Finding decades-old vials of smallpox, a highly contagious disease considered one of the deadliest known to man, was no doubt alarming to government workers who were cleaning out an old Maryland research center last week. Previously, world health authorities believed the only samples left were in high security laboratories in Atlanta, Ga., and Russia’s Novosibirsk, Siberia, but were surprised to find the six unaccounted for freeze-dried virus vials lying abandoned in cardboard boxes.

The disease has plagued human populations for thousands of years, until it was declared eradicated in 1980, thanks to a vaccination. The Associated Press reports the vials, which were found at the National Institutes of Health in Bethesda, Md., are sealed tight and no one has been neither infected nor can anyone find records of why or when the disease was stored in there to begin with. Smallpox can be deadly even after it is freeze-dried and stored. However, it needs to be kept cold to remain alive and dangerous.

Centers for Disease Control and Prevention Deputy Director Stephan Monroe said the vials may have been sitting there since the 1950s in room temperature, so it is unknown if the disease poses a health threat. "We don't yet know if it's live and infectious. It's possible it could be inactivated because of long length of storage," Monroe told Fox News.

Smallpox accounted for more than 300 million deaths in the 20th century, according to The College of Physicians of Philadelphia, with symptoms including fever, lethargy, headache, sore throat, and vomiting. Then, eventually, a rash spread through the face and body, and sores formed in the inside of the mouth, throat, and nose. After a few weeks, after fluid-filled pockets of skin grew over large areas of skin, scabs formed, and severe permanent scarring was left behind for the lucky that survived.

The debate about whether or not to destroy all found samples of smallpox has a long history in medicine. Many scientists believe the deadly virus should be completely destroyed in order to wipe it off the earth, while others believe it could be needed for research to improve vaccinations and treatments.

In May, the World Health Organization (WHO) met and decided to postpone the destruction of smallpox stocks. The health ministers, representing 194 member states, decided to set up a third advisory committee after the board was clearly divided and couldn’t reach a conclusion by the end of the day.

WHO’s 1967 eradication efforts were a success after sending freeze-dried vaccinations to the 30 countries in need of a cure. Once they developed a system, they monitored and investigated the cases in each country. The outbreaks were then contained and ongoing research took fear’s place until last week's discovery surprised everyone.