(NaturalNews) Officials with the Centers for Disease Control and Prevention in Atlanta have said they "may never know" how a relatively harmless form of bird flu was eventually cross-contaminated with a dangerous strain of the disease before it was sent to a laboratory outside of the CDC, according to an agency spokesman.
That's because the bulk of materials used in an experiment to culture the virus were thrown away shortly after they were used by the researchers and scientists who performed the work, which took place in March, said CDC spokesman Tom Skinner, in an interview with Reuters.
The agency admitted to the bird flu incident as part of an internal investigation into its mishandling of live anthrax in June, in which dozens of the agency's own lab workers were potentially exposed to the highly deadly pathogen.
Though no humans were sickened by the bird flu breach, CDC Director Dr. Thomas Frieden has labeled the incident "the most distressing" in a series of safety and security breaches at his agency due to the risk to the public the virus posed.
'We thought we were sending something else'
As further noted by Reuters:
Researchers at a high-security CDC influenza lab learned of their mistake in May. The contaminated bird flu samples had been sent to poultry researchers at the U.S. Department of Agriculture, who noticed their chickens all died.
It was another six weeks before the incident was reported to top officials at the agency in early July. The reporting triggered an outside inspection of the agency's labs, which concluded toward the end of the month.
Federal authorities investigating the incident are presently attempting to string together how it was possible that the lab never reported the incident up the agency's chain of command. Skinner offered that a key regulatory violation took place when the agency did not properly document what it had sent to the high-security biocontainment laboratory at the U.S. Department of Agriculture.
"We thought we were sending H9N2," a far less dangerous form of bird flu, Skinner told Reuters. "We didn't know it was cross-contaminated."
He added that cross-contamination can often occur if improperly disinfected instruments come in contact with some sort of growth medium, which is material that is used to grow up the organisms, or if an infected growth medium is inadvertently used.
"The mediums and all of the materials that were used to grow up this particular virus - all of that material likely has been discarded. We may never know exactly how cross contamination occurred," said Skinner.
The spokesman also said outside investigators from the USDA's Animal and Plant Health Inspection Service (APHIS) concluded its investigation into the bird flu incident July 18.
Frieden has promised to implement major changes to improve safety measures in the handling of dangerous bacteria and viruses at the agency's labs. The CDC has already shuttered two labs that were involved in the anthrax and bird flu accidents, and it has suspended the transfer of samples from high-security labs until safety procedures at those facilities are reviewed and, if needed, improved.
Also, the CDC is putting together a group of outside experts to provide advice about biosafety. That panel was announced by the agency near the end of July.
USA Today reported that three recent incidents of safety lapses were among a total of five over the past decade.
"This is a wake-up call," Frieden said of the latest incidents. "These events should never have happened, and they tell us we have to make significant improvements."
He added that the CDC's priority after these incidents will be "improving the culture of laboratory safety."
Michael Farrell, who had led the Bioterror Rapid Response and Advanced Technology Laboratory since 2009, "voluntarily resigned" July 22, the agency said, due to the recent mishaps, The New York Times reported.