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27 Feb 2003

Source: The Chronicle of Higher Education, October 26, 2001. 

One More Frightening Possibility: Terrorism in the Croplands


Imagine a terrorist attack on wheat fields. Cattle killed off by disease. Dying chicken populations. Those scenarios probably don't trigger as much anxiety as do better-known threats of bioterrorism such as anthrax, bubonic plague, and smallpox infection. But assaults on agriculture could just as easily cripple a country and would be far simpler to pull off, say a growing collection of experts.

Even if the resulting livestock or crop diseases did not, in turn, affect human health, such an attack could cause widespread harm: the destruction of millions of animals or plants, a loss of trade worth billions of dollars, rising food prices, and citizens' loss of confidence in food safety and government protection.

Mark L. Wheelis, a biologist at the University of California at Davis, says he and others who have studied agricultural bioterrorism are worried: "The fact that it would be fairly easy to do leads a lot of us to be pretty scared about it."

"If I were plotting a terrorist strategy, particularly to follow something so big and successful as the airliner attacks [on the World Trade Center and Pentagon], I would be looking at biological weapons. And I'd probably be including agricultural ones in that arsenal, with the specific intent of collapsing the U.S. economy if possible," he says.

Given the potential for widespread economic disruption, a number of researchers are now stepping up work that could protect the nation's livestock and crops from disease, at the same time that the government is increasing its surveillance of agriculture. The work is important but rarely eye-catching: It includes studies as mundane as figuring out the best way to clean farmers' boots.

Scientists, terrorism analysts, veterinarians, and others who have considered the possibility of agricultural terrorism have reached no consensus on its likelihood, with some noting that no documented cases have occurred in the United States. But experts -- and terrorists -- need only look at the economic damage caused by accidental introduction of foreign animal diseases to realize that intentional releases could be a potent weapon.

Britain already has killed four million animals and has spent $2.7-billion in its effort to control foot-and-mouth disease there. According to an article by Peter Chalk, an expert on terrorism at the RAND Corporation, an outbreak of the same disease in Taiwan in 1997 caused a 2-percent drop in that country's gross domestic product "almost overnight" because of trade embargoes established by other countries trying to keep the disease out.

Even small outbreaks have proved costly because of trade embargoes. According to Rocco Casagrande, a bioterrorism specialist who is also a biological engineer at Surface Logix, a biotechnology company, in 1951 and 1952 Canada killed just  2,000 animals at a cost of around $2-million to eradicate foot-and-mouth disease there. But embargoes then cost farmers more than $2-billion. The United States lost $250-million worth of wheat exports in 1996, when a small outbreak of the fungal disease karnal bunt was found in the Southwest.

Intentionally introducing a foreign animal or plant disease to the United States would not be difficult, say many agriculture, veterinary, and defense experts. Unlike most bioweapons directed toward killing people, many diseases of livestock and crops are easy to produce and stockpile, don't need to be "weaponized," and pose no risk of harm to the terrorists who might use them.

"You could bring in a vial" containing bacteria or a virus, says James H. Denton, head of the poultry-science department at the University of Arkansas at Fayetteville. "It's that simple." Depending on the disease's mode of transmission, an animal need only eat, touch, or inhale the pathogen, and then it would probably pass the disease on to other animals nearby. Crop diseases often circulate through the air or are transmitted by insects.

What's more, terrorists intending to kill animals or plants need fear less-severe reprisals. Though U.S. laws contain inconsistencies about whether weapons aimed at agricultural targets would fit under the definition of weapons of mass destruction, little doubt exists that attacks on livestock and crops would spark less public outcry for retaliation than would future assaults on people. "If you're a politically minded terrorist or a criminal who wants to make  money off [biological weapons that kill people], the backlash against you would probably thwart what you're trying to go after," says Mr. Casagrande. "If you kill a bunch of plants or livestock, people will go, 'Oh, it's a shame.'"

Because many diseases spread among countries naturally or accidentally -- much as West Nile virus came to the United States or foot-and-mouth disease to Britain -- investigators would have a hard time linking an outbreak to terrorists. "We and others have long thought that agricultural-biological weapons are the most likely to be used because they can be delivered most easily and most covertly, and they're hardest to trace," says Barbara H. Rosenberg, a research professor of environmental science at the State University of New York's Purchase College and chairwoman of the Federation of American Scientists' working group on biological weapons.

Martin E. Hugh-Jones, a professor of epidemiology at Louisiana State University at Baton Rouge, envisions an easy, economically devastating scenario: "All you need for agroterrorism is one case of foot-and-mouth disease."

That infection strikes cloven-hoofed animals -- cows, pigs, and sheep -- and is one of the most contagious diseases known, being transmittable through the air and able to survive on tires or in cloth, like a  terrorist's clothing. It does not generally sicken humans.

The United States has been free of foot-and-mouth disease since 1929. If a U.S. outbreak began with that one infected animal that Mr. Hugh-Jones imagined, "then everybody else shuts their borders against importing American beef and pork. About 20 percent of our production is [currently] exported. People at home won't eat it. So it reverberates back across the industry and you end up bankrupting grain farmers in the United States, who produce the food for animals in feedlots." About 15 percent of American jobs are related to agriculture, and the U.S. exports about $50-billion of agricultural products.

Although terrorists could easily spread agricultural diseases, experts suggest straightforward steps to protect the United States against such scenarios. Though erecting a shield against all pathogens would be impossible, common-sense practices could go a long way toward preventing catastrophe. Those include improving security and inspections at ports; tightening quarantines for sick animals or those that move from country to country, or even from farm to farm; and containing and eliminating outbreaks before they spread.

That job falls largely to the U.S. Department of Agriculture. Kevin Herglotz, a spokesman for the department, says that since September 11, "We have stepped up our security" at ports and introduced tougher inspections of farms and meat-production facilities. He says that was also part of a larger move to increase the number of inspectors at ports by 40 percent over 2000 levels by the end of this year, double the number of detection-dog teams, and improve computer systems.

If animal or plant diseases do get into the country, the first people likely to see their effects are farmers and veterinarians. To slow or contain an outbreak of disease, they need to know what they are dealing with. "There's a tremendous problem among United States veterinarians now in that many of them would not be able to recognize some of these diseases," says Corrie C. Brown, a professor of pathology at the University of Georgia College of Veterinary Medicine. "I would say less than 1 percent of all veterinarians in the United States have ever seen a case of foot-and-mouth disease."

To improve veterinary education, Georgia and other universities have begun teaching students about foreign diseases. In collaboration with Iowa State University and the University of California at Davis, members of the veterinary faculty at Georgia are developing a distance-education course on foreign animal diseases, and in collaboration with Texas A&M University, Dr. Brown is working on an online library of the diseases. The reference will help students or practicing veterinarians identify diseases based on symptoms. "Veterinarians not only have the opportunity but the obligation" to learn about the diseases, says G. Gale Wagner, a professor of veterinary pathobiology at Texas A&M.

Mr. Wagner also runs an international veterinary program that gives students firsthand experience in working with diseases that do not occur in the United States. Students go to Argentina, Brazil, or Chile for a week of intensive training on diseases like foot-and-mouth or bovine babesiosis, a tick-borne infection that causes severe weight loss in cattle.

Since many of the same methods that protect the country from accidental introduction of pathogens would also do so for intentional introduction, scientists working to improve food safety are suddenly reconsidering the value of their work, realizing that it could strengthen national security. Some scientists are developing vaccines or drugs to treat infected animals. Others are devising ways to monitor animals' health or stop transmission of germs. For example, Mr. Wagner has been working on an implantable device that would diagnose whether cows carry E. coli. The cows would walk past a sensor every day. "We could put signals on there for 50 different diseases," Mr. Wagner says.

Sandra Amass, an assistant professor of production medicine at Purdue University's School of Veterinary Medicine, recently discovered that a standard procedure for preventing the spread of dangerous bacteria is worthless. Most farmers walk through boot baths containing disinfectant, but Dr. Amass found that boots contained the same number of bacteria after that procedure. A more effective method is to "scrub off the visible manure and dirt, and soak those clean boots in a bath of disinfectant," she says.

"In a sense, we're working on bioterrorism, but we don't call it that," says Mr. Wagner. "Maybe we should. Maybe this whole thing has turned the world around."

If agroterrorism is easy to pull off, hard to detect, and effective at undermining economies, why haven't terrorists already used it? "One possible response is that it has happened and we're not sure," says Mr. Casagrande, pointing out how similar a terrorist attack and an accidental disease outbreak would appear. He says he knows of one instance of animal disease in the United States -- a medfly infestation in California -- that could have been caused intentionally, although it has not been proved. In 1989, a group called the Breeders sent letters to Mayor Thomas Bradley of Los Angeles, agricultural officials, and the news media claiming responsibility for spreading the Mediterranean fruit fly, which damages citrus fruits.

Others think that an agricultural attack would not give terrorists the drama they seek, the terror they hope to inspire. "They want something immediate -- a bomb flash,
  newspaper headlines, bodies," says Mr. Hugh-Jones. "Terrorists have not, to date, shown great interest in this," says Amy E. Smithson, the director of the chemical-and-biological-weapons project at the Henry L. Stimson Center. "Pretty much, terrorists have been interested in killing people." She says that an analysis of 853 cases of chemical or biological terrorism worldwide over 25 years found only 21 attacks on agriculture.

Of course, it's possible that some terrorists simply haven't thought of the strategy or realized how effective it could be.  Some researchers hesitate to talk about details for fear of planting ideas that would bear terrible fruit. Mr. Casagrande says that an article he published last year in The Nonproliferation Review was cut by about a third before it was published because the editors feared he might be providing a recipe for terrorism. "I had no objection" to the editors' cutting his article, he says.

Some experts would not comment on the topic, perhaps because they fear giving out too much information. Mr. Chalk, of RAND, published an ominous article in February in Jane's Intelligence Review but declined to be interviewed for this article. Mr. Chalk quotes Robert P. Kadlec, a professor of military strategy and operations at the National War College,  who said, "Agroterror offers an adversary the means to wage a potentially subtle yet devastating form of warfare, one which would impact the political, social, and economic sectors of a society and potentially threaten national survival itself." Dr. Kadlec did not return repeated phone calls.

But many of the scientists and experts contacted by The Chronicle say they think the benefits of raising awareness among veterinarians, the public, and policy makers outweigh the risks of tipping off would-be agroterrorists. They point out that people who want to perform an economic attack would probably have already come across the idea on the Internet. "For a while, it was believed that as long as we didn't talk about it, we didn't have to worry about it," says Dr. Brown of the University of Georgia.
"But you know what? [Terrorists] already know about it. We have to make the public aware that this is a possibility, to get the right kind of awareness and funding to be able to deal with the first incursion."