Hepatitis EEdit

Hepatitis E is an acute viral hepatitis caused by the hepatitis E virus (Hepatitis E virus), a non-enveloped, positive-sense RNA virus in the family Hepeviridae. In humans, HEV infection typically causes self-limited disease, but it can be more severe in certain populations and circumstances. The virus is divided into several genotypes that infect humans, most notably genotypes 1–4. Genotypes 1 and 2 are common in regions with inadequate sanitation and travel-related outbreaks, whereas genotypes 3 and 4 are zoonotic and can be contracted from undercooked meat or animal products in many parts of the world. A camel-associated genotype 7 has also been identified in humans in rare cases. The disease burden, clinical course, and public health responses vary by genotype and locale.

Virology and taxonomy HEV is the prototype member of the genus Orthohepevirus A (Orthohepevirus A). The virus replicates in the liver and is shed in feces, enabling fecal-oral transmission routes. The four major human-infecting genotypes—genotype 1, genotype 2, genotype 3, and genotype 4—show distinct epidemiological patterns: genotypes 1 and 2 are primarily associated with outbreaks in areas with poor sanitation, while genotypes 3 and 4 are found worldwide and often transmitted through animal reservoirs and animal-derived foods. See also Genotype 1, Genotype 2, Genotype 3, Genotype 4.

Epidemiology and transmission Hepatitis E occurs in both sporadic cases and outbreaks. In many low-resource settings, waterborne outbreaks driven by contamination of drinking water are typical for genotypes 1 and 2. In higher-resource regions, autochthonous infections commonly involve genotype 3 and are linked to zoonotic exposure, particularly through consumption of undercooked pork, liver, or other pork products, as well as other animal reservoirs and shellfish in some locales. Blood-borne transmission and organ transplantation have been documented, leading to recommendations for vigilance in transfusion safety in certain contexts. See Water sanitation and Zoonosis for background, and Pork as a food-safety consideration.

Clinical features Most HEV infections present as an acute hepatitis syndrome, with fatigue, loss of appetite, nausea, abdominal pain, jaundice, and elevated liver enzymes. The incubation period is typically 2–10 weeks. Most infections resolve spontaneously within weeks, but severe disease can occur, especially in pregnant individuals—most notably with genotype 1 outbreaks—where maternal mortality can be increased. Immunocompromised individuals may experience chronic HEV infection, particularly with genotype 3, which can progress to fibrosis or cirrhosis if not recognized and managed. See Acute hepatitis and Chronic hepatitis for related concepts.

Diagnosis Diagnosis relies on a combination of serology and molecular testing. Anti-HEV IgM antibodies indicate recent infection, and anti-HEV IgG antibodies indicate past exposure or longer-term immunity. HEV RNA detection by polymerase chain reaction (PCR) confirms active infection and is particularly important in immunocompromised patients who may have delayed or diminished antibody responses. Stool, blood, and occasionally other body fluids can be tested for HEV RNA depending on the laboratory context. See Serology and PCR for broader diagnostic methods.

Treatment and prognosis Most healthy individuals recover with supportive care, including rest and adequate hydration. There is no widely approved specific antiviral treatment for acute HEV in the general population. In chronic HEV infection, most often seen in immunosuppressed patients such as organ transplant recipients, ribavirin is used off-label with evidence of virologic response in some cases, and adjusting immunosuppressive therapy can also contribute to viral clearance. Prevention of relapse and monitoring for liver function are important during and after treatment. See Ribavirin and Liver failure for related topics.

Prevention and public health Public health measures center on reducing exposure to the virus and preventing transmission. In areas affected by waterborne outbreaks, improving water quality, sanitation, and hygiene is central. In regions where zoonotic transmission is common, safe handling and thorough cooking of meat products, especially pork and game meat, are important preventive steps. The virus is relatively resilient in the environment, so proper waste management and food safety practices are critical components of prevention strategies. See Water treatment and Food safety for broader context.

Vaccination A recombinant HEV vaccine (HEV-239, marketed as Hecolin) has been licensed in some countries and is studied for broader use. It has shown efficacy in preventing infection with certain genotypes in clinical trials and is considered a tool for protecting high-risk populations, particularly in areas with ongoing outbreaks or high exposure risk. Access, regulatory status, and recommendations for vaccination vary by country and health authority. See Hecolin and Vaccination for related topics.

Controversies and debates - Vaccination versus sanitation investments: Public health strategies often debate whether to prioritize vaccination campaigns or to prioritize improvements in water and sanitation infrastructure. Proponents of sanitation-focused approaches emphasize long-term, population-wide risk reduction, while supporters of targeted vaccination argue for immediate protection of high-risk groups or during outbreaks. See Public health policy and Vaccination for broader discussions. - Screening of blood supplies: Given the potential for transfusion-associated HEV transmission, some authorities consider implementing routine screening of blood products in high-incidence settings, while others weigh the costs and logistics in relation to overall transfusion safety priorities. See Blood safety. - Outbreak management and resource allocation: In resource-constrained settings, decisions about allocating limited public health resources to HEV control must balance competing infectious disease priorities. See Public health resource allocation. - Perceived risk and media framing: As with many infectious diseases, there are debates about how to communicate risk without causing undue alarm, especially when severe outcomes are concentrated in particular subpopulations. See Risk communication.

See also - Hepatitis A - Hepatitis B - Hepatitis C - Hepatitis E virus - Orthohepevirus A - Vaccine - Food safety - Water sanitation - Blood safety - Public health policy