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No coronavirus danger from drinking water or food

Some viruses can remain infectious in the environment for weeks, fortunately the Covid-19 pathogen is not one of them.


Photo: Zsolt Marton

Author: Florian Aigner  (Published  23. März 2020 for TU Wien)

Some viruses are only transmitted directly from person to person. Other viruses can also be transmitted via the environment. For example, we absorb them when we drink faecal-contaminated water or when we eat uncooked and unwashed food, such as vegetables or fruit. Fortunately, this is not the case with the coronavirus SARS-CoV-2. But how do we actually know this for sure?

Prof. Andreas Farnleitner heads our Research Centre "Water and Health" and the Research Group Environmental Microbiology and Molecular Diagnostics at the TU Wien. His team has been working for years on pathogens in the environment. "You only have to look at some of the very basic properties of the virus to understand how it behaves," says Farnleitner. "All the well-known water hygiene organisations on a national and international level can already say this with certainty, even though there are of course no experimental data available for precisely this virus".

 

The path of propagation: coughed from the lungs outside

First of all, it is important where a virus can multiply at all. In the case of SARS-CoV-2, this is clear: it mainly attacks the respiratory tract and is then coughed out of the lungs or excreted when breathing. It is therefore spread from person to person by droplet infection.

"However, we often find infectious viruses in faecally contaminated water samples, but these are completely different types of viruses," says Andreas Farnleitner. "These are usually viruses that multiply in the human intestine and enter the environment via excrement. These can be enteroviruses, rotaviruses or adenoviruses, some of which can remain infectious outside the body for weeks. Coronaviruses are much less stable. In the best case, they can survive for a few days outdoors; under realistic conditions, they can survive for hours or minutes.

 

A virus like a soap bubble

Stability depends on the basic blueprint of the virus: every virus has genetic material, either in the form of DNA or RNA. However, this genetic material alone is completely ineffective. It must be enclosed in a capsule of proteins - the so-called capsid. A protein capsid can be quite stable and allow some viruses to survive for a long time in the wild. The proteins of the capsid allow the virus to dock to a cell and infect it. After infection, the virus can use the cell to replicate itself: The cell is made to produce the proteins required by the virus, according to the virus' genetic blueprint. The genetic information of the virus itself is also copied within the cell. In this way the necessary components for other viruses are created.

However, coronaviruses not only have a simple capsid, but also a delicate membrane envelope of lipids. The proteins that the virus needs to dock to cells are embedded in this envelope. The virus simply takes these lipids from the outer cell membrane of the infected cell," said Andreas Farnleitner explaining that "the envelope of coronaviruses, which consists of lipids and embedded proteins, is very delicate and fragile. "You can imagine it like a soap bubble. Therefore the environmental persistence is low, the virus cannot survive outside the body for long".

 

Social Distancing and hygiene

It is therefore not necessary to boil clean drinking water (as supplied by the water supplier) and you will not be infected with SARS-CoV-2 through food. It is crucial to follow the hygiene recommendations: Washing your hands frequently is important - soap destroys the lipid shell of the virus. If you cough, you should be careful not to spread the virus further. It is best to cough into the crook of your arm or into a handkerchief, which is then thrown away. And if you limit contacts as much as possible, you will definitely slow down the speed of the spread.

 

Contact

Prof. Andreas Farnleitner
Research Centre "Water and Health"
Institute for Process Engineering, Environmental Technology and Technical Biosciences
Technische Universität Wien
T +43-1-58801-166557
andreas.farnleitner@tuwien.ac.at

 



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