Researchers working in a high-security bioterror response lab at
the U.S. Centers for Disease Control and Prevention were preparing
inactivated samples of the deadly organism, the CDC said on
Thursday. But the bacteria may still have been infectious when the
samples were transferred to lower-security CDC labs not equipped to
handle live anthrax.
Two of the three labs conducted research that may have aerosolized
the spores, the CDC said. The agency first detected the exposure on
June 13, when live bacteria were found on the original slides used
by scientists. Environmental sampling was done and the lab areas
remain closed for decontamination.
"No employee has shown any symptoms of anthrax illness," Dr. Paul
Meechan, director of the environmental health and safety compliance
office at the CDC, told Reuters. "This should not have happened," he
said. For those exposed, "we're taking care of it. We will not let
our people be at risk."
The safety breach in the nation's premier bioterror lab raises new
doubts about security measures at the CDC, whose infection control
protocols are held up as a model to the world.
The FBI is working with CDC to investigate the incident, but has no
evidence of foul play, a spokesman for the bureau said. U.S.
lawmakers said they would be monitoring the situation.
“There is no room for error or negligence when it comes to bioterror
research and every precaution must be taken to ensure the safety of
our scientists," House Energy and Commerce Committee Chairman Fred
Upton said in a statement.
Meechan said the CDC is conducting an internal investigation and
that disciplinary measures would be taken if warranted. He stressed
that there is no risk to the general public.
The handling of pathogens inside U.S. government laboratories has
been a growing concern since 2008, when the FBI identified Dr. Bruce
Ivins, a U.S. Army anthrax researcher, as the prime suspect in a
series of anthrax letter attacks in 2001.
The threat of insiders having access to lethal bioterror agents led
to a crackdown on lab security. The Ivins case touched off fears
that “malicious actors” would use the substances to harm humans,
according to a 2009 report by the American Association for the
Advancement of Science.
The CDC said that once the live bacteria were discovered, it
immediately began contacting people working in the labs who may have
been exposed. Meechan said seven researchers are the most likely to
have come into contact with live anthrax, but the agency is casting
as wide a net as possible to offer treatment to anyone who may be at
The normal incubation period for Bacillus anthracis can take up to
five to seven days, though there are documented cases of the illness
occurring some 60 days after exposure, Meechan said. Infection can
occur through a cut in the skin, breathing in anthrax spores or
eating tainted meat.
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Of the three, the biggest threat is inhalation anthrax, in which
bacterial spores enter the lungs. Once they germinate, they release
toxins that can cause internal bleeding, swelling and tissue death.
Inhalation anthrax occurs in two stages. In the first stage,
symptoms resemble a cold or the flu. In the second stage, anthrax
causes fever, severe shortness of breath and shock. About 90 percent
of people with second-stage inhalation anthrax die, even after
Meechan said CDC workers in the lower-security labs were likely not
wearing masks. Around 75 people are being offered a 60-day course of
treatment with the antibiotic ciprofloxacin and an injection with an
Meechan said it was too early to determine whether the transfer of
live bacteria was accidental or intentional. All employees who were
doing procedures to inactivate the bacteria had passed a security
check, he said.
The CDC said in a statement it has reported the lab-safety incident
to the Federal Select Agent Program, which oversees the use and
transfer of biological agents and toxins that pose a severe threat
to the public.
Dr. William Schaffner, an infectious diseases expert at Vanderbilt
University Medical Center, said the potential exposures are still
"profoundly unfortunate and serious."
"What's good about it is the exposures are minimal," he said. "CDC
responded appropriately, aggressively and transparently. The risk to
the individual is low and to the surrounding community, essentially
Schaffner said it is not yet clear exactly what the breach in
infection control protocol was, but said, "Whatever it was, it
should not have happened."
(Reporting by Julie Steenhuysen in Chicago; Additional reporting by
David Morgan and Marilyn Thompson in Washington; Editing by Michele
Gershberg, Eric Walsh and Lisa Shumaker)
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