Calibration of Methods for SARS-CoV-2 Environmental Surveillance: A Case Study from Northwest Tuscany

Int J Environ Res Public Health. 2022 Dec 9;19(24):16588. doi: 10.3390/ijerph192416588.

Abstract

The current pandemic has provided an opportunity to test wastewater-based epidemiology (WBE) as a complementary method to SARS-CoV-2 monitoring in the community. However, WBE infection estimates can be affected by uncertainty factors, such as heterogeneity in analytical procedure, wastewater volume, and population size. In this paper, raw sewage SARS-CoV-2 samples were collected from four wastewater treatment plants (WWTPs) in Tuscany (Northwest Italy) between February and December 2021. During the surveillance period, viral concentration was based on polyethylene glycol (PEG), but its precipitation method was modified from biphasic separation to centrifugation. Therefore, in parallel, the recovery efficiency of each method was evaluated at lab-scale, using two spiking viruses (human coronavirus 229E and mengovirus vMC0). SARS-CoV-2 genome was found in 80 (46.5%) of the 172 examined samples. Lab-scale experiments revealed that PEG precipitation using centrifugation had the best recovery efficiency (up to 30%). Viral SARS-CoV-2 load obtained from sewage data, adjusted by analytical method and normalized by population of each WWTP, showed a good association with the clinical data in the study area. This study highlights that environmental surveillance data need to be carefully analyzed before their use in the WBE, also considering the sensibility of the analytical methods.

Keywords: HCoV-229E; SARS-CoV-2; mengovirus VMC0; wastewater surveillance; wastewater-based epidemiology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19* / epidemiology
  • Calibration
  • Environmental Monitoring
  • Humans
  • RNA, Viral
  • SARS-CoV-2* / genetics
  • Sewage

Substances

  • Sewage
  • RNA, Viral

Grants and funding

This work was funded by Tuscany Region with the project “Monitoring and modeling of SARS-CoV-2 in sewer networks for COVID 19 pandemic spreading early warning system”(Regional Council resolution 8 March 2021, n. 174); by the Italian Ministry of Health, “CCM 2020 program” with the project “Wastewater based epidemiology: implementation of a surveillance system for the early detection of pathogens, and specifically SARS-CoV-2”; by the Italian Government, Decree of the Ministry of Health 30.10.2021 11 December 2021, n. 294 and by the EU Commission, Grant Agreement 060701/2021/864481/SUB/ENV.C2. This work was also supported by ESF-REACT-EU (National Operational Programme (NOP) on research and innovation 2014–2020).