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为何某些流感病毒更具传染性

Why Some Flu Viruses May Be More Contagious
为何某些流感病毒更具传染性

Not all flu viruses are the same. Some are hardy survivors.

Some influenza viruses can survive and remain infectious on the fingertips for at least 30 minutes, long enough to transmit the flu to oneself or others, says a study in the January issue of Clinical Microbiology and Infection.

Flu is transmitted from person to person mainly by inhaling tiny virus particles that are released into the air when infected individuals cough and sneeze. Direct contact with contaminated fingers is considered an equally important method of transmission. Researchers sought to find out if the type or size of the flu virus affects its survival.

Experiments in Geneva involved two common influenza viruses: H3N2 and H1N1, the virus that triggered a global flu pandemic in 2009. Both viruses are included in the 2013-14 flu vaccine and are causing most of the world's current flu illnesses, according to a recent World Health Organization bulletin.

Six volunteers with experience handling laboratory viruses were recruited. In separate experiments, droplets of H3N2 and H1N1 mixed with respiratory secretions from infected patients were deposited on three fingertips of each volunteer. The subjects' fingers were undisturbed and kept at room temperature before testing for the presence of viral particles at various intervals. Particles were classed as 'survived' if they were capable of propagating in laboratory cell cultures.

Both flu viruses were infectious on all 18 fingers after one minute. At three minutes, H3N2 was infectious on six fingers while H1N1 remained infectious on 15. At five minutes, H3N2 and H1N1 were infectious on five and eight fingers, respectively. H1N1 remained infectious on five fingers after 15 minutes compared with four fingers contaminated with the H3N2 virus. After 30 minutes, the number of infectious fingers dropped to two for each virus.

Larger droplets of H3N2 and H1N1 were found to contain a higher concentration of viral particles and remained infectious longer than smaller droplets with fewer particles. But smearing flu droplets over the fingertip reduced their infectiousness compared with untouched droplets, the study found.

H1N1 appeared to be hardier than H3N2, the researchers said.

The researchers noted that the study involved only a small number of subjects and viruses.

流感病毒各不相同,有些存活力极强。

1月份刊登在《临床微生物学与传染》(Clinical Microbiology and Infection)的一项研究表明,某些流感病毒可在人的指尖存活并延续传染性至少30分钟,足以传染自身或他人。<-->纽约时报中英文网 http://www.qqenglish.com<-->

流感病毒在人际间传播的主要形式是受感染者通过咳嗽和打喷嚏把细微病毒颗粒释放到空气中并被其他人吸入。直接接触沾有病毒的手指也被视为一种同样重要的传播形式。研究人员试图探究流感病毒的存活力与其种类或大小之间是否存在关联。

在日内瓦进行的这项实验采用了两种常见的流感病毒:H3N2和H1N1,后者曾在2009年引发全球流感大流行。根据世界卫生组织(World Health Organization)的最新公报,这两种病毒都被用于2013至2014年流感疫苗的研制,是目前全世界最常见的流感病毒。

该实验招募了六名拥有处理实验室病毒经验的志愿者。在两个独立分开的实验中,研究人员将混合有感染病人呼吸分泌物的H3N2和H1N1液体滴在了每位志愿者的三个手指尖上。受试者的手指在室温下静置后,研究人员在不同的时间段对病毒颗粒进行检测。如果病毒颗粒能够在实验室细胞培养皿中繁殖,则将其列为“存活”。

一分钟后,18个手指上的全部流感病毒都具有传染性。三分钟后,六个手指上的H3N2病毒有传染性,15个手指上的H1N1病毒仍具传染性。五分钟后,五个手指上的H3N2病毒和八个手指上的H1N1病毒具有传染性。15分钟后,五个手指上的H1N1病毒和四个手指上的H3N2病毒具有传染性。30分钟后,两种病毒各在两个手指上具有传染性。

研究发现,较大的H3N2和H1N1病毒液滴,其病毒颗粒的浓度更高,且传染性的持续时间也比小液滴更久。但将液滴置于指尖后,其传染性比未经触碰的液滴降低了。

研究人员称,可见H1N1的存活力比H3N2更强。

研究人员指出,该项实验只包含了少量的实验对象和病毒。

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