Hepatitis E virus, history and epidemiological trends

The hepatitis virus (HEV), the fifth viral hepatitis virus identified in 1983, is a small, naked ribonucleic acid virus with 8 genotypes distributed worldwide. In recent years, a better understanding of the natural history of HEV infection has clarified its epidemiology. Hepatitis E is the world's leading cause of acute non-A viral hepatitis of fecal-oral or enteric transmission. It is now recognized as a serious threat to global public health, and has become a major concern in both industrialized and underdeveloped countries. According to the World Health Organization, an estimated 2.3 billion people (a third of the world's population) have already been infected with HEV. In endemic regions such as Asia, Africa and Central America, HEV is the cause of major epidemics of acute hepatitis, mainly of waterborne origin linked to faecal peril. In various industrialized countries of Europe and America, hepatitis E has long been considered an infection contracted during a stay in an endemic zone. Improved virological tools have shown that many cases of hepatitis are in fact a sporadic, locally-acquired form, defining the emerging nature of this infection.