WHO raises flu threat level, becoming pandemic

"Influenza pandemics must be taken seriously precisely because of their capacity to spread rapidly to every country in the world," WHO Director General Margaret Chan told a news conference in Geneva as she raised the official alert level to phase 5, the last step before a pandemic.

"The biggest question is this: how severe will the pandemic be, especially now at the start," Chan said. But she added that the world "is better prepared for an influenza pandemic than at any time in history."

Nearly a week after the H1N1 swine flu virus first emerged in California and Texas and was found to have caused dozens of deaths in Mexico, Spain reported the first case in Europe of swine flu in a person who had not been to Mexico, illustrating the danger of person-to-person transmission.Both U.S. and European officials have said they expect to see swine flu deaths.

Despite worries that a major flu outbreak could hit the struggling global economy, world stocks rallied on Wednesday after the Federal Reserve said the U.S. recession appeared to be easing.Almost all cases outside Mexico have had mild symptoms, and only a handful have required hospitalization.