The CDC's bioterrorism response lab was involved in two of the incidents, including the June anthrax scare
US government infectious disease labs mishandled dangerous pathogens five times in the last decade, according to a health agency report.
This year alone, workers mishandled samples of anthrax and the highly-infectious H5N1 avian flu.
In replication, the Centers for Disease Control and Prevention (CDC) has closed the two labs involved.
The agency has additionally ephemerally barred high-security labs from conveying perilous pathogens.
There have been no reported infections from precedent cases, and no-one potentially exposed to anthrax has shown designations of illness, CDC officials verbally expressed.
"These events should never have transpired," CDC Director Tom Frieden told heralds on Friday.
"I'm disappointed, and frankly I'm irate about it," he verbalized, integrating later he was "astonished that this could have transpired here".
The incidents were listed in a report on a potential anthrax exposure in June, which occurred when researchers in a high-level biosecurity laboratory failed to follow felicitous procedures and did not deactivate the bacteria.
The anthrax bacterium, shown in a 2001 US defence department photo, can cause death if untreated
The samples were then peregrinate to a lower-security lab in the agency's Atlanta campus.
"This is not the first time an event of this nature has occurred at CDC, nor the first time it occurred from the [bioterror replication] laboratory," the report verbally expressed.
The CDC only recently learned of a separate incident in May in which a sample of the avian flu was cross-contaminated with a highly pathogenic version of the virus and then shipped to an agriculture department laboratory.
The influenza lab and the bioterror replication laboratory have been transitory closed in replication.
The other incidents reported by the CDC:
In 2006, the CDC's bioterror lab transferred anthrax DNA to outside labs, believing the sample had been deactivated
Also in 2006, samples from a different CDC lab were found to contain live botulism bacteria
Researchers sent an infectious strain of the bacterium Brucella to outside laboratories as early as 2001 because they mistook it for a vaccine version. Newly available test methods in 2009 attested it was not.
