In a recent study posted to the medRxiv* pre-print server, KU Leuven researchers investigated whether there was an association between the intensity of the co-circulation of adenovirus (AdV) 40/41 and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with the number of hepatitis cases of unknown origin emerging in Belgium.
To this end, they measured the circulation of AdV 40/41 and SARS-CoV-2 in the general population of Leuven, Belgium. Next, the team monitored the city’s wastewater systems and indoor air quality in nurseries. In addition, they examined the medical records of 12,672 children who visited a hospital between January 2019 and April 2022.
Study: Environmental circulation of adenovirus 40/41 and SARS-CoV-2 in the context of the emergence of acute hepatitis of unknown origin† Image Credit: Corona Borealis Studio / Shutterstock
There were several probable cases of severe acute hepatitis of unknown etiology in children under 16 years of age in Belgium. In fact, there were many more such cases in the World Health Organization (WHO) European region, with three in four cases in children under the age of five. Accordingly, of the 650 probable cases tested for AdV, 181 had 110 (60.8%) positive cases. Similarly, 23 of the 188 cases were positive for SARS-CoV-2.
About the study
In the present study, researchers hypothesized that Adv and SARS-CoV-2 were physiopathological contributors to the etiology of severe acute hepatitis of unknown origin, especially in children under 16.
The team collected weekly wastewater samples from a wastewater treatment plant in Belgium covering eight municipalities with 115,000 people. They used a time-proportional automated sampler between December 2020 and May 2022 to collect 50 ml of wastewater every 10 minutes.
Evolution of the circulation of AdV 40/41 and SARS-CoV-2 in the general population between December 2020 and May 2022. The intensity of the signal is determined by the Ct value of targeted PCR assays performed on wastewater.
Likewise, they collected the aerosol samples from two different institutions, depending on the age group of the children. For zero- to three-year-olds, they collected air samples from the room near the restrooms in the nursery, and three- to six-year-olds from the kindergarten dining room. Between November 2021 and April 2022, samples were taken for two hours, one to three times a week.
The researchers extracted viral ribonucleic acid (RNA) from wastewater and aerosol samples, which were then subjected to quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) tests to detect the presence of SARS-CoV-2 and AdV 41. They used Sanger sequencing for AdV subtyping on all positive sewer samples. The team has actively investigated cases of hepatitis of unknown origin in four time frames spanning pre- and post-coronavirus disease 2019 (COVID-19) periods. In addition, they screened the medical records of 63 children (all under the age of 16) who had elevated liver enzymes over all time frames.
A: Evolution of the circulation of Adv 40/41 and SARS-CoV-2 in nurseries between November 2021 and May 2022. The intensity of the signal is captured by the Ct/Cq value of targeted PCR assays performed on air samples . B: The ratio of positive samples to the total of tested samples is shown in the lower figure.
The team used the proportion test function to test the changes in the number of elevated liver enzyme cases and pathogen positivity between the study periods. Furthermore, they used the Kruskal-Wallis test to test differences between groups of continuous variables and a Dunn test for pairwise comparisons between groups. Finally, they used the Benjamin-Hochberg method for multiple test corrections with a false discovery rate (FDR) cut-off value of less than 0.05.
Between September 2021 and April 2022, the authors noted high circulation of AdV 40/41 and SARS-CoV-2 in the general population. In addition, they identified four probable and five possible cases of non-severe non-AE viral hepatitis of unknown origin in children under 16 years of age. All nine children developed hepatitis after October 2021, but recovered without requiring a liver transplant. Although adenovirus infection was not associated with any case, the authors identified one case directly related to SARS-CoV-2 infection. The child developed COVID-19 four days before the onset of hepatitis. Notably, they did not identify cases of hepatitis of unknown origin in the four pre- and post-COVID-19 time frames.
Sanger sequencing was possible for 57% of the sewage samples. The authors noted that AdV was detectable in 65% of those samples, but only after the increase in AdV 40/41 cases after July 2021. The authors analyzed 158 air samples, 128 of which came from day care centers and 30 from kindergartens. They first detected AdV 40/41 in these samples on December 10, 2021. They then consistently found AdV 40/41 and SARS-CoV-2 throughout the study period, concurrent with cases of hepatitis in Belgium.
Taken together, the study observations have not definitively ruled out or confirmed the contribution of AdV and SARS-CoV-2 to the emergence of acute cases of childhood hepatitis. Therefore, even in cases where they may have contributed, only a few cases progressed to severe hepatitis. In addition, the high transmission rates of both AdV and SARS-CoV-2 and lower hospitalizations of cases of viral hepatitis of unknown origin in children between September 2021 and April 2022 further support the study results. More importantly, the study emphasized the need for holistic disease surveillance in large populations to estimate secondary diseases, including hepatitis arising from a massive circulation of infectious viruses, such as AdV and SARS-CoV-2.
medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, that should guide clinical practice/health-related behavior or be treated as established information.
- Environmental circulation of adenovirus 40/41 and SARS-CoV-2 in the context of the onset of acute hepatitis of unknown origin, Elke Wollants, Els Keyaerts, Lize Cuypers, Mandy Bloemen, Marijn Thijssen, Sien Ombelet, Joren Raymenants, Kurt Beuselinck , Lies Laenen, Lore Budts, Bram Pussig, Katrien Lagrou, Marc Van Ranst, Emmanuel Andre, medRxiv pre-print 2022, DOI: https://doi.org/10.1101/2022.06.08.22276091† https://www.medrxiv.org/content/10.1101/2022.06.08.22276091v1
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