Epidemiological impact of human adenovirus as causative agent of respiratory infections: An Italian multicentre retrospective study, 2022-2023.

Human adenoviruses are the causative agents of 5-7% of viral respiratory infections, mainly caused by species B and C. They can infect all age groups, but children are usually at high risk of infections. Adenovirus epidemiology is well documented in East-Asian countries but little is known about adenovirus circulation in Europe in recent years. This multicentre retrospective study aimed to investigate the circulation and molecular epidemiology of hAdVs. This surveillance collected a total of 54463 respiratory specimens between January 1, 2022 and June 20, 2023 were tested for the presence of respiratory viruses. Our results showed that adenovirus was detected in 6.6 % of all cases of acute respiratory infection included in the study and the median age of positive patients was 3 years, with male children in 1-2 years age group being the most affected. 43.5 % of adenovirus cases were co-infected with at least one other respiratory virus, and rhinovirus was co-detected in 54 % of cases. Genotyping of adenovirus allowed the identification of 6 different genotypes circulating in Italy, among which type B3 was the most frequently detected.

Molecular characterization of emerging Echovirus 11 (E11) shed light on the recombinant origin of a variant associated with severe hepatitis in neonates.

Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. Due to the limited data available, the World Health Organization (WHO) considers public health risk to the general population to be low. The present study investigated the genetic variation and molecular evolution of E11 genomes collected from May to December 2023. Whole genome sequencing (WGS) was performed for 16 E11 strains. Phylogenetic analysis on WG showed how all Italian strains belonged to genogroup D5, similarly to other E11 strains recently reported in France and Germany all together aggregated into separate clusters. A cluster-specific recombination pattern was also identified using phylogenetic analysis of different genome regions. Echovirus 6 was identified as the major recombinant virus in 3Cpro and 3Dpol regions. The molecular clock analysis revealed that the recombination event probably occurred in June 2018 (95% HPD interval: Jan 2016-Jan 2020). Shannon entropy analyses, within P1 region, showed how 11 amino acids exhibited relatively high entropy. Five of them were exposed on the canyon region which is responsible for receptor binding with the neonatal Fc receptor. The present study showed the recombinant origin of a new lineage of E11 associated with severe neonatal infections.

Sequence analysis of respiratory syncytial virus cases reveals a novel subgroup -B strain circulating in north-central Italy after pandemic restrictions.

BACKGROUND: Following the pandemic restrictions, the epidemiology of respiratory syncytial virus (RSV) has changed, leading to intense hospitalization peaks. OBJECTIVES: This study, conducted at multiple sites in Italy, aimed to describe the temporal dynamics of two post-COVID-19 RSV epidemics. Additionally, the circulating RSV-A and -B lineages were characterized and compared to those found in 2018 and 2019. STUDY DESIGN: Respiratory specimens and data were collected from RSV-positive patients, both inpatients, and outpatients, of all ages at three sites in north-central Italy. To analyze these samples, roughly one-sixth were sequenced in the attachment glycoprotein G gene and subjected to phylogenetic and mutational analyses, including pre-pandemic sequences from north-central Italy. RESULTS: The first post-pandemic surge of RSV cases was quite intense, occurring from October 2021 to early January 2022. The subsequent RSV epidemic (from November 2022 to early March 2023) also had a high impact, characterized by a rise in elderly patient cases. Post-pandemic cases of RSV-A were caused by various strains present in Italy prior to COVID-19. In contrast, a distinct RSV-B lineage, which was concurrently spreading in other countries, was identified as the main cause of the surge in 2022-2023 but remained undetected in Italy before the pandemic. CONCLUSIONS: This study describes the temporal dynamics of post-pandemic RSV subgroups and uncovers a lineage of RSV-B with high genetic divergence that may have increased the impact of decreased population immunity.

RSV Disease Burden in Primary Care in Italy: A Multi-Region Pediatric Study, Winter Season 2022-2023.

INTRODUCTION: Human respiratory syncytial virus (RSV) is one of the most frequent causes of respiratory infections in children under 5 years of age, but its socioeconomic impact and burden in primary care settings is still little studied. METHODS: During the 2022/2023 winter season, 55 pediatricians from five Italian regions participated in our community-based study. They collected a nasal swab for RSV molecular test from 650 patients under the age of 5 with acute respiratory infections (ARIs) and performed a baseline questionnaire. The clinical and socioeconomic burden of RSV disease in primary care was evaluated by two follow-up questionnaires completed by the parents of positive children on Days 14 and 30. RESULTS: RSV laboratory-confirmed cases were 37.8% of the total recruited ARI cases, with RSV subtype B accounting for the majority (65.4%) of RSV-positive swabs. RSV-positive children were younger than RSV-negative ones (median 12.5 vs. 16.5 months). The mean duration of symptoms for all children infected by RSV was 11.47 ± 6.27 days. We did not observe substantial differences in clinical severity between the two RSV subtypes, but RSV-A positive patients required more additional pediatric examinations than RSV-B cases. The socioeconomic impact of RSV infection was considerable, causing 53% of children to be absent from school, 46% of parents to lose working days, and 25% of families to incur extra costs. CONCLUSIONS: Our findings describe a baseline of the RSV disease burden in primary care in Italy before the introduction of upcoming immunization strategies.

Increased circulation of echovirus 11 in the general population and hospital patients as elicited by the non-polio enterovirus laboratory-based sentinel surveillance in northern Italy, 2023.

OBJECTIVES: Following the alert of echovirus 11 (E-11) infection in neonates in EU/EEA Member States, we conducted an investigation of E-11 circulation by gathering data from community and hospital surveillance of enterovirus (EV) in northern Italy from 01 August 2021 to 30 June 2023. METHODS: Virological results of EVs were obtained from the regional sentinel surveillance database for influenza-like illness (ILI) in outpatients, and from the laboratory database of ten hospitals for inpatients with either respiratory or neurological symptoms. Molecular characterization of EVs was performed by sequence analysis of the VP1 gene. RESULTS: In our ILI series, the rate of EV-positive specimens showed an upward trend from the end of May 2023, culminating at the end of June, coinciding with an increase in EV-positive hospital cases. The E-11 identified belonged to the D5 genogroup and the majority (83%) were closely associated with the novel E-11 variant, first identified in severe neonatal infections in France since 2022. E-11 was identified sporadically in community cases until February 2023, when it was also found in hospitalized cases with a range of clinical manifestations. All E-11 cases were children, with 14 out of 24 cases identified through hospital surveillance. Of these cases, 60% were neonates, and 71% had severe clinical manifestations. CONCLUSION: Baseline epidemiological data collected since 2021 through EV laboratory-based surveillance have rapidly tracked the E-11 variant since November 2022, alongside its transmission during the late spring of 2023.