Dangerous Bacteria Mysteriously Escapes From Louisiana Monkey Lab Four monkeys unrelated to research have been infected so far, officials say.

 -- How a potentially deadly strain of bacteria escaped from a primate research lab infecting four monkeys is a mystery, government officials said, but they added the incident poses no threat to the public.

The bacterium in question, burkholderia pseudomallei, is widespread throughout Southeast Asia and northern Australia, infecting humans and animals via contaminated soil and water entering the blood stream through cuts in the skin, according to the Centers for Disease Control and Prevention.

The high-security laboratory at the Tulane National Primate Research Center in Louisiana, which is studying the bacteria, reported that at least five rhesus macaques not used in studies were infected with the bug, possibly as early as November of last year, according to spokesman Michael Strecker.

How the bacteria made its way from the lab to animals not used in experiments is still an open question despite weeks of investigation by multiple federal and state agencies, including the CDC, the U.S. Department of Agriculture and the Environmental Protection Agency.

“The only connection among these four animals was their presence in the veterinary hospital during the same period of time,” Dr. Andrew A. Lackner, the director of the center, said in a statement last week, adding that more than 50 soil and water samples from the 500-acre compound have tested negative for the bacteria.

A federal investigator also tested positive for burkholderia, after visiting the center, Jason McDonald, a CDC spokesman, told ABC News. It isn't clear whether he was exposed to the bacteria at the primate center or during travel to an infected region, McDonald said.

However, Strecker said he did not believe the investigator came into contact with the germ at the center.

"At present there is no evidence of Burkholderia pseudomallei in any human or other non-human primate at the TNPRC," he told ABC News.

Though the CDC stressed that there is no risk to the general public, the agency said it has directed Tulane to suspend all research until the investigation is complete. The infected animals were euthanized, according to the Tulane statement.

“The veterinary hospital has been thoroughly disinfected, and additional animal testing is ongoing,” Lackner said in a statement. “Tulane continues to work with the CDC, USDA and the EPA, as well as state and local officials on this matter.”

Melioidosis causes fever, headache, loss of appetite, muscle and joint pain. Although full-blown illness from the bacteria is rare, the fatality rate is up to 50 percent in some countries for those who do get sick, studies show.

Also of concern: The bacterium has been studied for use as a potential bioweapon, according to the UPMC Center for Health Security, an independent biosecurity think tank.