BALTIMORE (WJZ) — Live anthrax spores mistakenly shipped to labs across the world, including right here in Maryland. The Department of Defense says the mix-up is far more widespread than initially reported.

Meghan McCorkell has the demands to know how this happened.

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Officials have now doubled the number of labs they say received those shipments and say the numbers could go up even higher.

Potentially deadly live anthrax shipped in the mail. The Pentagon now admits the spores were mistakenly sent to 51 labs across 17 states and the District of Columbia, as well as three foreign countries.

“We expect this number may rise because the scope of the investigation is going on,” said Deputy Defense Secretary Robert Work.

The Edgewood area of the Aberdeen Proving Ground received the samples, but it was an unnamed private Maryland lab that first alerted the feds the spores were live.

The samples were supposed to be inactive.

“Everyone in the Department of Defense takes this issue very seriously,” said Work.

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WJZ has obtained a letter written by Maryland Senator Barbara Mikulski to the defense secretary and the head of the CDC, demanding answers about what happened.

In it, she writes: “…I have serious concerns about how such a potentially catastrophic mistake could have been made.”

Officials don’t believe there’s any risk to the public, but more than two dozen lab workers are being given antibiotics as a precaution.

“When I’m receiving material, I’m wearing a lab coat, face mask, gloves, especially if I don’t know what it is,” said Carson Pinney, lab worker.

Infectious disease specialist Dr. Amesh Adalja says officials need to find the breakdown in the system.

“We don’t want the public to lose confidence in our ability to do this kind of science, which is very, very important because anthrax is a potential biological weapon,” he said.

A federal investigation is expected to be complete by the end of June.

Officials say no one has shown any signs of exposure to anthrax.

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The anthrax attacks in 2001 killed five people and sickened more than 20 others.