A US government laboratory mistakenly mixed a common flu strain with a dangerous and deadly type of bird flu and shipped it to another lab, authorities said Friday. The latest news followed admissions of mishandled anthrax and forgotten smallpox vials at separate US government labs, and raised new concerns about the safety of dangerous agents which could be used as bioterror weapons. No one was endangered by the mixed flu strain, said Centers for Disease Control and Prevention director Tom Frieden, who nevertheless said he was "astonished" that protocols could have been violated in that way. "Everything we have looked...