Italian authorities said the number of people infected with the new coronavirus from China has more than quadrupled due to an emerging cluster of cases in the country’s north.

Many of the new cases represented the first infections in Italy acquired through secondary contagion and brought the country’s total to 17.

The first to fall ill in northern Italy met with someone who had returned from China on January 21 without presenting any symptoms of the new virus, called Covid-19, health authorities said.

The 38-year-old Italian man is in hospital in the northern town of Codogno in a critical condition.

A woman walks in the centre of Codogno, near Lodi, in northern Italy (Luca Bruno/AP)

The man’s wife and a friend of his also tested positive for the virus.

Three patients at the hospital where he went with flu-like symptoms a few days ago also have infections.

Five nurses and doctors contracted the virus as well.

Italian health minister Roberto Speranza said Italy is now seeing the same sort of “cluster” of cases that Germany and France have seen.

The mayor of Codogno has issued a decree ordering the closure of all restaurants, coffee bars, schools and public gathering spots such as discos and gyms.

A nurse carries a box into the hospital in Codogno (Luca Bruno/AP)

The Health Ministry advised area residents to stay home as a precaution.

Local officials in another town, Casalpusterlengo, ordered local schools closed until Tuesday.

A third town, Castiglione d’Adda, said its libraries, public offices, gyms and waste depots would be closed as a health precaution.

“In other parts of the world, and also in China, it has been demonstrated that this system (of self-isolation) helps in a substantial way to block the spread,” Lombardy regional president Attilio Fontana said.

“But we must not let ourselves be overcome by panic.”

Personnel bring new beds to the hospital (Luca Bruno/AP)

The Codogno hospital closed its emergency room, and staff were seen wearing masks as movers brought in new beds and furniture as the quarantine got under way.

Despite the calls for safeguards, Italians were having a hard time finding protective face masks.

A sampling of Milan pharmacies reported selling out weeks ago, as did a pharmacist in Codogno.