Tests reveal a fifth monkey had been exposed to a deadly bacteria that got released from a high-security lab at the Tulane National Primate Research Center in Covington, according to email correspondence among federal and state investigators, a USAToday.com report said.

Officials contend the fifth monkey, as the others animals before it, was not part of an experiment, however, it remains unknown how a dangerous pathogen got outside of the center’s secure laboratory.

A federal investigation last month revealed that two monkeys at the primate research center had been infected with a bacterium the U.S. government considered as severe threat to human and animal health.

After more than three weeks the federal Centers for Disease Control and Prevention confirmed two “Burkholderia pseudomallei” cases involving monkeys at the center, yet Tulane officials had not notified local officials about the incident.

Tests on a fifth monkey, a rhesus macaque also indicates possible infection with the same deadly bacteria, the report said.

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