Hepatitis E virus infection in Europe: regional situation regarding laboratory diagnosis and epidemiology.

Hepatitis E virus (HEV) was first identified in the excreta of an experimentally infected human volunteer and further confirmed by similar findings in clinical specimens from patients with acute jaundice disease different from hepatitis A and B. The HEV is a 27- to 34-nm spherical non-enveloped virus obviously represented by a single serotype; however, its final taxonomic definition remains to be established. Studies on molecular biology of this virus revealed some peculiar characteristics showing no homologies in its nucleotide sequence to any entries in the Genbank database. The HEV infection was experimentally transmitted to non-human primates producing a disease in many features similar to that occurring in humans. Recently cell lines persistently infected with the HEV have also been obtained. These studies provided valuable virus-specific reagents which were used in diagnostic tests. Currently immune electron microscopy, fluorescent antibody technique, latex agglutination, cDNA hybridization, and Western blotting are employed to prove the etiological involvement of HEV in suspected hepatitis cases; serological tests with synthetic substances analogous to HEV antigens are expected to be available soon. Reliable diagnostic procedures can be carried out in a number of laboratories with the locally produced reagents. The HEV infection is common in many hot climate countries being responsible for more than 50% of jaundice cases among young adults. The European region is considered to be free of natural foci of this infection, however, several sporadic cases of HEV disease were reported to occur in Europeans who developed jaundice shortly after returning from endemic areas. It is suspected that in the Mediterranean countries (Italy and Spain) the cases of HEV infection could be causatively related to the consumption of shell-fish cultivated in sewage-polluted waters.