A federal investigator who was sent to the Tulane National Primate Research Center near Covington to look into the escape of a potentially deadly bacterium and who later reported symptoms of the disease caused by the bacterium was not exposed to the pathogen while at the center, the federal Centers for Disease Control and Prevention has concluded.

A spokesman for the Governor’s Office of Homeland Security and Emergency Preparedness made the announcement Thursday.

The investigator, whose name has not been released, was at the center Jan. 20-22. She was there to investigate how two rhesus macaque monkeys became infected with Burkholderia pseudomallei, a bacterium native to southeast Asia and northern Australia that is on the government’s list of “select agents” — pathogens that could pose a severe threat to human, animal or plant health.

After leaving the center, the investigator reported symptoms she feared could be signs of melioidosis, the disease caused by the bacterium.

Testing revealed antibodies in her system that are a response to exposure to the bacterium, but because the investigator also had traveled to areas of the world where the bacterium is endemic, her exposure could have occurred while there.

Follow-up testing indicated that her exposure did not happen while at the Tulane center, GOHSEP’s Mike Steele said in an email.

So far, tests have confirmed that at least five monkeys at the center were exposed to the bacterium. Three of those have been euthanized. The other two never developed signs of illness but, like the inspector, had antibodies in their system that form in response to exposure to the pathogen.

All five monkeys were treated in the same room at the center’s veterinary clinic, leading the investigation to focus on that room. How the bacterium got out of the highly contained lab in which it was supposed to be kept remains a mystery, and the investigation is ongoing, officials have said.

None of the infected monkeys was part of any experiments at the center. Experiments on the bacterium were being conducted mainly on rodents, as scientists look for a vaccine against melioidosis, which is treatable with antibiotics if properly diagnosed. The symptoms of the disease often mimic those of other illnesses, making a correct diagnosis difficult in some cases.

Various federal and state agencies are conducting tests of soil, water and air around the primate center, which sits adjacent to a school and close to three neighborhoods near the heavily traveled U.S. 190 corridor. Blood tests on some employees of the center also are being conducted.

All of the environmental and blood tests so far have turned up negative, officials have said.

Follow Faimon A. Roberts III on Twitter, @faimon.