Hepatitis E

Hepatitis E is inflammation of the liver caused by infection with the hepatitis E virus (HEV), a positive-sense, single-stranded, nonenveloped RNA icosahedral virus belonging to the family Hepeviridae. It represents one of five recognized human hepatitis viruses (A, B, C, D, and E) and is etiologically distinct from other viral hepatitis agents despite sharing transmission characteristics with hepatitis A. The virus is classified into multiple genotypes, with genotypes 1, 2, 3, and 4 being the primary causes of human disease.

The incubation period ranges from 2 to 10 weeks, with an average of 5 to 6 weeks. Infection is typically acute and self-limiting, resolving within 2-6 weeks in immunocompetent individuals, though many infections remain asymptomatic. When symptomatic, manifestations include jaundice, fatigue, and nausea, often accompanied by elevated hepatic aminotransferase levels. A serious complication, fulminant hepatitis (acute liver failure), can develop and may prove fatal. Chronic infection can occur in immunocompromised persons, particularly solid organ transplant recipients, characterized by persistent viremia beyond three months and potential progression to cirrhosis. Extrahepatic manifestations involving neurological and hematological systems have also been reported.

Hepatitis E infection occurs worldwide but is most prevalent in low- and middle-income countries with limited access to essential water, sanitation, hygiene, and health services. The disease presents both as large-scale outbreaks affecting hundreds to thousands of individuals and as sporadic cases. Genotypes 1 and 2 predominate in Africa and parts of Asia, where they are associated with waterborne transmission and outbreaks in areas of conflict or humanitarian emergencies. Genotypes 3 and 4 have broader geographic distribution and are primarily zoonotic, infecting non-human mammals and occasionally causing human disease through consumption of undercooked meat. In endemic areas, symptomatic infection most commonly affects young adults aged 15-40 years, while children typically experience mild or asymptomatic disease that often goes undiagnosed.

HEV is transmitted predominantly via the fecal-oral route, with contaminated drinking water serving as the primary vehicle for large-scale outbreaks. The virus is shed in the stools of infected persons beginning several days before symptom onset and continuing for up to 3-4 weeks afterward. Genotypes 1 and 2 spread mainly through water contaminated with human waste, while genotypes 3 and 4 transmission is zoonotic, occurring through consumption of uncooked or undercooked meat from infected animals, with environmental sources also contributing to exposure. The virus is not transmitted through close personal contact in the manner of bloodborne hepatitis viruses.

Pregnant women, particularly in the third trimester, face substantially elevated risk of severe disease and fulminant hepatitis with mortality rates of approximately 20-25% during outbreaks of genotypes 1 and 2. Immunocompromised individuals, including solid organ transplant recipients and those receiving immunosuppressive therapy, are at risk for chronic hepatitis E infection. Young adults aged 15-40 years in endemic areas experience the highest rates of symptomatic infection, while children typically have milder or asymptomatic disease that may go undetected. Populations in low- and middle-income countries with inadequate water, sanitation, and hygiene infrastructure bear the greatest burden of disease.

Prevention of hepatitis E relies primarily on water, sanitation, and hygiene (WASH) measures, including ensuring access to safe drinking water, proper sanitation infrastructure, and hygiene promotion. At the individual level, risk reduction includes avoiding consumption of uncooked or undercooked meat, particularly pork and game products, in areas where zoonotic transmission occurs. A recombinant hepatitis E vaccine (HEV 239, marketed as Hecolin®) is available and offers protection for vulnerable populations, though vaccine availability remains limited in many endemic regions. Pregnant women require particular attention to prevention measures given their elevated risk of severe outcomes.

Hepatitis E surveillance should consider the epidemiologic context, including geographic location, water and sanitation conditions, and outbreak history. Cases are not clinically distinguishable from other forms of acute viral hepatitis, so laboratory confirmation through detection of anti-HEV IgM antibodies is recommended when feasible. Surveillance is particularly important in humanitarian emergency settings and low-resource regions where outbreaks can affect large populations. Monitoring of pregnant women with hepatitis E is essential given their elevated risk of fulminant disease. Chronic infection should be considered in immunocompromised patients with persistent elevation of liver enzymes beyond the typical acute course.

1. 1 WHO Fact Sheet. Hepatitis E.
2. 2 Wikidata. hepatitis E.
3. 3 Wikipedia. Hepatitis E - Wikipedia.

ICD-10

B17.2

ICD-11

1E50.4

Total cases

474K

Total deaths

296

Peak month

2011-03

Coverage

3 reporting countries · 2000-01-01 → 2026-05-02