One cough equals 20,000 viruses

Tuesday May 13, 2009 (foodconsumer.org) -- With the swine flu virus still hovering ominously about, you may want to run for cover the next time someone near you coughs. The average cough can spew as many as 20,000 viruses, enough germs to infect many people, especially those who aren’t vaccinated.

A recent study from Singapore’s National University Hospital says that as many as 3,000 tiny droplets are produced from one cough, says Julian Tang, consultant with the hospital’s Division of Microbiology.

Investigators used previous research on influenza viral loads in nasal secretions and estimated that each coughed airborne droplet measures between one to five micrometers in diameter, according to Yahoo! News.

And that, said Tang, can open the floodgates for flu viruses.

“Based on this research and assuming about 3,000 droplets are produced per cough, this range of influenza viruses produced per cough is about 195 to 19,500,” Tang told Reuters. The 3,000 droplets, said Tang, refers to those that remain suspended in the air for considerable periods and which can infect people.

As of May 12, the United States now has 3,009 confirmed cases of the H1N1 virus, according to the Centers for Disease Control, more than any other country. Mexico is reporting 2,059 confirmed cases.

With the spread of the virus, health agencies throughout the world are entreating people to observe personal hygiene. The CDC says to help stop the spread of germs, cover your mouth and nose with a tissue when you cough or sneeze.

And if you don’t have a tissue, they say, cough or sneeze into your upper sleeve, not your hands. When you cough into your hands, and you then touch anything else, you are spreading more germs.

Benefits of vaccine

Previous research for infective doses of a virus has found that it takes just 1 to 10 organisms to cause viral fevers, according to yahoo.com, and 10 to 100 organisms to cause viral encephalitis. But because of variations, said Tang, the number is hard to pin down.

“It is difficult to give an exact number for the infectious dose,” he said, “and this may even differ for the same individual throughout the year. But probably for immune people, the infectious dose will be higher than for non-immune people. Hence, the benefits of vaccination.”

(By Sheilah Downey, and edited by Heather Kelley)