Disease: Hepatitis E

This page provides general information about  this condition; reveal the text by clicking on  the green headers. Press releases, results from DWHC investigations as well as other useful documents and relevant literature can be found at the bottom of the page.

Pathogen

Hepatitis is an inflammatory disease of the liver caused by infection with the hepatitis E virus (HEV). Hepatitis E virus belongs to the Hepeviridae family of viruses. There are four known genotypes of this virus: Genotypes 1 and 2 which only infect humans and are seen in Africa and Asia and Africa and Mexico, respectively. Genotypes 3 (widely distributed) and 4 (Asia and more recently also in Europe) which are considered zoonotic (can be transmitted from animals to humans) are predominantly found in domestic and wild swine but the host range is continually expanding as researchers investigate which other animals species may be reservoirs for this virus. To date infection in European wildlife has been reported in wild boar, red and roe deer, rabbits and rats.

Another form of the virus, avian HEV causes mild disease and a mild increase in mortality in domestic chickens and is not thought to infect humans.

Susceptible species

In addition to infecting wild and domestic swine, HEV infection has been seen in red and roe deer in Hungary and brown rats in Germany. There are reports of infection in a variety of other species around the world ranging from oysters to black bears and mongooses.

Signs in animals

Infection with HEV does not appear to cause overt signs in wild animals; this is despite the fact examination of livers of some infected animals under the microscope shows mild inflammatory changes. Piglets of weaning age (3-4 months) are most susceptible to infection as the protection from the maternal antibodies in milk wears off.

Avian HEV is known to cause enlargement of the liver and spleen (it is also known as ‘big liver and spleen disease’).

Infection of animals

Infection in pigs tends to occur in young animals, aged 2-3 months and these animals may continue to shed the virus in the feces for several months. The route of infection is believed to be fecal-oral.

Symptoms in people

Humans infected with HEV typically do not develop clinical signs of illness with the important exception of transplant organ recipients and pregnant women in some parts of the world who may develop acute and severe liver disease.

Infection of people

In humans, the main route of infection with HEV types 1 and 2 is fecal-oral, particularly via contaminated drinking water.  Accordingly, infection rates tend to be high in countries where sanitation is poor.

It is believed that human infection with the zoonotic forms of the virus is foodbourne (e.g. consumption of meat or meat products from infected animals).

Geographical distribution

In Europe, HEV gentoype 3 infection has been identified in wild boars in Spain, France, Germany, Italy, Hungary, the Netherlands and Sweden. Genotype 4 is present in Asia and has not been found in Europe.

Preventative measures

An important step in minimising the risk of Hepatitis E infection in people is ensuring good sanitation and access to clean water. In addition, people should avoid eating under-cooked pork and game products.

In order to better understand the zoonotic risk posed by this pathogen, national and international monitoring of wild and domestic species should be performed to determine which species can act as a reservoir of this virus.

 

References

Infectious Diseases of Wild Mammals and Birds in Europe (1). Somerset, GB: Wiley-Blackwell, 2012. ProQuest ebrary. Web. 6 October 2016.
Lhomme S, Top S, Bertagnoli S, Dubois M, Guerin JL, Izopet J. Wildlife reservoir for hepatitis E virus, southwestern France. Emerg Infect Dis. (2015) 21:7
Meng X.J. Hepatitis E virus: Animal reservoirs and zoonotic risk. Vet. Microbiol. 2010;140:256–265.
Meng XJ. From barnyard to food table: the omnipresence of hepatitis E virus and risk for zoonotic infection and food safety. Virus Res. 2011 Oct;161(1):23-30
Thiry D, Mauroy A, Saegerman C, Licoppe A, Fett T, Thomas I, Brochier B, Thiry E, Linden A. Belgian Wildlife as Potential Zoonotic Reservoir of Hepatitis E Virus. Transbound Emerg Dis. 2015

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