In the extensive medical literature there is no study which gives any comprehensive appraisal of the general incidence of pellagra. Such reports as are available come from public health reports, mortality statistics and figures for hospitalizations in areas where the condition has long been recognized as a menace to health. Furthermore, there is no indication of the prevalence of pellagra in regions of this country where it has not been studied intensively.
As a consequence, there seems to be a widespread impression that this type of deficiency syndrome is very rare in the Northern states and exists only as a provincial problem peculiar to the endemic areas of the South. Indeed, case reports indicate that it is considered an exotic disease except in subtropical climates. For a number of years we have been engaged in the intensive study of pellagra in both sections of the country and have collected data
BEAN WB, SPIES TD, BLANKENHORN MA. THE INCIDENCE OF PELLAGRA IN OHIO HOSPITALS. JAMA. 1942;118(14):1176-1179. doi:10.1001/jama.1942.02830140006002