Washington: 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 today.
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 at strongly suggests that there was no exposure of anyone to influenza," said Frieden at a press briefing.
He told reporters he had lost sleep since learning of the flu mix-up on Wednesday, six weeks after it occurred.
"These events should never have happened," he said, adding that they raise "serious and troubling questions.
"Frankly, I'm angry about it," he said.
Frieden said he has issued a moratorium on the transfer of any biological samples, including infectious agents, within or outside the CDC until an investigation is complete.
He also called for appropriate disciplinary action for any staff members who knowingly violated protocol or failed to report a lab incident.
"It tells me we need to look at our culture of safety throughout all our laboratories," Frieden said.
The CDC said it learned of the flu mix-up while it was finalising a report about what happened with a separate incident involving anthrax on June 5, which it concluded was very unlikely to have exposed workers to dangers, though some 80 people were initially considered vulnerable.
"Earlier this year a culture of non-pathogenic avian influenza was unintentionally cross-contaminated at the CDC influenza laboratory with the highly pathogenic H5N1 strain of influenza and shipped to a BSL-3 select-agent laboratory operated by the United States Department of Agriculture (USDA)," the CDC said in a statement.
The lab is closed until better safety measures can be put in place, and an investigation is under way.
"For me personally, this is the most distressing," said Frieden of the flu incident, which took place on May 23.
The H5N1 bird flu is highly contagious and has killed about 60 per cent of humans who been sickened by it.