Table 1.

Epidemiological and clinical features of the four human hepatitis E virus genotypes

Genotype	1	2	3	4
Host	Human; also isolated from pigs	Human	Human, swine, and other mammalian species
Route of transmission	Waterborne (fecal contaminated water); human to human; maternofetal; probably zoonotic (genotype 1)		Zoonotic: mainly via consumption of raw or undercooked contaminated animal meat; environmental (shellfish); to date environmental shellfish has been reported exclusively for genotype 3; blood transfusion
Geographical distribution	Asia and Latin America (Cuba, Venezuela, and Uruguay)	Mexico and several African countries	Worldwide	East Asia and Central Europe
Epidemiological features	Endemic in Asia and Cuba; causes outbreaks and sporadic cases in developing countries; more common in young people and travelers	Endemic in Mexico? Causes outbreaks and sporadic cases in developing countries; more common in young people	Causes autochthonous sporadic cases in developed and nonendemic areas; highest attack rate in middle-aged and elderly men; higher overall mortality rate compared to genotype 1
Clinical presentation in humans	Mostly asymptomatic infections; acute self-limited hepatitis; high mortality in pregnancy and in patients with underlying chronic liver disease	Mostly asymptomatic infections; moderately severe acute self-limited hepatitis	Moderately severe acute self-limited hepatitis; asymptomatic; infection may lead to chronicity in solid organ transplant recipients (to date, only reported for genotype 3) and immunocompromised patients