经济学人下载:埃博拉的扩展 疏通还是围堵

The spread of Ebola

埃博拉的扩展

Bridges or walls

疏通还是围堵

A panicky response in the West may worsen conditions in west Africa
西方国家担心西非的疫情会进一步恶化

THE death toll from Ebola in Guinea, Liberia and Sierra Leone, the three most affected countries in west Africa, now stands at around 3,900. Among cases diagnosed outside Africa, the total is one: Thomas Duncan, a Liberian national, who died in Texas on October 8th. Yet fear of Ebola in relatively unaffected countries risks making the tragedy in Africa worse.

西非疫情最严重的三个国家几内亚、利比里亚和塞拉利昂的死亡人数现已达到3900人。非洲外的确诊病人仅有一例，是利比里亚国籍的托马斯·邓肯在10月8日死于德克萨斯州。然而未发现病例的国家仍恐慌不止，这给非洲雪上加霜。

On October 3rd Bobby Jindal, the Republican governor of Louisiana, called for flights from “Ebola-stricken” countries to America to be suspended. Other Republican politicians have done the same. Plenty of African countries have already introduced flight bans. Some Western airlines have also altered their schedules.

10月3日，美国共和党派的路易斯安那州州长鲍比·金达尔要求美国与“埃博拉高发”国家的航班停飞。其他共和党派人士也发出了相同的指示。许多非洲国家的航班已全面停止。一些西方国家的航线也改变了其既定轨道。

Public-health experts oppose shutting countries off. Humanitarian aid and medical staff struggle to get to afflicted areas, worsening the original outbreaks. Some would-be travellers find other routes that are harder to police. The economic consequences are grave. And it is a bit more complicated than the likes of Mr Jindal imply.

公共卫生专家对封锁国家提出抗议。人道主义援助和医务人员正努力对疫情日益严重的地区进行救助。一些自称是游客的人们正寻找一些其他警方难以监控的路线。这带来了重大的经济影响。因此带来了比金达尔预示的更为复杂的结果。

Dirk Brockmann, a specialist in complex networks at Humboldt University in Berlin, has used air-transport data to study how Ebola might spread across borders. His research, which assumes that a normal flight schedule is in operation, calculates how probable it is that an infected person boarding a plane in the worst-affected countries—Guinea, Liberia and Sierra Leone, in particular—will disembark in each of dozens of other destinations.

柏林洪堡大学合成网络的专家德克·布罗克曼正在利用航空数据分析埃博拉到底是怎样扩散并跨越国界的。他在研究中假设有一个正常的正在运营的航班，试计算一名来自疫情严重国家（尤其是几内亚、利比里亚和塞拉利昂）的埃博拉患者登录该航班并进入其他几十个国家的可能性。

Mr Brockmann's work offers three big messages. First, the risks to Western countries remain relatively low, even with normal flight schedules. For every 100 infected passengers embarking in Guinea, Liberia and Sierra Leone, 84 would normally disembark at another African airport. Three would arrive in Britain and France; only one in America. That infected people must get onto a plane in the first place further reduces the absolute risks. Well-prepared, well-funded health systems will be able to cope.
布罗克曼的研究表明了三个重要信息。第一，即使维持航班的正常运行，埃博拉患者进入西方国家境内的可能性也微乎其微。因为每100个在几内亚、利比里亚和塞拉利昂登机的患者中，有84人的目的地将是非洲的其他机场；有3人进入英国和法国；仅有1人前往美国。该患者必须要登陆飞机这一要求本身就大大降低了该事发生的风险。准备充分且资金充足的卫生系统足以应对此事。

Second, if a country is truly intent on keeping Ebola out, it has to go further than banning flights from the worst-affected places. Global hubs are also likely to spread the disease. America's single Ebola fatality may have disembarked in Dallas but the first leg of his journey from Monrovia, Liberia's capital, was to Brussels. Airports in London and Paris play a big part in linking Sierra Leone and Guinea to the rest of the world. Calls to cut off west Africa look, in Mr Brockmann's phrase, like “19th-century thinking”. Grandstanding might be more accurate.

第二，如果一个国家真的想要借此来阻止埃博拉病毒的扩散入侵，它需要做的远远不止停飞疫情最严重地区的航班。国际枢纽照样有可能传播此种疾病。美国的唯一一例埃博拉患者死于达拉斯市，但其从利比里亚首都蒙罗维亚返回后去的第一站却是布鲁塞尔。伦敦和巴黎的机场在塞拉利昂、几内亚与世界其他国家建立联系的过程中发挥了巨大的作用。用布罗克曼的话说，要求停止与西非的航班看起来更像是“十九世纪的思想”，更准确地说应该称之为哗众取宠

There is a role for better screening of passengers from affected areas; on October 8th America said it planned to start. But to screen well, it helps to know how travellers are moving around the system. That is the third lesson of the model: many passengers will find less predictable routes to their destinations if they must. Stopping flights between Conakry in Guinea and Charles de Gaulle in Paris, for example, increases the likelihood that people will fly to Dubai or to Abidjan in Ivory Coast. Others will eschew airports altogether: border crossings into Kenya are reportedly crowded with west Africans who have travelled overland in packed buses instead of taking flights. Turning your back on Ebola is not the same as stopping it.

审核筛选疫情爆发地区的乘客还有更好的方法；10月8日美国宣布将要实施这一计划。但为了筛选更为准确，还需帮我们了解游客在航班系统中是怎样流动的。那就是该模型的第三个要点：许多乘客将发现他能去往其不得不去的目的地的交通方式变得更少了。例如，停飞几内亚的科纳克里到巴黎戴高乐机场的航班增加了人们飞往迪拜和科特迪瓦阿比让市的可能性。其他人可能干脆避开机场选择其他交通方式：据报道，大量西非人民通过乘坐公共汽车的方式穿越非洲大陆前往肯尼亚而不是乘坐飞机。回头看看埃博拉的疫情扩散却仍未停止。