A recent study published in Nature Communications has raised fresh concerns about an emerging infectious threat, rat hepatitis E virus (ratHEV), highlighting its ability to infect humans and challenging long-held assumptions about hepatitis E infections. Traditionally, hepatitis E has been attributed to the hepatitis E virus (HEV), which causes nearly 20 million infections worldwide each year. Until recently, human infections were thought to arise mainly from strains affecting humans and certain animals such as pigs. However, researchers now report that ratHEV, once believed to infect only rodents, can cross species barriers and infect humans, marking a significant shift in the understanding of hepatitis epidemiology.
The first confirmed human case of ratHEV infection was reported in Hong Kong in 2018, involving a liver transplant recipient with unexplained chronic hepatitis. Since then, additional cases have been identified across Asia, Europe, and Canada, confirming ratHEV as a zoonotic pathogen. The virus belongs to the Rocahepevirus genus, with genotype C1 recognized as the primary strain capable of infecting humans. Researchers have found that ratHEV is widespread in urban rat populations, particularly in Asia and southern Europe, with infection rates in rodents estimated between 10- 30%. Human exposure appears more likely in individuals who have close contact with rodents or work in high-risk environments such as sanitation, agriculture, or densely populated urban settings.
Diagnosing ratHEV remains a major challenge due to the lack of standardized testing methods. Conventional antibody-based tests used for hepatitis E often show cross-reactivity and may fail to distinguish ratHEV from other strains, making accurate diagnosis difficult. Experts emphasize that molecular techniques, such as PCR-based testing, are currently the only reliable way to confirm active infection. Clinically, ratHEV infection can range from mild or asymptomatic cases to severe outcomes, including acute hepatitis, liver failure, and chronic infection, particularly in immunocompromised individuals. Cases involving neurological and kidney complications have also been reported, highlighting the broader clinical impact of the virus.
Treatment options remain limited, with management strategies largely based on existing hepatitis E protocols. While most infections resolve on their own, the antiviral drug ribavirin has shown promise in patients with severe or persistent disease. The study underscores the urgent need for enhanced global surveillance and improved diagnostic tools, with researchers recommending that ratHEV be incorporated into existing hepatitis E guidelines. As scientists continue to investigate its full impact, ratHEV highlights the growing importance of monitoring zoonotic diseases in an increasingly interconnected world.
References
- Rivero-Juarez A, Johne R, Sridhar S. Rocahepevirus ratti: molecular evolution, zoonotic potential and public health impact. Nat Commun. 2026 Apr 9. doi:10.1038/s41467-026-71382-3