Enterovirus D68 (EV-D68) causes respiratory disease ranging from mild to severe and in rare cases a paralytic syndrome, called acute flaccid myelitis (AFM). Since the global EV-D68 outbreak in 2014, the virus has mainly circulated in biennial epidemic cycles with peaks detected during even years. However, following the COVID-19 pandemic, the seasonal pattern of EV-D68 has been characterized by large yearly upsurges. Here, we describe the circulation of EV-D68 in Europe in 2023 and track its genetic evolution. Data was compiled from members of the European Non-Polio Network (ENPEN). This included monthly data on the total number of EV samples tested, EV positive samples, EV-D68 positive samples and cases, and other EV positive samples detected in 2023. Information on sample types and surveillance system was recorded. Sequence data from the VP1 gene was used for phylogenetic and amino acid sequence analysis. EV was detected in 13,585 out of 203,622 diagnostic samples tested (6.7 %), of which 402 (3.0 %) were determined as EV-D68, representing 386 cases. EV-D68 infections peaked in October 2023 (136/386; 35.2 %). 267/386 (69.2 %) of EV-D68 cases were captured through clinical EV surveillance, almost all of which (202/204 of positive samples with sample type information) were detected in respiratory specimens. Phylogenetic analysis performed on 99 VP1 sequences revealed a distinct B3-derived lineage with a previously undescribed residue change, D554E, in Europe. The study documents sustained circulation of EV-D68 in Europe in 2023, the evolution of B3-derived lineages, and appearance of previously undescribed amino acid substitutions in Europe. This stresses the need for continuous EV-D68 surveillance and harmonization of EV-D68 detection practices towards better data comparability across countries.

Wastewater-based epidemiology (WBE) was conducted to track Enteroviruses (EVs) circulation in the Milan metropolitan area (Northern Italy) during Covid-19 pandemic (March 2020-December 2022). 202 composite 24-hour wastewater samples (WWSs) were collected weekly from March 24, 2020, to December 29, 2022 at the inlet of two wastewater treatment plants (WWTP) in Milan (1.5 million inhabitants). EV-RNA was quantified and molecular characterization of non-polio EVs (NPEV) was performed by Sanger sequence analysis. Data from WWS were matched with virological data collected in the framework of Influenza-Like Illness (ILI) surveillance in the same place and time. EV-RNA was identified in 88.2 % of WWSs. The peak in EVs circulation was observed in late August 2020 (upon conclusion of the first national lockdown), in late August 2021, and in mid-April 2022. EV-RNA concentration in WWS (normalized as copies/d/1000 people) at peak of circulation presented a yearly increase (2020: 2.47 × 10¹⁰; 2021: 6.81 × 10¹⁰; 2022: 2.14 × 10¹¹). This trend overlapped with trend in EV-positivity rate in ILI cases, expanded from 21.7 % in 2021 to 55.6 % in 2022. EV trends in WWS preceded clinical sample detections in 2021 and 2022 by eight and five weeks, respectively, acting as an early warning of outbreak. Although sequencing of EV-positive WWSs revealed the presence of multiple EV strains, typing remained inconclusive. Molecular characterization of EVs in clinical samples revealed the co-circulation of several genotypes: EV-A accounted for 60 % of EVs, EV-B for 16.7 %, EV-D68 for 23.3 %. EVs were circulating in Milan metropolitan area between March 2020 and December 2022. The epidemiological trends unfolded the progressive accumulation of EV transmission in the population after removal of Covid-19 restrictions. The increased circulation of EVs in 2021-2022 was identified at least 35 days in advance compared to the analysis of clinical data. The inconclusive results of Sanger sequencing lookout for improvement and innovative molecular approaches to deepen track EVs.

The Encyclopaedia Cloacae is a novel and centralised digital platform designed to support and advance wastewater-based epidemiology (WBE) by cataloguing pathogens detectable in wastewater and their relevance to public health surveillance. The platform is hosted on the EU Wastewater Observatory for Public Health (EU4S) website, where it is populated with peer-reviewed research through a structured workflow under harmonised criteria which address the presence of pathogens in human excreta, detectability in wastewater, and integration into public health systems. This tri-criteria approach ensures that the database is both scientifically robust and operationally actionable. Complemented by the Visualising the Invisible dashboard, the platform offers geospatial insights into global WBE research activity. By consolidating peer-reviewed evidence on pathogen detectability in wastewater and human excreta, the Encyclopaedia Cloacae enables early detection of infectious diseases, whether already known or newly emerging. The continuously updated repository and geospatial dashboards help to identify surveillance gaps and research hotspots, to support timely public health responses, enhance pandemic preparedness, and strengthen global health security. In addition, it supports One Health strategies, connecting the health of humans, animals, and the shared environment. This article outlines the platform’s architecture, data curation methodology, and future directions, including automation and expansion to encompass broader health determinants such as antimicrobial resistance and chemical hazards.