[Hepatitis E virus: an emerging disease].

Hepatitis E virus (HEV) is a spherical, non-enveloped, single stranded RNA virus. Four genotypes (1-4) have so far been distinguished. HEV infection can occur either in large epidemics (in endemic regions only: southeast Asia, India, central Asia central, Africa, and Mexico) or in sporadic forms. HEV is transmitted principally by the fecal-oral pathway, that is, hand-to-mouth. There is a risk of transmission from animals to humans. Nearly half of all cases have no or few symptoms. Symptomatic forms can be severe. The mortality rate can reach 20% in pregnant women. Recent reports indicate that autochthonous cases have been contracted in France. Several aspects differentiate sporadic autochthonous hepatitis from that contracted in endemic areas: 1) mean age of onset is older in the former; 2) prognosis is more severe; and 3) prolonged even chronic forms can affect some immunocompromised patients, in particular, those with organ transplants. The diagnosis of hepatitis E must now be considered in any cases of acute hepatitis of unexplained origin in France. Diagnosis relies on RT-PCR testing of blood or stool.