The Oregon Zoo will begin treating two elephants this week for tuberculosis.
One is Packy, the zoo's senior male elephant. Zoo officials had not previously announced that Packy had tested positive for TB.
Packy has shown no signs of active TB, said Mitch Finnegan, the zoos lead veterinarian. But lab work on his blood indicates possible exposure, so its better to treat this now than risk an active infection down the line.
The other is Rama, a male Asian elephant who zoo officials had previously announced tested positive for TB.
Neither elephant shows any sign of illness, zoo officials say. The treatment takes about a year.
The zoo routinely tests all its elephants for TB by collecting fluid from the animals 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 Ramas 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 Dual Path Platform (DPP) assay, a broad but useful screening test. In addition to Rama, Packy, 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 wed look at a TB skin test for humans, Dr. Finnegan said. It doesnt 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. Thats the course well 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.
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 Ramas treatment regimen, which began on Tuesday, but now that the medicine is on site, Packys treatment can begin starting next week. The zoos veterinary staff will monitor both elephants progress through trunk cultures and blood tests during their prescribed treatment regimen.