Mosquito-borne West Nile virus (WNV) infection is benign in most individuals but can cause encephalitis in <1% of infected individuals. We show that ∼35% of patients hospitalized for WNV disease (WNVD) in six independent cohorts from the EU and USA carry auto-Abs neutralizing IFN-α and/or -ω. The prevalence of these antibodies is highest in patients with encephalitis (∼40%), and that in individuals with silent WNV infection is as low as that in the general population. The odds ratios for WNVD in individuals with these auto-Abs relative to those without them in the general population range from 19.0 (95% CI 15.0–24.0, P value <10–15) for auto-Abs neutralizing only 100 pg/ml IFN-α and/or IFN-ω to 127.4 (CI 87.1–186.4, P value <10–15) for auto-Abs neutralizing both IFN-α and IFN-ω at a concentration of 10 ng/ml. These antibodies block the protective effect of IFN-α in Vero cells infected with WNV in vitro. Auto-Abs neutralizing IFN-α and/or IFN-ω underlie ∼40% of cases of WNV encephalitis.

This paper outlines the role of Lombardy’s regional influenza reference laboratory (Northern Italy) in the surveillance of influenza-like illnesses (ILIs) in monitoring SARS-CoV-2 circulation by analyzing 631 consecutive nasopharyngeal swabs (NPSs) collected from ILI outpatients by sentinel physicians during the 2019–2020 season. The samples were tested by specific real-time RT-PCRs targeting SARS-CoV-2, influenza viruses, and RSVs. Results: Of these NPSs, 31% tested positive for influenza viruses, 10% for SARS-CoV-2, and 7% for RSV. No coinfections were detected. Influenza viruses and RSVs circulated throughout the surveillance period until the end of February (week 9-2020), when they suddenly ceased to circulate seven weeks earlier than during the previous five influenza seasons. After the first detection of SARS-CoV-2 in our ILI outpatients at the beginning of March (week 10-2020), SARS-CoV-2 remained the only virus identified throughout the surveillance period. Patients ≥ 65 years had a 3.2-fold greater risk of being infected with SARS-CoV-2, while school-age children (5–14 years) and children < 5 years proved to be the age groups most at risk of contracting influenza viruses and RSV, respectively. Our experience demonstrates that laboratory-based ILI surveillance networks are essential for identifying SARS-CoV-2 cases that would otherwise remain undetected, in order to stop their spread within our communities.

We report a considerable increase in enterovirus D68 (EV-D68) cases since July 2024, culminating in an ongoing outbreak of acute respiratory infections in northern Italy, accounting for nearly 90% of all enterovirus infections. The outbreak was identified by community- and hospital-based surveillance systems, detecting EV-D68 in individuals with mild-to-severe respiratory infections. These strains belonged to B3 and a divergent A2 lineage. An increase in adult cases was observed. Enhanced surveillance and molecular characterisation of EV-D68 across Europe are needed.

Wastewater-based epidemiology (WBE) has emerged as a valuable public health tool for monitoring the circulation of many pathogens, including influenza viruses (IVs). The general aim of this study is to systematically retrieve and summarize evidence on the use of WBE for supporting influenza surveillance. Specific objectives are: (i) to map influenza monitoring activities using WBE; (ii) to assess the performance of viral recovery methods; (iii) to explore association with clinical data; (iv) to evaluate the feasibility of typing/subtyping IVs directly from wastewater. We conducted a systematic review following the PRISMA guidelines, focusing on original data from peer-reviewed studies identified through PubMed/Medline, Scopus, and Web of Science. Of 882 identified citations, 42 studies were included in the review. IVs detection was reported in all but one study, although typically at lower concentration than SARS-CoV-2. Thirteen studies (38.09 %) performed comparative analysis of different protocols, with mostly inconclusive results. Detection of IVs in the solid fraction of wastewater samples generally outperformed detection in the supernatant/liquid. Additionally, we describe the findings from 22 studies (52.38 %) that examined the link between environmental viral concentrations and clinical data, and 14 studies (33.33 %) that described IVs subtyping in wastewater. WBE has the potential to monitor influenza circulation in humans and animals, offering insights into outbreak size and circulating IVs subtypes. However, several key areas remain unexplored. Further research is needed to refine experimental techniques and standardize protocols, and to understand how to successfully integrate WBE data into public health strategies for influenza control.

The quantification and molecular characterization of the AdV genome in urban wastewater samples (WWSs) collected weekly at a wastewater treatment plant (WWTP) in Milan from 1 January 2021 (week 2021-01) to 1 May 2022 (week 2022-17) were performed. The concentration of the AdV genome was graphically compared with the AdV positive rate observed in the respiratory/gastrointestinal specimens from individuals hospitalized with acute respiratory/gastrointestinal infections collected from one of the major hospitals in Milan in the same time series. An increase in the AdV circulation in WWSs was seen from November 2021, peaking in March 2022 and overlapped with an increase in the AdV positive rate in respiratory/fecal samples from individuals hospitalized with acute respiratory/gastrointestinal infections. The molecular characterization of the hexon hypervariable region of loop 1 of AdV revealed the presence of the species F type 41 in WWSs collected from February 2022 to April 2022. The wastewater surveillance of AdV can provide crucial epidemiological characteristics regarding AdV, particularly where no clinical surveillance is ongoing. The increase in the AdV circulation in Milan both in WWSs and clinical samples temporally overlapped with the outbreak of severe acute pediatric hepatitis observed in Europe and needs to be better investigated.