animal health/emerging animal diseases / International Lookouts for Infectious Animal Diseases

The Role of Disease Surveillance
in the Watch for Agro-terrorism or Economic Sabotage

Dorothy B. Preslar, Director AHEAD/ILIAD, November 2000
(Edited and Augmented for Web Publication)

The threats of terrorism and economic sabotage against agriculture in the United States are neither fixed nor certain. Some have said that it is not a matter of "if", but "when". Only the future will determine the accuracy of that assessment, because when either of the threats moves from the possible to the actual, then and only then does it answers the question of "if".

There are also those who say that terrorism political or economic is a greater threat against US agriculture than it is against US citizens. The underlying rationale is that terrorist-type use of biological agents against animal and plant populations:

  • Could introduce a new dimension to terrorist strategies
  • Is not as repugnant to prevailing sensibilities as use against humans;
  • Cannot easily be proved intentional if no "exotic" pathogen is used, and cannot definitively proved intentional if an "endemic" pathogen is used;
  • Can be instigated without violating international arms control agreements;
  • Would incite neither a crushing military response nor international man-hunt unless claimed by perpetrators
  • A. New Dimension: Although the history of biological weapons includes the production by several countries of anti-animal and anti-plant pathogens that could be used to sabotage food supplies and transport capabilities, in only one instance have such agents actually been used. Glanders and anthrax were used by Germany in World War I to intentionally infect horses being shipped from the United States, Argentina and Morocco to Europe. The presumption of military historians is that the agents may have played a role in the deaths of those animals that did not complete the journeys, but to what extent is not known because diagnoses were either not attempted or not recorded. Successful use of these anti-agro pathogens would be a "first", at least in contemporary history and, thus, perhaps constitute an appealing new weapon to add to the terrorist arsenal.

    B. Lack of Sensitivity: Notwithstanding the fact that many countries, including the U.S., have in the past developed, produced and stockpiled biological agents for possible military use, there has long existed in non-military circles a "norm" of repugnance against their use. It is this "norm" that provided the foundation for the Geneva Convention of 1925 and the Biological and Toxins Weapons Convention of 1972, and also prompted President Nixon in 1969 to order the destruction of the U.S. stockpiles and to limit the U.S. program to defensive research only. The "norm", however, is less compelling a protection for animals than for humans. As the canary was used to detect dangerous gases in mines, chickens are routinely used as sentinels for identifying the appearance of encephalitis viruses. In the current U.S. outbreak of West Nile virus, the deaths of crows, songbirds, horses and small wild mammals are, without apparent concern, pointed to by public health officials as barometers of the potential for more human infection.

    C. Proving Intentionality There are numerous serious animal and plant disease pathogens, as well as crop pests endemic to the U.S. In most cases, their appearance and damage are controllable by vaccination or pesticides, by sterile insect technology, by adherence to preventative agricultural practices and by "good sense" avoidance of exposure. And, in most cases, they are controlled . The downside in this fortunate situation is that the longer a disease or pest is not seen in a locale the larger the temptation to abandon the preventative measures. This is most aptly illustrated by the reappearance of whooping cough and measles in children whose parents were lulled by disease statistics into foregoing vaccination. With respect to animal and plant populations, occasional lapses in these measures bring the possibility of loss; continued lapses bring the certainty of loss, as has been demonstrated in countries formerly part of the Soviet Union, where disease prevention has largely collapsed. In recent years, a number of plant diseases and crop pests have been introduced into the U.S. Citrus canker is a serious problem in Florida; Pierce's disease threatens grapes and avocados in California. These two situations involve reappearances of diseases thought eradicated. There is absolutely no indication that they were intentionally re-introduced, but had they been it would be extremely difficult to prove. It seems reasonable, therefore, that the clever saboteur might forego diseases not before seen and consider those that have been detected previously, as well as those that are endemic to the U.S. or other countries in North America.

    D. Actions Outside Agreed Prohibitions The protocol now being negotiated to put some teeth into the BTWC includes language designed to act as blanket coverage of all hostile acts using biological or toxin agents. However, the definition of "hostile" is still in brackets (not yet adopted)
    "Hostile purposes mean
    [Any purpose, which has no prophylactic, protective or other peaceful intention.]
    [4 bis (a) The use of bacteriological (biological) or toxin weapons or the threat of use [by a State] with a view to inflicting military, economic, [moral] or other kind of damage; ....]"

    Until "economic...or other kind of damage" escapes the bracketing and becomes permanent provisions of the protocol, and until the protocol is adopted and ratified by States Parties, there is no prohibition against agro-terrorism or economic sabotage, absent development, production and stockpiling of prohibited agents. And what is further disturbing about the bracketed language is that even though the protocol has been in negotiation for more than six years there are still no definite parameters, no surety of what actions the protocol prohibits. At this juncture, the actions behind the hypothetical scenario described later in this paper would not constitute prohibited purposes, since the scenario implies the introduction of diseased animals rather than dispersal of pathogens.

    E. Uncertain Response: The potential response of the U.S. to hostile use of biological and toxin weapons against American agriculture is unknown, because it comes under the "intentionally vague" WMD response policy adopted during the past decade. Even so, it seems reasonable to conclude that an intentional use of anti-crop or anti-animal agents that results in zero human mortality will not trigger a crushing military response. And perhaps not even an international man- hunt. Much would depend on (1) whether the perpetrators claimed responsibility for the attack, something that was once de rigeur but increasingly declined by known terrorist groups, and (2)whether a trail to anyone associated or identified with a terrorist group was established early in the investigation and pursued to success.

    If these elements of the rationale have merit, then those who fear agro-terrorism more than a biological attack on human populations, may have a point. There are a number of biological agents among them: anthrax, tularemia, hemorrhagic fevers, plague, yellow fever, Q fever, equine encephalitis viruses that have been identified as prime possibilities for terrorist use against human populations. Few of these as cultures are efficient or predictable or capable of causing mass human casualties in a startling single event, which is the hallmark of terrorism. In the case of anthrax, the most media-hyped pathogen, it would require huge quantities of the lyophilized form, a non- interdictable dispersal mode, a large city or sports stadium filled to capacity as the target, and "perfect" weather conditions to cause such an event.

    US agriculture is, on the other hand, a tempting target for the use of biological agents that primarily kill animals and affect humans not at all or only secondarily and with lesser morbidity and mortality. Newcastle Disease and highly infectious avian influenza can temporarily wipe out entire poultry operations. Foot and mouth disease, swine fevers, rinderpest and the new Nipah virus can disrupt beef and hog production. Bovine tuberculosis can temporarily arrest milk supply and prejudice livestock products. The new Hendra virus (the equine morbillivirus that surfaced in Australia in 1994) and various equine encephalitis agents can be used with sufficient effect against horse breeding operations. Further, there are threats from toxins, fungi and, prospectively, novel combinations of disease agents.

    In using biological agents against US agriculture, the goals of a terrorist or saboteur would not be to destroy whole animal populations, or even to empty the meat bins of your local supermarket for any sustained period of time. The goals are far more subtle and, therefore, capable of insidiously undermining our society, political system and economy.
  • Make Americans aware of their vulnerabilities
  • Create skepticism that government can protect American interests
  • Build distrust in the national food supply
  • Incite anger at the particular administration in power and, if an "October Surprise", to sway voters to the other political party
  • Disrupt America's sizeable international trade in agricultural products
  • Increase the perpetrating country's market share
  • Retaliate against import bans or pejorative marketing schemes
  • Stymy growth in prosperous times or to deepen recessions

    It is thought by some analysts that much of the rhetoric about agro-terrorism exists because there is a trend in the US Congress to address certain needs not on the popular agenda only if it can be convinced of their importance to national security. Thus, when the USDA needs an additional argument for funding proper and necessary research at the Orient Point/Plum Island facility, or hiring more APHIS inspectors or engaging in more cooperative work with other countries to find out what is going on outside our own borders, the current winning argument is terrorism.

    In any case, what we need to do to meet potential terrorist-type threats is the same thing we need to do to ensure the continuity of a safe and ample food supply, to protect our international markets, to avoid the high costs involved in stamping out a disease that should not be here in the first place, and to enhance our scientific credibility. One essential element in a plan either to be prepared for these threats, or to take care of business as usual, is effective and inclusive disease monitoring and surveillance.

    The observations of the animal owner or farm manager, the general impressions of a herd or flock noted by a veterinarian or agriculture extension officer, or examinations or tests of individual animals when disease is suspected or evident are basic to surveillance. As are the records of the above activities and subsequent reports to authorities. However, with our system of notifiable diseases, this base of information may be set aside, and sometimes not even preserved in an easily accessible form, if the diagnostic test indicates a disease not on the notification list, or is inconclusive in a situation where the problem is confined to a few small farms, a kind of hit-and-run scenario. Thus, at the state and national level, this phase of surveillance can become what I think of as monitoring, because it takes the form of a compilation of basic information on notifiable diseases which notifiable disease, how determined, and where and when.

    Further, there are disconnect points along the path towards compilation. If the owner or farm manager does not call in a veterinarian or extension officer, no information will be generated. If the veterinarian or extension officer, perhaps as a favor to his client, makes no report to state authorities, or if the laboratory, perhaps as a favor to the veterinarian, makes no report, the compilation is incomplete.

    Surveillance is the creation of important and essential information on all significant factors of disease outbreaks information that may allow us to know how and why the disease has occurred, and if the disease is changing, spreading into new areas or infecting new species; and that may suggest ways to prevent future occurrences. Moreover, surveillance is not necessarily limited to a short list of notifiable or most feared diseases. The more productive parameter would be certain clinical syndromes that could involve differential disease diagnoses.

    Given computers and instant electronic communication, monitoring at state and national levels is the easier, and will quickly become the less expensive, activity, since it addresses only the diseases whose notification is required and since it is essentially a matter of collecting and integrating reports coming from private and state veterinarians and diagnostic laboratories and applying pre-designed software programs to generate analyses and risk assessments.

    When some people talk about national disease surveillance they often appear to be talking only about those activities distinguished above as monitoring. By whatever name it is known, it is an important function. But it is like gauging the size of an iceberg by looking at its tip.

    Surveillance, on the other hand, measures the total mass of the iceberg, plus (to stretch the analogy a bit) it explores the water around it, the air above it, the ice mass it broke away from, the rate of its melt, the direction it moves and at what speed, its relationship to other icebergs in the same area. As applied to outbreaks of animal disease, it is an investigation that measures the possibilities existing in individual herds and flocks, in breeding operations, in feed lots, in imports, in vaccination programs, in feed stuffs, in climate anomalies, and even in the disposal of aborted fetuses and manure. It takes time, it takes talent, it takes money and it takes enormous prescience to know where to deploy those resources to the best advantage.

    How is surveillance achieved? There are at least four generic categories of activity in our current approach, and all of them are investigative in nature.
  • Port-of-entry Import Inspection and Quarantine
  • Immigration Screening and Fumigation
  • Extension Services and Field Investigations
  • Diagnostics and Research
  • Port-of-entry Import Inspection and Quarantine: The US has a system, APHIS, that has been highly effective for many years. Information in the public domain indicates that failures to detect pests and to quarantine for pathogen possibility have been few and far between. What are the some of the pressures that could alter that record?

  • A) Changes in, and additions to, the list of trading partners resulting from globalization
  • B) Increased importation of relevant commodities
  • C) Cuts in funding, or failure to increase funding to cover heavier workloads
  • D) Inability to attract qualified inspectors
  • E) Political pressure (local or international)
  • F) Lack of timely information on international events
  • G) Failure to apply or to develop appropriate screening diagnostics
  • Immigration Screening and Fumigation: While the US system for barring entry of suspect or illegal aliens, and for detecting customs violations, is developed to a high degree of efficiency and effectiveness, its ability to prevent the introduction of pests, disease vectors and pathogens into the country by travelers is just short of abysmal, as is true for a number of other countries. What are some of the obvious deficiencies?

  • A) No requirement that returning US citizens specify where travel took them, type of area (urban, suburban, rural, park/sanctuary/reserve) and specific reason for travel (business, professional, conference, education, vacation, personal)
  • B) No requirement that US citizens specify their employment or profession
  • C) No routine fumigation of planes, cruise ships or vehicles upon arrival from countries where infectious disease vectors are prevalent
  • D) Insufficient and provincially oriented questioning ("Farm or ranch?")
  • E) Profiling of certain foreign visitors (e.g., those who are not required to have a visa for entry) as non-risks and treating them as casually as US citizens.
  • Curing these deficiencies would doubtless incur initial protest from both individuals and transport and tourism industries. Except, however, for the fumigation, the cure involves only a slightly longer disembarkation form and a slightly longer wait at the gate as more specific questions are asked if triggered by information supplied on the embarkation form. Further, the deficiencies may be considered acceptable risks and their cure not cost-effective. But it is something to think about, if the idea is to fine tune surveillance at entry ports.

    Extension Services and Field Investigations: Extension services are usually provided by state universities in cooperation with state and federal departments of agriculture. It is difficult to characterize their operations with respect to disease surveillance and clinical services, since each state cooperative extension service focuses on the needs of the majority of in-state farmers. In states where livestock and poultry production is preeminent, animal production programs would likely be more extensive than crop disease and pest programs. Extension services traditionally include farmer education and hands-on assistance.

    Field investigations are largely formed and carried out by state agriculture departments and by university researchers under grants from state and national agencies. As a general rule, investigations done within the context of research unrelated to a current or imminent threat are not immediately essential to an action plan. This is the case when an investigation comes after an outbreak and does not turn up new cases of the disease. The results of research investigations may be only summarized to the sponsoring institution, and the investigators are at leisure to produce a paper which is then submitted to an appropriate journal for publication. If errors have been made, they damage only the reputations of the authors. However, when done within the context of an emergency or a continuing threat, field investigations are critical to control and stamping out operations. If errors are made in this context, they can be serious.

    In 1995, Wisconsin had its first case of bovine tuberculosis in eleven years. It was a single case, at first reported to have occurred in Oconto County but later discovered to have occurred in Shawano County, in a heifer thought to have been traded in from Michigan. This one case, which immediately cast a cloud over the state's $4 billion-a-year livestock industry, turned up alarmingly lapses in record-keeping by livestock dealers. Even more discouraging, when the events of 1995 (including a temporary suspension of Wisconsin's disease-free status) were subjected to intense scrutiny as ordered by the governor, the Wisconsin Department of Agriculture, Trade and Consumer Protection was charged with "complacency, lack of professionalism and substandard performance in animal disease investigation". What had happened was that the sick heifer, the single case, was discovered in April but not quarantined until July. Fortunately, the disease did not spread to other herds.

    On October 11, 2000, USDA Secretary Dan Glickman declared a bovine tuberculosis emergency. In pertinent part, it reads:
    "A decline in testing for tuberculosis in recent years also threatens to allow the spread of the disease in the United States. As the number of tuberculosis-free States has increased, limitations on Federal resources have in many cases led Department inspectors to take samples only from those animals exhibiting obvious signs of tuberculosis. The number of samples taken from cattle at slaughter for testing for tuberculosis has decreased from approximately 4,000 in 1995 to 900 in 1999. However, APHIS estimates that 10,000 sample submissions are needed each year to adequately survey the U.S. cattle population for tuberculosis. APHIS needs additional funds both to provide assistance in taking the number of samples at slaughter necessary for adequate surveillance and to increase testing capacity at the Department's National Veterinary Services Laboratories.

    "Therefore, in order to address the tuberculosis threat to U.S. livestock, APHIS has determined that it is necessary to expand the tuberculosis eradication program in the United States by implementing the following: Improvement of Federal diagnostic capabilities and national surveillance for tuberculosis; payment of indemnity for the depopulation of herds affected with tuberculosis or at high risk for recurrence of the disease; establishment of identification requirements for animals imported into the United States for feeding and slaughter; assistance in eradicating tuberculosis from foreign areas adjacent to the United States that are at high risk for the disease; and research, control, and surveillance of tuberculosis in wildlife, captive cervids, and zoos in the United States. However, APHIS resources are insufficient to carry out these measures, and additional funds are needed. Therefore, in accordance with the provisions of the Act of September 25, 1981, as amended (7 U.S.C. 147b), I declare that there is an emergency that threatens the livestock industry of this country and hereby authorize the transfer and use of such funds as may be necessary from appropriations or other funds available to the agencies or corporations of the United States Department of Agriculture to expand the tuberculosis eradication program in the United States." (65 FR 63227)

    With respect to bovine tuberculosis, this action is an important move away from the ad hoc intervention mode and perhaps signals a new era in which routine random sampling for other diseases will inform our efforts in prevention and control.

    Diagnostics and Research: Over the past two decades we have witnessed an explosion in biotechnology and the concomitant creation of diagnostic tools that not only distinguish between different strains of disease pathogens, but also between sub-types of those strains. We have tests that inform us if antibodies to certain disease pathogens have been formed by reaction to an infection or by vaccination. Moreover, some of these tools are being miniaturized into hand-held laboratories, and packaged as kits for field use. Many yield results in minutes, some in seconds.

    This bounty is counter-balanced by the realizations that it is now theoretically possible to create dangerous novel pathogens, and that the next generation of diagnostics must be capable of detecting the faint traces of genetic engineering magnification or diminution of virulence; insertion of highly pathogenic virus into, or encapsulation within, a bacterium; alteration of pathogenic sensitivity, like increasing the tolerance of a virus to heat or light. These accomplishments, if we may use that word loosely, may lie down the road a bit, but they are all but certain, simply because there is no turning back, and because there exists no universal ethical imperative against them.

    Research is crucial. But it must be research that explores possibilities not just the standard buzzword threats, not just the OIE's A and B Lists, and not just pathogens still in their birthday suits. To this end, there should be flexibility built into the agenda for the proposed BL-4 laboratory at Orient Point. Perhaps one gets that by opening up all activities to Congressional oversight and by total and continuous commitment to safety and containment.

    How can monitoring and surveillance assist in distinguishing between a natural outbreak and an intentional release of a disease agent? By informing the process by which the origin of an epidemic is discovered. The process is a combination of two major investigations conducted in tandem.

    A. Diagnostics = Forensics
  • Sample (blood, tissue, skin scrapings, nodes, etc)
  • Identify causative agent, sequence for strain and sub-type
  • Compare the causative agent with
    a)strains and sub-types of agents previously diagnosed in the US
    b)strains and sub-types of agents found in Mexico and Canada
    c)strains and sub-types found in countries of trading partners
    d)strains and sub-types found around the world
  • This part of the process is informed by disease surveillance on a global scale. At the present time, it is non-existent in some countries, inadequate in many others and incomplete even in our own. It is also informed by the pathogen banks at various diagnostic reference centers and collaborating centers associated with the OIE and WHO.

    B. Epidemiology = Detective Work
  • Inspect site and adjoining farms/facilities
  • Sample animals on other farms/facilities
  • Determine origin of animals (in-herd offspring, purchase, trade, stray?)
  • Determine recent history and movements of the animals
  • Examine food, pasture and water
  • Interview farmers/owners and inspect records
  • Investigate movements in and out of facility (visitors, employees, family members, vehicular traffic, light aircraft)
  • Review weather and wind patterns
  • Analyze all of the above to establish or rule out a common pattern
  • Identify index case or index situation
  • Construct and test alternative hypotheses on origin of outbreak
  • Conduct further investigations as necessary
  • Arrive at conclusions backed up by sound evidence
  • This part of the process is informed by surveillance and record-keeping on the local, state and national levels, and supplemented as necessary by national intelligence.

    One danger is that if the results of diagnostics show the causative agent identical to one associated with another country or region, there will be a temptation to focus the investigation on a suspect foreign origin and shortcut the process. Investigation is time consuming, but if followed methodically will produce scientifically sound conclusions and prevent premature reactions that could embarrass the US government and our scientific community.

    Another danger is that because economic and political needs to control the outbreak are of such immediate consequence, resources may be devoted entirely to the stamping out, with detective work left until later. If this should happen, the investigation could easily be compromised and skewed.

    To counter both of these possibilities, the U.S. needs to have investigative teams similar to those used by the National Transportation Safety Board teams composed of persons who can be objective and have no ongoing relationship with the USDA or state agriculture agencies, who are immediately available for dispatch to the outbreak location and who have the same jurisdictional authority as the NTSB vis a vis the FBI, National Guard, local or state police, etc.

    A Hypothetical Case

    On a family-run tobacco farm in southeast Texas, 20 miles from the Gulf coast, a cow gets sick. Within several days three more cows become ill. All of them are drooling. At that point, the farmer calls a neighbor to come take a look. The neighbor shakes his head and tells his friend to call Doc Jenkins, who is not a veterinarian but has long been the community's substitute shoes horses, assists in difficult calvings, and so forth. Later that day, Doc Jenkins stops by. Taking note of sores in the cows' mouths and in their feet, he says it looks like vesicular stomatitis. "Nothing to be done. No cure. I'll have to call the district offices and report this. Regulations you know. They'll send somebody down to take a look. But I'd lay off slaughter. It's a serious disease, but one or two of them may be better in a week or so." Jenkins calls the district vet office before leaving to visit another farm in the area.

    The next day, the district vet shows up, takes scrapings from sores on the cows, and says he'll get back to the farmer in a day or so. "In the meantime I don't want anyone or anything coming or going from here." The next day, the neighbor calls to say his cows are sick, too. The district vet calls to say that the first test was negative, and more tests will be done. Ten days have now passed since the first sick cow. The farmer's entire herd is sick, with most down and not getting up, their hooves raw and disfigured. Checking with his neighbor, he learns that other farms in the area have the same problem but none other than his own has been inspected. "No need for all of us to call. Once we know what you have, we'll know what we have," says his neighbor.

    On the 12th day, listening to the morning farm report, he hears that a large livestock producer to the north has been hit hard by an outbreak and that officials fear it may be foot and mouth disease. If so, first time in US since 1929. No animals are to be moved off farms until further notice. Road blocks are up. Two days later, a state disease control team arrives with the bad news. It is foot and mouth disease. All cattle and swine are to be destroyed. The farmer will be compensated for the loss. By sundown there is a graveyard back of the barn. The acrid smell of disinfectant hangs in the air.

    The evening news is that a six-county area is under quarantine after a lab in Iowa confirmed foot and mouth. Tens of large ranches and scores of small farms involved. The Congressman from the district is on television, saying it's believed to be the work of bio-terrorists from the other side of the world. But politics is always local, and the neighbor is on the phone saying "I'll get you for this. You ignorant wet back!" The state's agriculture department is dropping leaflets by helicopter, so farmers all over the state will know what to look for.

    The next morning another team arrives at the farm and starts asking questions. After covering what we already know of the tale, the farmer is asked "When was the last time you got any new stock?" He replies "Over a year ago. Except for two goats we got a few weeks back but didn't keep." To other questions come more answers: they were a gift; his cousin found them near the causeway to the beach at Galveston. "Knew they didn't belong to anybody around there. Fancy houses. No farms. My cousin had no place to keep them. Gave them to me. Birthday present, he said. I don't like goats that much. And these two walked funny. We slaughtered them when we got home. Meat's in the freezer."

    Later that week, the farmer gets a call. "We found the virus in the meat. So, it was probably the goats that did it. Lucky for us you froze the meat. Too bad you didn't know what to look for. Sore feet on a goat can be a sign."

    What to look for. . .

    A recent study entitled "Potential Impact of Foot-and-Mouth Disease in California," done by Javier Eckboir while he was a post-doctorate fellow at the University of California at Davis, is an overview of the disease and a detailed analysis of a hypothetical outbreak in Tulare County, California. In a published comment to the study, Hans Riemann, Professor Emeritus at UC School of Veterinary Medicine, writes:
    "The creation of huge data bases and large committees for early detection or tracing of FMD is only one approach, and not necessarily the most important. Farmers and their employees are the ones who must be relied upon for reporting of infected herds. Tracing exposed herds depends on local conditions, and the detective aceumen of the responsible veterinarians(s). Misdiagnosis is likely, and farmers should be encouraged to report not only suspect lesions. The first things that happens when an animal gets FMD is that it stops eating and producing milk. This is something the dairy operator will invariably observe, and should be encouraged to report if two or more animals are affected.

    "During the Pennsylvania avian influenza epidemic in 1983, it was observed retrospectively that the affected flocks showed a significant drop in feed and water consumption two weeks before peak mortality. Early warning systems based on abnormal changes in consumption or production parameters may be applicable to other diseases such as Newcastle disease and FMD. There will be false alarms, but even these will provide opportunity to educate farmers and improve their operations."

    What to look for. . .

    The FAS work in promoting global disease surveillance has, since 1996, been focused primarily on establishing an operational program in a sub-Saharan Africa country that will focus on the interface between wild animals and livestock in remote farming communities. The foundation of this bottom-up approach to disease surveillance is training others in what to look for and providing the tools necessary to do the looking.

    Over the past three years there have been repeated reminders by provincial and district veterinary officers that the small farmers and pastoralists of Africa know their animals to the point they can recite the full family tree and personal history of each head of cattle, and that what they don't know is how to recognize the earliest signs of certain diseases and how to get help when they need it as opposed to getting help when they don't. As one reviews disease outbreaks in the United States and the threat of more to come from whatever source and in whatever way the thought occurs that the need for disease recognition training for farmers and the employees of large production enterprises may be as great here as it is there. Given the differences in the respective livestock systems and the prevalence of serious disease outbreaks, education may perhaps be an even greater need in the U.S.

    More and more it has become evident that it will be wise to amend the focus on the investigative elements of surveillance -- disease forensics and detective work -- to include the "eyewitness" -- the first person always at the scene of the crime -- the people who day by day have the most contact with the potential targets of agro-terrorism and economic sabotage. Teaching these farmers and facility employees, and rewarding in some way their participation as sentinels, might make the difference in addressing the threat of agro-terrorism and economic sabotage.