And for a nation racing to piece together how it happened and how to contain further spread, even the most basic questions give a sense of the challenge: Officials still are not sure how the virus arrived in the country.
“Looking for [patient zero] makes less sense by the day,” said Giulio Gallera, health chief of the Lombardy region, where the majority of Italy’s cases are located.
Italy’s experience — with more than 200 confirmed cases as of Monday and five deaths — shows how the virus can slip onto a new continent undetected, only to then erupt as a sudden crisis, while bringing with it the interruptions and fears that once seemed far away.
Four days ago, Italy had only three confirmed cases of the virus. Now, it has the largest known outbreak outside Asia, pushing the world closer to a pandemic, in which epidemics spread across multiple countries and continents at the same time.
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And although China has tried to restrict the virus’s spread with forceful controls in Hubei province, its arrival in Italy brings new complications, testing whether a democratic government is willing to impose its own prolonged restrictions. A sustained outbreak also was expected to deal a blow to the Italian economy, which is the fourth-largest in Europe but weakened by two decades of stagnation.
Containing the virus in northern Italy is no given: Milan, the city closest to the outbreak, has Italy’s second-busiest airport and rail connections in all directions, including dozens of daily high-speed trains to Rome.
If the virus expands across Italy, neighboring European countries will face pressure to back away from this continent’s open-border ideals in the name of security. Or the coronavirus will pop up elsewhere across the continent as it did in Italy: without much warning. Some infectious-disease experts have speculated that the virus was already in Italy for weeks, carried by one or more people with negligible symptoms, before it was detected.
In recent days, Italy has scrambled to close off a cluster of small towns south of Milan, some of the primary hot spots. Police have set up checkpoints outside those areas, and only people with special permission can enter or exit. Video from inside those towns shows largely deserted town centers, except for the occasional person walking a dog or searching for a mini market to buy groceries. One church, where a funeral was scheduled, allowed only family members inside.
“All the things you used to see in films that are far from us, now you see them here,” said Carlo Benuzzi, 56, a shop owner in the sealed-off hot spot town Codogno who is friends with one of the first Italians to contract the virus.
At a closed church in Codogno, priests have been holding Mass by themselves. The diocese has ordered the closure to continue for at least two weeks, so Fabrizio Senneca, a church caretaker, dumped the holy water into a flower bed.
“The atmosphere is pretty eerie,” Senneca said. “We are trying not to let psychosis take hold. I have very little to do.”
Elsewhere across the north, most major gatherings have been called off, from soccer matches to school, and it is unclear for how long the closures will last. Milan’s landmark cathedral and opera house both shut down, and Venice’s Carnival was suspended two days before its planned conclusion.
On Monday morning, Italy’s stock index opened down 3.5 percent, as traders worried about sustained interruptions in the country’s economic and industrial heartland. As people prepared to hunker down, grocery stores were picked dry in Milan, and people raced to scoop up masks and hand sanitizer.
“Half of Italy in quarantine,” a headline in one of the country’s major newspapers, La Repubblica, said Monday.
In the capital of Rome, which is three hours by train from Milan, life continued as normal, and only a few people wore masks.
But some regions in the south mandated that people visiting from northern areas report to authorities or submit to a 14-day quarantine. Other countries were on guard as well. On Sunday night, trains heading through Austria to Italy were briefly halted while two passengers were screened for the coronavirus and tested negative. Monday, an Alitalia plane was held up in the island nation of Mauritius as authorities there requested that all passengers from Lombardy and Veneto either return home or be subject to quarantine.
For Italians, part of what has made the virus’s spread so vexing is the sense of uncertainty about how to stay safe. Authorities have talked about cases popping up that have no obvious connection to people coming from China or to people already infected.
At first, Italian authorities had theorized that the infection was started by an Italian businessman returning from China, who in turn met with people in the hot spot towns south of Milan. But testing subsequently indicated that he had never carried the virus.
Even without identifying how the virus started, Italian officials have managed to draw a partial picture of how it may have furtively spread before exploding into view. One of the first detected cases came from a 38-year-old who lives in Codogno, about 40 miles southeast of Milan. It is unclear when the man might have contracted the virus, but according to Italian officials and media accounts, he was active and social before a fever hit, meeting with people at bars and participating in running events, including a half-marathon, while visiting nearby towns that are now sealed off.
In turn, the virus was spread to his pregnant wife and to a fellow runner. A handful of health workers at the hospital where the 38-year-old was treated also tested positive.
“The initial suspected patient zero was not the real patient zero,” said Carla Torti, a professor of infectious diseases at Magna Graecia University in Catanzaro, in the southern region of Calabria. “The infection came from other people, and we don’t know — maybe a person coming from China. I think the more reliable explanation is that a person coming from the endemic countries was not detected and spread the infection.”