[Hepatitis E virus: A new entity].

Hepatitis E virus (HEV) is a RNA enterically transmitted virus that causes large waterborne epidemics of acute hepatitis E in endemic regions (Asia and Africa). Sporadic hepatitis E is an emerging disease in developed countries such as France. The majority of acute hepatitis E in France is indigenous (non travel-associated) and is due to infection with HEV genotype 3. Diagnosis is made on the presence of specific serum antibodies and on viral RNA detection in serum or stools. Characteristic pathological signs of acute hepatitis E are severe intralobular necrosis, polymorph inflammation and acute cholangitis in portal tract with numerous neutrophils. Severe forms of hepatitis are associated with underlying chronic liver disease such alcoholic disease. In immunocompetent patients, HEV causes acute resolutive hepatitis and there is no chronic evolution. Conversely, chronic hepatitis E is frequent in immunocompromised patients with a risk of rapid evolution to cirrhosis. Histologic lesions of chronic hepatitis E are similar to those observed in patients chronically infected with hepatitis C virus with dense lymphocytic portal infiltrate, constant peacemeal necrosis and fibrosis.