Plica Polonica (Lat. plicare, to knit together), a disease of the hair and hairy scalp, endemic in Poland, and characterized by a matting together of the hairs. It was formerly common in Poland, but is now rare and almost exclusively confined to wretched and filthy persons. The preliminary symptoms are fever, loss of appetite, headache, vertigo, and pains in the scalp. Then a glutinous secretion makes its appearance upon the hairy scalp, and afterward upon the hairs themselves, which become adherent to each other, and at the same time acquire a morbid sensibility, so that the least touch or movement of them causes acute pain. They become arranged in three different modes: 1, in long flexible locks or strings of agglutinated and pendent hairs; 2 (the most common and characteristic form), in an inextricably tangled mass, consisting of hairs matted together in every direction, and often exhaling a fetid odor and overrun with vermin; 3, in a long mass of disproportioned growth like a horse tail, called plica caudata (Fr. plique d queue). The malady lasts thus for several months or years. In the majority of cases it gradually subsides after a time, and healthy hair begins to take the place of the diseased growth.
It is then sufficient to cut off the tangled mass and allow the new crop of hair to occupy its place; but this measure is not effectual unless the disease already shows signs of having exhausted itself. During its height the best treatment is attention to cleanliness and the prevention of any further irritation to the scalp. A microscopic fungoid vegetable growth, the tricophyton tonsurans, was discovered by Giinsburg in 1843 in the diseased hairs of plica polonica, and the malady was attributed by the discoverer to the presence of the vegetable parasite. But it is still doubt • ful whether it occurs in all cases, and whether it may not be the accompaniment rather than the cause of the malady. Experiments have been tried in the inoculation of plica polonica, with varying and indecisive results.