Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 28, 2026 1 hour, 17 minutes ago
Medical News: Researchers in Italy have identified a previously undetected subtype of the Hepatitis E virus (HEV) infecting humans, marking an important development in the country's ongoing monitoring of infectious diseases. The newly identified HEV subtype 3i was found in five patients from Central Italy, providing the first confirmed evidence that this viral subtype has crossed into humans in the country after previously being detected only in wild boars.
Italian researchers have identified the first human cases of Hepatitis E virus subtype 3i, linking the infections to locally
circulating strains found in wild boars
The study was conducted by scientists from the Istituto Superiore di Sanità (Italian National Institute of Health), the University of Perugia, Santa Maria della Misericordia Hospital, the Istituto Zooprofilattico Sperimentale Abruzzo-Molise "G. Caporale", the University of L'Aquila, Santa Rosa Hospital, the Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, the National Institute for Infectious Diseases "L. Spallanzani" IRCCS, and several collaborating institutions in Italy and Albania.
A New Discovery in Human Hepatitis E Cases
Hepatitis E is a viral disease that primarily affects the liver. While many infections resolve on their own, some cases can become severe, particularly in older adults, pregnant women, and individuals with weakened immune systems.
Italy has traditionally reported human infections caused mainly by HEV subtypes 3f, 3c, and 3e, with subtype 3a appearing only occasionally. The discovery of subtype 3i in human patients represents a significant change in the country's hepatitis E landscape.
The researchers identified five patients diagnosed between 2019 and 2023 who carried an unusual virus that did not match the commonly circulating strains. Advanced whole genome sequencing confirmed that all belonged to subtype 3i.
Strong Evidence Linking Humans and Wild Boars
One of the study's most important findings was the close genetic relationship between viruses found in patients and viruses previously detected in wild boars living in the same region of Umbria.
Scientists compared the complete viral genomes and found remarkable similarities, with some human and wild boar viruses sharing more than 98 percent genetic identity. Three of the five patient viruses clustered very closely with strains collected from wild boars sampled one to five years earlier in nearby locations.
These findings strongly suggest that the virus has been circulating among wild boars in Central Italy for several years before spilling over into humans.
How Did the Infections Happen?
Investigators examined possible exposure risks for all five patients. Three patients reported eating raw or undercooked pork products, including traditional cured sausages made from pigs or wild boars. Since these foods are known sources of hepatitis E infection, researchers believe they were the most likely route of transmission in those cases.
Howeve
r, the remaining two patients had no history of consuming such products.
One patient worked at a wastewater treatment facility, raising the possibility of exposure through contaminated wastewater. Another patient reported eating only home-grown vegetables before becoming ill. Researchers noted that vegetables may become contaminated if irrigation water or surrounding soil has been exposed to infected animal waste.
This
Medical News report highlights that these findings suggest hepatitis E transmission may occur through more routes than previously recognized, especially in areas where wild boar populations are expanding.
Advanced Genetic Analysis Revealed Important Details
Using next-generation whole genome sequencing, the scientists obtained nearly complete viral genomes from three patients, allowing them to perform highly detailed genetic comparisons.
The analysis showed that although the viruses formed two slightly different genetic clusters, all belonged to the same subtype 3i based on internationally accepted classification standards.
Interestingly, one cluster appears to be evolving independently and could eventually become a distinct subtype if additional genetic changes accumulate over time. The researchers believe continued surveillance will be essential to determine whether this evolutionary process continues.
The study also showed that subtype 3i is much more common in local wild boars than previously appreciated, accounting for nearly 40 percent of the virus-positive wild boar samples examined during regional surveillance.
Why the Discovery Matters
The findings demonstrate how viruses circulating in wildlife can gradually enter human populations without immediately attracting attention.
The close geographical and genetic relationship between infected wild boars and human patients suggests that local animal reservoirs continue to play an important role in hepatitis E transmission. The research also raises awareness that environmental contamination, including wastewater and contaminated vegetables, may occasionally contribute to infections, particularly in regions where wild boar populations are increasing.
Conclusion
The discovery of HEV subtype 3i in humans represents an important milestone in understanding hepatitis E in Italy. The study provides compelling evidence that this viral subtype has been circulating among wild boars before crossing into humans, with several patient viruses showing exceptionally close genetic relationships to animal strains found nearby. While eating undercooked pork and wild boar products remains the most likely source for many infections, the findings also point to the possibility of environmental transmission through wastewater or contaminated vegetables. Continued monitoring of both human infections and wildlife will be essential for detecting emerging viral variants early, improving food safety measures, and strengthening public health surveillance against future outbreaks.
The study findings were published in the peer reviewed journal: Viruses.
https://www.mdpi.com/1999-4915/18/7/709
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