In what can only be described as a colossal blunder, 26 Department of Defense (DOD) employees were exposed to live anthrax after the US military shipped samples of the live microbe by accident. Thought in error to be dead samples, they were simply shipped via FedEx.

A Maryland lab received the samples, and upon realizing they were live, launched an urgent investigation to see just how much live anthrax was shipped, how, and to which locations. The samples originated in a Utah lab.

Four workers that received the shipments in nine states were placed on post-exposure treatment after handling samples. Up to 22 military lab workers were also exposed.

"All personnel were provided appropriate medical precautionary measures to include examinations, antibiotics and in some instances, vaccinations," the DOD statement says. "None of the personnel have shown any signs of possible exposure."

Jim McCluskey, a FedEx spokesperson, wouldn't directly confirm the details to CNN.

"FedEx is committed to the safe transport of all customer shipments, and our priority is the safety of our employees," McCluskey says. "We will be working closely with the Department of Defense and the Centers for Disease Control to gather information about these shipments."

Pentagon spokesman Colonel Steve Warren said another sample was sent to Osan Air Base in South Korea.

"The sample was destroyed in accordance with appropriate protocols," Warren says.

The Centers for Disease Control and Prevention (CDC) and the DOD are investigating. The CDC says it suspects no risk to the public.

"CDC is working in conjunction with state and federal partners to conduct an investigation with all the labs that received samples from the DOD," says Jason McDonald, a CDC spokesman. "The ongoing investigation includes determining if the labs also received other live samples, epidemiologic consultation, worker safety review, laboratory analysis and handling of laboratory waste."

Warren also stated that there is no known public risk and confirmed that no illnesses have been reported.

"The DOD lab was working as part of a DOD effort to develop a field-based test to identify biological threats in the environment," Warren says. "Out of an abundance of caution, DOD has stopped the shipment of this material from its labs pending completion of the investigation."

A private commercial lab's reports triggered the investigation. Before samples are shipped for research purposes they are supposed to be killed.

"The lab was working as part of a DOD effort to develop a new diagnostic test to identify biological threats," McDonald says. "Although an inactivated agent was expected, the lab reported they were able to grow live Bacillus anthracis (anthrax)."

All labs that may have received samples, whether commercial, government, or military, are now reassessing any anthrax inventory. CDC officials are on-site at the military labs investigating. CDC spokeswoman Kathy Harden said any samples from the investigation will be transferred to CDC securely "for further testing."

A Dangerous Pattern

This incident is one of several in recent months. About 11 months ago CDC employees mishandled Anthrax in the same way and admitted that this was one of five times deadly pathogens were mishandled since 2006.

Researchers in one CDC lab that was fully-equipped to handle live anthrax shipped live samples to another CDC lab. Although one might think that employees in any CDC lab would be following protocols that would keep the lab workers safe, in fact they lacked sufficient safeguards. Although no one fell ill, CDC employees were "potentially exposed" to live anthrax.

The CDC has made the same mistake with bird flu, also last year.

Researchers working with the most dangerous pathogens must follow the "two-person rule" for both handling and shipping samples. These actions are never to be taken alone, as the extra person is meant to safeguard scientists and make adherence to proper protocols more likely.

Experts in biosafety are "astonished" by the lapse. Hardly surprising, they are also calling for greater precautions.

"These events shouldn't happen," says Stephen Morse of Columbia University, a former DARPA program manager for biodefense. "We can put greater safeguards in place."