The potential exposure took place Monday when scientists conducting research on the virus at a high-security lab mistakenly transferred a sample containing the potentially infectious virus to another CDC lab, also in Atlanta on the CDC campus.
The technician has no symptoms of illness and is being monitored for 21 days. Agency officials said others who entered the lab have been contacted, and based on assessments, it’s likely no one else was exposed. They said the number of people who entered the lab could be as many as a dozen but more likely far fewer.
Color-enhanced Transmission Electron Micrograph of the ebola virus. © CDC/Phanie/Rex Features Color-enhanced Transmission Electron Micrograph of the ebola virus.
Agency officials said there was no possible exposure outside the secure laboratory at CDC and no exposure or risk to the public. The mistake took place Monday afternoon and was discovered by laboratory scientists Tuesday; it was reported to leadership within an hour of the discovery.
The event is under internal investigation by the CDC, and it was reported to Secretary of Health and Human Services Sylvia Burwell and to the program that has oversight over “select agents” such as Ebola and anthrax.
The accident comes after a series of incidents earlier this summer involving the mishandling of dangerous pathogens at the nation’s labs, including one in June at a CDC lab that potentially exposed dozens of employees to live anthrax because employees failed to properly inactivate the anthrax when transferring samples.
“I am troubled by this incident in our Ebola research laboratory in Atlanta,” said CDC Director Tom Frieden in a statement. “We are monitoring the health of one technician who could possibly have been exposed and I have directed that there be a full review of every aspect of the incident and that CDC take all necessary measures. Thousands of laboratory scientists in more than 150 labs throughout CDC have taken extraordinary steps in recent months to improve safety. No risk to staff is acceptable, and our efforts to improve lab safety are essential — the safety of our employees is our highest priority.”
The lab where Monday’s potential exposure occurred was decontaminated and the material destroyed as a routine procedure before the error was identified. The laboratory was decontaminated for a second time and is now closed, and transfers from the high-security lab have stopped while the review is taking place.
The high-security lab where the mistakes were made also performs diagnostic tests for Ebola, and has conducted hundreds of those tests since July. Stuart Nichol, a top CDC official, said diagnostic testing for Ebola will be moved to a different lab.
No materials will be transferred from the high-security lab, pending an internal investigation.
The CDC officials said two experienced technicians made mistakes at the high-security lab, known as a BSL-4 lab. One technician mistakenly put samples of material that could have contained live Ebola virus into the equivalent of the lab’s out basket, for transfer to the second lab, a BSL-2 lab. That material should have remained and been stored in a freezer.
The second mistake came on the receiving end: The technician in the BSL-2 lab should have recognized, via the color coding on the test tubes, that this was material that should have stayed at Level 4. That second technician is the person who could have exposed, and is now in the 21-day monitoring period, agency spokeswoman Barbara Reynolds said.
The CDC has technologically advanced biosafety laboratories in which dangerous pathogens such as Ebola can be handled by investigators who wear elaborate biohazard suits that keep them from being exposed. But what happened this week illustrates the impossibility of eliminating human error from even a state-of-the-art facility.
The mistake was discovered when workers looked in the freezer and saw material that was supposed to be sent down the hall for a genetic analysis. They realized the samples had been switched.
This latest incident comes at a time when the CDC is taking a leading role to fight the epidemic that has killed more than 7,500 people in Guinea, Liberia and Sierra Leone, and to improve domestic preparedness against Ebola. More than 170 CDC infectious disease specialists are in West Africa. Frieden returned late Saturday night from his second trip to the region.
After the summer’s incidents, the CDC temporarily banned transfer of all biological materials from its labs, conducted a wide-ranging safety review, appointed a new director of lab safety, and created an outside lab safety advisory group. The CDC labs conduct some of the world’s most sophisticated research into infectious disease.
At hearings before Congress, Frieden vowed to improve the agency’s overall safety culture as well as put in place stronger oversight measures.
In the June anthrax incident involving live anthrax, more than 80 workers may have been exposed after employees unknowingly sent samples of the bacterium from one CDC lab to other CDC labs. During the anthrax investigation, agency officials learned about several other instances where deadly pathogens had been improperly sent to other laboratories over the past decade.
No one became infected or fell ill in those incidents, and all the organisms were safely disposed of, officials said.
The most serious of those previously undisclosed incidents took place in March, when a CDC lab in Atlanta sent a sample of flu virus contaminated with the deadly H5N1 influenza virus, a much-feared bird flu strain, to a U.S. Department of Agriculture laboratory in Athens, Ga. CDC staff members failed to report the incident to top leaders at the time.
Biosafety experts have criticized the lack of coordination and oversight at laboratories inside and outside the federal government that conduct research on microbes that could be used as bioterrorism agents.
Michael Osterholm, director of Center for Infectious Disease Research and Policy at the University of Minnesota said:
“Such events like this are absolutely unacceptable even once. When they occur multiple times you have to ask yourself what systems are in place to prevent this from happening.”
“To err is to be human. We expect that to happen in any kind of high tech setting. So what you do is build in a set of procedures and checks and balances. They need to be in place to account for human error
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