A multifactorial analysis finds that the ignition of a flu epidemic stems from a blast of colder weather striking an otherwise warm, humid, urban environment, and driving people indoors into close quarters.

对多种因素进行分析后发现，流感的流行源于寒冷天气突然袭击温暖潮湿的城市并将人们紧关在室内。

撰文播音：Karen Hopkin

翻译：张艺箫

审校：张清越

If you’ve got the flu, your focus is on getting better—not on how you caught it. But from a public health standpoint, tracking how flu spreads can help keep the virus contained.

如果你得了流感，你会更关注怎样才能快点好起来，而不是你为何患上了流感。但站在公共卫生的角度，追踪流感的传播方式有助于控制流感疫情。

In the past, models predicting the path of epidemics have focused on travel by plane—in some cases combining data on population density with airport locations. And when studies showed that influenza transmission is modulated by humidity, scientists injected information on climate into the mix.

过去，预测流感流行路径的模型主要集中在飞机旅行——在某些情况下，将人口密度数据与机场地点相结合。当研究表明流感传播受湿度影响时，科学家将气候因素也加入到了模型中。

Now, a new study combines data on a variety of factors, from doctors’ visits and vaccination coverage to weather patterns and the movement of individuals as recorded by Twitter. The finding: in the U.S., influenza typically arises in the warm, humid conditions of the south and spreads quickly thanks to the high degree of social connectivity in the region. The finding is in the journal eLife. [Ishanu Chattopadhyay et al., Conjunction of factors triggering waves of seasonal influenza]

现在，一个新的研究结合了多种因素的数据——从医生接诊率到调查疫苗接种覆盖率再到Twitter的记录的天气模式和个人出行情况。结果发现：在美国，流感通常发生在南部暖湿的环境中，并且该地区人们热情好客、社会联系紧密等特点使病毒传播迅速。 这一研究结果发表在eLife杂志上。

The researchers started by poring over health care records from more than 40 million families, looking for reports of flulike symptoms. The analysis covered nine season’s worth of data, from 2003 to 2011. And it pointed toward outbreaks starting near the Gulf of Mexico or the southern Atlantic, a surge that seemed to coincide with the southward migration of ducks.

研究人员从仔细研究超过4千万家庭的就医记录开始，寻找流感症状的报告。这项分析涵盖了从2003年到2011年中9个季度的有效数据。它指出墨西哥湾或南大西洋附近流感的爆发，似乎与鸭子南迁有关。

“We did our first analysis and it did look like ducks could be possible carriers of the virus, starting spark of the influenza epidemic.”

Andrey Rzhetsky of the University of Chicago, the study’s senior author. He says they wrote up their “duck hypothesis” and submitted the paper for review.

“我们做的第一个分析结果指出，鸭子可能携带流感病毒，这可以作为流行病的开始。” 芝加哥大学的Andrey Rzhetsky是该研究的主要作者。 他说他们写下了他们的“鸭子假说”并提交了文件供审查。

“Reviewers, so to speak, strongly encouraged us to include additional factors into the model, specifically climate variables, temperature, wind speeds, solar radiation, humidity.”

And when they did…

“Lo and behold, duck hypothesis collapsed. Ducks as predictor were not important anymore and climate took the first place.”

但是，审稿人强烈建议我们将其他因素纳入模型，特别是气候变量，温度，风速，太阳辐射，湿度。“

当他们做到了......

瞧，鸭子的假设崩溃了。 作为预测指标的鸭子不再重要，气候居首位。

Based on the data they collected, the researchers liken the spread of flu to a wildfire. The spark that ignites the epidemic is provided when a blast of colder weather strikes an otherwise warm, humid, urban environment. That chill allows the virus to remain viable in water droplets and perhaps forces people indoors into close quarters.

根据他们收集的数据，研究人员将流感的传播情况比作野火。当寒冷的天气袭击温暖潮湿的城市时，会引发点燃疫情的火花。 这种寒冷使得病毒在水滴中保持活力，并且可能迫使人们在室内与水滴中的病毒近距离接触。

That’s where Southern hospitality comes in. Folks in the south are more highly socially connected than elsewhere in the country. So friends, neighbors and community members have plenty of opportunity to pass the virus to one another face to face.

南方人的热情好客就体现在这个地方。南方人比其他地区的人更具社交性。 因此，一个人有很多机会面对面地将病毒传播给朋友、邻居或同一组织的成员。

Finally, driving from county to county or traveling by plane, allows the flu to spread like wind carries a fire. So ya’ll come back now—but first make sure you’re no longer contagious

最后，开车或乘飞机进行跨国旅行，会让流感蔓延速度像风吹火灾一样快。 所以你可以现在回来 - 但首先确保你没得传染病。