This is Scientific American — 60-Second Science. I'm Karen Hopkin.
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.
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.
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.
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.
"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.
"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.."
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.
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.
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.
Thanks for listening for Scientific American — 60-Second Science. I'm Karen Hopkin.
如果你感染了流感，你关心的是赶紧好起来，而不是怎么得的流感 。但是从公共健康角度来看，追踪流感传播的方式可以帮助遏制流感病毒 。
过去，预测流行病传染路径的模型主要集中在飞机旅行传播上，有时会将人口密集度数据与机场地点结合起来 。而当研究显示流感传播受湿度影响时，科学家又将气候信息纳入研究之中 。
现在，一项新研究将各种因素的数据结合起来，从医生访问和疫苗接种覆盖率到气候模式和推特记录的个人运动情况 。结果发现：在美国，流感通常在温暖潮湿的南方出现，因该地区频繁的社会联系而迅速扩散 。这项研究发表在《e生活》期刊上 。
研究人员先仔细阅读了4000多万个家庭的医疗保健记录，寻找类似流感症状的记录 。然后对2003年至2011年9个季节的数据进行分析 。分析结果指出，流感疫情在墨西哥湾或南大西洋附近爆发，似乎与鸭子向南迁徙的时间相吻合 。
这项研究的第一作者、芝加哥大学的安德烈·柴斯基说到 。他表示，他们把“鸭子假说”整理成文并提交审阅 。
“结果‘鸭子假说'失败了 。就预测流感疫情来说，鸭子已经不再重要了，而气候成为最重要的因素 。”
基于他们收集的数据，研究人员将流感传播比作山火 。当一股冷空气袭击本来温暖且潮湿的城市环境时，就会触发流感疫情的火花 。这种寒流使病毒在小水滴中能继续存活，而且可能会迫使人们在室内近距离感染 。
这是“南方盛情”在发挥作用 。南方民众的联系度在美国社会中是最高的 。因此，朋友、邻居、社区成员有很多机会面对面传播病毒 。
最后，驾车在美国进行全国游或坐飞机旅行会让流感像借助风力的火灾一样迅速蔓延 。所以，你现在要回家，那首先要确保的是你不再具有传染性 。
谢谢大家收听科学美国人——60秒科学 。我是凯伦·霍普金 。
1. pore over 仔细阅读；认真钻研；
We spent hours poring over travel brochures.
2. coincide with 巧合；同时发生；
Operation Amazon is timed to co incide with the start of the dry season.
3. write up 把…整理成文；详细写出（所做的事或所说的话）；
He wrote up his visit in a report of over 600 pages.
4. so to speak 可以说；可谓；
It was putting the cart before the horse, so to speak.