Matteo Carnevale

Introduction: Hepatitis E virus (HEV) represents a major public health concern. Beyond the main zoonotic genotypes HEV‐3 and HEV‐4, with pigs and wild boars recognized as the primary reservoirs of infection, a genetically distinct hepevirus of rodent origin (species Rocahepevirus ratti, genotype C1) (rat HEV, RHEV) has recently been implicated in human hepatitis cases worldwide. Although several risk factors have been proposed, contact with rats has been documented in one human case only, and the sources and transmission routes of RHEV remain largely unclear. Of interest, RHEV RNA has recently been detected in farmed pigs, highlighting livestock environments as potential interspecies transmission interfaces. In light of these findings, we performed a molecular investigation for RHEV in rodents captured on farms raising different livestock species in Northwestern Italy (Piemonte region). Methods: A total of 98 rodents, collected on 32 livestock farms, were tested for RHEV by a combined molecular approach based on RHEV specific real‐time reverse transcription (RT)‐PCR assay and a pan‐hepevirus heminested RT‐PCR. Positive samples were further processed to attempt full‐genome amplification. Results: RHEV RNA was identified in a Norway rat ( Rattus norvegicus ) and in house mice ( Mus musculus ) , with detection rates of 16.6% (1/6; 95% CI: 0.41–64.1) and 7.0% (6/86; 95% CI: 2.6–14.5), respectively. The positive rodents were captured in five livestock farms, raising cattle, goats, and poultry, located across three municipalities. The nearly full‐length genome of a rat strain (RHEV/ Rattus norvegicus /38129‐22/ITA) was reconstructed. Pairwise nucleotide alignment showed high genetic relatedness of RHEV/ Rattus norvegicus /38129‐22/ITA with sequences previously identified in rodents and human patients, including those from European countries. Conclusions: The identification of infected rodents in livestock farms highlights RHEV circulation in rural environments, where interactions among rodents, domestic animals, and humans may be facilitated. Additional studies are necessary to elucidate RHEV transmission dynamics and assess public health implications.

Mammarenaviruses are enveloped, ambisense, single-stranded RNA viruses capable of causing fatal hemorrhagic fevers and severe neurological disorders in humans. Although muroid rodents have historically been recognized as the primary reservoirs for major pathogens like Lassa virus, recent surveillance has revealed a significant expansion of their host range. This review aims to synthesize current global data regarding the epidemiology of mammarenaviruses in conventional reservoirs and the emergence of novel arenaviruses in non-traditional mammalian hosts. To achieve this, we comprehensively analyzed recent molecular and metagenomic surveillance data, evolutionary studies, and epidemiological reports published worldwide. Key discoveries include Wenzhou virus in Asian house shrews, Plateau Pika virus in plateau pikas, and an independent, geographically clustered of hedgehog-associated arenaviruses across Europe. Ultimately, this review underscores the global distribution of these pathogens and the critical need for continued, multi-host surveillance worldwide.

Hepatitis E virus (HEV) is an emerging zoonotic pathogen in Europe, where most autochthonous infections are caused by genotype 3 (HEV-3) and are due to ingestion of raw or undercooked pork meat products. Pigs and wild boars are recognized as the main reservoirs of infection. In this study, we investigated the epidemiology of HEV in wild boars from the Liguria and Piedmont regions (northwestern Italy) by screening, molecularly, a total of 98 liver samples from Liguria (n = 66, collected during the 2023–2024 hunting seasons) and Piedmont (n = 32, collected during 2022–2025) regions. HEV RNA was detected in 11 out of 98 liver samples, with an overall prevalence of 11.2%, a finding consistent with a significant viral circulation within the investigated animal population. Molecular characterization of the partial capsid coding gene was successfully achieved for eight strains revealing genetic heterogeneity and a diverse spatial distribution of the viral strains identified, with subtype 3a detected in Liguria and subtypes 3c and 3f identified in Piedmont.