Staff also plans preventive treatment of Packy, who may have latent infection
The Oregon Zoo this week began its yearlong treatment regimen for Rama, the Asian elephant who cultured positive for tuberculosis in late May, officials announced. Zoo staff is also preparing to administer preventive treatment to Packy, who reacted to a subsequent blood-serum test and could have a latent infection.
“Packy has shown no signs of active TB,” said Mitch Finnegan, the zoo’s lead veterinarian. “But lab work on his blood indicates possible exposure, so it’s better to treat this now than risk an active infection down the line.”
The zoo routinely tests all its elephants for TB by taking an annual trunk culture (collecting fluid from the animal’s trunk and sending it to a certified laboratory for testing) as part of its comprehensive health program and in compliance with U.S. Department of Agriculture standards. Following Rama’s diagnosis last month, each of the elephants was retested, with preliminary results coming back negative once again for all but Rama.
As a further precaution, the zoo also submitted blood samples from each of its elephants for testing, using the serologic DPP (Dual Path Platform) assay, a broad but useful screening test. Packy, in addition to Rama, was reactive to this assay, so his blood serum was submitted for further testing. A more specific test known as MAPIA (multi-antigen print immunoassay) indicated possible exposure to TB. While only a positive trunk culture test is considered definitive, Dr. Finnegan — in consultation with the USDA — has recommended treating Packy as the most prudent course of action.
“For elephants, we are using the MAPIA the same way we’d look at a TB skin test for humans,” Dr. Finnegan said. “It doesn’t necessarily indicate active tuberculosis — it indicates exposure to the TB bacteria at some point in the past. In humans, only a small percentage of those who react positively to the skin test ever develop TB, and treating a latent TB infection reduces that risk even further. That’s the course we’ll be taking with Packy.”
Dr. Finnegan said neither Rama nor Packy have shown any signs of illness and, although Rama is being kept apart from the herd during his treatment, no similar measures are needed for Packy at this time.
“TB is typically very manageable,” Dr. Finnegan said. “Neither elephant has shown signs of being sick, and we’re hopeful that with proper treatment they never will. Getting early results like this is very helpful and the prognosis is good for both animals.”
After receiving the initial report about Rama in late May, Dr. Finnegan immediately contacted the public health authorities and veterinarians at the Oregon Department of Health and Human Services and U.S. Department of Agriculture. Zoo personnel were also informed of the results, and those working in prolonged close proximity to Rama were tested to ensure they did not have the disease.
Zoo visitors were not at risk, according to Justin Denny, M.D., public health officer for Multnomah, Washington and Clackamas counties.
“Transmission of tuberculosis requires prolonged periods of close contact,” Dr. Denny said. “So we wanted to make sure we tested anyone who spent time close to Rama. But as far as the general public is concerned, there is nothing to worry about.”
It took until this month to amass enough medication to begin Rama’s treatment regimen, which began on Tuesday, but now that the medicine is on site, Packy’s treatment can begin starting next week. The zoo’s veterinary staff will monitor both elephants’ progress through trunk cultures and blood tests during their prescribed treatment regimen.
While not common, TB has been reported in elephants as far back as 1875 and has a history of successful treatment at several North American elephant facilities.
How is TB spread?
Among humans, TB bacteria are spread through the air from one person to another when an infected person coughs, sneezes or speaks. People nearby who breathe in the air may become infected. More information can be found on the US Centers for Disease Control (CDC) website: www.cdc.gov/tb.
How is it possible that an elephant could test positive for the human form of TB?
Elephants have been known to test positive for the human strain of TB in other zoos and in the wild. While we don't have concrete information on what made Rama or Packy test positive for TB, we are continuing to conduct tests and analyze results.
Can an elephant give TB to humans?
This strain of TB could be transferred to humans but only in instances that involve prolonged periods of close contact. We have been working with county health officials to make sure anyone who needs to be is tested.
What happens if any zoo personnel test positive?
A positive skin test indicates that a person has been exposed to TB bacteria at some point — but very few who test positive ever develop active TB. In its latent form, TB is not transmittable to others, and treating it early further reduces the chance of an active infection.
Can other elephants get it?
TB can be spread among elephants that are in close contact with each other if one of the elephants has an active infection. Given the behaviors and social patterns of the zoo's elephant herd, veterinarians believe it is unlikely any of the other elephants could be infected.
How was TB discovered in Rama and Packy?
The zoo routinely tests all its elephants for TB by taking an annual trunk culture (collecting fluid from the animal's trunk and sending it to a certified laboratory for testing) as part of its comprehensive health program and in compliance with U.S. Department of Agriculture standards. Following Rama's diagnosis, each of the elephants was retested, with preliminary results coming back negative once again for all but Rama. As a further precaution, the zoo also submitted blood samples from each of its elephants for testing. Packy's blood-test results indicated he might have a latent (inactive) infection.
What is being done to prevent the other elephants from getting TB?
Rama was immediately placed into quarantine once we received notice from the USDA of his positive test results. Such measures are not necessary for Packy at this time since the disease is not active in him. All of the elephants will continue to be tested and monitored.
Is Lily at greater risk of getting TB?
No, Lily has not spent time with Rama.
What is the treatment regimen for elephants?
Veterinarians treat elephants using the same medicines doctors recommend to fight TB in humans. Working with experts at the USDA and officials at the state and Multnomah County, our veterinary team has developed a comprehensive regimen for both Rama and Packy.