British researchers have discovered that copper and copper alloys can rapidly destroy norovirus – the most common cause of acute gastroenteritis worldwide.

Norovirus belongs to the viral family Caliciviridae. The virus is highly infectious and can be contracted from contaminated food or water, person-to-person contact, and contact with contaminated surfaces.

The new mice study, reported in the open-access journal PLoS ONE, showed norovirus was rapidly destroyed on copper and its alloys, with those containing more than 60 per cent copper proving particularly effective.

Copper alloys have previously been shown to be effective antimicrobial surfaces against a range of bacteria and fungi. The current study reported rapid inactivation of murine norovirus on alloys, containing over 60 per cent copper, at room temperature but no reduction of infectivity on stainless steel dry surfaces in simulated wet fomite and dry touch contamination.

The rate of inactivation was initially very rapid and proportional to the copper content of alloy tested. Viral inactivation was not as rapid on brass as previously observed for bacteria but copper-nickel alloy was very effective.

One of the targets of copper’s antimicrobial activity was the viral genome and a reduced number of the gene for a viral encoded protein, VPg (viral-protein-genome-linked), which is essential for infectivity, was observed following contact with copper and brass dry surfaces.

“The use of antimicrobial surfaces containing copper in clinical and community environments, such as cruise ships and care facilities, could help to reduce the spread of this highly infectious and costly pathogen,” said study lead author Dr Sarah Warnes from the University of Southampton.

“Copper alloys, although they provide a constant killing surface, should always be used in conjunction with regular and efficient cleaning and decontamination regimes using non-chelating reagents that could inhibit the copper ion activity.”

“Although the virus was identified over 40 years ago, the lack of methods to assess infectivity has hampered the study of the human pathogen,” said co-author Prof Bill Keevil, also from the University of Southampton.

“The virus can remain infectious on solid surfaces and is also resistant to many cleaning solutions. That means it can spread to people who touch these surfaces, causing further infections and maintaining the cycle of infection. Copper surfaces, like door handles and taps, can disrupt the cycle and lower the risk of outbreaks.”

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Bibliographic information: Warnes SL, Keevil CW. 2013. Inactivation of Norovirus on Dry Copper Alloy Surfaces. PLoS ONE 8 (9): e75017; doi: 10.1371/journal.pone.0075017