Experts are concerned that coronavirus could be spread through our drains.
Environmental biologists from the University of Stirling warned that after researchtraces of the virus were found in the stool for 33 days after someone had Covid-19.
Professor Quilliam and colleagues from Stirling’s Faculty of Science write in the prestigious journal Environment International, calling for ‘an investment of resources’ to investigate their concerns.
Professor Quilliam said, “We know that Covid-19 is spread through drops from coughing and sneezing, or through objects or materials that carry infection. However, it has recently been confirmed that the virus can also be found in human faeces – up to 33 days after the patient has been tested negative for the respiratory symptoms of Covid-19.
‘It is not yet known whether the virus can be transmitted via the faecal-oral route, but we know that viral secretion via the digestive system can take longer than excretion via the respiratory system. Therefore, this could be an important, but as yet unqualified, path for increased exposure. ”
The team said there are historical lessons to be learned.
Using the example of the 2002-2003 Sars outbreak when the virus, closely related to Covid-19, was detected in sewage discharged from two hospitals in China.
Professor Quilliam emphasizes that since most coronavirus patients are asymptomatic or experience only mild symptoms and remain at home, not in hospitals, there is a significant risk of “widespread” distribution through sewers.
The biologists said that a lack of testing “makes it difficult” to predict the magnitude of the potential spread and the public health impact of the virus arriving at waste water treatment plants, while the consequences of the resulting discharge into the wider environment remain just starting to be explored.
They added that Covid’s structural makeup suggests that it will behave differently in aqueous environments, compared to other viruses that usually occur in the gut.
There is currently limited information on the persistence of Covid-19 in the environment, but other coronaviruses may remain viable in the sewer for up to 14 days depending on environmental conditions.
Concerning the risk of human exposure, the authors said: “Transporting coronaviruses in water could increase the risk of aerosolization of the virus, especially during sewage pumping, sewage treatment and discharge and subsequent transport. via the river basin drainage network.
“Atmospheric loads of coronaviruses in water droplets from wastewater are poorly understood, but could provide a more direct respiratory route for human exposure, especially at sewage pumping stations, wastewater treatment plants and near waterways receiving wastewater.”
The risk can be further increased in parts of the world with a high degree of open feces, or where safely managed sanitation systems are limited and waterways are used as open sewers and as a water source for household purposes.
“Such institutions are often accompanied by inadequate resources and vulnerable healthcare systems, increasing both exposure risk and potential death,” the authors said.
Currently, all published data on faecal excretion of Sars-CoV-2 comes from hospitalized patients – with limited information on mild and asymptomatic cases.
The paper concludes, “Funds should be invested in the near future to improve our understanding of the risks of faecal transmission of Sars-CoV-2, and whether this respiratory virus can be spread by enteric transmission.
“Understanding the risk of spread via the faecal-oral route while it is still in the early stages of the pandemic will allow more evidence-based information about viral transmission to be shared with the public.
In addition, the risks associated with wastewater loading during the remainder of the COVID-19 outbreak need to be quantified rapidly so that wastewater managers can act quickly and take control measures to reduce human exposure to this potentially infectious material.
“At a time when the world is so focused on the respiratory system of a respiratory virus, it should not be neglected to ignore the potential for the spread of SARS-CoV-2 via the faecal-oral route.”
Professor Quilliam co-wrote the document with Professor Manfred Weidmann, Dr. Vanessa Moresco, Heather Purshouse, Dr. Zoe O’Hara and Dr. David Oliver.