19th-century and early 20th-century jaundice outbreaks, the USA.

Historical enquiry into diseases with morbidity or mortality predilections for particular demographic groups can permit clarification of their emergence, endemicity, and epidemicity. During community-wide outbreaks of hepatitis A in the pre-vaccine era, clinical attack rates were higher among juveniles rather than adults. In community-wide hepatitis E outbreaks, past and present, mortality rates have been most pronounced among pregnant women. Examination for these characteristic predilections in reports of jaundice outbreaks in the USA traces the emergence of hepatitis A and also of hepatitis E to the closing three decades of the 19th century. Thereafter, outbreaks of hepatitis A burgeoned, whereas those of hepatitis E abated. There were, in addition, community-wide outbreaks that bore features of neither hepatitis A nor E; they occurred before the 1870s. The American Civil War antedated that period. If hepatitis A had yet to establish endemicity, then it would not underlie the jaundice epidemic that was widespread during the war. Such an assessment may be revised, however, with the discovery of more extant outbreak reports.