Epidemiological surveillance of respiratory pathogens in wastewater in Belgium (preprint)

ABSTRACT Background Detailed information on the circulation of respiratory viruses in the community is crucial to gain better understanding of the burden of respiratory infections on society. Methods By using an in-house respiratory panel for simultaneous detection of 29 respiratory pathogens (22 viruses and 7 bacteria/fungi), we explored the possibility to use wastewater sampling to monitor the circulation of respiratory pathogens at population level. Results We were able to detect all respiratory viruses included in the panel (influenza A, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), parainfluenza viruses (PIV) 1-4, adenovirus (Adv), human bocavirus (HBoV), enterovirus/rhinovirus (EV/RV), enterovirus D68 (EV-D68), parechovirus (HPeV), human coronaviruses (HCoV)-NL63, -229E, -OC43, -HKU-1 and -SARS, cytomegalovirus (CMV) and herpes simplex virus (HSV)-1 and -2), except for influenza B and HCoV MERS which were not circulating in Belgium during the two year study period. An upsurge of EV-D68 infections in Europe in September 2021 was clearly reflected in the wastewater samples. For the viruses where epidemiological data on virus circulation in Belgium were available, these matched the wastewater data. The wastewater pretreatment that was used, optimized for viral enrichment, was as such not suited for the surveillance of bacteria and fungi. Conclusions Community circulation levels of respiratory viruses were well reflected in wastewater samples, indicating that wastewater-based epidemiology can be a valuable tool in the epidemiology and management of respiratory infections.

Natural ventilation, low CO2 and air filtration are associated with reduced indoor air respiratory pathogens (preprint)

Currently, the real-life impact of indoor climate, human behavior, ventilation and air filtration on respiratory pathogen detection and concentration are poorly understood. This hinders the interpretability of bioaerosol quantification in indoor air to surveil respiratory pathogens and transmission risk. We tested 341 indoor air samples from 21 community settings for 29 respiratory pathogens using qPCR. On average, 3.9 pathogens were positive per sample and 85.3% of samples tested positive for at least one. The number of detected pathogens and their respective concentrations varied significantly by pathogen, month, and age group in generalized linear (mixed) models and generalized estimating equations. High CO2 and low natural ventilation were independent risk factors for detection. CO2 concentration and air filtration were independently associated with their concentration. Occupancy, sampling time, mask wearing, vocalization, temperature, humidity and mechanical ventilation were not significant. Our results support the importance of ventilation and air filtration to reduce transmission.

Environmental circulation of adenovirus 40/41 and SARS-CoV-2 in the context of the emergence of acute hepatitis of unknown origin (preprint)

The recent surge of hepatitis of unknown origin in children is hypothesized to be caused by adenovirus 41 and/or SARS-CoV-2 infections. A relatively high proportion of patients testing positive for these viruses concomitantly with the development of acute hepatitis supports this hypothesis. To formally incriminate these viral infections as causative agents of hepatitis, both a plausible physiopathological pathway and supporting epidemiological dynamics in the community need demonstration. In this study, we measured the level of circulation of adenovirus 40/41 and SARS-CoV-2 in the general population of the city of Leuven in Belgium using wastewater monitoring between December 2020 and May 2022 and indoor air sampling in day care centers between November 2021 and May 2022. We also retrospectively analyzed medical records of 12.672 children attending a tertiary hospital draining the same region between January 2019 and April 2022. Our results demonstrate a recent but modest increase in hepatitis of unknown origin concomitant with a surge of circulating adenovirus 41 and SARS-CoV-2 in the general population, including in children under 5.

Genetic diversity and evolution of SARS-CoV-2 in Belgium during the first wave outbreak (preprint)

SARS-CoV-2, the causative agent of COVID-19 was first detected in Belgium on 3rd February 2020, albeit the first epidemiological wave started in March and ended in June 2020. One year after the first epidemiological wave hit the country data analyses reveled the temporal and variant distribution of SARS-CoV-2 and its implication with Belgian epidemiological measures. In this study, 766 complete SARS-CoV-2 genomes of samples originating from the first epidemiological were sequenced to characterize the temporal and geographic distribution of the COVID-19 pandemic in Belgium through phylogenetic and variant analysis. Our analysis reveals the presence of the major circulating SARS-CoV-2 clades (G, GH and GR) and lineages circulating in Belgium at that time. Moreover, it contextualizes the density of SARS-CoV-2 cases over time with non-intervention measures taken to prevent the spread of SARS-CoV-2 in Belgium, specific international case imports and the functional implications of the most representative non-synonymous mutations present in Belgium between February to June 2020.

No SARS-CoV-2 carriage observed in children attending daycare centers during the first weeks of the epidemic in Belgium. (preprint)

To gain knowledge about the role of young children attending daycare in transmission risk of SARS-CoV-2, a random sample of children (n=84) aged between 6 and 30 months attending daycare in Belgium was studied shortly after the start of the epidemic (February 29th) and before the lockdown (March 18th). No asymptomatic carriage of SARS-CoV-2 was detected, whereas common cold symptoms were common (51.2%).