- Sep 1, 2003
September 11, 2001, did more to the American consciousness than make us aware that we are vulnerable to something as heinous as hijacked airplanes being crashed into densely populated office buildings. The September 11 attacks also brought with them the realization that if terrorists want to strike a blow against this country, there are a variety of approaches they might take, including the use of our own animals as weapons. That concern was underscored with the anthrax attacks on humans that occurred in late 2001. The anthrax attacks killed five people and sickened 13 others as well as spreading terror throughout the country.
Today, veterinarians and food-health professionals across the country are mobilizing to protect this nation's animals and crops from terrorist attacks. Leading the way in this mobilization is the National Animal Health Emergency Management Systems (NAHEMS), a federal steering committee that includes in its membership the American Association of Equine Practitioners (AAEP) and the American Veterinary Medical Association (AVMA).
Concerns regarding animal health center around two basic types of diseases--non-zoonotic and zoonotic. Non-zoonotic diseases are not transmissible to humans. Zoonotic, on the other hand, refers to diseases that are transmissible from animals to man under natural conditions. Anthrax is a zoonotic disease.
Richard Carmona, MD, surgeon general for the United States, gave this chilling assessment during a Jan. 17, 2003, speech to 125 veterinarians representing 46 states at a special gathering in Orlando, Fla.: "Of the 1,600 pathogens known to infect humans, about one-half are zoonotic. That puts veterinarians on the front lines of detection of biological weapons of mass destruction."
The University of Minnesota's Center for Infectious Disease Research and Policy has listed the following reasons why animal agriculture is a potential target for terrorists:
- Relative ease (compared to incidents affecting exclusively human populations) of implementation of an ag-terrorist act;
- The resulting disruption of the nation's food supply and the negative multiplier effects throughout the food processing and transportation infrastructure of the U.S. economy;
- Public fear regarding the safety of food purchases;
- Public confusion and apprehension resulting from media coverage of response activities; for example, destruction and disposal of affected livestock, quarantines, etc.; and
- Disruption of the United States' ability to export food products.
The outbreak of foot and mouth disease in England in 2001--believed to have resulted from the inadvertant introduction of the causal virus rather than bioterrorism--demonstrates just how devastating such a disease can be to a country's economy. Although it didn't cause loss of human life, foot and mouth disease resulted in the destruction of millions of animals. It also resulted in movement restrictions on animals--including horses traveling to and from major competition events--for fear that the causal virus could be spread by them.
How Horses Fit In
It is obvious that the greatest concern involving agricultural bioterrorism centers around food-producing livestock species, but the horse should not be excluded. For example, two of the diseases designated List A diseases by the Organization Internationale des Epizooties (OIE, the international standard-setting body for animal health and international trade) that can affect horses are African horse sickness and vesicular stomatitis (VS). List A diseases are defined as those with the potential to spread between countries and also have serious socio-economic and sometimes public health significance.
African horse sickness is a highly fatal viral disease that can affect horses, mules, and donkeys. The horse is particularly susceptible to infection. There are nine viral types that can cause the disease, which is normally spread by certain small biting flies. The mortality rate ranges from 60-90% in susceptible equids, especially horses.
Any horse imported into the United States from a country where African horse sickness has been reported is required to remain in quarantine at the New York import center for 60 days to make certain that it is not infected.
Vesicular stomatitis (VS) is a viral disease characterized by fever, together with vesicles (small blisters) and subsequent erosions in the mouth and epithelium (external covering) on the teats and feet of several species of livestock, including horses. The causative virus normally is transmitted by biting flies.
While VS can be serious disease on its own, it's also important because it's clinically indistinguishable from foot and mouth disease in cloven-hooved animals. A laboratory test is required to distinguish between these diseases when characteristic clinical signs are found in animals. It is important to understand that horses can contract VS, but not foot and mouth disease.
Vesicular stomatitis can also infrequently affect humans. It takes four to seven days for the disease to run its course once contracted by a human, and during that time the affected person suffers from an influenza-like illness with fever, headache, muscular aches, and blisters in the mouth.
The OIE also has a separate tally of List B diseases, which are considered significant but not as potentially serious as the List A maladies. There are 15 List B diseases that affect the horse, including:
- Contagious equine metritis (CEM);
- Epizootic lymphangitis;
- Eastern, Western, and Venezuelan equine encephalomyelitis (EEE, WEE, and VEE, respectively);
- Equine infectious anemia (EIA);
- Equine piroplasmosis;
- Equine rhinopneumonitis;
- Horse pox;
- Equine viral arteritis (EVA);
- Japanese encephalitis;
- Horse mange; and
A major problem with VEE, in contrast to EEE and WEE, is that the horse is an amplifying host (can spread the disease) for the causative virus, which is transmitted by mosquitoes. The arthropod-borne alphavirus that causes VEE is also a significant human pathogen.
A List B disease that is not considered specific for horses is anthrax, which is highly fatal to animals and humans alike. It affects cattle more frequently than horses. The disease often is spread to humans through the handling of sick or dead animals.
Plans of Action
The goal of NAHEMS and state animal health organizations is, first of all, to prevent outbreaks of infectious diseases. If there is an outbreak, their job is to have a plan of action in place to detect, diagnose, and deal with the disease.
A state using federal funds to develop such an approach, which could possibly serve as a model for other states, is North Dakota. The program is centered at North Dakota State University (NDSU) in Fargo under the direction of Douglas A. Freeman, DVM, PhD, chair of the department of veterinary and microbiological sciences and head of the department of veterinary diagnostic services. Also involved in the program are researchers and staff from Dickinson State University in Dickinson, N.D., as well as state and local veterinarians, cattle producers, and law enforcement personnel.
The basic thrust of the bio-surveillance program, says Freeman, is to identify, diagnose, and contain any disease outbreak that might occur in the state. At present, the program is operating under a one-year federal grant, but Freeman is hopeful that future federal funding will enable it to expand.
"We don't want to hang this program on bioterrorism," says Freeman. "It is bio-surveillance that will help us do a better job with our normal work and, at the same time, help us be prepared if the unthinkable (a bioterrorism attack) should occur."
Three key components of the North Dakota approach involve development of a rapid response team with a mobile diagnostic laboratory, enhancement of the NDSU Veterinary Diagnostic Laboratory, and extension education for potential "first observers."
Here's a possible scenario of how the developing North Dakota plan of action might work, according to Freeman:
A cattle producer or cowboy is checking stock in a 10,000-acre pasture. He detects something significantly unusual in a number of the cattle and contacts his veterinarian. (Or it could involve a band of broodmares instead of cattle.) The veterinarian is concerned by what he sees and notifies the state veterinarian. The state bio-surveillance team is called in. The steps that follow diagnosis can range from herd quarantine to treatment, or nothing at all if the diagnostic tests are negative.
Here's where the circle widens if there is a disease problem. Law enforcement might play a role in quarantining the livestock. If that occurs, the next task is to inform the public concerning what is happening and how it might affect other animals and humans in the area. To that end, a crisis communications expert at NDSU is assigned to work with the bio-surveillance team.
The goal, Freeman says, is to avoid disseminating confusing and misleading information from a variety of sources when a crisis occurs.
Recently, he says, there was a situation at a Kansas stock sales yard where a number of cattle exhibited what could be interpreted as symptoms of foot and mouth disease. The inspecting veterinarian, Freeman says, very correctly called for diagnostic tests to be undertaken. As it turned out, the cattle had consumed a caustic substance that caused salivating and slobbering, and they did not have foot and mouth disease.
However, Freeman notes, it was a "real circus" with dissemination of information and misinformation until the final diagnosis was reached. It's important to disseminate accurate information from a centralized source when a crisis occurs, he adds.
Meanwhile, veterinarians across the country are being educated and educating others concerning steps to take in detecting, diagnosing, and treating diseases that might be introduced by bioterrorists. The U.S. surgeon general told attendees at the Orlando meeting that: "You are here to learn how to recognize the signs of the likely disease agents, particularly in the case of those that have not been prevalent in the United States, but which can cause great damage. I thank you for taking that step--to get educated and help educate others. It will be important for private practitioners to educate their clients as well. Agricultural produce and even pet owners may be the first Americans to witness an attack of agro-terrorism or bioterrorism."
The USDA has asked for an additional $47 million this year to strengthen a federal and state government network to respond to bioterrorism and animal disease outbreaks, and another $23 million for the Animal and Plant Health Inspection Service (APHIS).
APHIS trains federal, state, military, and private veterinarians how to respond to suspected cases of foreign animal disease. The goal is to prevent a catastrophic outbreak.
"The sooner we can detect a foreign animal disease, quarantine it, and shut down the movement of livestock, the sooner we will be able to contain it," Bobby Acord, administrator of APHIS, told the Associated Press.
The goal of the Agriculture Department is to train hundreds of veterinarians to diagnose animal diseases that are found in other parts of the world, but are rare or unknown in the U.S.
From the AAEP Convention
A special section on new and emerging diseases was held at the 2002 AAEP Convention. "When you hear hoofbeats on the covered bridge, please think about the zebra!" stressed Corrie Brown, DVM, PhD, Dipl. ACVP, of the Department of Veterinary Pathology at the University of Georgia, in her presentation to the equine veterinarians. Her point was that when veterinarians are considering a diagnosis, they need to include foreign animal diseases. "The amount of damage that a foreign animal disease will cause is directly proportional to the time between introduction and accurate diagnosis," she said. "In other words, we have to accurately recognize a foreign animal disease at first blush if we are to implement effective control measures. It is imperative that practitioners consider foreign animal diseases in their diagnostic rule-outs."
For example, "Glanders used to be a low priority, but with bioterrorism, the threat (that it could be seen in the United States) ratcheted it up," noted Brown. She explained that during World War I, glanders was used to deliberately infect horses of enemy troops. The deadly disease was eradicated from the United States in 1937, but it was developed as a biological weapon during the cold war era.
John R. Irby, DVM, advised that while screwworms and equine piroplasmosis are not currently present in the United States, they could be re-introduced. Irby formerly worked for the Texas Animal Health Commission and now is with the Florida Department of Agriculture and Consumer Services. He noted that, "In the post-September 11th atmosphere, there is the concern that livestock could be the target of a bioterrorist attack using a disease agent available in another country." In discussing anthrax, screwworms, and piroplasmosis, Irby said that they are related in that each "can affect equids, has the potential to devastate domestic livestock, is present in many foreign countries, and may first be detected by veterinarians in private practice."
So, one might ask, what does all of this mean to the horse owner? True, it might seem that horse owners can do little to prevent importing disease via equines; however, they can contribute to the safety of such importations by ensuring that any animal/animal products they import meet the necessary official import requirements. This can help prevent zoonotic diseases such as encephalomyelitis from being spread.
In 1995, there was an outbreak of Venezuelan equine encephalomyelitis in Venezuela and Colombia, according to a NAHMS official. Between 75,000 and 100,000 human cases were reported in eight months, and thousands of horses died as a result. A vaccination program likely could have prevented the outbreak.
Vaccines are available in the United States for combatting encephalomyelitis and other diseases to which equids are susceptible (such as West Nile virus), and the wise horse owner will make certain that his or her animals are protected.
The final message is that if you think something is unusual, report it. Tell your veterinarian, the state veterinarian's office, your local extension agent, and even your closest university. Whether bioterrorism attack or natural occurrence, the sooner a problem is recognized, the sooner it can be dealt with properly.
Herbert, K. Foreign Animal Diseases with Equine Potential. Article #4121 at www.TheHorse.com.
Herbert, K. Infectious Diseases Subdued/Not Eradicated. Article #4118 online.
Herbert, K. A Review of Equine Zoonotic Diseases. Article #4119 online.
Herbert, K. Foreign Animal Disease Investigations. Article #4120 online.
Pavlin, et. al. Clinical Techniques in Equine Practice. Bioterrorism and Equids, 1(2), 109-115, 2002.
About the Author
Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.
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