Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Feb 20:860:160317.
doi: 10.1016/j.scitotenv.2022.160317. Epub 2022 Nov 25.

Wastewater monitoring in tourist cities as potential sentinel sites for near real-time dynamics of imported SARS-CoV-2 variants

Jatuwat Sangsanont  1 , Surapong Rattanakul  2 , Prasert Makkaew  3 , Nopadol Precha  3 , Pratchaya Rukthanapitak  4 , Montakarn Sresung  5 , Yadpiroon Siri  6 , Masaaki Kitajima  7 , Tomoko Takeda  8 , Eiji Haramoto  9 , Jiratchaya Puenpa  10 , Nasamon Wanlapakorn  10 , Yong Poovorawan  10 , Skorn Mongkolsuk  11 , Kwanrawee Sirikanchana  12
Affiliations

Wastewater monitoring in tourist cities as potential sentinel sites for near real-time dynamics of imported SARS-CoV-2 variants

Jatuwat Sangsanont et al. Sci Total Environ. .

Abstract

Wastewater-based epidemiology (WBE) complements the clinical surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants' distribution in populations. Many developed nations have established national and regional WBE systems; however, governance and budget constraints could be obstacles for low- and middle-income countries. An urgent need thus exists to identify hotspots to serve as sentinel sites for WBE. We hypothesized that representative wastewater treatment plants (WWTPs) in two international gateway cities, Bangkok and Phuket, Thailand, could be sentineled for SARS-CoV-2 and its variants to reflect the clinical distribution patterns at city level and serve as early indicators of new variants entering the country. Municipal wastewater samples (n = 132) were collected from eight representative municipal WWTPs in Bangkok and Phuket during 19 sampling events from October 2021 to March 2022, which were tested by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) using the US CDC N1 and N2 multiplex and variant (Alpha, Delta, and Omicron BA.1 and BA.2) singleplex assays. The variant detection ratios from Bangkok and Phuket followed similar trends to the national clinical testing data, and each variant's viral loads agreed with the daily new cases (3-d moving average). Omicron BA.1 was detected in Phuket wastewater prior to Bangkok, possibly due to Phuket's WWTPs serving tourist communities. We found that the Omicron BA.1 and BA.2 viral loads predominantly drove the SARS-CoV-2 resurgence. We also noted a shifting pattern in the Bangkok WBE from a 22-d early warning in early 2021 to a near real-time pattern in late 2021. The potential application of tourist hotspots for WBE to indicate the arrival of new variants and re-emerging or unprecedented infectious agents could support tourism-dependent economies by complementing the reduced clinical regulations while maintaining public health protection via wastewater surveillance.

Keywords: COVID-19; Gateway cities; Lineage; Normalizer; Omicron; Wastewater surveillance.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Unlabelled Image
Graphical abstract
Fig. 1
Fig. 1
Sampling locations in Bangkok's municipal wastewater treatment facilities (sites L1–L4), and an international airport (site A1) and municipal wastewater treatment facilities (sites P1–P3) in Phuket.
Fig. 2
Fig. 2
Detection percentages of the SARS-CoV-2 variants based on Thailand's COVID-19 clinical data (https://www.gisaid.org/) (A), in the wastewater influent from four Bangkok wastewater treatment facilities (B), in the wastewater influent from three Phuket wastewater treatment facilities and one international airport (C) from January 2021 to March 2022. The dates are shown as day/month/year.
Fig. 3
Fig. 3
Flow-normalized and crAssphage-normalized SARS-CoV-2 RNA loads (CDC N1 assay) in the wastewater influent from four Bangkok wastewater treatment facilities (A) and the wastewater influent from three Phuket wastewater treatment facilities and one international airport (B) compared with the corresponding 3-day moving averages of new clinically confirmed cases. The dates are shown as day/month/year. GC, gene copies; PE, population equivalent.
Fig. 4
Fig. 4
Detection percentages of the Omicron BA.1 and BA.2 variants from January to March 2022 in the Bangkok (A) and Phuket wastewater (B). An asterisk (*) indicates that more than one variant was detected in the same sample.
Fig. 5
Fig. 5
Flow-normalized viral loads of the Delta and Omicron BA.1 and BA.2 variants from each site, and the total SARS-CoV-2 N1 combined from all the sites in Bangkok (A) and Phuket (B). The dark symbols indicate data above the limit of quantification (LOQ), while the white symbols represent data below the LOQ.
Fig. 6
Fig. 6
Time-series cross-correlation function (CCF) between the 3-d moving averages of daily new cases at different lag times from 0 to 15 days and flow-normalized SARS-CoV-2 N1 in Bangkok (A) and Phuket (B) and crAssphage-normalized SARS-CoV-2 N1 in Bangkok (C) and Phuket (D). Dashed lines indicate 95 % confidence limits.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Adelodun B., Ajibade F.O., Ibrahim R.G., Bakare H.O., Choi K.-S. Snowballing transmission of COVID-19 (SARS-CoV-2) through wastewater: any sustainable preventive measures to curtail the scourge in low-income countries? Sci. Total Environ. 2020 doi: 10.1016/j.matdes.2019.108334. - DOI - PMC - PubMed
    1. Agrawal S., Orschler L., Schubert S., Zachmann K., Heijnen L., Tavazzi S., Gawlik B.M., de Graaf M., Medema G., Lackner S. Prevalence and circulation patterns of SARS-CoV-2 variants in European sewage mirror clinical data of 54 European cities. Water Res. 2022;214 doi: 10.1016/j.watres.2022.118162. - DOI - PMC - PubMed
    1. Agrawal S., Orschler L., Tavazzi S., Greither R., Gawlik M., Lackner S. Genome sequencing of wastewater confirms the arrival of the SARS-CoV-2 omicron variant at Frankfurt airport but limited spread in the City of Frankfurt, Germany, in november 2021. Microbiol. Resour. Announc. 2021;11:1–3. - PMC - PubMed
    1. Ahmed W., Bertsch P.M., Bibby K., Haramoto E., Hewitt J., Huygens F., Gyawali P., Korajkic A., Riddell S., Sherchan S.P., Simpson S.L., Sirikanchana K., Symonds E.M., Verhagen R., Vasan S.S., Kitajima M., Bivins A. Decay of SARS-CoV-2 and surrogate murine hepatitis virus RNA in untreated wastewater to inform application in wastewater-based epidemiology. Environ. Res. 2020;191 doi: 10.1016/j.envres.2020.110092. - DOI - PMC - PubMed
    1. Ahmed W., Bertsch P.M., Bivins A., Bibby K., Farkas K., Gathercole A., Haramoto E., Gyawali P., Korajkic A., McMinn B.R., Mueller J.F., Simpson S.L., Smith W.J.M., Symonds E.M., Thomas K.V., Verhagen R., Kitajima M. Comparison of virus concentration methods for the RT-qPCR-based recovery of murine hepatitis virus, a surrogate for SARS-CoV-2 from untreated wastewater. Sci. Total Environ. 2020;739 doi: 10.1016/j.scitotenv.2020.139960. - DOI - PMC - PubMed

Supplementary concepts