Eurosurveillance - Volume 30, Issue 12, 27 March 2025

Despite vaccine availability, rotavirus persists as a leading cause of gastroenteritis in children younger than 5 years.

We aimed to evaluate temporal changes in rotavirus epidemiology in Belgium between 2009 and 2023, including the period of the COVID-19 pandemic.

We collected 8,024 rotavirus-positive stool samples throughout Belgium. For 6,352 samples, we determined the G and/or P genotypes through sequencing of the genes encoding the outer capsid proteins VP7 and VP4.

Before the COVID-19pandemic, we received on average 622 samples per rotavirus epidemiological year, which decreased to 114 and 111 samples during the two pandemic rotavirus epidemiological years, followed by a peak of 1,048 samples in the first post-pandemic year. Notably, the proportion of cases in the age group 2–5-years increased from 20.3% before to 33% after the pandemic (p < 0.001). Over the 14-year study period, the most common genotypes were G2P[4], G3P[8] and G9P[8]. Post-pandemic data show an unusually strong dominance of the equine-like G3P[8] genotype which carried a DS-1-like genotype constellation in the period 2021 to 2023. Additionally, vaccinated individuals were significantly overrepresented among patients infected with the equine-like VP7 carrying G3P[8] rotavirus compared with other genotypes, including typical human VP7 G3P[8].

Despite the presence of typical yearly genotype fluctuations, several epidemiological changes were associated with the COVID-19 pandemic, including the unusual dominance of an emerging rotavirus strain against which current vaccines may be less effective. It is essential to closely monitor this strain to determine if the phenomenon is temporary.

Rat hepatitis E virus (ratHEV) is an emerging virus causing acute and chronic hepatitis in humans. Rats are the main natural reservoir of this pathogen. Large-scale studies assessing ratHEV circulation in rodents in Spain are lacking.

We aimed to determine the prevalence of ratHEV in rats in Spain and evaluate potential transmission risk to humans.

We designed a cross-sectional nationwide study where black (Rattus rattus) and Norway (R. norvegicus) rats were collected and analysed between 2022 and 2023 for ratHEV infection using real-time (RT)-qPCR testing of liver tissue. Sequencing and analysis of ratHEV shedding in faeces were carried out in positive animals.

RatHEV was detected in 125 of the 481 rats analysed, supposing a prevalence of 26.0% (95 CI%: 22.3–30.1). Positive rats were found in urban (25.6%), and farm (29.8%) settings. Black rats (31.3%) had 1.5 times higher odds of being infected by the virus than Norway rats (22.5%) (p = 0.049). Significantly higher prevalence of ratHEV was detected in rodents sampled from southern (31.9%) than northern (17.8%) Spain (p = 0.003). Viral RNA was detected in faeces from 45.5% of infected rats. Phylogenetic analysis evidenced a wide genetic diversity of ratHEV sequences, some showing high homology with ratHEV strains found in patients from Spain.

Circulation of ratHEV appears to be heterogeneous and the virus appears to be endemic among rat populations in Spain, highlighting the possible risk of zoonotic transmission of this emerging virus in this country.