Cold plasma can kill norovirus, researchers find

Chuck Bednar for redOrbit.com – Your Universe Online

The pathogen responsible for most cases of gastroenteritis worldwide could be killed off by cold atmospheric pressure plasma (CAPP), researchers from the University of Veterinary Medicine in Hannover report in a recent edition of the online, open-access journal mBio.

Treating surfaces with CAPP, also known as cold plasma, could reduce the risk of transmitting norovirus, a contagious virus leading to stomach pain, nausea and diarrhea and which has gained international notoriety by causing multiple outbreaks on cruise ships in recent years.

According to BBC News, tens of millions of cases of the illness are reported worldwide every year, and complicating matters is the fact that norovirus is highly resistant to several different types of chemical disinfectants. Chlorine-based bleach is currently the most effective treatment, though scientists have long been searching for a better alternative.

Cold plasma, the so-called “fourth state of matter” made up of ionized gas molecules at room temperature, could be the solution, the British media outlet added. These ions are capable of killing several types of microbes, though their effectiveness against viruses has been unknown.

A matter of fecal

However, a series of experiments led by Dr. Birte Ahlfeld and Professor Günter Klein of the University of Veterinary Medicine in Hannover investigated cold plasma’s effect on norovirus by preparing sterile petri dishes containing three dilutions of a stool sample collected from a German soldier who was infected with the disease-causing agent in 2011.

They treated the samples using CAPP for different lengths of time in a plasma chamber, and found that samples treated for the longest time (15 minutes) has the lowest content of the virus. The cold plasma treatment reduced the amount of potentially infectious virus particles from 22,000 (similar to what would be found on an untreated surface touched by someone who had been infected with norovirus) to 1,400 in 10 minutes and to 500 after 15 minutes.

In a statement, Klein called cold plasma “an environmentally friendly, low energy method that decreases the microbial load on surfaces.” He noted that the technology has been demonstrated to be effective “against viruses with a high tenacity, like noroviruses, and that its “successful application in medical therapy should be transferred to other areas.”

“Cold plasma was able to inactivate the virus on the tested surfaces, suggesting that this method could be used for continuous disinfection of contaminated surfaces,” Klein added. While CAPP treatment could not completely eliminate the virus, he said that “a reduction is still important to lower the infectious dose and exposure for humans.”

In future research, Klein’s team (which include experts from the Max Planck Institute for Extraterrestrial Physics and the Central Institute of the Bundeswehr Medical Service Kiel) plan to test CAPP’s disinfection properties on other types of surfaces, as well as on other forms of norovirus. They also plan to use electron microscopes to examine the structure of the pathogen both before and after treatment with cold plasma.

“A spread of norovirus can be inhibited at crucial points, which as we know from our previous studies are all surfaces with frequent contact to human skin or hands,” Klein told BBC News. “Handheld devices can be used to disinfect different surfaces or a plasma box for hands or cutlery or plates is possible.”

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