Emerging Animal Diseases: Global Markets, Global Safety: Workshop Summary (2002)

The importance of preparedness and the need for stronger biosecurity measures to reduce potential threats to animal health and food safety were recurrent themes at the workshop. Several speakers noted that foot-and-mouth disease (FMD) exists in many countries, and, therefore, the FMD virus has probably been brought into the United States unintentionally numerous times each year, although so far it has failed to produce detectible infections or take hold in the agricultural industry. Some expressed the view that the risk of accidental or intentional introduction of both FMD and BSE, or “mad cow disease,” remains high.

“Emerging diseases are the norm and not the exception,” and being prepared is crucial in dealing with new diseases when they happen, said Dr. William Hueston, Director of the Center for Animal Health and Food Safety at the University of Minnesota. “So, where should we look? How should we be prepared? We should be looking for new diseases to emerge where the pressure for change is the greatest,” he told the gathering.

Reiterating a point made by several other speakers, Hueston said FMD

and “a whole range of other disease agents enter the United States multiple times each year.” Arrival of the agent does not automatically mean emergence of the disease, since this is contingent on interactions among the agent, host, and the environment. “Because agents, host characteristics, and the environment are constantly changing, there are always new opportunities for diseases to emerge,” he said.

Hueston also described key trends in demographics, agriculture, and the environment that can help one predict where and when diseases are likely to emerge or re-emerge. Population growth in cities and suburbs is causing increasing encroachment of suburban areas on “what heretofore have been wilderness or wildlife areas,” he said, noting that this has led to more interactions between humans and wildlife. He cited as an example problems caused by the overabundance of deer in the suburbs of Washington, DC, and many other cities. Hueston said that it is within these “ecoclines,” or locations where ecosystems meet, that new diseases are most likely to emerge. He recommended expanded surveillance in these areas, especially where humans, domestic animals, and wildlife interface. He also argued for more integration of the animal health and human health infrastructures. “Remember, diseases work both ways, from humans to animals and from animals to humans, and I think it is a dynamic interface.”

Diseases are also likely to emerge in high-population agricultural areas with large animal populations, where demographics are changing the most, and where there is pressure to intensify production. Environmental changes caused by changing weather patterns and human interventions, such as the draining of wetlands, construction, and landscaping, also increase our vulnerability to new diseases. “As the environment changes, it creates new ecologic niches,” he noted.

On the issue of public policy, Hueston noted what he referred to as the “conundrum of prevention”: As countries attain a higher health status, they tend to reduce their investment in animal health infrastructure. This is because governments get credit for solving problems, but not for preventing them. “If we are successful in preventing a disease, we will be condemned for having wasted money for something that never occurred. If, on the other hand, we fail to prevent disease, then we will be condemned for not taking more aggressive actions and spending more money.”

Hueston concluded that “anticipating and responding to the next major animal disease threats is going to require an integrated and coordinated interdisciplinary approach.” Hueston added that this approach would require flexibility and broader use of resources in public and animal health, civilian agencies, and the military.

The Food and Drug Administration’s (FDA) regulation of BSE is “probably the most visible issue that we have in the area of animal feeds” because of its potential for adverse effects in humans, as well as animals, Dr. Stephen P. Sundlof, Director of the FDA’s Center for Veterinary Medicine, told the gathering. One key measure against BSE is an FDA rule that prohibits the feeding of most mammalian proteins to cattle and other ruminants. “What we learned from the United Kingdom experience was that BSE is spread almost exclusively through feed and that, by establishing a rule that would prevent any infectious or potentially infectious materials from being fed to ruminants, we have a single point of transmission or a choke point on which to stop the disease, should it enter the country,” Sundlof said.

Enforcement of this ban is “absolutely critical” in keeping BSE out of the United States, and therefore the FDA has stepped up its inspection of feed mills, renderers, transporters, and protein blenders that handle prohibited material, he added. The FDA also works closely with the USDA and the customs service to keep infectious materials from entering or getting beyond U.S. ports. These controls have been very effective, he said, as not a single case of BSE has been diagnosed in the United States. It is also the responsibility of U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Agency (APHIS) to provide the domestic surveillance and monitoring, should BSE enter the United States, Sundlof said.

Salmonella in animal feeds is another concern because feed can be a vehicle for transmitting Salmonella not only to animals, but also to humans, Sundlof said. He added that the FDA is working to define what the Salmonella standard should be in animal feeds and to inform livestock producers and feed manufacturers about the issue. If educational efforts are not sufficient to control the pathogen, the agency may have to take stronger regulatory measures.

Another prominent issue that the FDA is studying is antimicrobial resistance resulting from the use of antibiotic drugs in food animals. Preliminary research using Enterococcus as a marker indicates that the problem is linked more to the production environment than to feed. Still, “we are finding bacterial loads in virtually all animal feeds,” he said. “It is more heavily associated with those animal feeds that contain meat and meat by-products than it is for those that are purely vegetable in origin.”

In addressing how the various agencies with responsibilities for animal Because of the time required to obtain results, serology (testing the blood

health and food safety, particularly those with overlapping duties, are working together, speakers said that interagency collaboration and communication have improved recently, driven by the new sense of urgency in this area.

Brackett said the FDA and USDA’s Food Safety Inspection Service have some areas of overlapping jurisdiction. Problems arise not so much from turf battles as “just a failure to communicate,” he said, noting that the current systems of communications are “probably better than they have ever been,” due in large part to the need to work together on public health and animal health issues such as BSE.

Rexroad said collaboration between the Agricultural Research Service (ARS) and APHIS in emergency management “has been quite good.” The ARS will provide APHIS with facilities and scientists whenever there is an outbreak, he said, and the two agencies work together on the development and validation of assays. The National Animal Health Emergency Management System, though formally managed by APHIS, is really a collaborative function involving various federal, state, and commodity groups, he added.

Australia remained free of BSE and FMD in 2001 and has been successful in keeping other diseases under control, Dr. Philip Corrigan of the Australian Embassy told the gathering. Australia’s success in building a multipronged, multi-stakeholder system for disease management has been achieved with great effort, much planning, and at tremendous cost, he said. Corrigan added that the nation is “totally reliant on exports” of livestock and other products and thus is highly motivated to protect the agricultural industry from diseases.

One of the key features of Australia’s system is the close collaboration between government and industry in disease management, Corrigan said. An industry council works closely with the federal and state governments in deciding on priorities for disease control and on funding for eradication and control programs. This collaboration even extends to cost-sharing. “There is a formal cost-sharing agreement for 12 designated foreign diseases, and the cost-sharing arrangement is enshrined in legislation,” he said, noting that it includes FMD and classical swine fever. An agreement on BSE is now being negotiated.

Another feature of the Australian system is its linkage of foreign disease management and emergency management. “The introduction or

management,” which means that the State Emergency Service (similar to the Federal Emergency Management Agency in the United States) intervenes and assists with veterinary and other services. Australia also has produced a detailed manual on disease management, called the AUSVET Plan, which provides guidance on the epidemiology of various diseases, diagnostic and control procedures, training resources, and the like for various sectors. Australia is also an active participant in multilateral organizations such as the Office of International Epizootics and the World Trade Organization. identification of a foreign disease in Australia would be treated like a flood disaster, a drought disaster, a natural disaster in terms of mitigation and