At a time when the world is so focused on the respiratory pathways of a respiratory virus, this recent paper in Environment International argues that understanding the opportunities for SARS-CoV-2 to be spread by the faecal-oral route must not be neglected. They state that the public health implications of significant concentrations of SARS-CoV-2 arriving at sewage treatment plants, and the consequent discharge into the wider environment are only just beginning to be investigated.
As previously documented on this blog, coronaviruses can remain viable in sewage for up to 14 days depending on the conditions such as temperature. However, the presence of solvents and detergents in wastewater can compromise the viral envelope.
The authors of this paper argue that although there is not yet any robust evidence for coronaviruses being directly transmitted by the faecal-oral route, the increase of viral load in the environment could increase potential human exposure. In particular, the transport of coronaviruses in water increases the potential for the virus to become aerosolised, particularly during the pumping of wastewater through sewerage systems and at the sewage treatment plant, and during its discharge and subsequent transport through the catchment drainage network.
Other situations where there is increased risk of human exposure from wastewater include high rainfall events which exceed sewage infrastructure capacity, resulting in discharge from combined sewer overflows and sewer flooding. The risk of exposure via the faecal-oral route is also of particular concern in parts of the world where safely managed sanitation systems are limited, and particularly where there are high levels of open defecation or other forms of non-sewered sanitation.
Quilliam RS, Weidmann M, Moresco V, Purshouse H, O’Hara Z and Oliver DM (2020) COVID-19: The environmental implications of shedding SARS-CoV-2 in human faeces. Environment International, 140, 105790.