Tracking COVID-19 with wastewater

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as the most important viral disease of zoonotic origin already directly affecting more than 109 million and causing more than 2,4 million deaths as of February 18, 2021, according to WHO.

Real-time reverse transcription polymerase chain reaction (RT-PCR) is one of the most widely used laboratory methods for detection of COVID-19 because of its high sensitivity in exponentially amplifying RNA molecules. Therefore, most countries depend on doing RT-PCR on the general population to track and monitor the actual prevalence of SARS‐CoV‐2. However, this is not a practical surveillance approach for the general population over the long term or for a sustained period of time. Environmental microbiologists have investigated foodborne, waterborne, fecal-oral, or enteric viral pathogens such as poliovirus, hepatitis A virus, and norovirus from the sewage and used it as a public health surveillance tool, and more recently for tracking SARS-CoV-2.

Recent studies found that SARS-CoV-2 RNA could be detected in feces, leading to speculation that COVID-19 can be transmitted via the fecal-oral route. In Valencia, Spain, a team of scientists and engineers are accessing the sewage network as an attempt to figure out the next possible COVID-19 outbreaks. Haramoto and colleagues carried out the first environmental surveillance for COVID-19 in Japan. They detected SARS-CoV-2 RNA (2.4 × 103 copies/L) in secondary-treated wastewater. The noticeable remark is that SARS-CoV-2 RNA was detected in wastewater when there was a high number of COVID-19 cases, implying that SARS-CoV-2 wastewater surveillance may be considered to be an ideal surrogate for community cases.

In Spain, Randazzo and colleagues detected SARS‐CoV-2 RNA in samples taken when communicated cases in that area were only incipient. They also reported that the wastewater SARS‐CoV-2 RNA context markedly increased and anticipated the subsequent ascent in the number of declared cases. They proposed that SARS-CoV-2 was present in the community earlier than previously believed, suggesting that wastewater analysis is a cost‐effective and sensitive method for epidemiological surveillance of COVID‐19.

Medema and colleagues reported the first detection of SARS-CoV-2 in sewage in the Netherlands. They found that there is a positive correlation between the prevalence of COVID-19 in the community and the detection of SARS-CoV-2 in sewage, indicating that sewage surveillance could be a sensitive tool to monitor the circulation of SARS-CoV-2 in the population. In France, Wurtzer and colleagues reported that the increase in the SARS-CoV-2 genome units in raw wastewater perfectly followed the increase in human COVID-19 cases seen in specific areas.

Detection of SARS-CoV-2 in wastewater includes three main steps: concentration of wastewater samples, RNA extraction, and RT-PCR. Most of the previous studies used approximately 200 mL of wastewater. Different methods were used for viral concentration such as aluminum-driven flocculation, specific filters, or electronegative membrane-vortex (EMV) method. Then, RNA extraction kits or automatic RNA extractors were also used for RNA extraction. After extraction of RNA, the presence of SARS-CoV-2 was determined using various RT-PCR kits.

COVID-19 wastewater surveillance could help in making properly targeted shutdowns as well as reopening in heavily populated sectors that lack resources and facilities. This also could give a good sign and indication if COVID-19 cases are high or low in these specific areas. In conclusion, tracking of COVID-19 in wastewater could give a good picture of cases in specific or selected areas instead of doing RT-PCR on all populations in these geographic regions. COVID-19 sewage surveillance may be used as an early alarm, similar to the poliovirus sewage surveillance, which has been long used for this goal.


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Haramoto, E., Malla, B., Thakali, O. and Kitajima, M., 2020. First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan. medRxiv.

Medema, G., Heijnen, L., Elsinga, G., Italiaander, R. and Brouwer, A., 2020. Presence of SARS-Coronavirus-2 RNA in sewage and correlation with reported COVID-19 prevalence in the early stage of the epidemic in the Netherlands. Environmental Science & Technology Letters7(7), pp.511-516.

Randazzo, W., Cuevas-Ferrando, E., Sanjuan, R., Domingo-Calap, P. and Sanchez, G., 2020. Metropolitan Wastewater Analysis for COVID-19 Epidemiological Surveillance. Available at SSRN 3586696.

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