• The number of cases in Italy surged from 3 to more than 200 in just four days
  • At least 10 cities in northern Italy are under lockdown
  • The virus is expected to further hurt Italy's fragile economy

Italy became the European nation worst hit by the spread of coronavirus as confirmed cases in the country surged to at least 219 over the weekend. Also, five people – all elderly -- have thus far died from the virus in northern Italy as of Monday.

The Milan Stock Exchange plunged nearly 6% as of 10:30 a.m. EDT on Monday.

The number of confirmed cases skyrocketed from only three infections four days ago. Almost 100 infected people have been hospitalized.

Authorities have quarantined at least 10 towns in northern Italy in an attempt to contain the spread of the coronavirus.

Local governments have shut down all public events and gatherings, schools, nurseries, museums and public offices. The last two days of the Venice Carnival were cancelled.

The northern regions of Lombardy and Veneto have recorded 167 and 27 cases of virus thus far, respectively.

Lombardy and Veneto, two wealthy regions, account for about 30% of Italy’s economic output.

Despite the sudden emergence of the virus, Italian health officials remain baffled by how it entered the country and why it’s spreading, given that almost all reported cases have no apparent link to China, where the virus originated.

“Looking for [patient zero] makes less sense by the day,” said Giulio Gallera, health chief of the Lombardy region.

If the virus spreads, Italy, as a western democratic nation, may be forced to consider quarantining larger numbers of people, restricting their movements and curtailing or even shutting down transportation to other countries (thus violating the EU’s open-border arrangements).

Italy’s vice minister for health, Pier Paolo Silveri, appealed to Italians’ “civic sense” to obey the measures for the two weeks that the quarantine will be imposed.

While some small towns near Milan have been locked down, a similar measure in Milan itself – a metropolis of 1.35 million and a major transport hub – would require extraordinary effort and compromise the normal rules of a free society. Milan’s famous cathedral and opera house, La Scala, have already been shut down. The final two shows of Milan Fashion Week were also canceled.

Meanwhile, Austria is considering tighter border controls with neighboring Italy.

“All the things you used to see in films that are far from us, now you see them here,” said Carlo Benuzzi, a shopkeeper in the town of Codogna which is now under lockdown.

Codogna is also the home of one of the first reported cases of the virus, a 38-year-old man who apparently led an active social life. His pregnant wife and workers at a hospital where he was treated also tested positive for the virus. However, it’s unclear if he was the source of the spread in Italy.

“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 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.”

Angelo Borrelli, chief of the country’s Civil Protection Agency said on Sunday: “We still cannot identify patient zero, so it’s difficult to forecast possible new cases.”

Virologist Ilaria Capua of the University of Florida, and a former member of Italian Parliament, said: “it is likely that the more we look [for virus cases], the more we will find.”

“These rapid developments over the weekend have shown how quickly this situation can change,” EU Health Commissioner Stella Kyriakides said in Brussels. “We need to take this situation of course very seriously, but we must not give in to panic, and, even more importantly, to disinformation.”

The virus and related quarantine will likely further weaken Italy’s already fragile economy – slated to grow only by 0.5% in 2020, according to Bank of Italy.

A team from the World Health Organization and the European Center for Disease Prevention and Control were also scheduled to visit Italy.

Christian Lindmeier, spokesperson for WHO, told CNBC the agency feared “pockets” of virus outbreak in countries like Italy, Iran and South Korea.

“What we have been warning about, or warning against, and what we have been worried about, is exactly what we see now, that some countries across the world see pockets of this virus popping up and everyday life is being disrupted ... by something that we don’t yet know what it is exactly, and that is scary,” he said.

Some officials are calling for calm.

Paolo Gentiloni, European commissioner for the economy and a former prime minister of Italy, told CNBC “there is absolutely no reason for panic.”

“There is a reason to have confidence in institutions and Italian authorities,” he added. “They know the situation. They are taking the good measures. So the European Union is perfectly confident on what the Italians are doing. But I repeat, there is no reason for panic.”

However, political infighting over the virus has already erupted in Italy.

Matteo Salvini, leader of the right-wing, anti-immigrant Northern League party, condemned Prime Minister Giuseppe Conte for not adequately defending the country’s borders and called on Conte to resign “if he isn’t able to defend Italy and Italians.”

Conte had been planning to bolster the moribund economy through tax reforms and investments –but now the virus has superseded those plans.

“Conte is on difficult ground: He’s got to find an explanation for the big spread of the virus,” said Sofia Ventura, a political science professor at Bologna University.

Speaking of Salvini, Ventura commented: “Borders are the perfect issue for Salvini, and he’s out for revenge, with his ally and rival Giorgia Meloni of the Brothers of Italy party rising in opinion polls.”