Hepatitis E virus: a global view of its seroepidemiology and transmission pattern.

Hepatitis E virus (HEV) infection causes epidemic outbreaks as well as sporadic disease in many parts of the world. It has been detected in travellers from endemic regions and also in native citizens of developed countries. In contrast to epidemics where predominantly adults are infected, HEV is found to be a common cause of acute sporadic hepatitis in children as well. A high incidence of HEV infection has been noted in pregnant ladies. Further, HEV has an association with other hepatotropic viruses and induces fulminant hepatic failure both with and without the simultaneous presence of other viruses. Transmission of HEV occurs predominantly by the faeco-oral route. However, the parenteral route has also been implicated. There is evidence to suggest vertical transmission of HEV via the intrauterine and perinatal routes. However, a number of questions remain unanswered. The available data do not explain the occurrence of HEV infection predominantly in adults during epidemics, possibility of contact transmission and means of protection against this infection. More detailed studies are needed to provide the actual status of HEV epidemiology in different parts of the world.