Low risk of contracting Covid from human waste

Infection with Covid-19 is unlikely to occur through contact with human waste, research has found.

There is very low risk to the general public of infection through contact with human waste from infected people, according to a review involving Roslin scientists.

The risk of contracting Covid-19 in this way is highest for carers of very sick or elderly patients, such as in intensive care units or care homes, the team found.

There is also a risk from busy, poorly maintained public toilets.

Overall, however, the risk from faeces and urine is low compared with infections such as norovirus, and Covid-19 is much more likely to spread through viral particles in the breath.

Digestive tract

A team of scientists examined findings from previous studies on the risk of infection from the feces and urine of people with Covid-19.

Stomach upset occurs in a small proportion of Covid-19 cases – about one in eight – and the virus affects the gastrointestinal tract, where it can replicate.

Evidence of coronavirus can be found in the feces and urine of patients in the form of genetic material derived from the virus.

However, this waste contains relatively small amounts of live virus compared with particles in saliva, and the risk of spreading the virus is comparatively small.

In addition, the risk of infection through contact in seas and rivers, or consumption of seafood is minimal, as the wastewater treatment process degrades and dilutes the virus.

Testing tool

The presence of coronavirus in human waste may be beneficial for diagnosing infection, as it can occur for several days before symptoms appear, enabling speedy detection of disease.

Infection in the gastrointestinal tract may be part of the infection cycle, researchers suggest, and better understanding of this could inform ways to test for and manage the disease.

The research, published in Science of the Total Environment, was led by Bangor University with University of Western Australia, Newcastle University, Cardiff University, Public Health Wales and others.

Our findings show that contamination risk from coronavirus in human waste is low where person-to-person contact is limited and as long as good hygiene is practised. The likelihood of contagious contact may be higher where cleanliness is difficult to maintain, such as poorly kept public facilities.

Dr Alex Corbishley

** The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of the University of Edinburgh’s Royal (Dick) School of Veterinary Studies. **

Related links

Scientific publication

Roslin Institute Covid-19 research

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