Hepatitis E virus hepatitis

HEV is a non-enveloped RNA virus, 32-4 nm in diameter. It is a member of the calcivirus group. Transmission is by the faeco-oral route, usually by contaminated sewage water. The Hepatitis E virus has Genotypes 1-4.

• reservoir - humans (G1/2) and animals including swine (G3/4)

Hepatitis E virus accounts for sporadic and major epidemics of viral hepatitis in under-developed countries, particularly, SE Asia, Nepal, Algeria, Japan, Siberia, Mongolia, and in traveller's returning from these areas

• endemic/epidemic (G1/2) in countries with poor sanitation (Africa, Asia and Central America)
• zoonotic (G3/4) in industrialised countries including UK

Transmission:

• in developed countries, a zoonosis primarily through consumption of undercooked/raw pork products especially those retailed un-cooked. Onward person-to-person transmission is only documented via blood transfusion and transplantation
• faeco-oral transmission via sewage-contaminated food and water in the developing world and epidemic in dispossessed populations
• person-to-person spread is rare

Infectivity:

• good personal hygiene probably reduces the very minimal infection risk to effectively zero risk

HEV has an incubation period of an average 40 days (range 15-60 days).

98% of cases are asymptomatic. Symptoms are more commonly associated with G1/2 infection. Symptoms include jaundice, dark urine, pale stools, tiredness, fever, nausea, vomiting, abdominal pain and loss of appetite Usually self-limiting with recovery in 4-6 weeks

The clinical presentation is similar to that of HAV. An important difference is the high mortality observed in women in the last trimester of pregnancy; 20% in HEV hepatitis compared to 1% in HAV. There are no chronic sequelae

• if infection in a pregnant woman is thought to have been acquired from a country where G1/G2 are endemic, genotyping should be undertaken to exclude G1
• if a G1 infection is identified in a pregnant woman she may require closer monitoring due to the potential serious outcome of G1 infection in pregnancy

Immunocompromised individuals presenting with acute hepatitis E should be investigated for pre-existing persisting infection and the development of persistence (2)

Serum IgM and IgG anti-HEV can be detected by ELISA.

Treatment is supportive.

Immunoprophylaxis is not yet available but may be possible using immunoglobulin prepared from donors from countries with a high prevalence of the disease. Prevention is primarily by improving hygiene and ensuring a clean water supply.

Hepatitis E virus may be transmitted vertically from infected mothers to their infants and carries significant morbidity and mortality for the infant (1).

Reference:

• 1) Khuroo MS et al (1995). Vertical transmission of hepatitis E virus. Lancet, 345, 1025.
• 2) PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections