IN 1546 Girolamo Fracastoro, a doctor and poet, published an elegant theory of contagion. Infections spread in three ways, he argued: by direct contact, via an intermediary, or at a distance, through the air. In medicine, his theory is now considered quaint. In economics, however, it still works pretty well.

1546年，医生兼诗人弗莱卡斯特罗（Girolamo Fracastoro）发表了一个精练的传染病理论。他认为，传染病有三种传播方式：直接接触，间接接触，或通过空气远距离传播。在医学上，他的理论现在也让人感觉古怪有趣，不过，在经济学领域，这一理论也适用。

On August 10th President Donald Trump sent a pathogenic tweet, announcing a doubling of tariffs on Turkish steel and aluminium. It followed earlier sanctions on two Turkish ministers involved in detaining Andrew Brunson, an American pastor, on dubious charges. The lira, which had already lost 38% of its value since the start of the year, shed another eight percentage points in the tweet’s aftermath.

8月10日，美国总统特朗普发布了一条有连锁效应的推特，宣布对土耳其钢铁和铝加征双倍关税。此前，两名土耳其部长因涉嫌以莫须有罪名拘留美国牧师安德鲁·布朗森（Andrew Brunson）案而受到美国制裁。土耳其货币里拉自今年初以来贬值38%，但在特朗普的发布推特后又下跌了8个百分点。

Early medical scholars believed gluttons were more susceptible to disease than cleaner-living folk. Similarly, Turkey has become vulnerable to financial disorder through macroeconomic intemperance. Businesses have borrowed heavily in foreign currencies. The government, which has manageable debt of its own, has guaranteed large amounts of private credit.

早期的医学学者认为，暴食者比卫生干净的人更容易感染疾病。同样，由于宏观经济调整过松，土耳其很容易受到金融混乱的影响。企业大举借贷外币，自身债务可控的政府之前为大量私人信贷做担保。

Inflation is now over 15%, far above the central bank’s target. But the monetary authority’s freedom to respond has been hampered by President Recep Tayyip Erdogan’s distaste for higher interest rates. The current-account deficit exceeds 5% of GDP. To fill that growing gap, Turkey relies on foreign capital inflows. But rising interest rates in America make capital harder to attract.

土耳其当前的通胀率超过15%，远高于土耳其央行的目标。不过，土耳其总统雷杰普·塔伊普·埃尔多安反对高利率，因此限制土耳其央行采取措施的自由度。土耳其当前经常账户赤字超过GDP的5%。为填补这一日益扩大的缺口，土耳其需依赖外资流入。不过，美国利率不断上升，使得土耳其很难吸引到资金。

Turkey must now cut back. The country’s new finance minister, Berat Albayrak, who also happens to be the president’s son-in-law, says the government will strengthen fiscal discipline and narrow Turkey’s current-account deficit. Turkey’s central bank has also tightened monetary policy indirectly, suspending some of its regular auctions of cash, thereby forcing banks to borrow overnight at an interest rate higher than its declared policy rate.

土耳其现在必须削减开支。土耳其总统的女婿，新任财政部长阿尔巴伊拉克（Berat Albayrak）表示，土政府将加强财政纪律，缩小经常项目赤字。土央行还间接收紧了货币政策，暂停了了一部分定期现金拍卖活动，迫使土银行以高于其宣布的政策利率的利率隔夜借款。

The slowdown in import spending will pass some of Turkey’s sickness on to its trading partners. This is a direct form of transmission, akin to one rotten grape touching and tainting another, in Fracastoro’s analogy. The countries that export the most to Turkey, relative to their GDP, include Bulgaria, Iran and Georgia. But Turkey is not otherwise a big part of the global fruit bowl, buying 1.3% of the world’s traded goods.

在进口支出放缓的情况下，土耳其的一部分问题可能传导至其贸易伙伴。就像弗莱卡斯特罗所阐述的一样，这是一种直接的传播方式，如同一颗腐烂的葡萄触碰另一颗葡萄后致使后者腐烂。从GDP占比来看，对土耳其出口最多的国家包括保加利亚、伊朗和格鲁吉亚。但除此之外，土耳其在全球市场所占份额不大，购买的全球贸易商品仅占1.3%。

The more worrying form of transmission is the second: via an intermediary. In Turkey’s case, the intermediaries of concern are its foreign lenders, which are also important sources of credit to many other markets.

更令人担忧的传播形式是第二种，即通过介质间接传染。就土耳其的情况而言，当前的介质是其外国贷款机构，后者也是许多其他市场的重要信贷来源。

Most foreign lending to the country flows through the local subsidiaries of European banks. On August 10th, reports suggested that the European Central Bank was worried about the exposure of some of the euro zone’s financial institutions. That prompted a noticeable fall in the Euro STOXX bank stock-price index. As The Economist went to press, shares of the two most exposed lenders were over 9% lower.

大多数外国贷款援助是通过欧洲各国银行在希腊当地分支机构发放的。8月10日，有报道称欧洲央行对欧元区一些金融机构的风险敞口感到担忧。这导致欧洲斯托克银行股价指数明显下跌。截至本期《经济学人》出版时，两家风险敞口最大的银行股价跌幅超过9%。

Euro-area banks have lent about $150bn to Turkey, amounting to about 10% of their combined equity. The majority of those loans ($80bn) belong to Spanish banks, especially to BBVA, which owns half of Garanti, Turkey’s second-largest private bank. Other exposures are mainly scattered among the subsidiaries of Italy’s UniCredit and France’s BNP Paribas.

欧元区的银行向土耳其提供了约1500亿美元的贷款，约占总股本的10%。大部分的贷款（有800亿美元）大部分属于西班牙的银行，尤其是西班牙对外银行（BBVA），后者拥有土耳其第二大私人银行Garanti一半的股份。其他风险敞口主要分散在意大利联合信贷银行（UniCredit）和法国巴黎银行（BNP Paribas）的子公司身上。

For this handful of banks, the immediate risk is that Turkish borrowers struggle to repay foreign-currency debts that are now worth much more in lira terms. Thus far, the country has relatively few non-performing loans (around 3%). But defaults are expected to rise sharply.

对这几家银行来说，当下的风险是土耳其借款人难以偿还外币债务，而以里拉计算，这些债务现在的价值要高得多。迄今为止，土耳其的不良贷款相对较少（约3%），但违约率预计会有大幅攀升。

The infection should, however, remain minor. In a worst-case scenario, European parent banks would walk away from their local affiliates and write off the equity losses. That would cost them between 1% and 12% of group equity, according to Deutsche Bank. Such costs would certainly hurt the banks’ shareholders and perhaps oblige them to strengthen their capital buffers. But it would not threaten their solvency or require outside intervention, says Alexandre Tavazzi from Pictet Wealth Management. He thinks “the market is selling before looking at the numbers.”

然而，债务传染的情况应是不足为虑。最糟糕的情况会是欧洲的母公司将放弃在当地的分支机构，冲销股本损失。德意志银行（Deutsche Bank）的数据显示，这种情形将使损失集团1%至12%的股权，肯定会损伤股东利益，有可能迫使他们加强资本缓冲。不过，百达资产管理（Pictet Wealth Management）的Alexandre Tavazzi表示，这不会威胁到这些银行的偿付能力，也不需要外部干预。他认为“市场在看数据之前，就会抛售。”

That tendency to sell before looking represents the third, and perhaps most worrying, mode of transmission in emerging-market epidemiology. Fracastoro worried about “noxious air” transmitting disease across distances. Economists, mustering equal precision, worry that the dampened “spirits” of investors can transmit a crisis across countries, undeterred by the fundamental economic distinctions between them.

这种先卖后看的趋势则是新兴市场“流行病学”中的第三种传播模式，或许也是最令人担忧的一种。弗莱卡斯特罗担心疾病通过感染的空气远距离传播。经济学家也同样谨慎，担心投资者受到抑制的“精神”会将一场危机传递到各国，而不顾各国之间的经济的根本性差别。

On August 13th, India’s rupee weakened to a record low (70 to the dollar) despite the country’s modest inflation and light foreign-currency debt. Argentina’s central bank hiked interest rates from 40% to 45% to demonstrate its commitment to stabilising prices and the peso. And South Africa suffered horrible palpitations in its currency. The rand fell by almost 10% after Mr Trump’s tweet before settling down.

8月13日，尽管印度的通货膨胀率和外债不高，卢比还是跌到了历史最低点（1美元兑70卢比）。阿根廷央行将利率从40%调高至45%，以兑现其稳定物价和比索的承诺。南非的货币也遭受了可怕的震荡。在特朗普发布推文后，兰特下跌了近10%才稳定下来。

But that day’s mania did not persist. Turkish regulators eased reserve requirements, giving banks greater access to the dollars on their balance-sheets, and curtailed currency-swap deals, making it harder for foreign speculators to target the lira. The government also said that Qatar will make $15bn of direct investments in the country, though the details were hazy.

但那天出现的疯狂并没有持续下去。土耳其监管机构放宽了存款准备金的要求，允许银行在资产负债表上获得更多的美元，并控制了货币互换交易，使得外国投机者卖空里拉的难度加大。土耳其政府还表示，卡塔尔将在该国进行150亿美元的直接投资，不过具体细节尚不清楚。

The effect on Turkey’s currency was surprisingly powerful. Having traded at over seven to the dollar at the start of this week, the lira was hovering closer to six by August 15th. Global investors moved on to other worries, such as the disappointing earnings of Tencent, a Chinese tech firm that weighs far more heavily in most emerging-market investors’ portfolios than all of Turkey’s shares combined. Turkey’s crises, sadly, are more communicable than its rallies.

这些措施对土耳其货币的影响惊人。美元在本周初的交易价格超过了1：7里拉，在8月15日的时候一直徘徊在接近1：6里拉的水平。于是，全球投资者开始转向其他担忧，比如腾讯令人失望的业绩。在大多数新兴市场投资者的投资组合中，腾讯的权重远远超过土耳其所有股票的总和。遗憾的是，土耳其的危机比它国内的集会更容易传播。

编译：贾胶荣

编辑：翻吧君