Previously, people had put these patterns down to younger people being more likely to encounter birds, or the virus being more aggressive in elderly people.
过去人们认为，发生上述模式是因为年轻人更容易感染禽流感，或禽流病毒对老年人的攻击力更强。
The virus is transmitted to humans by close contact with infected birds or their excrement, and cannot be passed from human to human.
该病毒通过与受感染的鸟类或其粪便的密切接触传播给人类，不能在人与人之间传播。
The gypsy moth is also subject to attack by the nucleopolyhedrosis virus, or wilt disease, a particularly important killer of the caterpillars in outbreak years.
舞毒蛾还会受到核多角体病毒或萎蔫病的攻击，在毛虫爆发的年代，这是一种特别重要的杀手。
A top priority at present is to prevent the virus from establishing a foothold in densely populated urban or peri-urban parts of the country.
目前一项首要重点是防止病毒在该国人口密集的城市或城郊地区立足。
A person who has chickenpox can spread the virus even before he or she has any symptoms.
水痘患者在出现任何症状之前都可以传播病毒。
It could be a virus, or it could be all in the mind.
这可能是种病毒，或者可能全是凭空想像。
If the virus had been capable of spreading through the air, or if one infected person had unknowingly entered a large population center, Ebola might have become a worldwide epidemic.
如果这种病毒能够通过空气传播，或者如果一名感染者在不知情的情况下进入了人口密集的地区，那么埃博拉可能已经成为一种全球流行病。
This type of coronavirus is often called 2019-nCoV, novel coronavirus, or COVID. It is believed that the virus was transmitted from animals to humans.
这种类型的冠状病毒通常被称为2019年新型冠状病毒、新型冠状病毒或新冠。人们认为这种病毒是由动物传播给人类的。
Many mutations do not alter any important features of the virus or the illness it causes.
许多变异对病毒本身或病毒所造成的疾病的任何重要特征不会带来影响。
Despite intensive investigations extending over several years, research has failed to find an animal reservoir of the virus or determine where it hides in nature between outbreaks.
尽管延续几年的强化调查，但是研究未能发现该病毒的动物储主或确定两次暴发之间它隐藏在自然界的何处。
Sharing needles, syringes, spoons, filters or water can pass on the virus.
共用针头，注射器，勺子，过滤器或水都可能传递病毒。
The team found no laboratory evidence suggesting that human infections are occurring with greater frequency or that the virus is spreading readily among humans.
专家小组认为没有实验室证据表明在人类中发生较频繁的感染或该病毒正在人类中迅速传播。
We have good reason to believe that pregnant women are at heightened risk of severe or fatal infections with the new virus.
我们有绝对的理由相信孕妇是感染这种严重或致命新病毒的最高危险人群。
Life insurance remains beyond the means of millions of South africans-whether they carry the virus or not-and very few apply for cover.
数以百万计的南非人还是无力承担人寿保险，只好望而却步—无论他们是否携带病毒—只有极少数人投保。
As infected birds shed large quantities of the virus in their faeces, opportunities for exposure to infected droppings or to environments contaminated by the virus are abundant under such conditions.
由于受染鸟类在其粪便中排泄大量病毒，在这种情况下接触受染粪便或病毒所污染环境的机会很多。
Exhaustion occurs when large amounts of virus, or pieces of the virus (known as antigens), are seen by cells of the immune system over a prolonged period.
当免疫系统的免疫细胞长期接触大量的病毒或病毒片段(也叫做抗原)的时候，就会出现免疫疲劳现象。
The human immunodeficiency virus (HIV) infects cells of the immune system, destroying or impairing their function.
人类免疫缺陷病毒(HIV，也称艾滋病毒)感染免疫系统细胞，破坏或损伤其功能。
When an infected person sneezes, coughs or talks, the virus is released into the air and can be spread to other people.
当被感染的人打喷嚏、咳嗽或说话时，病毒被释放出来并向周围的人群扩散。
The flu, or influenza, is caused by a virus that affects the respiratory system.
流感是有病毒引起的呼吸系统疾病。
The virus may cause the tumour, as Dr Cobbs suspects, or the tumour may simply provide the virus with a congenial home.
像Cobbs医生怀疑的那样，这种病毒或许引起了肿瘤，或者是肿瘤仅仅是为病毒提供了一个适宜的空间。
Once inside the cell, if the RNA computer finds tracers of a virus or cancer it could release the appropriate drugs to kill just that one cell.
RNA计算机一旦进入某一细胞内部，如果发现病毒或癌症的踪迹，它就可以释放相应药物来仅仅杀死这一个细胞。
It is not clear if this is due to genetic changes in the virus, however, or to other factors like the weather.
然而，目前尚不清楚的是，造成此现象的原因是病毒的基因变化还是天气等因素。
"Well, perhaps you'll be the doctor who stops the spread of epidemics," Tony said, "or the scientist who eradicates the AIDS virus."
“那么，也许你会成为一名能防止传染病传播的医生，”托尼说，“或者成为一位根除艾滋病病毒的科学家。”
These improvements are a permanent strength, whether this H5N1 virus causes the next pandemic or not.
这些改进是一种永久的力量，无论h5n 1病毒是否引起下一次疾病大流行。
While we cannot predict when or if the H5N1 virus might spark a pandemic, we cannot ignore the warning signs.
虽然我们不能预言H5N1病毒何时或是否会引发一次大流行，但我们不能忽视一些警告性征兆。
At present, the only method of controlling or preventing dengue virus transmission is to combat the vector mosquitoes.
当前，控制或预防登革热病毒传播的惟一方法是与蚊虫媒介作斗争。
In no instance has the virus spread beyond a first generation of close contacts or caused illness in the general community.
在任何情况下，病毒的传播还没有超出第一代密切接触者或在整个社区引发疾病。
In no instance has the virus spread beyond a first generation of close contacts or caused illness in the general community.
在任何情况下，病毒的传播还没有超出第一代密切接触者或在整个社区引发疾病。
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