The WHO declared smallpox eradicated in 1980 and no known naturally occurring cases have occurred since. Before its eradication, smallpox killed about a third of the people it infected. Photo courtesy CDC
Nov. 18 (UPI) -- Federal health and law enforcement officials are investigating the discovery of several frozen vials that were labeled "smallpox" at a Pennsylvania facility that does vaccine research, authorities said.
The Centers for Disease Control and Prevention confirmed the discovery.
The vials were found by a lab worker who was cleaning out a freezer on Tuesday at a Merck facility in Montgomery County.
Officials said there's no indication that anyone was exposed to the small number of vials.
"CDC, its administration partners and law enforcement are investigating the matter and the vials' contents appear intact," the CDC said, according to WPVI-TV.
"The laboratory worker who discovered the vials was wearing gloves and a face mask."
Health officials said there were more than a dozen questionable vials, five of which were labeled as smallpox.
The World Health Organization declared smallpox eradicated in 1980 and no known naturally occurring cases have occurred since. Before its eradication, smallpox killed about a third of the people it infected. Symptoms generally include high fever and a pockmarked complexion that typically leaves permanent scarring.
Richard Ebright, a Rutgers University professor of chemistry and chemical biology, told The Philadelphia Inquirer that smallpox samples were highly restricted after 1984 and were only stored at two government sites in the United States and Russia.
Ebright added that there was little to no risk to the lab worker and even less risk of a public outbreak.
Smallpox is an infectious disease caused by the variola virus that can spread from one person to another, mainly through direct and prolonged face-to-face contact.
The last natural outbreak of smallpox in the United States occurred in 1949.