Type of the virus

HEV has at least 8 different types: genotypes 1 to 8. Genotypes 1 and 2 have been found only in humans, and are commonly present in developing countries. Genotypes 3 and 4 are zoonotic and widely circulating in several animals including pigs, wild boars and deer without causing apparent disease in these animals. These zoonotic strains are highly prevalent in industrialized countries and occasionally infect humans. A single case of infection with genotype 7, a camel HEV strain, was found in a liver transplant patient from the United Arab Emirates. Genotypes 5, 6 and 8 only infect animals, and have not been found in humans. Rat HEV, that is very different from the classically genotyped HEV, has been found to infect humans in Canada, Europe and Hong Kong, China.

Type of the disease

Acute hepatitis E

Typical signs and symptoms of hepatitis include:

· an initial phase of mild fever, reduced appetite, nausea and vomiting lasting for a few days;

· abdominal pain, itching , skin rash, or joint pain;

· jaundice (yellow color of the skin), dark urine and pale stools; and

· a slightly enlarged, tender liver.

These symptoms typically last 1-6 weeks.

In rare cases, acute hepatitis E can be severe and result in fulminant hepatitis (acute liver failure). These patients are at risk of death. Pregnant women with hepatitis E, particularly those in the second or third trimester, are at increased risk of acute liver failure, fetal loss and mortality. Up to 20-25% of pregnant women can die if they get hepatitis E in third trimester, especially with genotypes 1 and 2 HEV infection.

Chronic hepatitis E

Cases of chronic hepatitis E infection—lasting longer than 3-6 months—have been reported in immunosuppressed people, particularly organ transplant recipients on immunosuppressive drugs, with genotype 3 or 4 HEV as well as rat HEV infection. These cases are mostly found in industrialized countries, especially in Europe.