The US military accidentally shipped at least one live anthrax sample across the country to a commercial lab in Maryland and four workers were undergoing medical treatment as a precaution, officials said.

The samples had been irradiated in March last year at a military lab in Utah and were supposed to be "dead."

But on Friday, a private firm in Maryland notified authorities that its sample was still active, setting off an urgent review of all material sent out to other labs, defense officials said.

More than a dozen other government and commercial labs in nine states -- as well as a US military base in South Korea -- received samples over the past year from the original batch that was irradiated in 2014 at Dugway Proving Ground in Utah, near Salt Lake City, officials said.

Four people at three different companies that had "worked with the live anthrax" were receiving post-exposure prophylaxis treatment as a precaution, officials said.

But the Pentagon and health officials said there was no threat to public health.

"There is no known risk to the general public, and there are no suspected or confirmed cases of anthrax infection in potentially exposed lab workers," Pentagon spokesman Colonel Steven Warren said in a statement.

However, precise information about what had gone wrong and how many labs might be affected remained unclear.

The Centers for Disease Control and Prevention (CDC), backed up by the Defense Department, was investigating the mishap.

The live anthrax sample, which had been transported by truck, was discovered by the commercial lab late on Friday and the other laboratories were then informed, officials said.

One sample of anthrax was sent to a lab at Osan Air Base in South Korea, Warren said.

"The sample was destroyed in accordance with appropriate protocols," he said.

Referring to the commercial lab in Maryland, the CDC said "although an inactivated agent was expected, the lab reported they were able to grow live Bacillus anthracis."

- Past safety lapses -

The CDC said in a statement the investigation is examining if other labs "also received other live samples, epidemiologic consultation, worker safety review, laboratory analysis and handling of laboratory waste."

The Pentagon's announcement came less than a year since health officials faced severe criticism over a spate of safety lapses at CDC labs handling deadly pathogens, including anthrax.

The Defense Department lab at Dugway Proving Grounds routinely transfers "dead" anthrax samples, which are inactivated through radiation, for scientific research.

The lab was working on a project "to develop a field-based test to identify biological threats in the environment," Warren said.  

As a precaution, the Defense Department "has stopped the shipment of this material from its labs pending completion of the investigation," he said.

After the military lab in Utah irradiated a batch of Anthrax on March 18, the material was divided into nine samples that were then sent out to labs over the course of several months.

One sample was shipped to an army facility in Maryland, the Edgewood Chemical Biological Center. That material was then shipped to different private labs, including the firm in Maryland that reported finding the live sample, officials told AFP.

The other labs in the United states receiving samples from the original batch were located in California, Delaware, Maryland, New Jersey, New York, Tennessee, Texas, Wisconsin and Virginia.

The lethal anthrax disease is spread by spores and has been used for bioweapons programs in the United States and elsewhere. Washington long ago scrapped its bioweapons effort as part of an international treaty, which the United States ratified in 1975.

US government laboratories came under fire last year over reports of sloppy management of deadly bacteria.  

As a result, health officials suspended the shipment of potentially dangerous pathogens from government labs in Atlanta and the CDC shut down two of its laboratories, including one implicated in the mishandling of anthrax samples.

Investigators from the Agriculture Department last year found anthrax was stored in unlocked refrigerators in an unrestricted corridor, and that dangerous materials were transferred using resealable plastic bags.
Source: AFP