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The next time you cough or sneeze, there is good reason to cover your mouth.
As many as 20,000 viruses are expelled in an average cough, which may be sufficient to infect many people - particularly those who are not vaccinated.
Julian Tang, a consultant at Singapore's National University Hospital's Division of Microbiology, said as many as 3,000 tiny droplets are produced in a standard cough.
Using previous research on influenza viral loads in nasal secretions, and assuming that each coughed airborne droplet measures between 1 to 5 micrometers in diameter, that adds up to many, many viruses in a single cough.
"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 said.
He added that this figure of 3,000 droplets refers to those that remain suspended in the air for considerable periods - long enough to infect people.
" Larger droplets carrying influenza viruses may also be produced during a cough, but these will fall to the ground relatively quickly and will no longer be considered to be significant in the airborne transmission of influenza," he said.
With a new N1N1 influenza virus spreading around the world, governments in many countries have revived advertisements entreating people to observe personal hygiene.
However, experts are uncertain as to what constitutes an infective dose when it comes to influenza viruses.
But as a guide, previous research has found that it takes just one to 10 organisms to cause viral hemorrhagic fevers, and 10 to 100 organisms to cause viral encephalitis.
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(Agencies) |
今后你咳嗽或打噴嚏時，就有充分的理由捂住嘴了。
據統計，每咳嗽一次平均會釋放多達2萬個病毒，這足以讓很多人感染——尤其是那些沒有進行預防接種的人。
新加坡國立大學附屬醫院微生物科的顧問Julian Tang說，一次普通的咳嗽能產生3000個微滴。
根據此前有關鼻腔分泌物中流感病毒載量的研究，并假設每個咳出的通過空氣傳播的微滴的直徑在1至5微米之間，那么一次咳嗽產生的病毒量就非常之多。
Julian Tang說：“根據該研究，并假設每次咳嗽會產生約三千個微滴，那么一次咳嗽產生的流感病毒量約在195到19500個之間。”
他說，這三千個微滴指的是那些長時間懸浮在空氣中微滴——它們存留在空氣中的時間足以感染人群。
他說：“咳嗽可能也會產生較大的攜帶流感病毒的微滴，但這些微滴會相對較快地落到地上，所以對流感在空氣中的傳播幾乎不起作用。”
眼下一種新型的N1H1流感病毒正在全球廣泛傳播，很多國家的政府紛紛重新打出廣告，提醒人們注意個人衛生。
然而，專家們也不能確定多少流感病毒能讓人感染。
但此前的研究發現，僅1至10個微生物體就可導致病毒出血熱，10至100個微生物即可導致病毒性腦炎，這可作為一個參考。
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