pellagra
Pellagra is a nutritional disorder caused by a deficiency in niacin (vitamin B3) or its precursor (tryptophan) that is mainly observed in Asia and Africa where it is generally due to poor nutrition. It is characterized by dermatitis (symmetrical photodistributed erythema that may be accompanied by vesicles and bullae, and that develops into hyperkeratotic and hyperpigmented skin), gastrointestinal symptoms (diarrhea), and neuropsychiatric disorders (dementia). It can be life-threatening without a correct management.