hepatitis E viruses (HEV)

Introduction

the primary cause of enterically transmitted non-A, non-B hepatitis; most outbreaks occur in developing countries.
these viruses are spherical, nonenveloped, single-stranded, single-serotype, RNA viruses belonging to the Hepeviridae family
HEV is relatively stable in the environment but can be inactivated by chlorination or by heating to ≥70°C (≈160°F) for 5 minutes
the virus usually enters the human body through the intestine
the virus is shed in the stools of infected persons beginning from a few days before to 3-4 weeks after onset of the disease
the virus may also infect the kidneys as well as neurons, pancreas, and muscle cells ¹⁾

each year, 20 million HEV infections occur globally of which 3.3 million cases are symptomatic hepatitis E, and c70,000 deaths occur (accounting for 3-5% of the mortality due to viral hepatitis)
- travelers are at greatest risk when they visit endemic countries and drink contaminated water (mostly in the Indian subcontinent)
- clinical attack rates are highest among people aged 15–49 years, although in HEV-3 endemic areas highest rates are in those older than 50yrs
- in areas endemic for HEV-1, infection in a pregnant person can progress to liver failure and death
  - miscarriages and neonatal deaths are common complications of HEV infection during pregnancy
large waterborne outbreaks have occurred in Africa, Central America, South and central Asia, and tropical East Asia
- many large outbreaks have occurred among refugees and in people living in camps for displaced persons
hepatitis E can progress to chronic infection in those who are immunocompromised such as solid organ allograft recipients

consumption of shellfish was implicated in an outbreak of hepatitis E on a cruise ship
transfusion-related hepatitis E increasingly is reported in Europe
vertical transmission of HEV from people infected during pregnancy to their fetuses is common
HEV-1 and HEV-2 predominantly affect humans in developing countries and spread through contaminated water
- HEV-1 is the most prevalent cause of hepatitis E
HEV-3 and HEV-4 are zoonotic, impacting both humans and various animal species, often leading to self-limiting liver disease but posing a heightened risk to pregnant women
- Pigs and wild boars are considered the main reservoirs of HEV-3
- rising zoonotic risk of HEV-3 infection from eating under-cooked pork (esp. liver) or wild boars in Europe due to increasing consumption of wild boar meat in Europe, especially Portugal²⁾
HEV-7
- has been associated with consumption of camel meat and milk

in HEV-3 endemic areas:
- thorough cooking, gloves for hunters, reconsidering traditional practices, avoiding carcass contamination, testing meat cuts, enhancing control programs, and educating hunters on safe slaughtering
in HEV-1 or HEV-2 endemic areas:
- maintaining hygienic practices
- avoid drinking unboiled or unchlorinated water or any beverages containing unboiled water or ice
- eat only thoroughly cooked food (especially seafood or meat)
- public service measures:
  - maintaining quality standards for public water supplies
  - establishing proper disposal systems for human faeces
in HEV-7 endemic areas, avoid camel meat or milk unless thoroughly cooked
a vaccine to prevent hepatitis E virus infection has been developed and is licensed in China, but is not yet available elsewhere

many are asymptomatic - especially those who are immunocompromised (but if HEV-3 they may develop chronic infection and progressive liver injury)
for most people, hepatitis E is a mild, self-limited disease resolving within 2–6 weeks
some may develop fulminant hepatitis and die
- most likely with HEV-1 in pregnant women infected in the 3rd trimester or neonates
- those with preexisting liver disease might have further hepatic decompensation with HEV superinfection
clinical features are the same as other viral hepatitis infections:
- abdominal pain, anorexia, fever, jaundice, and lethargy

HEV-3 can progress to chronic infection, whereas infection with other genotypes results only in acute infection
progression to chronic infection is mainly in those who are immunocompromised such as solid organ allograft recipients

mainly supportive care
avoid alcohol and medications that can adversely affect the liver such as paracetamol
infected people should be advised to maintain strict personal hygiene, and avoid preparing meals for others unless adequate food safety can be guaranteed
oral ribavirin has been shown to be effective in the treatment of chronic hepatitis E

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