A 65-year-old Frenchman is hospitalized after contracting France's first case of a deadly new respiratory virus related to SARS, and French health authorities said Wednesday they are trying to find anyone who might have been in contact with him to prevent it from spreading.

It's unclear how or where the man was infected with the novel coronavirus, which has killed 18 people in four countries and raised new public health concerns since being identified last year in the Middle East. It can cause acute pneumonia and kidney failure.

A novel coronavirus has killed 18 people in four countries. (Beth Fischer/Canadian Press)

The Frenchman fell ill after returning from a trip to the United Arab Emirates, the Health Ministry said. He has been under isolation and medical surveillance at a hospital in Douai in northern France since April 23, and is receiving respiratory assistance and blood transfusions, said Jean-Yves Grall, the government health director.

Paris' Pasteur Institute analyzed the man's virus and confirmed that it is a novel coronavirus, the ministry announced Wednesday.

Since September 2012, the World Health Organization has been informed of 30 confirmed cases of the virus, and 18 of the patients have died. Cases have been emerged in Saudi Arabia, Jordan, the UAE, Qatar, Britain and Germany, and health officials have said the virus has likely already spread between people in some circumstances.

France's health minister, Marisol Touraine, said "this is an isolated case" in France but said authorities are "fully mobilized" to prevent it from spreading. Authorities are trying to reach anyone who was in contact with the patient before he was hospitalized, and a national hotline was established Wednesday for the public to call about the virus.

WHO has advised countries to test any people with unexplained pneumonia.

"Any virus that has the potential to develop into something that is highly transmissible between people, including the coronavirus, is a major concern," WHO spokesman Gregory Hartl said.

"We need to follow up on all possible routes of infection, i.e. animal to human, whether it's being spread in hospitals or from human-to-human," he said.

Health authorities are trying to determine how humans are contracting and spreading the virus and how best to treat it. It does not appear to be as contagious as SARS or the flu, but it has probably spread between people who had close contact. It seems to have spread among family members in Britain and in health workers in Jordan who were caring for patients, for example.

The new coronavirus is most closely related to a bat virus and scientists are considering whether bats or other animals like goats or camels are a possible source of infection.

"We still don't know the animal reservoir of this virus or the source of exposure," Hartl said. "We need a solid epidemiological investigation to nail down a common behavior between patients...All we can tell people at the moment is they should be very vigilant about their basic hygiene practices."

He said it's unclear whether there is something specific in the environment in the Middle Eastern countries where cases have been confirmed.

Several cases have been reported in Saudi Arabia. In the most recent Saudi outbreak, the Health Ministry has said five people have died and at least five others are hospitalized with confirmed cases of the virus.

SARS, or severe acute respiratory syndrome, killed some 800 people in a 2003 epidemic.