Zoo says DNA analysis backs up preliminary results it received in late May
Oregon Zoo veterinarians are preparing to begin an 18-month treatment regimen for Tusko, the 44-year-old male Asian elephant who has tested positive for tuberculosis, officials announced. A culture grown from Tusko's March trunk wash indicated a mycobacterial infection, and subsequent DNA analysis has now confirmed it as M. tuberculosis, the organism that causes TB.
"This is not unexpected following the preliminary results," said zoo veterinarian Tim Storms. "We've been moving forward under the assumption that Tusko does have TB, and we plan to start treatment immediately to help ensure he doesn't get sick. He is showing no signs of illness, which is not unusual when an infection is caught early. It's one advantage of consistently testing our elephants, which is part of their extensive healthcare program."
TB has been reported in elephants as far back as 1875, and the zoo routinely tests all its elephants for the disease by taking a trunk-wash 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.
Dr. Storms said he and his colleagues have been working with the USDA and other TB experts to develop Tusko's treatment regimen. Over the weekend, elephant-care staff began offering the elephant placebo capsules, so that when they start administering actual medications he'll be more likely to accept them.
The zoo's four female elephants and 5-year-old male Samudra have all tested negative. Packy and Rama, who tested positive for TB last year, continue to show no signs of illness, according to Dr. Storms.
Rama, diagnosed with TB last May, is now halfway through his 18-month regimen and continuing to progress well. He is no longer actively shedding, according to Dr. Storms. Treating Packy — the oldest male Asian elephant in North America — has been more challenging, in part due to his advanced age and his musth cycles.
"The effects of these medications can be very different from one patient to another," Dr. Storms said. "You see the same thing with human patients, and in fact the medications we're using are the same ones used in human TB cases. Packy seems to be more sensitive to one of the drugs, so we're working to come up with a different regimen."