Biological terrorism is described as the use of microorganisms or toxins derived from living organisms to induce death or disease in human beings, animals, or plants.1 Biological agents have been used throughout history to inflict harm. There is evidence as early as 300 BC of the use of animal or human corpses to poison drinking water,2 and during medieval times, corpses were catapulted over city walls with the intention of starting disease epidemics.3 In 1972, the Convention on the Prohibition of the Development, Production, and Stockpiling of Bacteriologic (Biological) and Toxin Weapons, or the Biological Weapons Convention, was signed by 158 nations and ratified by 140 of those nations.4 However, recent events have documented that some countries, including the former Soviet Union and Iraq, developed and stockpiled biological weapons in direct violation of the treaty. Terrorism is on the rise throughout the world, and biological weapons, because of the relatively low cost, ease of production, low volume of material needed, and potentially slow onset of action, have been described as ideal for use by terrorists.5
Veterinarians, veterinary diagnostic laboratories, and public health veterinarians provide an important first line of detection for potential bioterrorism agents. Because most biological weapons developed for use against humans are zoonotic, animals can serve as sentinels for disease (Appendix). In fact, Bacillus anthracis, Yersinia pestis, and Francisella tularensis are considered high priority agents that pose a risk to national security.6 In addition, biological weapon agents, especially in the form of foreign animal diseases, could be used against the livestock or poultry industries in the United States, causing devastating effects on animal health and the US economy.7 Currently, 40 diseases and 26 arthropod pests are considered foreign to the United States.8 Eighteen of the foreign animal diseases are considered zoonotic and 4 are listed as potential biological weapon agents.
State veterinary surveillance systems require the reporting of specific animal diseases by veterinarians, laboratories, or others to state veterinary health officials for the protection of animal health in their respective states. Diseases with human health implications should be reported to public health officials who may perform further disease investigations. To understand the current veterinary surveillance capacity for zoonotic bioterrorism agents, a survey of state animal health officials was performed to determine which agents are reportable to state departments of agriculture, the amount of communication between veterinary and public health officials, and the involvement of animal health officials in planning measures for bioterrorism preparedness.
A standardized 1-page survey was sent by facsimile to all members of the National Assembly of Chief Livestock Health Officials in the United States in May 1999. This assembly consists of state veterinarians or animal health officials whose mission is to protect, maintain, and improve the health of the state's domestic animals. All those who did not respond were contacted by telephone, and the questionnaire was facsimiled a second time. The questionnaire was designed to identify which potential bioterrorism agents were reportable on a state-by-state basis. Twelve zoonotic diseases that have been listed as potential biological weapon agents9 as well as a general category of "foreign animal diseases – all" were listed, and state veterinarians were requested to indicate which of the diseases were reportable in their state. It was also determined who is responsible for reporting diseases and who is responsible for investigating reported incidents of the listed diseases. Additionally, state animal health officials were asked under what conditions potential zoonotic diseases were reported to state public health officials. The final questions addressed the educational efforts directed toward veterinarians regarding the issue of bioterrorism and whether state animal health officials had been personally involved with any planning, preparedness, or increased surveillance efforts in relation to bioterrorism.10
Forty-six of 50 responses (92% response rate) to the survey were obtained and analyzed. The percentage of states in which the reporting of each of the listed diseases is required ranged from 23.9 to 100% (Table 1). All states required the reporting of foreign animal diseases and brucellosis. Reporting of anthrax, equine encephalitis, avian influenza, and chlamydiosis was required in most (> 60%) states, whereas reporting of swine influenza, Rocky Mountain spotted fever, leptospirosis, and tularemia was required in fewer (< 40%) states. Plague, Q fever, and salmonellosis were reportable diseases in approximately half the states.
Most states require veterinarians and state diagnostic laboratories (95.7%) or other laboratories (80.4%) to communicate incidents of reportable animal diseases to state animal health officials. A few state officials mentioned that anyone with knowledge of a reportable disease is required to report that disease. In most states, state or federal veterinarians investigate incidents of reportable diseases in animals.
All respondents said that they report incidents of zoonotic disease to public health officials. Communication of these incidents was accomplished by telephone (91.3%), facsimile (52.2%), letter (28.3%), or e-mail (15.2%). Although some state officials commented that investigations of these diseases were performed at the discretion of public health officials, state animal health officials recommended that these reports be investigated when a risk of human infection (58.7%) or evidence of human infection (41.3%) was present.
Eighteen of 46 (39.1%) respondents reported that they knew of educational efforts that were performed at the state level to alert veterinarians about bioterrorism issues. Twenty-eight of 46 (60.9%) respondents said that they were involved in state planning efforts with regard to the issue of bioterrorism.
Results of the survey highlighted the following important issues: some high-priority bioterrorism organisms such as plague and tularemia are not reportable in all states; 39% of state animal health officials have not been involved in bioterrorism planning and coordination; and efforts to educate veterinarians regarding issues surrounding the impact of bioterrorism have been initiated in only a few states.
Because a biological attack may be insidious in onset, state and local health departments may be the first to recognize an act of bioterrorism through surveillance for infectious diseases. However, the use of zoonotic agents or an event involving a foreign animal disease with zoonotic implications could also be detected by veterinary surveillance systems. Veterinarians have an important role in the surveillance for potential biological weapon agents through the prompt reporting of foreign animal diseases, zoonotic or other reportable diseases, or any unusual disease occurrence to animal health officials. Results of our survey of chief livestock officials indicated that although communication between veterinary and public health officials appears to be good, the likelihood that various potential bioterrorism agents are reported varies from state to state. To establish an effective surveillance system, zoonotic diseases such as anthrax, plague, tularemia, and arboviral encephalitides should be made reportable to state animal health officials. This should also include the reporting of any unusual increase in unexplained illness or deaths in animals. Surveillance capability will be strengthened by emphasizing prompt reporting and the maintenance of clear lines of communication between veterinary and public health systems.
Educational efforts directed toward practicing veterinarians will be important for early detection of a biological weapon event. Early detection is necessary to enact appropriate protective measures, treat exposed individuals, or initiate proper emergency response activities. The effects of biological weapons are not immediate nor are they pathognomonic for specific agents. Detection is dependent on awareness of potential diseases used as biological weapons, knowledge of the clinical manifestation of these diseases, and vigilance and prompt reporting of diseases to the proper officials. Results of our survey indicated that efforts to educate veterinarians on the potential for acts of bioterrorism, the agents involved, and response capabilities could be improved.
Veterinarians also have an important role in the planning and preparation for the anticipated consequences of an act of bioterrorism. Veterinary diagnostic laboratories have the capability to identify many zoonotic biological weapon agents and are an integral resource in determining the cause of an unusual disease event. The value of the veterinary surveillance network and its implication for human health need to be emphasized to surveillance and response planners at state and federal levels. Other aspects of a response by veterinarians could include direct animal care, participation in disaster response teams, communication of risk to the public, expertise on zoonotic diseases, food safety, and handling of hazardous waste. Although the majority of state livestock officials indicated some involvement in bioterrorism planning efforts, survey comments suggested that oftentimes veterinary participation was minimal. Expansion of the role of veterinarians not only through state and local government efforts but also through community involvement and emergency preparedness will put the expertise of veterinarians to use and enhance response capability.
In addition, veterinarians are in a powerful position as individuals, professionals, and scientists to exert pressure along with the entire scientific and medical communities to condemn the development and use of biological weapons. Veterinary support for existing treaties, laws, and regulations governing biological agents and actions to improve such measures can also serve to deter bioterrorism. Veterinarians have the responsibility as health professionals to be aware of the potential for bioterrorism and to participate in the protection of public health.