Detecting COVID-19 in wastewater to identify hotspots

Canadian researchers have proposed a method to detect COVID-19 infection rates in wastewater through sewer sensors.

The COVID-19 pandemic has posed a challenge for researchers as some of the virus's spread comes from people who do not show symptoms of the virus (1). Known as Asymptomatic Carriers, it is unknown how many cases of COVID-19 were spread from asymptomatic versus patients with symptomatic COVID-19.

COVID-19 is usually detected through diagnostic tests, antibody tests, or COVID-19 management tests (2). However, people who are asymptomatic are unlikely to get tested. With the restrictions being relaxed, there is an increased risk that people with asymptomatic COVID-19 will unwittingly spread COVID-19.

Detect COVID-19 early

Detecting and treating COVID-19 early on could help reduce the spread and harm to vulnerable populations. Early detection methods include the detection of physical symptoms such as cough, fever, fatigue, nausea and vomiting, and the appearance of mucous membranes.

Most early detection methods, however, require patients to travel to a test site, which further increases their risk of infection transmission rather than social distancing or staying at home. Researchers in Canada have proposed a unique early warning system that uses duct sensors to identify COVID-19 hotspots (4). They published their results in the journal PLOS ONE.

Detect COVID-19 in wastewater

Researchers at the University of Toronto's Rotman School of Management suggested using a sophisticated algorithm to calculate COVID-19 infection hotspots. The calculation would be based on data collected by sensors that are part of a wastewater-based epidemiology (WBE) program.

Sewage-based epidemiology is a new tool that can quickly monitor the spread of disease by analyzing a population's sewage (5). Most people with COVID-19 excrete remains of the SARS-Cov-2 virus with their waste, which ends up in the local sewer system. With the help of advanced mathematical models, WBE data can be used to identify newly infected individuals or sources of infection (4).

Identifying COVID-19 hotspots

In order to closely follow hotspots, the researchers identify the sewage transport network from the neighborhood to the sewage treatment plants (WTP). Individual shafts are identified from which wastewater samples can be taken for analysis. If the samples test positive for SARS-Cov-2 virus residues, the researchers assume that there are people with COVID-19 in a neighborhood upstream of this sampling point, as it has been detected in the wastewater. If the samples are negative, the neighborhood is negative.

Due to the size of the cities and the number of potential sampling points, it would be impossible for researchers to sample and test every single sample. Using the mathematical algorithm, researchers can more accurately identify shafts and neighborhoods that are hotspots for COVID-19 infection. As part of the WBE, semi-permanent sensors would be placed in selected shafts. These sensors could detect all “red light” COVID-19 infections in wastewater in real time.

Practical tests

While sensors built into the shaft have not yet been developed, the WBE method for sampling and analyzing wastewater has been tested at several university dormitories. For example, in the fall of 2020, the University of Arizona monitored and tested sewage from manholes next to student dormitories. When signs of COVID-19 infection were found in the sewage, all students in the dormitory were tested. The student with COVID-19 was then isolated to ensure the health and safety of the remaining students (6).

Study authors say additional research is needed for a quick, inexpensive, and easy COVID-19 test for the wastewater samples. In addition, sensors in the shaft must be developed. Finally, there is a need to examine how the sewer systems themselves would affect the detection and testing methods proposed by the researchers (4).

In a press release, study author Professor Oded Berman said, "It's exciting to be working on something that is badly needed and has the potential to help people soon," he said. "It's very different from what I did before."

References:

Dobrovolny HM. Modeling the role of asymptomatic symptoms in the spread of infection with application to SARS-CoV-2. Lo Iacono G, ed. PLUS ONE. 2020; 15 (8): e0236976. doi: 10.1371 / journal.pone.0236976
Health C for D and R. In Vitro Diagnostic EUAs. FDA. Published May 24, 2021. Accessed June 7, 2021. https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/in- vitro-diagnostik-euas # individual-antigen
Hashmi HAS, Asif HM. Early detection and evaluation of Covid-19. Limits in Medicine. 2021; 7. doi: 10.3389 / fmed.2020.00311
Nourinejad M, Berman O, Larson RC. Placing sensors in sewer networks: a system to locate new cases of coronavirus. Oliva G, ed. PLUS ONE. 2021; 16 (4): e0248893. doi: 10.1371 / journal.pone.0248893
Sims N, Kasprzyk-Hordern B. Future prospects of wastewater-based epidemiology: monitoring the spread and resistance of infectious diseases at the community level. Environment International. 2020; 139: 105689. doi: 10.1016 / j.envint.2020.105689
Larson RC, Berman O, Nourinejad M. Sampling of manholes to study SARS-CoV-2 infections. Adrish M, ed. PLUS ONE. 2021; 15 (10): e0240007. doi: 10.1371 / journal.pone.0240007
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