PARIS--France on Friday announced the first cases outside Asia and the United States of the deadly new virus from China, and the country's health minister said Europe should brace for other new cases from the spreading epidemic that she said must be fought like a wildfire.

The three confirmed cases, Europe's first, all involved people who had traveled to China, where hundreds of people have fallen ill and more than two dozen have died.

The first two French cases were announced by Health Minister Agnes Buzyn at a hastily called news conference on Friday night. The third was announced in a statement from her ministry about three hours later. All three were hospitalized, in isolation — two in Paris, the other in the southwestern city of Bordeaux. The third person sickened is a parent of one of the first two people diagnosed, the ministry said.

In part because of Europe's open borders, the minister said she expects more cases.

“We see how difficult it is in today's world to close the frontiers. In reality, it's not possible,” she said.

“We will probably have other cases."

Buzyn said speed in diagnosing new cases will be essential in slowing the spread of the virus. She said the likely reason that France has the first European cases is that it quickly developed a test allowing medics to rapidly diagnose the sickened.

“You have to treat an epidemic as you would a fire, that's to say find the source very quickly,” she said. “We identified the first positive cases very quickly."

One of people sickened, a 48-year-old man, passed through Wuhan, the epicenter in China for the virus, before traveling to France on Wednesday, the minister said. He has been hospitalized in Bordeaux since Thursday. She said he is a French national who traveled to China for work and who lives in the Bordeaux area.

The health ministry didn't give the age, nationalities or other personal details about the other two people hospitalized in Paris, other than saying that they traveled to China. The first of the Paris cases was confirmed just minutes before Buzyn announced it at her news conference. The other was still being investigated and was only confirmed later on Friday night.

The ministry said efforts are underway to find all those who came in close contact with the three patients. They will be told to limit their contacts with anyone else, to try to contain the spread of the outbreak.

The Bordeaux patient was in contact with about 10 people before he was taken into care, the minister said.

The minister urged people who suspect they've been sickened to call emergency services and to stay at home to avoid spreading the virus. She said those who came into contact with the sickened patients would be told likewise.

“It's important to control the fire as quickly as possible. Hence the need to piece together patient histories and to find people who were in contact with the patient,” she said.

“We will do everything possible to confine this epidemic," she pledged.

The French minister promised “total transparency” as the country battles the outbreak and said her ministry would give daily news updates “so there is no false information on social networks.”

She said informing the public is “the most effective barrier" against the spread of the virus, more so than taking people's temperatures as they arrive at airports and other entry points to test if they have a fever. Such tests are easily fooled and provide a false sense of security, she said.

“People only need to take aspirin 15 minutes before landing to no longer have a fever,” she said.

The number of confirmed cases around the world has climbed sharply to more than 850, the bulk of them in China. There have been at least 25 deaths, all of them in China.

The vast majority of cases have been in and around Wuhan or involved people who visited the city or had personal connections to those infected.

Fewer than two dozen cases in all have been confirmed outside mainland China, in Hong Kong, Macao, the U.S., South Korea, Japan, Singapore, Thailand, Taiwan and Vietnam.

The U.S. reported its second case, involving a Chicago woman in her 60s who was hospitalized after returning from China. She was reported to be doing well.