Rapid resolution of delusional parasitosis in pellagra with niacin augmentation therapy

Pellagra is associated with low levels of vitamin B3 (niacin) and/or tryptophan and often involves other other B vitamins. Since the time Gasper Casal first described the disease in 1972, it was observed that the patients with pellagra were all poor, subsisted mainly on maize, and rarely ate fresh meat. Subsequent occurrences have been in the form of epidemic outbreaks, consequent to either introduction to maize as a major food or increased consumption of other niacin-deficient diets like Jowar (Sorgum vulgare). The virtual disappearance of pellagra as an endemic health problem in recent years can be attributed to a rise in the standard of living of farmers and diversification of the diet globally. The clinical picture is a combination of multisystem alterations typically involving gastrointestinal, skin and central nervous system abnormalities. The cardinal manifestations have been popularly known as the three D's, which are dementia, dermatitis and diarrhea. Psychiatric manifestations are fairly common but are easily overlooked due to their non specific nature. These are commonly seen as irritability, poor concentration, anxiety, fatigue, restlessness, apathy and depression. The occurence of psychosis in pellagra is an uncommon finding, which is usually seen in advanced stages of pellagroid encephalopathy, commonly found in chronic alcoholics. Delusional parasitosis has been also reported in this condition, although the association is still controversial. We report a case of pellagra manifesting with delusional parasitosis in a man whose delusion resolved rapidly after he started niacin-augmentation therapy. This case may provide clues to the biological underpinnings of delusional parasitosis as well as niacin treatment as treatment option in similar cases.