Scientists say that traces of SARS-CoV-2 genetic material -- viral RNA -- in the poo we flush down the toilet and into the sewage system might reveal how badly coronavirus has hit a given community.
Analyzing sewage could show the true scale of an outbreak, in the absence of available testing, they say.
Looking for outbreak markers in wastewater could also be used to detect the coronavirus if
it comes back to communities, reports Nature.
Using this method, researchers have found traces of the virus the Netherlands, the USA and Sweden, and correlated their findings with known outbreaks.
One treatment plant can capture wastewater from more than one million people, says Gertjan Medema, a microbiologist at KWR Water Research Institute in Nieuwegein, the Netherlands. Monitoring effluent at this scale could provide better estimates for how widespread the coronavirus is than testing because wastewater surveillance can account for those who have not been tested and have only mild or no symptoms, says Medema, who has detected SARS-CoV-2 genetic material -- viral RNA -- in several treatment plants in the Netherlands: "Health authorities are only seeing the tip of the iceberg."
But to quantify the scale of infection in a population from wastewater samples, researchers say the groups will need to find out how much viral RNA is excreted in faeces and extrapolate the number of infected people in a population from concentrations of viral RNA in wastewater
samples. Researchers will also need to ensure that they are looking at a representative sample of what is being excreted by the population and not just one snapshot in time, and that their tests can detect the
virus at low levels.
Infection-control measures, such as social distancing, will probably suppress the current pandemic, but the virus could return once such measures are lifted. Routine wastewater surveillance could be used as a non-invasive early-warning tool to alert communities to new COVID-19 infections, says Ana Maria de Roda Husman, an infectious-disease researcher at the Netherlands National Institute for Public Health and the Environment in Bilthoven. The institute has previously monitored sewage to detect outbreaks of norovirus, antibiotic-resistant bacteria, poliovirus and measles.
de Roda Husman's group detected traces of SARS-CoV-2 in wastewater at
Schiphol Airport in Tilburg only 4 days after the Netherlands confirmed its 1st case of COVID-19 using clinical testing.
How sewage could reveal true scale of coronavirus outbreak
Date: Fri 3 Apr 2020