Sewage Surveillance to Assess Possible COVID-19 Spread in Tempe Wastewater

by Patrick J. Paul

Researchers from Arizona State University are evaluating Tempe wastewater for traces of COVID-19, which could serve as an early warning system of the virus’s spread in communities.  Although believed to be among the first cities in America to study the possible connection between community spread of the coronavirus through wastewater systems, the study itself is not novel.  Wastewater surveillance is a proven method of detecting poliovirus and antibiotic-resistant bacteria, as well as the use of illicit and prescription medications.  Sewage surveillance could also serve as early warning of the emergence and re-emergence of COVID-19 in municipalities.

Dutch scientists detected the coronavirus in a city’s wastewater prior to any COVID-19 reported cases, establishing one early warning system for the presence of the coronavirus.  While scientists believe that it is unlikely that sewage will become an important route of transmission, the pathogen’s circulation in communities will increase the amount of it flowing into sewer systems.  Data collection about the occurrence and fate of COVID-19 in sewage therefore may be critical not only to better understand the risks to sewage workers, but also to determine if sewage surveillance might be an effective tool in monitoring community spread of COVID-19.

The Centers for Disease Control and Prevention (CDC) continues to review all data on COVID-19 transmission as information becomes available and notes that currently, “the risk of transmission of the virus that causes COVID-19 through sewerage systems is thought to be low.”  The CDC further observes that while transmission of COVID-19 through sewage may be possible, there is no current evidence that this has occurred.

SARS, a similar coronavirus, has been detected in untreated sewage for up to 2 to 14 days. In the 2003 SARS outbreak, there was documented transmission associated with sewage aerosols.  Data suggests that standard municipal wastewater system chlorination practices may be sufficient to inactivate coronaviruses, as long as utilities monitor free available chlorine during treatment to ensure it has not been depleted.  The CDC recommends that sewage workers practice basic hygiene precautions, and wear personal protective equipment (https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html).

Tempe officials believe that more data on how widespread the virus is in the city could help staff better deploy protective equipment and other resources, access testing kits and better prepare first responders and health care workers to handle the outbreak

The ASU Biodesign Center for Environmental Health Engineering research team has been monitoring wastewater in 30 U.S. cities to detect other viruses to develop early warning systems for flu and other outbreaks.  Researchers are in the early stages of determining at what levels, if any, SARS-CoV-2, the virus that causes the COVID-19 disease, can be detected in wastewater.  The ASU team has created a test to determine whether genetic material from COVID-19 can be detected in untreated sewage.  Tests are being conducted to determine if the detection method works.  If successful, researchers will collect samples from different parts of the city’s sewer system and monitor for trends, such as whether the amount of the virus present in the wastewater increases or decreases.

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