[Hepatitis E: an emerging disease].

The hepatitis E virus is endemic in countries with poor sanitation, where it has many similarities with the hepatitis A virus. It causes a strictly human, feco-oral transmitted, acute, self-limited hepatitis in young adults. The outcome is excellent, except in pregnant women and cirrhotic patients, who experience a high mortality rate. The first cases described in industrialized countries were travellers coming from endemic areas. However, there is now growing evidence that locally-acquired hepatitis E is common in these areas, where it is an emergent disease, despite it is still misdiagnosed. In industrialized countries, hepatitis E spreads sporadically and has a predilection for elderly men with comorbidity, particularly chronic liver diseases. The mortality seems to be higher in this population. In these areas, hepatitis E is due to the genotype 3 virus that is thought to be zoonotically transmitted by pigs and wild boar. Hepatitis E may evolve towards a chronic infection in immunocompromised subjects, particularly in solid organ-transplanted patients. In case of chronic infection, it may cause liver fibrosis and cirrhosis. The diagnosis of hepatitis E is based on serological tests (IgM and IgG) and detection of the viral genome by reverse transcription polymerase chain reaction (RT-PCR) on blood and stools. Acute hepatitis E does not require any treatment but in chronically infected patients, a sustained viral response and finally a definitive viral clearance has been observed after a three-month course of low-dose ribavirin (600 to 800 mg/day). Two vaccines underwent successful human trials but are not yet commercially available.