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Corona: viral material in human excretions - risk of infection in toilets?
The number of infections with the coronavirus SRAS-CoV-2 continues to increase worldwide. According to current knowledge, the novel pathogen is transmitted primarily from person to person, for example when speaking, coughing or sneezing. Both droplets and aerosols play a role here. Infection via objects is also not excluded. There may also be a risk of infection in public toilets.
Viral material has already been found in human excretions in corona studies. Does toilet cleaning result in virus spinners? A certain detail could be decisive for this.
When floating, small floating particles are distributed in the air
Public toilets could play a role when it comes to risk locations for corona infection. This is suggested by at least one study by Chinese scientists, the results of which were published in the journal "Physics of Fluids".
The researchers investigated how small suspended particles are distributed in the air when flushing a toilet. It is possible that virus-contaminated aerosol clouds could be inhaled by other people, they conclude.
Studies previously had shown that the stool of infected people may contain coronavirus material.
Contagion risk via aerosol clouds
The experts at the University of Yangzhou used detailed computer models to trace the water and air currents that arise when flushing with different types of toilets.
According to this, vortices are generated in the toilet, which continue in the form of aerosol clouds above the bowl - up to a height of just under one meter, where they can be inhaled or deposited on surfaces.
Aerosols are a mixture of solid or liquid suspended particles in the air. The tiny droplets, a few micrometers in size, can hover in the air for more than a minute, as the researchers explain. With toilet types with two water influences, the aerosols flew up even faster.
"It can be assumed that this speed will be even higher if a toilet is used frequently, for example in a family toilet or a public toilet in a densely populated room," explains co-author Ji-Xiang Wang.
The solution, however, is simple: close the toilet lid before flushing. However, many toilets in public spaces, especially in the United States, would not have a lid - a fact that Clemens Wendtner from Munich Clinic Schwabing also points out in an independent comment.
SARS-CoV-2 in the gastrointestinal tract
In this context, the infectiologist recalls discussions about the spread of the virus on cruise ships. "I don't think such spreading is out of the question." In addition, there are more and more studies on viral load in the stool of COVID-19 patients.
Wendtner himself, together with the virologist Christian Drosten from the Berlin Charité, published an analysis in the journal "Nature" in which the course of the infection was reconstructed by nine German corona sufferers. It was shown that SARS-CoV-2 probably also increased in the gastrointestinal tract.
However, no infectious viruses could be documented in the stool of the sick. "However, this is always difficult with stool samples because E. coli bacteria always overgrow everything else," notes Wendtner. "However, we were unable to detect any replication-capable viruses."
Nevertheless, it cannot be entirely ruled out that faecal excretions also pose a risk of infection. At least that's the warning from researchers at the US Swedish Medical Center, who analyzed 29 studies on gastrointestinal consequences of COVID-19 disease with 4,805 patients in a meta-analysis.
As they report in the journal "JAMA Network Open", diarrhea, nausea or vomiting were symptoms of more than ten percent of all infected people.
Infection risk is rather low
Irrespective of this, the virus was found in stool in 40 percent of those affected. "In our analysis of some studies in which Sars-CoV-2-RNA was isolated from the stool, the fecal-oral route of transmission could be an additional potential source for the spread of infections," summarize the physicians.
A possibly crucial detail here: Only one study reported viable viruses in stool and only in two out of 153 stool samples. However, no infection is possible from dead virus material.
For the researchers, the gastrointestinal problems are above all other symptoms that doctors should watch out for in the course of a corona infection; and above all with a view to appropriate tests.
Clemens Wendtner also notes that stool samples can be a diagnostic tool, especially in children. With regard to the risk of infection, the toilet problem is more of a minor issue.
"It is an interesting aspect when it comes to toilets in confined spaces such as on cruise ships, trains, airplanes, collective accommodation or asylum centers," says the chief doctor. Accordingly, one should not sit on toilet glasses in public spaces and observe common hygiene recommendations.
But he also emphasizes: "After the infection chain runs over the lungs, it is definitely more relevant to observe distance rules in public spaces and to avoid mass events." (Ad; source: dpa)
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- Yun-yun Li, Ji-Xiang Wang, Xi Chen: Can a toilet promote virus transmission? From a fluid dynamics perspective; in: Physics of Fluids, (published: June 16, 2020), Physics of Fluids
- Sravanthi Parasa, Madhav Desai, Viveksandeep Thoguluva Chandrasekar, et al .: Prevalence of Gastrointestinal Symptoms and Fecal Viral Shedding in Patients With Coronavirus Disease 2019; in: JAMA Network Open, (published: 11.06.2020), JAMA Network Open