Up to 75 researchers face possible infection by anthrax after a laboratory mistakenly transferred live samples of the agent, the New York Times reports.
None of the individuals have yet shown any sign of having contracted the disease, and some are receiving treatment drugs "out of an abundance of caution," said Thomas Skinner, a spokesman for the U.S. Centers for Disease Control and Prevention. The possible exposures took place between June 6 and June 13, when an experimental chemical procedure failed to deactivate anthrax bacteria later transferred out of the CDC Bioterror Rapid Response and Advanced Technology laboratory, Reuters reported on Friday.
The anthrax went to three lower-security facilities at the Atlanta complex, where researchers handled the agent without safety equipment, the Times reported. Response crews launched cleanup efforts at the CDC facility and collected materials for analysis after the incident came to light, according to the health agency.
Site workers took nearly a week to discover the breach. Paul Meechan, head of the CDC Health and Safety and Environment Office, linked the event to a new chemical technique intended as an alternative to costly radiation equipment for neutralizing the bacteria.
Personnel assumed the chemical procedure had killed the agent after Petri-dish samples showed no sign of reproduction after 24 hours.
"It didn't work as well as they thought," Meechan said. Scientists found anthrax growing in the sample plates six days later, as they prepared to throw them away.
"CDC continues its internal review to determine why validated procedures were not used by the lab," the agency said in a Thursday statement. "Disciplinary action[s] will be taken as necessary."
The anthrax belonged to the Ames strain, a deadly variety used in the 2001 anthrax mailings. An infection by the bacteria can take weeks or even months to produce visible symptoms, leaving open the possibility that any infected worker has yet to show signs of the disease.