Every July 28, World Hepatitis Day reminds us that not all forms of hepatitis receive the same level of attention. Hepatitis A, B, and C are the most widely recognized, but there is another form that progresses quietly and deserves to step out of the shadows: hepatitis E.
Hepatitis E is caused by the hepatitis E virus (HEV). For many years, it was considered a problem almost exclusively affecting countries with limited access to safe drinking water and sanitation, where the virus is transmitted mainly through contaminated water. However, we now know that this view was incomplete. Hepatitis E also circulates in industrialized countries, including those in Europe, and many infections are acquired locally rather than through international travel.
One of the key features of hepatitis E is its zoonotic nature, meaning it can be transmitted from animals to humans. In Europe, pigs and wild boars serve as major reservoirs of the virus. As a result, an important route of transmission is the consumption of raw or undercooked meat, particularly pork products such as liver, fresh sausages, and pâté. Increased risks have also been described among people who work in close contact with animals, including farmers, veterinarians, and hunters.
In most healthy individuals, the infection may go unnoticed or cause an acute hepatitis that resolves spontaneously. However, this is not always the case. In pregnant women, immunocompromised individuals, transplant recipients, or people with pre-existing liver disease, hepatitis E can be severe. In some immunocompromised patients, HEV may persist for months and develop into a chronic infection, increasing the risk of progression to cirrhosis.
Diagnosis has improved thanks to serological and molecular testing, particularly the detection of viral RNA by RT-PCR. Even so, hepatitis E remains underdiagnosed, partly because it is not always considered in the differential diagnosis. Including hepatitis E in the evaluation of acute hepatitis of unknown origin can significantly influence the clinical management of many patients.
Prevention begins with simple measures: thoroughly cooking meat, avoiding raw or undercooked pork products in vulnerable individuals, maintaining strict food hygiene practices, and strengthening surveillance of blood, organs, and food products. A vaccine has been approved in some countries, but it is not yet globally available and there is still insufficient evidence to support its use across all high-risk groups.
Hepatitis E reminds us that human, animal, and environmental health are interconnected. Preventing this infection requires looking beyond the hospital, to our water, our food, the animals around us, and our everyday habits. In public health, what remains unseen is just as important.
Professor of Microbiology at CEU Cardenal Herrera University, where she combines teaching and research in the fields of infectious diseases and public health. Her work has focused particularly on the hepatitis E virus, including its epidemiology, diagnosis, zoonotic transmission, and clinical significance. She is the author of numerous scientific publications on viral hepatitis and is actively involved in communicating biomedical knowledge from a One Health perspective, which recognizes the interconnectedness of human, animal, and environmental health.