Following or along with precursory symptoms denoting general systemic disturbance, or independently of any prodromal indications, a hyperaesthetic condition, in localized areas or more or less general, is observed. Lancinating pains along the nerves and an irregular pemphigoid eruption are also commonly noted. There soon follows the special eruption, coming out from time to time, and consisting of several or more, usually non-elevated, well-defined, pale-yellowish patches, one or two inches in diameter. As a rule, they are at first neither hyperaesthetic nor anaesthetic, but may be the seat of slight burning or itching. They spread peripherally, and tend to clear in the centre. The patches eventually become markedly anaesthetic, and the overlying skin, and the skin on other parts as well, becomes atrophic and of a brownish or yellowish color. The subcutaneous tissues, muscle, hair and nails undergo atrophic or degenerative changes, and these changes are especially noted about the hands and feet. These parts become crooked, the bone tissues are involved, the phalanges dropping off or disappearing by disintegration or absorption (_lepra mutilans_). Sooner or later various paralytic symptoms, showing more active involvement of the nerve trunks, present themselves. #State the cause of leprosy.# Present knowledge points to a peculiar bacillus as the active factor, while climate, soil, heredity, food and habits exert a predisposing influence. #Is leprosy contagious?# The consensus of opinion points to the acceptance of the possible contagiousness of leprosy; probably by inoculation, but only under certain unknown favoring conditions. #What are the pathological changes?# The lesions consist essentially of a new growth, made up of numerous small, more or less aggregated round cells, beginning in the walls of the bloodvessels. In this way the tubercular masses and various other lesions are formed. As yet, positive involvement ot the central nervous system has not been shown, but some of the nerve trunks are found to be inflamed and swollen, with a tendency toward hardening. #What several diseases are to be eliminated in the diagnosis of leprosy?# Syphilis, morph[oe]a, vitiligo, lupus, and syringomyelia. When well advanced, the aggregate symptoms of leprosy form a picture which can scarcely be confused with that of any other disease. In doubtful cases microscopical examinations of the involved tissues, for the bacilli, should be made. #State the prognosis of leprosy.# Unfavorable; a fatal termination is the rule, but may not be reached for a number of years. The tubercular form is the most grave, the mixed variety next, and the anaesthetic the least. Patients are not infrequently carried off by intercurrent disease. Proper management will often delay the fatal ending, and exceptionally, in the anaesthetic variety, stay the progress of the disease. #What is the treatment of leprosy?#