Elephant sanctuaries are cited as hotbeds of tuberculosis. But they have embraced testing and treatment regimens that many zoos and circuses opposed.

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When communities debate what’s best for elephants — zoos or sanctuaries — one subject is almost certain to come up: tuberculosis.

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From Toronto to Dallas to Topeka, representatives from zoos as well as zoo-industry groups have warned against sending animals to sanctuaries, which they portray as hotbeds of the disease. When officials at Woodland Park Zoo decided to send Seattle’s aging females, Chai and Bamboo, to the Oklahoma City Zoo instead of a sanctuary, TB was one of the reasons cited.

The country’s two elephant sanctuaries have, indeed, taken in several animals with confirmed or suspected cases of the disease. But TB is by no means exclusive to sanctuaries.

It flared first in circus elephants, with infection rates in some herds as high as 40 percent. Since then, tuberculosis has cropped up in zoos from San Francisco to St. Louis. Three males at Oregon Zoo in Portland were recently diagnosed in quick succession, and six staff members tested positive for exposure.

But while sanctuaries were quick to embrace the most stringent testing, quarantine and treatment regimes, many zoos — including Woodland Park — fought guidelines that several experts say could slow the spread of the disease and lower the risk to elephants and the public.

“I’m not sure everybody involved with elephants is truly vested in eliminating the disease and protecting elephants from infection,” said Dr. Chuck Massengill, former director of the animal health laboratory at the Missouri Department of Agriculture and a contributor to the new guidelines.

“I think there were clear indications that some people had vested interests that were diametrically opposed.”

“Trunk wash”

Developed under the auspices of the independent U.S. Animal Health Association, the guidelines emphasize the use of blood tests to detect signs of infection before full-blown disease develops.

In some cases, the guidelines would prevent zoos or circuses from transferring suspect animals around the country — a provision that drew furious opposition.

Woodland Park Zoo joined other zoos and zoo associations in challenging the validity of blood tests and arguing the rules would raise costs and unfairly restrict movement of animals. Zoos also downplayed the severity of the problem.

“This disease in elephants is slow-moving, has a low incidence and a low prevalence in the captive elephant population,” said a statement submitted to the U.S. Department of Agriculture by Woodland Park and endorsed by Ringling Bros.

The USDA received nearly 1,600 comments on its 2013 proposal to adopt the guidelines. Most came from members of animal-welfare groups who favored stricter standards. Response from the zoo and circus industry was uniformly negative.

The guidelines have not been adopted, though an agency spokeswoman said they are still under consideration. An older version remains in use.

But the Performing Animal Welfare Society (PAWS) sanctuary in California, The Elephant Sanctuary in Tennessee and some zoos opted to voluntarily adhere to the tougher rules.

Reports of TB-like symptoms in captive Asian elephants date back 2,000 years, but the disease does not afflict wild herds. All indications point to humans as the original source.

The first high-profile outbreak in the U.S. occurred in 1996, when two emaciated circus elephants collapsed and died in a three-day span.

Elephants can infect each other, as can elephants and humans. The common practice of transferring elephants between zoos, circuses and performing troupes is believed to be a major factor in spreading TB.

Staff who work closely with elephants are at risk, but the threat to zoo or circus visitors is extremely low, said Dr. Joel Maslow, a TB expert who investigated early outbreaks and worked on the guidelines.

Between 1994 and 2013, 57 U. S. elephants were confirmed with TB. The disease is rare in captive African elephants, but their Asian cousins have a one-in-six chance of falling ill.

Experts suspect the numbers are actually higher. Just as in humans, TB in elephants can be devilishly difficult to diagnose.

The standard method is called trunk wash. It’s kind of like collecting a sputum sample from a person — but a lot trickier. Elephants are trained to suck up saline solution with their trunks and spit it back into a plastic bag.

Trunk wash is called the gold-standard test because a positive result is slam-dunk proof of active TB. But a negative test is far from a clean bill of health.

The method can only confirm TB if an elephant is giving off bacteria — something that only occurs intermittently during the chronic disease. Many elephants have been diagnosed only after death, despite decades of trunk washes. During an outbreak at a Swedish Zoo, just 7 samples out of 189 tested positive, though all the elephants involved had TB.

“Trunk washes are just totally unreliable unless the elephant is shedding the day you do the trunk wash,” said Walter Cook of the Tennessee Wildlife Resources Agency, who oversees tuberculosis control at The Elephant Sanctuary.

Blood tests

Blood tests can spot signs of infection earlier and with greater sensitivity, allowing quicker treatment and quarantine, explained Dr. Mo Salman, a veterinary epidemiologist at Colorado State University who did much of the early research.

The tests rely on the fact that when elephants or people are exposed to tuberculosis — usually by inhaling bacteria — their bodies’ defenses react quickly.

Skin tests are used to detect those reactions in people, but don’t work on elephant hide. So scientists instead focus on antibodies cranked out by the immune system.

There’s little disagreement that the tests do a great job of detecting antibodies. What’s contentious is the meaning of a positive result.

In people, only 5 to 10 percent of those with positive TB skin tests develop active infections. The immune system usually keeps the bacterium in check, but rarely eliminates it from the body. It lurks in a state called latent infection.

A person — or elephant — with latent infection isn’t sick or infectious. But if the immune system is weakened by stress or disease, the disease can break out quickly.

No one knows what percentage of TB-exposed elephants will develop active disease. Dr. Susan Mikota, the leading authority on elephant TB, says zoo and circus animals may be particularly vulnerable due to the stress of captivity.

“The occurrence of TB in elephants may be a symptom of a greater problem,” she writes. “Namely our inability to meet the social and biological needs of this amazing and intelligent animal.”

Massengill said he and his colleagues focused on science, not cost or inconvenience, when they drafted their proposed guidelines. The evidence convinced them positive blood tests are a warning sign.

“If it walks like a duck and quacks like a duck, it’s probably going to be a duck,” he said.

One study of 16 elephants found warning signs in the animals’ blood months to years before the disease was diagnosed with trunk wash. Oregon Zoo’s infected elephants had positive blood tests months before their disease was confirmed. Zoo staff took the results seriously and started treatment right away.

The disputed guidelines suggested all elephant owners do the same, and proposed restrictions on transport of animals with multiple positive blood tests.

“In my mind, the likelihood is higher that they are infected,” said Maslow, chief of infectious disease at Morristown Medical Center in New Jersey.

But zoos and circuses argued that the evidence of the tests’ effectiveness isn’t good enough to justify additional treatment and testing. Curing TB in an elephant can take 18 months and cost $50,000.

Alternative guidelines recently drafted by an industry-dominated task force say blood tests should not be used at all for regulatory purposes.

Salman, at Colorado State, agrees more studies are needed and that the tests can give false-positive results. He’s working on a more sensitive, DNA-based approached.

But elephant captivity and TB have become so controversial that zoos and circuses are reluctant to share information, Salman said. USDA mandates annual TB testing for elephants, but those results are not easily accessible. Research has nearly ground to a halt.

“In my opinion, our knowledge about TB in elephants in the last 10 years has not really expanded or increased,” Salman said.

Rarely life-threatening

Sanctuaries became synonymous with TB because of their willingness to care for old, sick and unwanted elephants. The Tennessee sanctuary adopted several survivors from the “index herd” ravaged by the 1996 outbreak.

With the luxury of space, sanctuaries can more easily than zoos separate infected from healthy animals. At the 2,700-acre Elephant Sanctuary, five uninfected Asian females share 2,100 acres and a barn, while five elephants with confirmed or suspected TB are quarantined in a 220-acre tract with its own barn.

The PAWS sanctuary is currently home to only one Asian female, named Gypsy. She has never had a positive trunk wash, so under current guidelines there would be no restriction on shipping her across country. But PAWS keeps her quarantined because of positive blood tests and past exposure to an infected elephant, said PAWS spokeswoman Julie Woodyer.

PAWS is willing to adopt the Seattle zoo’s Chai and Bamboo, and private donors offered to pay for the move and help build a new, 15-acre enclosure where they would be kept separate from Gypsy. Managers at the Tennessee sanctuary said they would consider adopting the Seattle elephants. But they would need approval from Cook and his agency, which imposed a moratorium on new Asian elephants after an incident in 2009, when a TB-infected animal passed the bacteria to nine workers.

Since then, the sanctuary improved its management, implemented cutting-edge infection-control procedures and cooperated with researchers and medical experts, Cook said. “They have done everything that could possibly be done.”

Despite its use as a wedge between zoos and sanctuaries, elephant TB is rarely life- threatening.

Out of nearly 400 elephant deaths in accredited U.S. zoos between 1962 and 2012, four were attributed to TB. A 2012 Seattle Times investigation found most captive elephants die from arthritis, bad joints and other conditions aggravated by life in captivity.

Herpes infections, like the one that killed a six-year-old calf at Woodland Park Zoo in 2007, are far more virulent than TB. Chai and Bamboo were exposed to that virus, which attacks young elephants, yet there are no restrictions on moving them to Oklahoma City to live alongside two calves.

But even if TB and other diseases are removed from the equation, the question of what’s best for elephants isn’t easily resolved.

Zoo officials say Chai and Bamboo will benefit most from living in a multigenerational herd at Oklahoma City. Sanctuary advocates insist freedom to roam, a more natural environment and a milder climate are more important.

Barring a last-minute legal victory by opponents, though, Oklahoma will be the new — and likely final — home for Chai, 36, and Bamboo, 48.

There they will meet a bull called Rex, who exemplifies the ongoing uncertainty about elephant TB.

In his 47 years, Rex has lived at zoos in Canada and California and was once owned by a company that hires out elephants for parties. When he arrived at Oklahoma City in 2011, he tested positive for TB exposure on a type of blood test with a false-positive rate of about 5 percent. The test has since been replaced with a more accurate version.

Rex shows no signs of infection on follow-up blood tests or trunk wash, which the zoo says is evidence that he’s TB-free.

But Maslow said he wouldn’t be as confident.

“If I have any positive test, my concern is raised.”