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 The U.S. Centers for Disease Control and Prevention said the
number of lab workers who may have been exposed rose from the 75
people first disclosed on Thursday. As of early Friday, 32 staff
were taking the powerful antibiotic ciprofloxacin, or Cipro, and 20
were taking another antibiotic called doxycycline, CDC press officer
Benjamin Haynes said in a statement.
In addition, as many as 27 people were getting the anthrax vaccine
to prevent infection. No illnesses have been reported, but the
agency expects more people to step forward now that news of the
anthrax scare is public. The agency did not give reasons why other
workers were not taking medication.
The safety breach, which originated in the CDC's bioterror lab,
raised new concerns about the way laboratories around the world
conduct research into the deadliest known pathogens, from anthrax to
Ebola and avian flu. The CDC has already faced repeated scrutiny
over security lapses and mechanical malfunctions at some of its labs
dating back to at least 2007.
The CDC said it will cede control of the investigation to the U.S.
Department of Agriculture "to avoid potential conflicts of
interest." (Full Story) President Barack Obama was briefed on the matter on Friday by his
homeland security and counterterrorism adviser, Lisa Monaco, the
White House said. The incident also is drawing scrutiny from
Congress about whether the CDC has the appropriate safety procedures
in place to protect federal employees from contamination. (Full
Story)
 Dr. Paul Meechan, director of the CDC's environmental health and
safety compliance office, first disclosed the possible anthrax
exposure to Reuters on Thursday. (Full Story)
The agency discovered the lapse on June 13. It has since launched an
internal investigation and is cooperating in a probe by the Federal
Select Agent Program, which oversees the use and transfer of
biological agents. It is also working with the FBI.
LIVE BACTERIA
According to Meechan, researchers in the CDC's high-security
Bioterror Rapid Response and Advanced Technology laboratory realized
they had sent live anthrax bacteria, instead of what they thought
were harmless samples, to fellow scientists in two lower-security
labs at the agency.
The initial safety lapse occurred as scientists in the bioterror lab
were trying out a new protocol for inactivating anthrax, using
chemicals instead of radiation.
Scientists in the Bioterror Rapid Response unit had been preparing
an especially dangerous Ames strain of the bacteria for use at the
two lower-security CDC labs, the Biotechnology Core Facility and the
Special Bacteriology Reference Laboratory, Meechan said. The strain
had been used in a bioterror attack in the United States in 2001.
Those teams were experimenting with methods to more quickly identify
anthrax in substances and powders sent to CDC from authorities
across the country.
"If there was a bioterrorism incident, we could more quickly
identify yes or no, this sample has anthrax," Meechan said.
Meechan said the team in the bioterror lab used a new process to
purify anthrax samples. To check their work, they took a sample of
what they thought was dead bacteria and put it on a nutrient-rich
lab dish called an agar plate to ensure that the bacteria wasn't
still live.
"They waited 24 hours," Meechan said. "They took a look at the
plate, and they didn't see any new growth. At that point, they
assumed the material was safe."
THE DISCOVERY
Researchers took the samples to the two lower-security CDC labs,
which were developing the new tests. Their experiments did not work,
and a week later, one of the labs asked for additional inactivated
samples.
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That is when researchers in the bioterror lab discovered that they
had left the agar plates containing the bacteria in an incubator for
an additional week, Meechan said. As they were about to dispose of
them, the researchers noticed growth on one of the plates, which
turned out to be live anthrax. At that time, the scientists
realized the samples they sent to the two lower-security labs might
have contained live anthrax bacteria. People working in those labs
take fewer safety precautions and were unlikely to be wearing a
respirator, putting them at higher risk for infection.
The team immediately pulled back the samples and contacted the staff
members who had handled them.
CDC reached some of the lab workers that same night. Since then,
they have been interviewing managers and using electronic
surveillance and keycard data to identify anyone who might have been
inside one of the two labs testing the samples.
Agency spokesman Tom Skinner said the internal probe is focusing on
why safety protocols were not followed to the letter. An FBI
official said there was no evidence of criminal activity.
"Clearly something needs to be altered," Skinner said. "We are going
to find out what went wrong and we are going to fix it. If that
requires discipline, that will happen in due time."
The Office of Inspector General in the U.S. Department of Health and
Human Services said it is also evaluating the incident, but gave no
further details.
TRACKING WORKERS' HEALTH
In the meantime, CDC workers who may have been exposed are being
evaluated for any health issues. One worker had cold-like symptoms,
but no signs of respiratory illness that would suggest anthrax
infection.
Ciprofloxacin is the drug of choice for warding off anthrax
infections, but has a long list of side effects. The agency is also
offering the milder doxycycline antibiotic. CDC employees are
expected to take the drugs for at least two months. Anthrax can enter the body through a cut in the skin, through
ingesting anthrax-tainted material or breathing anthrax spores into
the lungs.
Since most of the lab workers were likely wearing gloves and
protective goggles but not masks, the biggest worry is respiratory
anthrax. Skinner said the lab samples largely involved live anthrax
cultures, but some of the samples may have developed into spores,
which can be inhaled.
 Once inhaled, anthrax spores can germinate, a process that takes one
to six days. The bacteria then release several deadly toxins that
can cause internal bleeding, swelling and tissue death, making early
treatment crucial. About 90 percent of people with second stage
inhalation anthrax die, even after antibiotic treatment.
(Reporting by Julie Steenhuysen; Additional reporting by Toni Clarke
and David Morgan in Washington; Editing by Michele Gershberg, Lisa
Von Ahn, Martin Howell and Bernard Orr)
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