Hepatitis E

Abstract

Hepatitis E, previously known as enterically transmitted non-A, non-B hepatitis, is an infectious viral disease with clinical and morphologic features of acute hepatitis. The disease was recognized first as a distinct clinical entity in the 1980s, when sera from persons affected during a large waterborne epidemic of viral hepatitis during 1955-1956 in Delhi, India116 and another epidemic in Kashmir were found to lack serologic markers of acute hepatitis A and B.56 and 119 The first proof of the existence of a new viral hepatitis agent was obtained in 1983, when viruslike particles were detected by immune electron microscopy in feces collected from a volunteer infected with fecal material from patients who had suspected enterically transmitted non-A, non-B hepatitis.12 The disease was transmitted successfully to cynomolgus monkeys that excreted similar viruslike particles in their feces.12 The genome of this virus, known as hepatitis E virus (HEV),90 was cloned in 199093 and fully sequenced shortly thereafter.99 and 104 The occurrence of the first recorded epidemic of hepatitis E as late as 1955 and the infrequency of this disease in developed countries suggest that hepatitis E is a new, emerging infectious disease. However, several epidemics of enterically transmitted hepatitis with epidemiologic features similar to those of hepatitis E outbreaks occurred in Europe and the United States in the 18th and 19th centuries.17 and 28 It can be postulated, therefore, that HEV infection may have occurred in various parts of the world and only recently has become restricted to certain geographic areas, mostly underdeveloped with poor environmental sanitation.