Scientists at a research center in Bethesda, Maryland, came across forgotten vials of smallpox last week that they believe date back to the 1950s.
The vials were immediately secured in a containment laboratory in Bethesda before they were transported to the U.S. Centers for Disease Control and Prevention’s high-containment facility in Atlanta, officials say. Further tests are now being done to determine if the virus is still viable, meaning it could grow in tissue culture.
The six glass vials of freeze-dried smallpox were intact and sealed with melted glass, and the virus might be dead, the CDC said Tuesday.
"We don't yet know if it's live and infectious. It's possible it could be inactivated because of long length of storage," Stephan Monroe, deputy director of the CDC center that handles highly dangerous infectious agents, told The Associated Press.
CDC said that a scientist found the virus samples on July 1 while cleaning out an old storage room at the Food and Drug Administration’s laboratory, located at the Bethesda campus of the National Institutes of Health.
Because it’s so infectious and considered to be a credible terrorist threat, only two labs in the world are allowed to hold variola, a smallpox variant. One is headquartered at the CDC in Atlanta, the other is at the State Research Centre of Virology and Biotechnology in Russia.
Smallpox, which killed approximately 300 million people during the 20th century, was declared eradicated in 1979. A university photographer who worked above a lab handling smallpox was the last person to die of the disease in 1978, according to the AP.
“There is no evidence that any of the vials labeled variola has been breached, and onsite biosafety personnel have not identified any infectious exposure risk to lab workers or the public,” according to a statement from the CDC.
“CDC has notified WHO about the discovery, and WHO has been invited to participate in the investigation. If viable smallpox is present, WHO will be invited to witness the destruction of these smallpox materials, as has been the precedent for other cases where smallpox samples have been found outside of the two official repositories,” the statement said.
Officials said this is the first time that unaccounted-for smallpox has been found in the U.S.
However, this is the second time a government health agency has mishandled extremely dangerous bacteria. A laboratory safety lapse at the CDC in Atlanta last month led the agency to give several employees antibiotics as a preventative measure against anthrax.