Risk of hepatitis E infection to travelers.

Hepatitis E virus (HEV), previously referred to as enterically transmitted non-A, non-B hepatitis, is a major cause of epidemic hepatitis and acute, sporadic hepatitis in endemic areas of the world. The existence of HEV was suspected based upon epidemiological grounds for many years. However, it was only in the early 1990s that confirmation occurred when two prototype strains of HEV from Burma and Mexico were sequenced.1-3 Outbreaks of HEV infection as well as sporadic transmission commonly occur in Asia, Africa, Central and South America, the Middle East, and the Republics of the former USSR. Southeast Asia seems to be a particularly high HEV endemic region. HEV is transmitted via the fecal-oral route, and contaminated drinking water is a common source of infection.4 Many of the large outbreaks have occurred after heavy rains and flooding.4 During interepidemic periods sporadic infections occur frequently. This suggests a constant environmental reservoir, allowing for transmission between epidemics. The existence of a zoonotic reservoir for the virus is likely. HEV has been detected in a number of species, including swine, rats, and chicken.