LONDON >> In Iran, a spike in coronavirus infections has prompted fears of a contagion throughout the Middle East. In Italy, one of Europe’s largest economies, officials are struggling frantically to prevent the epidemic from paralyzing the commercial center of Milan. And in New York, London and Tokyo, financial markets plummeted on fears that the virus will cripple the global economy.

From Asia to Europe to North America, the lethal spread of the coronavirus accelerated today, putting a heavy strain on a world already fractured by trade wars, populist politics and sectarian conflict.

An equal-opportunity epidemic, the virus is afflicting open and closed societies, autocracies and democracies, developed countries and war zones alike. That makes the task of containing it even more daunting.

The emergence of Italy, Iran and South Korea as new hubs of the outbreak underscored the lack of a coordinated global strategy to combat the coronavirus, which has infected nearly 80,000 people in 37 countries, causing at least 2,600 deaths. The number of infected people in the United States reached 53 today, up from 34 Friday, according to the Centers for Disease Control and Prevention.

A delegation of the World Health Organization, sent to China to assess the epidemic, warned today the world was not ready for a major outbreak. Infectious disease experts said a unified response is critical to mitigating the damage and slowing an outbreak that they say can no longer be stopped.

“Six new countries have reported cases this morning,” said Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “This is an inflection point in this experience. The world needs to say, ‘What can we do together to combat this?’”

For weeks, most of the world’s focus has been on China, which has placed tens of millions of people under strict lockdowns to try to staunch the spread of new cases. But today, the newer outbreaks in South Korea, Italy and Iran were testing very different political systems, with very different health systems.

In Iran, authorities shut down schools, universities and cultural centers across 14 provinces to try to curb the outbreak. Iranian officials said 61 people had been infected, with 12 others dying. But their credibility was ridiculed by critics, who claimed the death toll was much higher, with memories still fresh across Iran of an attempt to cover up the downing of a commercial airliner last month by the country’s military forces.

The dearth of reliable information alarmed Iran’s neighbors, several of which share long, poorly patrolled borders with the country. Pakistan and Turkey temporarily closed their borders with Iran on Sunday. Afghanistan, which reported its first coronavirus case today, banned all travel to the country, except for “essential humanitarian needs.”

Yet already coronavirus cases, some linked to Iran, were emerging elsewhere in the region: in Iraq, Lebanon, Israel, Egypt, Kuwait and Oman. Several of those countries are autocracies, which could lead to the same suppression of information that critics say is hampering the response in Iran.

“Countries will start underreporting cases, so they don’t seem to be suggesting a terrible tragedy has hit them or they don’t want to be accused of unsettling the rest of the world,” Osterholm said.

At some point, he said, the virus would spread so far and become such a common worldwide problem that its point of origin would no longer be relevant.

For now, though, Chinese people traveling abroad were still encountering suspicion and even hostility. In South Korea, popular with Chinese tourists, some shops have begun posting signs saying, “No Chinese.”

Today, South Korea, the hardest hit country outside China, reported 231 more cases, bringing its total to 833 cases and seven deaths. The South Korean president, Moon Jae-in, put the country on the highest possible alert, opening the way for the government to lock down cities and take other sweeping measures.

In Italy, authorities quarantined more than 50,000 people in 11 towns clustered in the northern Lombardy region, partly in an effort to prevent the virus from spreading to Milan, where an outbreak could cripple the Italian economy. Italy has reported at least six deaths.

In Brussels, officials with the European Union said they were in constant contact with the Italian government, while powerful neighbors such as Germany and France have mostly committed to keeping their borders open. European officials said they were not advising members to introduce border controls in the Schengen zone, which allows travelers to pass across borders without passport checks.

“Any decisions made need to be based on risk assessment and scientific advice, and need to be proportionate,” said Stella Kyriakides, the EU’s commissioner for health and food safety. “We stress that, for the moment, WHO has not advised changing or imposing restrictions on either travel or trade.”

Still, there is a heightened vigilance. On Sunday, Austria held up a train at the Italian border amid suspicion that two of the 300 passengers from Venice had the virus. The train was allowed to cross into Austria after the passengers tested negative.

Today, authorities in Lyon, France, stopped a bus from Milan and confined the passengers inside after suspicion of a case onboard, the newspaper Le Parisien reported. Passengers on an Alitalia flight from Rome to Mauritius decided to return home after being told they would have to go into quarantine.

At this stage in the crisis, experts said, closing borders was a largely futile exercise. In many cases, the virus has been carried into a country before the border was sealed. And detection is harder because the virus is now being transmitted from people with minimal or even no flulike symptoms.

“People always find a way to move,” said professor Devi Sridhar, director of the global health governance program at Edinburgh University. “Even before the lockdowns in China, 3 million people moved.”

Sridhar said the emphasis should now be on vaccination campaigns and equipping medical centers with adequate respiratory facilities. She also said hospitals needed to take measures to stop being spreading grounds for the virus.

Europe, she said, was in a better position to combat the coronavirus than other parts of the world because it has reliable reporting systems and a fairly high level of trust between the public and health authorities.

In Britain, which has 13 confirmed cases, a spokesman for Prime Minister Boris Johnson issued a statement today saying the country was well prepared for any additional infections.

“We are using tried and tested procedures to prevent further spread and the NHS is extremely well prepared and used to managing infections,” the statement said, referring to the National Health Service.

Yet even in Europe, there are troubling signs of a lack of coordination. When the Italians went into crisis mode over the weekend, officials in Brussels struggled to persuade other EU member states to share information swiftly and coordinate on how to respond to the outbreak.

Such weaknesses sound eerily similar to China, which drew harsh criticism for its secretive approach and slow initial response after the outbreak first emerged in Hubei province.

China’s president, Xi Jinping, acknowledged that it was the country’s most serious public health crisis, and “the most difficult to prevent and control,” since the founding of the People’s Republic. Underscoring the point, the country’s leaders today were forced to postpone their biggest political conclave of the year, the National People’s Congress.

Yet health experts said that once China woke up to the threat, it acted decisively.

The WHO team in China concluded that the draconian measures imposed by the government there may have saved hundreds of thousands of people from infection.

“There’s no question that China’s bold approach to the rapid spread of this new respiratory pathogen has changed the course of what was a rapidly escalating and continues to be a deadly epidemic,” said Bruce Aylward, a Canadian doctor and epidemiologist who led the WHO delegation.

But with the virus spreading rapidly, Aylward warned that other countries would need to respond swiftly and aggressively, too. “We have all got to look at our systems because none of them work fast enough,” he said.

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