Could something in the environment of northeastern Brazil, the epicentre of the outbreak, be partly responsible, perhaps a chemical or a natural toxin?
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）是否可能是其中的部分原因？
No one had firm answers.
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幸运的是，突发事件委员会的专家们获得了一些全新的证据。
Fortunately, experts on the emergency committee could draw on some brand new evidence.
In an elegant piece of detective work, a retrospective investigation of the outbreak in French Polynesia unearthed findings strongly suggesting a link between Zika infection during pregnancy and microcephaly in newborns.
A year ago, when I declared an international health emergency, it was this suspected link between Zika infection and microcephaly and other neurological complications that, according to my advisers, turned the outbreak into an “extraordinary” event.
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寨卡疫情还符合宣布发生国际关注的突发公共卫生事件的另外两个条件。
Zika also satisfied two further criteria relevant to declaring a public health emergency of international concern.
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由于人群很少对这种以前罕见的疾病有免疫力，而病毒可以借助于大量的国际航空流通，如野火一般蔓延开来。
As few populations had any immunity to this previously rare disease, the virus could spread, unchecked, like wildfire, sparked by the volume of international air travel.
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所有存在寨卡主要病媒埃及伊蚊的地区，均被视为处于危险之中，而其地理分布覆盖了将近一半的世界人口。
Any area that hosted the competent mosquito species, Aedes aegypti , was considered at risk – a geographical area estimated to comprise nearly half the world’s population.
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受威胁的人口如此之多，而防控工具又是如此之少，控制疫情显然需要协调一致的国际应对策略。
With so many people at risk and so few control tools, the outbreak clearly required a coordinated international response.