Antibiotic-resistant asymptomatic TB strain had epidemic potential
PORTLAND, Oregon––Oregon Zoo veterinary staff on February 9, 2017 euthanized Packy, 54, the oldest male elephant in the U.S., after a multi-year losing battle against an antibiotic-resistant strain of the lung disease tuberculosis which had already killed two other Oregon Zoo elephants and infected seven zoo staff plus a volunteer.
The tuberculosis strains that afflict humans and elephants are transmitted through the air in tiny liquid particles shed when the victims sneeze, cough, blow their noses, sing in the case of humans, or trumpet in the case of elephants. The disease is transmissible both from elephant to human [zoonosis] and human to elephant [reverse zoonosis].
Diagnosed tubercular in December 2013, Packy had probably been ill for much longer, but TB in elephants tends to be asymptomatic until it reaches late stages, often in combination with other health stresses.
Until improved testing protocols became available in 2007, many cases of TB among elephants were diagnosed only posthumously.
In Defense of Animals furious
Euthanizing Packy was furiously denounced by some animal advocates, incited by social media postings from “Team Packy,” apparently representing one or more Oregon Zoo elephant keepers, and by ill-informed commentary from In Defense of Animals and The Dodo web site.
But the well-documented case history suggests that if the Oregon Zoo can be faulted at all for the euthanasia decision, zoo personnel could be faulted for waiting too long.
The first Asian elephant born in the U.S. since 1918, Packy was the Oregon Zoo’s leading attraction from his birth on April 14, 1962 until he was taken off exhibit in 2016.
Life magazine covered Packy’s birth with an 11-page spread. More than a million visitors paid their way into the Oregon Zoo in 1962. Founded in 1888, the Oregon Zoo had never before drawn paid attendance topping a million, but now routinely draws more than 1.6 million, with a record high of 1.68 million.
As well as having been the Oregon Zoo’s best-known and most popular animal, Packy was among the more successful stud bulls in the dwindling U.S. zoo elephant herd of about 140, albeit less successful than some of his Oregon Zoo elders.
“From the time of Packy’s birth to that of his daughter Shine, in 1982, Portland was the birthplace for 21 of the 27 Asian elephants born in North America,” recalled Steven DuBois of Associated Press.
Packy sired seven offspring in all, but such is the rate of mortality among captive-born elephants in the U.S. that among Packy’s seven offspring, only Shine survived him.
Rama & Tusko
Among the offspring whom Packy outlived were Rama, a son, the first Oregon Zoo elephant known to have contracted TB. Discovered to have been infected in May 2013, Rama was euthanized in March 2015 after a failed 18-month course of antibiotic treatment.
Tusko, another Oregon Zoo male elephant, was found to be tubercular in June 2014. Suffering from other painful health conditions as well, Tusko was euthanized in December 2015.
Out of options
“We’d run out of options for treating Packy,” said Oregon Zoo chief veterinarian Tim Storms in a prepared statement. “The remaining [possible] treatments involved side effects that would have been very hard on Packy, with no guarantee of success, plus a risk of creating further [antibiotic] resistance,” if the TB bacterium failed to respond to the initially prescribed dosage.
“None of us felt it would be right to do that,” Storms said. “But without treatment, his TB would have continued to get worse.”
Packy was euthanized three months after the zoo disclosed that testing done in September 2016 had found he was again shedding TB bacteria, after nearly two years of testing free from the infection.
Elephant TB not always detectable
But “Even in the absence of clinical signs, infected elephants can shed TB bacteria and infect others,” warns Program for Monitoring Emerging Diseases animal disease and zoonoses moderator Arnon Shimshony, DVM.
Shimshony, now teaching veterinary medicine at Hebrew University in Jerusalem, Shimshony formerly was chief veterinary officer for the State of Israel from 1974 to 1999.
“In a TB outbreak in Sweden, five elephants were affected,” recounted Shimshony in a 2008 review of relevant scientific literature. “Of 189 trunk wash samples collected, only seven were positive from the five elephants who were confirmed on postmortem to be infected.”
Skin tests for TB, commonly used to screen humans, are “not accurate in elephants,” Shimshony added.
“We had been feeling increasingly optimistic about Packy’s treatment regimen,” Storms told Kale Williams of The Oregonian/Oregon Live on December 2, 2016, “and he had been tolerating it well, so this recent result was disappointing,” Tim Storms, the zoo’s senior veterinarian, said in a statement.
“After some testing,” Williams explained, “vets ascertained that Packy’s strain of the disease was resistant to the two most common classes of antibiotics used to treat the ailment: rifampin and quinolones.”
“Without those options, we’re very limited in our ability to treat this infection,” said Storms. “We’ve stopped Packy’s treatment for the time being, since we now know that it has been ineffective. We’re consulting with veterinarians and pharmacologists around the country, considering what to do next.”
Attempts were made to treat Packy with another antibiotic known to be effective against TB, isoniazid, but “Despite adjusting dosage levels and administration methods, the side effects of the drug––including appetite loss and elevated liver enzymes––proved too detrimental to continue,” Williams reported.
Bob Lee, the Oregon Zoo elephant curator since 2000, told Williams that “Packy’s keepers are doing everything they can to keep the pachyderm comfortable,” Williams summarized, “giving him daily exercise routines and trying their best to stimulate him mentally. We don’t really know exactly how he’s feeling.”
Because Packy was known to be carrying TB while the other surviving Oregon Zoo elephants have tested clear, Packy was kept in isolation after the euthanasias of Rama and Tusko, and was kept more than 100 feet away from zoo visitors.
According to the January 8, 2016 edition of Morbidity and Mortality Weekly Report, published by the Centers for Disease Control and Prevention, Packy, Rama, and Tusko were found to have previously had close contact with 118 humans, of whom 96 (81%) were located for follow-up screening.
Human contacts were infected
“Seven close contacts were found to have latent TB infection,” Morbidity and Mortality Weekly Report said.
Elaborated Lynn Terry of The Oregonian/Oregon Live, “Multnomah County health officials identified seven zoo staff who had close contact with the elephants who had a latent form of TB without symptoms and a volunteer who was treated.”
The Team Packy postings to Facebook consistently ignored or downplayed the risks of an asymptomatic, antibiotic-resistant strain of TB spreading either among humans or other animals.
Team Packy dismissed the risk
Packy “is showing no signs of pain or discomfort. He is active, playful and engaged with keeper staff every day,” Team Packy claimed on December 31, 2016. “Putting him down is one of the options on the table currently and the reason for our Facebook page. We do not want this to happen. Euthanasia is used to end irreversible pain and suffering. Since neither applies to Packy at this time it would not be euthanasia.”
Added Team Packy on January 22, 2017, “We have been told that they [zoo veterinarians] ‘have to make the decision soon’ about Packy. Why the rush? His health is good, great even, he’s active and engaged, he’s in a safe place, they have assured us the herd and the staff are safe. We all accept that Packy will eventually need to be euthanized because of this disease or other health issues, but the decision boils down to whether he is euthanized now because of the fear of transmission or whether he is euthanized later because we have determined a decline in quality of life and don’t want him to suffer. Why is the decision urgent?”
Any epidemiologist could have answered that question, but apparently Team Packy didn’t ask.
In Defense of Animals & The Dodo
“If Packy really is not suffering, the zoo owes him hospice, not death,” commented In Defense of Animals president Marilyn Kroplick,” disregarding that Packy had already been receiving the equivalent of hospice care since September 2016, when the failure of his treatment regimen and lack of viable alternative treatments became known to the Oregon Zoo veterinary staff.
Alleged In Defense of Animals staff member Toni Frohoff, “This is not by any means euthanasia — this is murder.”
Claiming “a doctorate in behavioral biology, an M.S. in wildlife and fisheries sciences, and a B.S. in psychology,” Frohoff was identified by Elizabeth Claire Alberts of The Dodo as “an elephant biologist.” That credential is not on Frohoff’s resumé, though she does list having been for two years and four months an “elephant and cetacean scientist,” a time frame coinciding with her employment by In Defense of Animals.
TB killed 1.8 million people in 2015 alone
Alberts’ article, headlined “This Zoo Just Killed A Beloved Elephant For No Good Reason,” disregarding that tuberculosis killed about 1.8 million people worldwide in 2015 alone, of 10.4 million who fell ill, and may have killed even more animals, between those animals who actually died of the disease and those who were culled to contain it.
About 90% of TB victims host the disease in asymptomatic form, often for years, before another health condition causes it to become apparent. If promptly detected after symptoms appear, TB in humans is usually treatable, with difficulty, but more than 10% of human cases are fatal: more than 2.5 times as many as were fatal before antibiotic-resistant TB was medically identified in 2006.
Antibiotic-resistant TB is about four times more likely to kill the victims, with treatment costs for those who recover of as much as $500,000 per victim, according to CDC data. The treatment comes with ‘potentially life-threatening side effects,” including “depression or psychosis, hearing loss, hepatitis, and kidney impairment.”
Without treatment, about two-thirds of human victims of tuberculosis eventually die from it.
According to Guidelines for the Control of Tuberculosis in Elephants, published on October 29, 2008 by the U.S. Animal Health Association, euthanasia “may be considered for those animals that are showing clinical signs, considered to be poor candidates for treatment, or for other factors based on the clinician’s discretion,” including risk of transmission to staff, public, and other animals.
Not new disease in elephants
Though only relatively recently recognized, tuberculosis has afflicted elephants for millennia.
Recounted Shimshony in his 2008 literature review, “Sanskrit documents from about 2,000 years ago describe a disease in elephants that is clearly TB. The pathogen has also been implicated in the extinction of the mastodon (Mammut americanum); in one study of mastodon skeletons, 59 of 113 (52%) had bone lesions diagnostic for TB.
“The first zoo elephant reportedly affected by TB,” Shimshony found, “was an Indian elephant who died at the London Zoo in 1875.”
13% of U.S. captive elephants infected
As of 2008, Shimshony summarized, about 13% of the elephants in the U.S. were known to have been infected with TB, almost entirely without showing symptoms.
“Between 1994 and 2005, there were 34 confirmed cases of tuberculosis in elephants in the United States: 31 of them in Asian elephants and three in African elephants,” Shimshony wrote. “In 33 of the cases, the etiologic agent was found to be M. tuberculosis,” the human form of TB, “and in one, M. bovis,” or bovine TB, endemic among cattle and badgers in Britain, and the reason for ongoing badger culls meant to keep cattle herds from becoming re-infected after infected cattle are culled.
“Potential reservoir could infect humans & wildlife”
“TB-infected elephants are a potential reservoir that could infect humans and wildlife,” Shimshony warned, “perhaps even with more virulent and novel forms of TB,” especially if they are antibiotic-resistant.
The greatest threat to humans from elephant-carried TB, Shimshony found, is in India.
“In a recent study in southern India involving 387 captive elephants in four states,” Shimshony summarized, “59 of the elephants had TB. The largest percent of TB affected elephants were in temples, where 16 of the 63 animals were found infected.
“Of 160 privately owned elephants, 24 had TB,” Shimsony wrote. “Of the 164 elephants owned by forest departments of various state governments, 19 had TB.”
Spreading throughout Asia
A year after Shimshony’s summary, veterinarian K.C. Panicker told Ignatius Pereira of The Hindu that tuberculosis had killed about 100 elephants in Kerala state alone since 2005––about a seventh of the Kerala captive elephant herd.
The Nepal Elephant Healthcare and TB Surveillance Program, begun in 2007 by Elephant Care International and World Wildlife Fund Nepal, reportedly tested 133 captive elephants, about half of the total Nepalese captive herd. Of the 29 Nepalese elephants found to be infected, only 22 were treated.
The overall status of TB among Indian and Nepalese wild elephants is unknown, except that it is believed to be occurring among them, and among both wild and domestic elephants in Thailand, and has been identified among elephants of Thai origin at the Taronga Zoo in Australia.
Performing Animal Welfare Society
Ironically, in light of In Defense of Animals’ dismissal of the threat of TB to elephants and humans in connection with the Packy case, the issue emerged among the zoo and public health communities largely through the work of longtime IDA campaign partners Pat Derby, who died in February 2013, and her companion Ed Stewart. Derby and Stewart were cofounders in 1984 of the Performing Animal Welfare Society and in 2000 of the Ark 2000 elephant sanctuary near Galt, California.
Derby and Stewart learned and warned about the spread of tuberculosis among the U.S. captive elephant herd while researching elephant attacks on zoo and circus staff. The USDA Animal & Plant Health Inspection Service did not become visibly responsive to their concerns until after an elephant named Joyce collapsed and died from TB during dental treatment in August 1996, shortly after performing for the Circus Vargas in Los Angeles.
Joyce, part of a herd owned and leased to various circuses by the Hawthorn Corporation, died 10 weeks after the USDA rejected a PAWS request that she be taken out of performances because she had lost about 1,000 pounds during the preceding year.
Los Angeles County director of disease control Shirley Fannin discovered in necropsy that at death, Joyce’s lungs were 80% destroyed by tubercular scar tissue. Joyce’s companion elephant, Hattie, died of TB a week later.
TB meanwhile appeared among the Los Angeles Zoo elephants. Whether transmission somehow occurred when Joyce was weighed on Los Angeles Zoo equipment was not determined.
One tubercular elephant had been sent from the Los Angeles Zoo to the San Francisco Zoo. TB was soon identified among the San Francisco zoo elephants as well, and was then found in other zoos throughout the world.
TB continued to spread among the Hawthorn elephants and elephants known to have had contact with them, in particular, leading eventually to the 2004 dissolution of the Hawthorn Corporation and the retirement of the surviving elephants to The Elephant Sanctuary in Hohenwald, Tennessee.
That led, indirectly, to a 2009 tuberculosis outbreak at the Elephant Sanctuary that spread from an elephant to eight staff members. A dispute over how the outbreak was handled brought the 2010 exit of founder Carol Buckley.