Emerging zoonoses on the rise

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Concern over the growing list of new and emerging zoonotic diseases—avian influenza, West Nile, monkeypox, and Nipah—drew experts on veterinary medicine, public health, ecology, conservation, microbiology, and disease modeling and forecasting from around the world to the World Health Organization headquarters in Geneva, Switzerland. They met May 3-5 to identify the factors causing diseases to jump from animals to human, and to improve systems for monitoring and controlling zoonoses.

The WHO, the United Nations Food and Agriculture Organization, and the Office International des Epizooties held the meeting jointly, with financial support from the Dutch Health Council. Attendees identified several priorities for tackling the rise of new and emerging zoonotic diseases, including more collaboration among organizations, improved surveillance systems, and more communication among veterinarians, physicians, and public health practitioners. At press time, the WHO and meeting participants were compiling a comprehensive report on the proceedings. When completed, the proceedings will be posted on the WHO Web site, www.who.int.

Though they brought with them various perspectives, attendees agreed on one thing—there are going to be more emerging zoonoses in the future, and combating them will require multidisciplinary cooperation on a global scale.

"This new era of emerging diseases will continue and maybe even accelerate," said Dr. Lonnie King, the dean of the Michigan State University College of Veterinary Medicine, who attended the meeting as a representative of the OIE and works as a consultant for the national Centers for Disease Control and Prevention.

The WHO identified the ecologic impact of human activities as the most important risk factor in the rise of emerging diseases. Specifically discussed were the roles of international travel, global warming, trade in exotic and wild animals, population growth of humans and domestic animals, encroachment of humans and domesticated animals into wildlife habitat, and concentrated agriculture operations in close proximity to human populations.

Attendee Dr. Jonathan Epstein, senior program officer of the Wildlife Trust's Consortium for Conservation Medicine, said the recent outbreaks of severe acute respiratory syndrome perfectly illustrate how human actions contribute to the emergence of zoonotic diseases.

"(SARS) was something that stemmed from the wildlife trade-animals in the marketplace at high density affecting people in close contact with those animals," he said.

Global travel then allowed the disease to travel quickly to other parts of the world, including North America.

"Travel around the world is faster than the incubation period of these diseases," Dr. King said.

The SARS outbreaks also were an example of how scientists can work together on a global scale to try to understand a disease, and try to contain outbreaks, Dr. Epstein said.

"The key message (of the meeting was) the importance of collaboration and teamwork in identifying emerging zoonotic diseases," said Dr. Bruno Chomel, a professor of zoonoses at the University of California-Davis and the director of the WHO and Pan American Health Organization Collaborating Center on New and Emerging Zoonoses.

According to Dr. Chomel, more meetings between the WHO, the FAO, and the OIE will follow to work on improving surveillance systems.

"The WHO will certainly take a lead role working with the OIE and FAO to better collaborate on reporting of zoonotic diseases," he said.

"One plane trip ... away"
The recent SARS, West Nile, and monkeypox outbreaks illustrated how new and emerging zoonoses can have a global impact, and that North America is not immune to this phenomenon.

"We are one plane trip or one import away from a major epidemiologic event," Dr. King said.

This puts veterinarians on the front lines, according to meeting attendees. Dr. Epstein said the monkeypox outbreak, which started with the importation of infected Gambian rats and other African rodents and spread to prairie dogs through the exotic pet trade, was a great example of the important role veterinarians play in combating those diseases.

"Not only were (veterinarians) affected directly as cases, but also, they were the first people to see the source of this zoonotic disease," Dr. Epstein said. "It's important for clinicians to be aware of these issues."

Dr. King agreed that veterinarians must be aware of emerging diseases. He explained that the growing popularity of exotic pets in North America could lead to the importation of other emerging, zoonotic diseases. Also, 80 percent of bioterrorist agents are zoonotic, he said.

"We are just as likely to find these new diseases in our clinics or veterinary diagnostic laboratories, as we are to find them in a human hospital," Dr. King said.