Estimating the minimum number of SARS-CoV-2 infected cases needed to detect viral RNA in wastewater: To what extent of the outbreak can surveillance of wastewater tell us?
Rachmadi, Andri Taruna
Mantilla Calderon, David
Bashawri, Yasir M
Al Qarni, Hamed
O'Reilly, Kathleen M
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Microbial Safety and Biotechnology Lab
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
Permanent link to this recordhttp://hdl.handle.net/10754/667171
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AbstractThere is increasing interest in wastewater-based epidemiology (WBE) of SARS-CoV-2 RNA to serve as an early warning system for a community. Despite successful detection of SARS-CoV-2 RNA in wastewaters sampled from multiple locations, there is still no clear idea on the minimal number of cases in a community that are associated with a positive detection of the virus in wastewater. To address this knowledge gap, we sampled wastewaters from a septic tank (n = 57) and biological activated sludge tank (n = 52) located on-site of a hospital. The hospital is providing treatment for SARS-CoV-2 infected patients, with the number of hospitalized patients per day known. It was observed that depending on which nucleocapsid gene is targeted by means of RT-qPCR, a range of 253-409 positive cases out of 10,000 persons are required prior to detecting RNA SARS-CoV-2 in wastewater. There was a weak correlation between N1 and N2 gene abundances in wastewater with the number of hospitalized cases. This correlation was however not observed for N3 gene. The frequency of detecting N1 and N2 gene in wastewater was also higher than that for N3 gene. Furthermore, nucleocapsid genes of SARS-CoV-2 were detected at lower frequency in the partially treated wastewater than in the septic tank. In particular, N1 gene abundance was associated with water quality parameters such as total organic carbon and pH. In instances of positive detection, the average abundance of N1 and N3 genes in the activated sludge tank were reduced by 50 and 70% of the levels detected in septic tank, suggesting degradation of the SARS-CoV-2 gene fragments already occurring in the early stages of the wastewater treatment process.
CitationHong, P.-Y., Rachmadi, A. T., Mantilla-Calderon, D., Alkahtani, M., Bashawri, Y. M., Al Qarni, H., … Zhou, J. (2021). Estimating the minimum number of SARS-CoV-2 infected cases needed to detect viral RNA in wastewater: To what extent of the outbreak can surveillance of wastewater tell us? Environmental Research, 110748. doi:10.1016/j.envres.2021.110748
SponsorsThe authors would like to thank the medical team of the studied hospital for providing access to wastewater samples and for saving lives during this pandemic. The authors would also like to thank Professor Arnab Pain for providing the RNA sample that serves as positive control, Professor Matthew McCabe and Mr Samir Almashharawi for providing the ambient temperature and solar irradiance measured at the Hada Al Sham monitoring station.
PubMed Central IDPMC7831732
Except where otherwise noted, this item's license is described as This is an open access article under the CC BY-NC-ND license.