A disease caused by deficiency of niacin or tryptophan (or by a defect in the metabolic conversion of tryptophan to niacin); characterized by gastrointestinal disturbances and erythema and nervous or mental disorders; may be caused by malnutrition or alcoholism or other nutritional impairments. Synonyms: Alpine scurvy, mal de la rosa, mal rosso, mayidism, pellagra, Saint Ignatius' itch.
