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Potential Threats to Animal Health and Food Safety
The recent outbreak of foot-and-mouth disease (FMD) and the appearance of bovine spongiform encephalopathy (BSE) in the United Kingdom have increased awareness and concern about the potentially devastating impacts of these and other animal diseases. Building on the presentations of Moseley and King, several speakers described measures the United States is taking to prevent outbreaks of FMD, BSE, and other diseases and to deter sabotage within the agricultural system, as well as describing ongoing areas of concern and vulnerability. U.S. government officials discussed a range of additional threats to animal health and food safety, including diseases such as classical swine fever and highly pathogenic avian influenza.
EMERGING THREATS
In addition to the diseases mentioned above, participants expressed concern about several others that could emerge or re-emerge in the United States. These include classical swine fever, considered a very high-risk disease because of its presence south of the United States and in the Caribbean, according to Dr. Caird Rexroad, Associate Deputy Administrator of the U.S. Department of Agriculture’s Agricultural Research Service. Rexroad said researchers are also concerned about the re-emergence of the Texas cattle fever
tick, which was eradicated from the United States, but has since developed a resistance to classic methods of control.
New strains of existing diseases, such as highly pathogenic avian influenza and Newcastle disease that could be brought into the United States via imported or migratory birds, and previously unknown diseases like chronic wasting disease also present a growing threat and challenges in terms of new treatment methods. “In the extreme, we have to worry about recombinant organisms … how organisms might be put together or modified to attack, and we hope that extreme scenario is not the one, but it can’t be dismissed,” Rexroad added.
Other speakers discussed how ticks could be used as an agent for the spread of certain diseases such as Texas cattle fever, caused by Babesia bovis, and heartwater, caused by Cowdria ruminantium. Heartwater disease could be spread to deer by the Amblyomma ticks; from there it would “spread geometrically, and it would be really difficult to eradicate,” Brown said.
In areas with disease-spreading tick populations, one could achieve the same results by simply introducing the disease, without having to bring in the ticks, added Dr. Gary Weber, Executive Director of Regulatory Affairs, National Cattlemen’s Beef Association. Another factor, just as important as the disease and the vector, is the development of resistance to insecticides used to control ticks and other vectors. In combination, these factors can complicate control efforts, Weber said.
IMPLICATIONS OF SEPTEMBER 11 TERRORIST ATTACKS
Animal health issues are very closely linked to food safety and security, Dr. Robert Brackett, Director of Food Safety in the Federal Drug Administration’s (FDA) Center for Food Safety and Applied Nutrition, told the gathering. To illustrate his point, he displayed a list of bacterial and viral risk agents associated with animals (See Box 3-1). The list, published by the Centers for Disease Control and Prevention (CDC), include bacteria, such as the anthrax pathogen, and viruses, such as the one that causes yellow fever, that could be used for bioterrorism.
Brackett said the agency’s traditional approach to inspections of food imports was based largely on volume, i.e., the largest exporters to the United States, such as Canada and Mexico, would have more of their products scrutinized. Now the agency is rethinking that strategy, considering whether to target certain countries or products. The scope of surveillance has also been broadened, with more focus on intentional biologic, chemical, and radiologic threats, he said.
In addition, the FDA no longer assumes that industry and individual producers are concerned only with unintentional contaminants in foods, Brackett
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BOX 3-1 Category A Diseases/Agents High-priority agents include organisms that pose a risk to national security because they can be easily disseminated or transmitted from person to person, cause high mortality and have the potential for major public health impact, might cause public panic and social disruption, and require special action for public health preparedness. Category B Diseases/Agents Second highest priority agents include those that are moderately easy to disseminate, cause moderate morbidity and low mortality, and require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance. Category C Diseases/Agents Third highest priority agents include emerging pathogens that could be engineered for mass dissemination in the future because of availability, ease of production and dissemination, and potential for high morbidity and mortality and major health impact. Category A Bacterial Agents Bacillus anthracis (Anthrax) Yersinia pestis (Plague) Francisella tularensis (Tularemia) Category B Bacterial Agents Coxiella burnetti (Q Fever) Brucella species (Brucellosis) Bukholderia mallei (Glanders) Clostridium perfringens Epsilon Toxin Staphylococcus aureus Enterotoxin B Category C Bacterial Agents Multidrug-Resistant Tuberculosis Category A Viral Agents Viral hemorrhagic fever Lassa fever Rift Valley fever Ebola hemorrhagic fever Marburg hemorrhagic fever Category C Viral Agents Hantavirus Nipah virus (encephalitis) Yellow fever |
said. There is more awareness of the possibility of tampering or the premeditated manufacture of harmful products, including the pirating of existing products. Concerns about terrorism have also prompted the agency to issue guidance to food producers and processors to help them identify their risks and to establish new relationships with intelligence and law enforcement agencies to enhance intelligence gathering.
