Although hepatitis E is one of the most important cause of acute clinical hepatitis in young adults throughout the developing world, hepatitis E is rare in western countries (25 to 60 annually by country). In these countries, clinical hepatitis is more common in older people (over 50 years). The possible transmission zoonotically (principally) from swine reservoir opens unexpected insights as an emerging disease. Direct foodborne and occupational exposure to pigs have been identified as routes of transmission. Other routes of transmission should be defined. Human sequences of hepatitis E virus are closely related to swine hepatitis E virus. Anti-HEV seropositivity rates ranges from 2-3% in blood donors to 20% in people exposed to animal reservoir.