The mere act of breathing can spread viruses, results of a new study hint.
While it is well recognised that coughing and sneezing can generate droplets that spread respiratory viruses, senior investigator Dr Euan R. Tovey said, "breathing alone can also generate small particles carrying some airborne virus".
Thus, continued Tovey, "you could be sitting next to someone with no apparent symptoms, for example, on the subway, and they -- at least in theory -- could give you a cold or flu."
Tovey of the Woolcock Institute of Medical Research in Glebe, New South Wales, Australia, and colleagues fitted 10 children and 40 college students with masks to collect exhaled aerosols generated by forced coughing, natural talking, and quiet breathing.
What the study showed
Twenty-five participants -- 21 of 33 with cold symptoms - had virus-positive nose swabs.
Common respiratory viruses were present in breathing samples from 12 of these individuals, in talking samples from nine, and in coughing samples from two, the researchers found.
In 10 patients known to be infected with the common cold virus (rhinovirus), mask samples were also examined and infectious rhinovirus was detected in two.
"We showed," Tovey said, "that we can detect infective rhinovirus in this way. We have not tried, or done this yet for influenza." However, "at present this is an important piece of information to have." – (Reuters Health, August 2009)
How flu viruses change