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Vol. LIX, No. 11
June 1, 2007

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The 800-Pound Gorilla as Patient
Wildlife Vet Calls For Global

  Dr. William Karesh  
  Dr. William Karesh  
Dr. William Karesh is a different breed of vet. Although his home office is at the Bronx Zoo, he isn’t there a lot. As head of the Field Veterinary Program of the Wildlife Conservation Society (WCS), Karesh tracks diseases from the forests of central Africa to the steppes of Mongolia. He recently touched down at NIH to speak on “Wildlife Surveillance: An Early Warning System for Ebola, Avian Flu and Other Disease Outbreaks.”

“We think distinctions between human health, livestock and wild animals are completely artificial,” he told the crowd in Bldg. 50’s conference room. “There is only one world, only one health.”

While his mission rhymes with that of NIH, it calls for a different focus. As a conservationist, Karesh’s practice isn’t about zoonoses—diseases transmitted from animals to humans. Yet his work dovetails with public health and so connects him with the emergency preparedness and biodefense interest group, his campus host.

“We use a matrix: find a disease with a common concern,” he says, “and use it as a tool to bring people together, to work together.” Karesh surveils “sentinel animals” such as wild swans, which are particularly sensitive to a highly pathogenic strain of bird flu. He builds interdisciplinary teams of veterinarians, biologists, public health and conservation professionals and local people, engaging them to build capacity, do research and advocate for smarter policies and guidelines.

Here’s how it works. “The traditional approach in Ebola was to wait for people to start dying,” he explains. “These areas [in central Africa] are really remote; there are no phones. So we pushed forward to have intervention and education before outbreaks.”

Enter the animals. Gorillas are very susceptible to human diseases such as salmonellosis and tuberculosis, as well as Ebola and measles, to which they have no immunity. “There are only 600 mountain gorillas left,” says Karesh. “Even a respiratory infection can lead quickly to death. We wanted to protect them—but how?”

Karesh heads the Field Veterinary Program of the Wildlife Conservation Society.
Karesh heads the Field Veterinary Program of the Wildlife Conservation Society.

The WCS started the first comprehensive preventive health program for gorillas in central Africa, where Karesh’s teams taught local people to do simple lab tests, trained them in record-keeping and urged them to stay alert to animals around them. He found that because hunting is a way of life there, the bushmeat trade drives disease. But once WCS staff convinced hunters to think about contact rates as a way to protect their families, they started to listen. A pattern emerged: a month or two before a human Ebola outbreak, hunters would notice animal carcasses; but now, if they spotted a dead gorilla, they knew not to touch it and would instead notify officials.

Result: “We came up with a link to Ebola from the consumption of apes and we couldn’t have done that without having trained the [national] park guards and raised awareness of local people.”

WCS vets and collaborating scientists were able to respond quickly to the crisis. Karesh’s staff remains on-site year round, ensuring that conservation becomes part of disease education in central Africa, as well as in over 300 field projects in 60 countries around the world. “Now we have a new partner in conservation,” he says, “and they have a new partner in health.” WCS also has a wide range of public/private partners among non-government organizations and government agencies, including NIH and the Centers for Disease Control and Prevention.

Karesh also surveils poultry and wild birds, which can be reservoirs for the H5N1 bird flu virus. “We already know what’s going on in animals,” he says. “It has to do with human behavior and how we live our lives, and it’s not hard to know how diseases cross species lines.” He pointed to a letter published in The Lancet; its writer, a British scientist, proposed that the SARS virus was brought to Earth on a comet or meteorite. SARS is severe acute respiratory syndrome, a human illness caused by a coronavirus. “You don’t need to send a virus from outer space,” Karesh says wryly.

“You don’t need to send it on dry ice—it’s easier to send it in an animal.” The bird trade in Asia is huge, with China moving 2 billion ducks per year, he notes, and there’s a lot of money involved in these markets where “there’s no sanitation, no control, no quarantine.” Cockfighting, crowding and humans co-habiting with birds offer plenty of chances to swap viruses. And given that domestic mallard ducks are used to control snails in rice fields, where their stools shed H5N1, “there’s a system in place for contamination by the duck production system.”

Still, ducks aren’t as susceptible to H5N1 as are wild swans, so Karesh traveled to Mongolia to gather environmental and census data on what birds were there: “What has been missing are sound epidemiological investigations to understand how wild birds fit into the H5N1 story. In the process, we were able to collect H5N1 samples from a dead swan and send them to USDA, CDC and WHO, who selected the isolate as a potential human vaccine candidate. It only took 3 weeks because people had already agreed to work together and we served as a neutral, non-governmental facilitator.”

Swans were fitted with satellite tags. Since they nest thousands of miles from where they spend the winter, Karesh’s team was able to map their flight and observe a vivid correlation: the swans flew over poultry outbreaks from China to South Korea. With support of USAID, CDC, USDA and others internationally, WCS has begun rolling out wildlife disease surveillance around the world.

“As people do these investigations, they can share data even before they do the lab work,” says Karesh. “Avian influenza is a good model to get people to work together—we’re not waiting to publish.”

For more information on the Global Avian Influenza Network for Surveillance, visit NIH Record Icon

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