Natural Host–Environmental Media–Human: A New Potential Pathway of COVID-19 Outbreak

Abstract

Identifying the first infected case (patient zero) is key in tracing the origin of a virus; however, doing so is extremely challenging. Patient zero for coronavirus disease 2019 (COVID-19) is likely to be permanently unknown. Here, we propose a new viral transmission route by focusing on the environmental media containing viruses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or RaTG3-related bat-borne coronavirus (Bat-CoV), which we term the “environmental quasi-host.” We reason that the environmental quasi-host is likely to be a key node in helping recognize the origin of SARS-CoV-2; thus, SARS-CoV-2 might be transmitted along the route of natural host–environmental media–human. Reflecting upon viral outbreaks in the history of humanity, we realize that many epidemic events are caused by direct contact between humans and environmental media containing infectious viruses. Indeed, contacts between humans and environmental quasi-hosts are greatly increasing as the space of human activity incrementally overlaps with animals’ living spaces, due to the rapid development and population growth of human society. Moreover, viruses can survive for a long time in environmental media. Therefore, we propose a new potential mechanism to trace the origin of the COVID-19 outbreak.

SARS-CoV-2 spillover into hospital outdoor environments

“…To our knowledge, this is the first report showing the presence of SARS-CoV-2 viral RNA in soils. Since wastewater and soils are environmental matrices rich in organic matters that can protect and shield viruses, SARS-CoV-2 might not be sanitized by disinfectants as evidenced by previous studies on other viruses ( Hurst et al, 1980 , Vettori et al, 2000 ), and possibly survive for a prolonged time in hospital outdoor environment, like over 12 hours in aerosols, over 7 days in wastewater ( Bivins et al, 2020 ), up to 28 days on surfaces ( Riddell et al, 2020 ) and >10 weeks in soils or groundwater ( Li et al, 2020a ). Thus, the presence of SARS-CoV-2 RNA on surface and in soils might pose long-term risks to surrounding residents.…”

Ecological Barrier Deterioration Driven by Human Activities Poses Fatal Threats to Public Health due to Emerging Infectious Diseases

“…Natural hosts can release viruses to the surrounding environment through secretions, feces, urine, corpses, and so forth [ 77 ],. Viruses can survive in soil or water and on various surfaces in wild habitats for a prolonged period of time [ 78 ], causing potential infection in other species including humans via direct contact or intake. Domestic animals can also be infected by viruses through contact with environmental media polluted by wild animals carrying viruses [ 35 ], which makes it easier for viruses to break the ecological barrier and enter human societies through the excreta, fluids, or wastes of domestic animals during the life cycle of breeding, transportation, slaughter, and sale.…”

Inactivation and risk control of pathogenic microorganisms in municipal sludge treatment: A review

“…Recently, the risks of SARS-CoV-2 spreading through fecal-oral and fecal-respiratory transmission have received great attention, but transmission and spread via sludge is far from well-illustrated (Carraturo et al, 2020;Foladori et al, 2020;Li et al, 2020b). A recent study showed that because sludge contains more virus particles and longer residence times, it is easier to detect SARS-CoV-2 in sludge than in sewage (Balboa et al, 2021).…”