pruritus, which leads to scratching and the development of certain secondary lesions which may be conveniently termed scratch-marks. These, in milder cases, may consist simply of little black points, slightly, if at all, elevated above the surface of the skin. They are produced by the desiccation of a small droplet of blood, resulting from the wounding of a few papillae with the finger-nail; next we may find red lines or streaks, surmounted with blackish red ridges of dried blood. These minute incrustations are rarely absent, and, to a certain extent, are pathognomonic of the affection. As the insects increase in numbers, the irritation likewise increases, and the pruritus becomes intense, keeping the patient busy with his nails the greater part of the time. A superficial scratching, however, will not afford sufficient relief, and the unhappy sufferer tears the skin with his nails until he is a mass of bleeding excoriations. Under the influence of the continual irritation the skin darkens, and the body is covered with lines and blotches more or less deeply pigmented. When the disease is severe upon the lower extremities it is not unusual to find enlargement and tenderness of the inguinal glands. The affection is most frequently met with in advanced life.
The pediculus corporis having once effected a lodgment, makes its nest or habitation among the undergarments of the patient, and not beneath the skin like the acarus, nor upon the skin and among the hairs as do the other species of pediculus. It seeks by preference points where the clothes are thrown into folds, and there lays its eggs. When hungry it promenades the surface of the skin and seeks a convenient spot for a repast. This is effected by the insertion of a long haustelhum through which it sucks up a sufficient quantity of blood. If undisturbed, it feeds most leisurely, and until its abdominal cavity is quite distended, and even then it will not always stop, but sometimes rejects,per anum, that which it has just taken, in order to make room for a fresh supply. It is the irritation produced by these insects that gives rise to the symptoms we have already considered.
The majority of cases of severe pruritus met with, at least in this city, are examples of Phthiriasis ana no case of general pruritus should be passed without special examination as to its connection with vermin. The presence or absence of pediculi should be positively determined, and they usually can be without difficulty. Search for the insect should not be made on the skin, as, unless very abundant, they will not be found there, but on the undergarments. Once found, the diagnosia is made. If after thorough and repeated examinations they are not found, the pruritus must be referred to some other cause. In Phthiriasis the regions that usually exhibit the most distinct evidences of scratching are the upper part of the chest, the thighs, legs, and back; the bead, belly, and genital region being comparatively free. In advanced cases the patient's expression, gait, and behavior are so characteristic that the experienced observer will frequently make a correct diagnosis before a single lesion is brought to his eye.
The form and appearance of the insect are shown in Fig. 25.
This affection is always curable, provided the patient is in circumstances that will permit proper measures of relief to be carried out. The great majority of cases met with here is in hospitals and at dispensaries, that is among the pauper class, and if cured they are very apt to recontract the trouble, and thus suffer from it to a greater or less extent for years. In the upper classes it is sometimes though rarely met with, and under these circumstances is readily relieved.
A warm bath, thorough soaping, and a good scrubbing will free the body of the patient from the parasite. The clothes and bed-clothes, however, must be disinfected by baking, prolonged boiling, or sulphur fumigation. If practicable they had better be destroyed. A certain amount of pruritus will remain for some time after the destruction of the insect. This may be alleviated by applications of tincture of Delphinium, of Stramonium and other antipruritics.
Fig. 25. - Phthirlus or pediculus corporis. also called pediculus ves