Leaving no stone unturned in light of the COVID-19 faecal-oral hypothesis? A water, sanitation and hygiene (WASH) perspective targeting low-income countries

Abstract

The human coronavirus disease (COVID-19) is now a global pandemic. Social distancing, hand hygiene and the use of personal protective equipment dominate the current fight against COVID-19. In developing countries, the need for clean water provision, sanitation and hygiene has only received limited attention. The current perspective examines the latest evidence on the occurrence, persistence and faecal-oral transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent causing COVID-19. Evidence shows that SARS-CoV-2 proliferate in the human gastrointestinal system, and is shed via faeces. SARS-CoV-2 can survive and remain viable for up to 6 to 9 days on surfaces. Recent wastewater-based epidemiological studies from several countries also detected SARS-CoV-2 RNA in raw wastewaters. Shell disorder analysis shows that SARS-CoV-2 has a rigid outer shell conferring resilience, and a low shell disorder conferring moderate potential for faecal-oral transmission. Taken together, these findings point to potential faecal-oral transmission of SARS-CoV-2, which may partly explain its rapid transmission. Three potential mechanisms may account for SARS-CoV-2 faecal-oral transmission: (1) untreated contaminated drinking water, (2) raw and poorly cooked marine and aquatic foods from contaminated sources, (3) raw wastewater-based vegetatble production systems (e.g., salads) and aquaculture, and (4) vector-mediated transmission from faecal sources to foods, particularly those from open markets and street vending. SARS-CoV-2 faecal-oral transmission could be particularly high in developing countries due to several risk factors, including; (1) poor drinking water, wastewater and sanitation infrastructure, (2) poor hygiene and food handling practices, (3) unhygienic and rudimentary funeral practices, including home burials close to drinking water sources, and (4) poor social security and health care systems with low capacity to cope with disease outbreaks. Hence, clean drinking water provision, proper sanitation, food safety and hygiene could be critical in the current fight against COVID-19. Future research directions on COVID-19 faecal-oral transmission are highlighted.

COVID-19 infection risk from exposure to aerosols of wastewater treatment plants

“…It has been proposed that the analysis of wastewater could be a powerful tool for COVID-19 surveillance. However, the documented presence of SARS-CoV-2 in wastewater raises the question regarding the potential transmission risk of this virus through wastewater, especially for those working with human waste and wastewater ( Foladori et al., 2020 ; Yang et al., 2020 ; Gormley et al., 2020 ; El Baz and Imziln, 2020 ; Gwenzi, 2021 ). Aerosols from wastewater treatment processes have the ability to carry infectious agents, including respiratory viruses, and therefore, might contribute to transmission of viral infections to the wastewater workers through aerosols/droplets produced in wastewater treatment plants (WWTP) ( Kitajima et al., 2020 ).…”

“…Aerosols from wastewater treatment processes have the ability to carry infectious agents, including respiratory viruses, and therefore, might contribute to transmission of viral infections to the wastewater workers through aerosols/droplets produced in wastewater treatment plants (WWTP) ( Kitajima et al., 2020 ). Although, no evidence has emerged to support the role of wastewater in transmission of COVID-19, the ongoing global pandemic of this viral infection highlights the need for further studies to address any public concerns related to the wastewater ( Gwenzi, 2021 ). Rimoldi et al.…”

“…Evidence from an outbreak of SARS-CoV in the Amoy Gardens apartment building in Hong Kong showed that aerosolized droplets of fecally contaminated water were responsible for the spread of the viral infection in large numbers of people ( McKinney et al., 2006 ). Structural similarities between the SARS-CoV and SARS-CoV-2 ( Corpuz et al., 2020 ), in combination with relatively high stability of SARS-CoV-2 in the aerosol state ( Fears et al., 2020 ), calls for WWTPs to be considered as a potential source for transmission of COVID-19 through bioaerosols produced by wastewater treatment processes ( Corpuz et al., 2020 ; Kitajima et al., 2020 ; Gwenzi, 2021 ). In other words, it is of considerable importance to understand the potential risk of SARS-CoV-2 transmission via wastewater for the sake of wastewater workers and public health.…”

“…In other words, it is of considerable importance to understand the potential risk of SARS-CoV-2 transmission via wastewater for the sake of wastewater workers and public health. This is particularly important in developing countries, where the personal protective equipment has received limited attention and there is a lack of efficient barrier for controlling the aerosols emitted from wastewater processes ( Gwenzi, 2021 ).…”

When silence goes viral, Africa sneezes! A perspective on Africa's subdued research response to COVID-19 and a call for local scientific evidence

“…A typical example is the potential human exposure and health risks associated with the possible transmission of SARS-CoV-2 through fecal contamination of drinking water via raw wastewater discharges and on-site sanitation systems ( Guerrero-Latorre et al, 2020 ; Gwenzi, 2020a , b ). Moreover, the potential of food cross-contamination via the vector-mediated transmission of SARS-CoV-2 (e.g., by houseflies) from fecal matter to human food has been discussed in recent papers ( Gwenzi, 2020a , b ; Heller et al, 2020 ). Hence, the novel transmission of SARS-COV-2 via the fecal-oral route requires further investigation, especially in Africa and other low-income countries.…”