Hepatitis E

Hepatitis E is inflammation of the liver caused by hepatitis E virus (HEV), a viral infection classified as a form of viral hepatitis ^[1][5]. The sources describe HEV as a genetically diverse virus with multiple genotypes, with genotype-based differences in distribution and transmission pattern ^[4][5]. Current source-backed detail on additional virologic characteristics is not yet available in a concise surveillance format beyond these genotype-level distinctions ^[4][5].

Most HEV infections are asymptomatic and are often followed by spontaneous viral clearance without treatment ^[4]. When symptomatic, the illness is described as acute hepatitis, and acute infection may present with jaundice, fatigue, and nausea; the symptomatic phase coincides with elevated hepatic aminotransferase levels ^[5]. HEV 1 and HEV3 can cause fulminant hepatitis, while HEV3 may lead to chronic hepatitis and cirrhosis in immunocompromised patients ^[4]. Both acute and chronic HEV infections can have extrahepatic manifestations, but the source set does not provide a complete syndrome inventory ^[4].

The sources estimate approximately 20 million HEV infections worldwide annually and describe HEV as one of the commonest causes of acute hepatitis globally ^[4][3]. HEV was previously regarded as limited to certain developing countries, but is now described as endemic in most high-income countries as well ^[3][2]. Genotype 1 and genotype 2 are reported as common in developing countries, whereas genotype 3 and genotype 4 are common in developed countries and are emphasized in European guidance because locally acquired HEV is now a common cause of acute viral hepatitis in many European countries ^[4][2]. The sources also characterize HEV as largely zoonotic, but do not provide a full reservoir map or surveillance denominator ^[3][2].

The principal transmission pathways described in the sources are fecal-oral spread via contaminated water for genotype 1 and genotype 2, and occasional human infection through undercooked meat for genotype 3 and genotype 4 ^[4]. The virus is also described as largely zoonotic in high-income-country settings ^[3][2]. Source-backed detail on additional transmission mechanisms is not yet available in the provided material ^[4][3].

Source-supported higher-risk groups for severe disease include pregnant women infected with genotype 1 and older men or people with underlying chronic diseases infected with genotype 3 ^[3]. Immunocompromised persons are highlighted as being at risk for chronic HEV infection, chronic hepatitis, cirrhosis, and more persistent disease ^[4][5]. Pregnant women are specifically described as having a more severe course, with reported adverse maternal and fetal outcomes in outbreak settings ^[5].

The source set emphasizes prevention through safe water, avoidance of undercooked meat, and caution when traveling or residing in highly endemic countries ^[3]. These measures align with the described fecal-oral and zoonotic exposure routes ^[4][3]. No approved HEV vaccine is mentioned as available in the United States, and the provided sources do not support a broader vaccine-prevention schedule ^[4].

In surveillance terms, HEV should be interpreted as a globally distributed viral hepatitis with substantial asymptomatic infection and variable clinical severity ^[4][5]. The sources indicate that testing is recommended for patients with symptoms consistent with acute hepatitis, and also in unexplained flares of chronic liver disease ^[3]. Monitoring should pay particular attention to genotype-associated context, immunocompromised persons, and settings where waterborne or zoonotic exposure is plausible ^[4][3][2].

1. 1 Wikidata contributors. hepatitis E [Internet]. Wikidata. cited 20 May 2026. Available from: https://www.wikidata.org/wiki/Q326643
2. 2 European Association for the Study of the Liver et al. EASL Clinical Practice Guidelines on hepatitis E virus infection. J Hepatol. 2018 Jun. PMID: 29609832. doi: 10.1016/j.jhep.2018.03.005. PubMed: https://pubmed.ncbi.nlm.nih.gov/29609832/
3. 3 Gunsar F et al. Hepatitis E update. Hepatol Forum. 2020 Jan. PMID: 35949660. doi: 10.14744/hf.2020.0001. PubMed: https://pubmed.ncbi.nlm.nih.gov/35949660/
4. 4 Songtanin B et al. Hepatitis E Virus Infections: Epidemiology, Genetic Diversity, and Clinical Considerations. Viruses. 2023 Jun 17. PMID: 37376687. doi: 10.3390/v15061389. PubMed: https://pubmed.ncbi.nlm.nih.gov/37376687/
5. 5 Wikipedia contributors. Hepatitis E - Wikipedia [Internet]. Wikipedia. cited 20 May 2026. Available from: https://en.wikipedia.org/wiki/Hepatitis_E
6. 6 Hepatitis Viruses: Hepatitis B and Hepatitis D. Viral Infections of Humans. 2022. doi: 10.1007/978-1-4939-9544-8_32-1. DOI: https://doi.org/10.1007/978-1-4939-9544-8_32-1

ICD-10

B17.2

ICD-11

1E50.4

Total cases

485K

Total deaths

298

Peak month

2011-03

Coverage

7 reporting countries · 2000-01-01 → 2026-04-01