To reduce the risk of catching the flu, wash your hands frequently and use tissues when you sneeze -- those are the recommendations from the national Centers for Disease Control and Prevention. But there's another way to protect yourself, even if it's not so good for the economy: Stop handling money.
How likely is that? Despite the pervasiveness of cash in society, its role in transmitting illness has been the subject of surprisingly little study. But some recent research suggests that flu bugs can show some staying power when they land on one of the countless bank notes that change hands every day.
Nothing to sneeze atGenerally speaking, scientists interviewed by SmartMoney estimate the lifetime of a plain flu virus deposited on money at an hour or so. But mix in some human nasal mucus, and the potential for the virus to hang on long enough to find a victim increases, according to one of the few scientific studies done on flu transmission through cash.
In a study conducted at Switzerland's Central Laboratory of Virology at the University Hospitals of Geneva, researchers tested to see what would happen when flu virus was placed on Swiss franc notes. In some of these tests, researchers placed flu virus mixed in with nasal secretions from children on bank notes and saw some unexpected results.
When protected by human mucus, the flu cells were much hardier, lasting up to 17 days on the franc notes. The virus that persisted for 17 days was a form of influenza A called H3N2. In an e-mail interview, Dr. Yves Thomas said samples of an influenza A strain called H1N1 also endured for quite a bit -- in some cases, up to 10 days. That bug was similar but not identical to the virus at the center of the current swine flu outbreak, which is considered a new strain of H1N1.
The research suggested that in the real world, where runny noses get wiped by hands that then handle money, flu viruses may have more persistence than previously thought. (Read the study "Survival of Influenza Virus on Banknotes" in the May 2008 issue of the journal Applied and Environmental Microbiology.)
To be sure, many kinds of frequently touched surfaces could temporarily harbor the flu virus. Broadly speaking, scientists consider the risk of transmission in this way to be low, particularly if hand washing and other hygiene measures are practiced, says Dr. Philip Tierno, the director of clinical microbiology and immunology at New York University's Langone Medical Center and author of "The Secret Life of Germs."
How you'd catch itThree things likely must happen for a flu virus to be transmitted from one person to another via paper money:
- First, a person who is infected with the flu must sneeze or cough onto the bill or blow his/her nose and leave remnants of mucus on the currency.
- Next, an uninfected person needs to touch the money while the virus is still present.
- Finally, that person needs to put his (or her) contaminated hand in his mouth or pick his nose, says Dr. Murray Grossan, an otolaryngologist at Cedars-Sinai Medical Center in Los Angeles.