COVID-19: The environmental implications of shedding SARS-CoV-2 in human faeces

Abstract

First paragraph: The ongoing COVID-19 pandemic is having significant public health repercussions, with a global response to limit the predicted mortality associated with this outbreak. The virus, ‘severe acute respiratory syndrome coronavirus 2’ (SARS-CoV-2), is a respiratory virus disseminated though droplets from coughs and sneezes from an infected person or from fomites (Hellewell et al., 2020). Therefore, many countries have put ‘social distancing’ measures in place to reduce person-to-person spread of the disease. However, recently it has been confirmed that infectious virions can also be present in human faeces (Ling et al., 2020), and there are reports that viral RNA can be persistently shed in faeces for a maximum of 33 days after the patient has tested negative for respiratory viral RNA (Wu et al 2020). Although it remains unclear whether SARS-CoV-2 can be transmitted via the faecal-oral route (Xu et al., 2020), viral shedding from the digestive system can last longer than shedding from the respiratory tract. As such, faecal-oral transmission may be an important, but as yet unquantified, pathway for increased exposure during the current outbreak (Wu et al., 2020). Therefore, safely managing faecal wastes from infected, recovering and recovered patients poses a significant nosocomial challenge. For example, during the SARS outbreak of 2002–2003, the closely related SARS-CoV-1 was detected in sewage discharged by two hospitals (Wang et al., 2005), which emphasises the care needed when handling such faecal wastes. However, these challenges are not limited to hospital wastes, as it has been predicted that most of the population will experience only mild symptoms of COVID 19 and convalesce at home, whilst others, including children, can carry the virus asymptomatically, and are still capable of shedding the virus in their faeces (Kam et al., 2020, Tang et al., 2020). This means that the virus could soon become widespread throughout wastewater systems (Naddeo and Liu, 2020). Whilst a lack of testing for the majority of the population makes it difficult to predict the spatially-distributed volume of potentially infectious faeces delivered through the sewerage infrastructure to wastewater treatment works (WWTWs), wastewater surveillance may be a useful tool to indicate where the virus is circulating in the human population (Lodder and de Roda Husman, 2020). However, whilst knowingly infected individuals can take steps to increase their level of hygiene, asymptomatic carriers do not change their behaviour, and can anonymously spread enteric pathogens within the community (Quilliam et al., 2013).