Stay away from Snot Drenched Money

Flu could hitch a ride on banknotes

Debora MacKenzie

The flu virus persists so well on banknotes that money could help spread the next pandemic, researchers say.
Yves Thomas and colleagues at the University Hospitals of Geneva in Switzerland dripped various strains of flu virus – including some that were circulating during winter 2007 – onto Swiss banknotes and left them at room temperature for varying amounts of time before testing for live virus.

"We wanted to assess the survival of human flu on banknotes, knowing that billions of them are exchanged daily," Thomas says.

Money is so widely exchanged among all members of society that its movement has been studied as a model for the way infections spread.

At home in mucus
Some strains of flu lasted only two hours, but the most common flu, H3N2, lasted up to 72 hours.

However, all the strains lasted longer when they were dripped onto the notes along with human nasal mucus. Some lasted as long as 17 days. One strain that lasted only two hours on its own lasted 24 hours in mucus.

"I'm surprised the virus persisted so long," says Graeme Laver, an expert in the spread of bird flu, formerly of the Australian National University in Canberra. But the flu virus likes wet environments – and mucus is ideal because it is designed to retain water.

Touch transmission
Typically humans with flu shed copious amounts of virus in their nasal secretions, the main route by which flu is believed to spread.

The extent to which flu spreads by floating through the air is debated by scientists, but experiments have shown that it is transmitted when people with flu touch surfaces that are then touched by other people.

This means that handling money within the lifespan of the virus could pass on the illness.

The findings were presented at the Options for the Control of Influenza Conference in Toronto, Canada, 17 to 23 June.

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