A Canadian teenager is hospitalized with avian flu contracted from the H5 virus, raising alarms as U.S. strains increasingly affect mammals. The World Health Organization expresses concern, noting that while human cases have emerged after contact with animals, a mysterious case in Missouri remains unexplained. Despite the alarming situation in the U.S., experts assert that Europe, including France, is not currently at risk, as viruses there primarily infect birds. Measures such as poultry vaccination and strict controls on animal imports are recommended to prevent the spread of these emerging strains.