- Waste water containing coronaviruses poses a serious health threat.
- This is according to 35 international researchers who analysed studies on coronaviruses in waste water.
- The researchers are urgently advising regular wastewater monitoring and testing.
In an effort to understand more about the constantly evolving SARS-CoV-2, the virus responsible for Covid-19, researchers have been testing sewage for months.
A new global study – led by researchers from the Zuckerberg Institute for Water Research at the Ben-Gurion University of the Negev (BGU) – warns that waste water containing coronaviruses may be a serious threat.
"There is ample reason to be concerned about how long coronaviruses survive in waste water and how it impacts natural water sources," said lead author Dr Edo Bar-Zeev of the BGU Zuckerberg Institute.
The paper was published in Nature Sustainability, and the research was carried out by an international team of 35 researchers. They evaluated recent studies on coronaviruses in waste water, as well as previous airborne infectious diseases, including SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome).
Still not enough evidence, but investigations should continue
"Can waste water contain enough coronaviruses to infect people? The simple truth is that we do not know enough and that needs to be rectified as soon as possible," Bar-Zeev said.
The team's analysis of the potential threat of the virus in waste water has led them to conclude that sewage leaking into natural watercourses might lead to infection via airborne spray, and that treated waste water flowing into recreational water facilities, such as rivers and lakes, could also become a source of contagion.
The researchers wrote that fruits and vegetables not properly disinfected and irrigated with waste water could also be an indirect infection route.
"Wastewater treatment plants need to upgrade their treatment protocols and in the near future also advance toward tertiary treatment through micro- and ultrafiltration membranes, which successfully remove viruses," Bar-Zeev and his colleagues wrote.
To shed further light on existing studies about the presence and potential for infection by SARS-CoV-2 in various bodies of water, as well as how long coronaviruses can survive under these conditions, they are recommending immediate, new research into waste water.
If attention is given to the regular monitoring of waste water, authorities will receive advance warning of coronavirus hotspots, since the virus starts showing up in faeces before the onset of symptoms, such as coughing and fever. This will also be helpful in detecting asymptomatic cases.
Previous studies on SARS-CoV-2 and waste water
In May, researchers involved in two studies on waste water – in the UK and Israel – warned that sewerage systems themselves could pose a transmission risk and "must not be neglected".
In the UK analysis of sewage, the virus was found in human faeces up to 33 days after the patient had tested negative for the respiratory symptoms of Covid-19. However, they are uncertain whether the virus found in sewage is able to infect humans.
Study lead author Professor Richard Quilliam said according to their findings there is an increased risk of infection in parts of the world where there is a lot of open defecation, as well as in many places without properly managed sanitation. These authors agree that sewerage systems all over the world should not be neglected.
According to the World Health Organisation (WHO), only 45% of the global population has safely managed sanitation systems, and at least 10% is thought to consume food irrigated by waste water.