Hepatitis E virus: has anything changed?

Infection with hepatitis E virus (HEV) is a global health concern, yet a clinically underdiagnosed cause of acute and chronic hepatitis. The WHO estimates that 20 million people are infected with HEV annually, yet the epidemiology, diagnosis and prevention remain elusive in many clinical settings.

Orthohepevirus A (HEV-A) genotypes 1 and 2 cause acute, self-limited hepatitis through faecal-oral transmission. In 2022, the first-ever vaccine campaign was implemented as a response to an HEV outbreak in an endemic region. HEV-A genotypes 3 and 4 are zoonotic infections that primarily cause chronic HEV infection in immunosuppressed populations. Pregnant women and immunocompromised persons are at high risk for severe illness in some settings. Another recent advance in our knowledge of HEV is the zoonotic transmission of Orthohepevirus C (HEV-C) to humans, presumably from contact with rodents and/or their excrement. Previously, HEV infection in humans was presumed to be limited to HEV-A only.

Clinical recognition and accurate diagnosis are essential to the management of HEV infection and understanding the global burden of the disease. Epidemiology affects clinical presentations. Targeted response strategies in HEV outbreaks are needed for the prevention of disease, and vaccine campaigns may prove to be an effective part of these strategies.