An affection of the skin, characterized by redness, especially in exposed areas, scaling and shedding of the skin, and accompanied with severe gastrointestinal disturbance and nervous symptoms. It is due to a deficiency of niacin (vitamin B3; nicotinic acid) and protein in the diet, and may be caused by malnutrition, or, in some cases, by a heavy dependence on maize for food. It was at one time (ca. 1890) endemic in Northern Italy, and was called Alpine scurvy. It may also be caused by alcoholism or diease causing an impairment of nutrition. It is also called St. Ignatius's itch, maidism, mal de la rosa, mal rosso, and psychoneurosis maidica. A variety of pellagra seen in children is called infantile pellagra or kwashiorkor.
a severe niacin deficiency disease characterized by the three D's: dermatitis, diarrhea and dementia. This disease can also be caused by a lack of nutrients needed to transform the amino acid tryptophan into niacin (vitamin B3). At least three other vitamins (thiamin, pyridoxine and riboflavin) are necessary for the conversion into niacin.
A clinical condition caused by niacin deficiency and characterized by tissue damage, chiefly of the skin, gastrointestinal tract, and nerves. The most striking symptom is a reddish skin rash, especially on the face, hands, and feet when exposed to sunlight. Other associated disorders include inflamed membranes in the digestive tract with bloody diarrhea and distressing nervous and mental disturbances (hence "the 3 Ds" of pellagra: dermatitis, diarrhea, and depression or dementia).