Lepra (Gr. scaly), a skin disease which in the most common form (lepra vulgaris) is characterized by circular patches, the centre depressed with the skin sound or nearly so, the circumference slightly elevated and covered with small, dry, shining scales. It commences with an eruption of small, red, elevated points, each covered with a minute scale; the disease advances at the circumference, the centre gradually becoming sound. The eruption is perfectly dry. The circular patches rarely become more than an inch in diameter. Where the eruption is copious, these patches intersect each other at the circumference, and the circular form is lost, but characteristic segments of a circle can still be traced. The disease commonly commences in the extremities, and often extends over the trunk; the head and face are very rarely affected. When it is very chronic and extensive, the roots of the nails are sometimes affected, and the nails become thickened, curved, and of a dirty yellow color; according to Rayer (Maladies de la peau), the matrix of the nails sometimes becomes inflamed and furnishes a sanious discharge.
The general health is very slightly affected by the disease, and the patient only suffers from an annoying itching;, aggravated by warmth, exercise, or full diet, and chiefly present at the commencement of the complaint or while it is spreading. Lepra alphoides is a variety of the disease in which there is less redness of the skin and elevation of the circular margin of the patches, while the scales are smaller and of a more pearly whiteness. In lepra nigricans the scales have a dark or blackish color; it is a rare form, and according to Biett always of syphilitic origin. Lepra is mainly an affection of youth and adult life, but no age is exempt from it. It is unattended with danger to life, but obstinate and uncertain of cure, sometimes disappearing in one place to appear in another, or reappearing directly after remedial means have been discontinued. Its essential causes are unknown. - Treatment. Internally the remedy from the use of which benefit is derived in the greatest number of instances is undoubtedly arsenic. Fowler's solution may be given in doses of from 3 to 5 drops three times a day, its effects being carefully watched. Biett in many instances has derived great advantage from the tincture of cantharides, commencing with small doses, which are gradually increased.
Externally, alkaline baths (from 4 to 8 oz. of the sub-carbonate of potassa to a bath) and vapor baths have been particularly recommended. Tar ointment (1 part to 8 of lard) is of undoubted efficacy. Biett also recommends the use of an ointment of iodide of sulphur (12 grs. to the ounce of lard), and of calomel ointment (1 dram to the ounce).