Bioterrorism: An Update with a Focus on Anthrax

The current problem with anthrax, a disease of antiquity with a reputation that has exceeded its actual impact on human health, has brought into reality the meaning of bioterrorism. No matter how prepared a population may be, bioterrorism cannot be prevented. The first case or cases will occur and will serve to alert the authorities to initiate the preexisting plan to limit the quantitation of the bioterrorist event. Although much effort may have been expended in developing a response to a bioterroristic event, it is likely that deficiencies will become apparent as the plan is implemented, partly because some aspects of any plan will vary depending on the agent involved. This is portrayed by the current bioterroristic anthrax event. Although not the preferred method of testing a plan, lessons will be learned from the current activities, necessitating corrections and additions to the plans. This will strengthen our ability to respond more effectively and efficiently to another bioterroristic attack. Bioterrorism is the use or threatened use of biologic agents against a person, group, or larger population to create fear or illnesses for purposes of intimidation, gaining an advantage, interruption of normal activities, or ideologic objectives. The resultant reaction is dependent upon the actual event and the population involved and can vary from a minimal effect to disruption of ongoing activities and emotional reaction, illness, or death. Bioterrorism is distinct from biologic warfare. Although there may be similarities in agents considered for use in the desired effect or the method of dispersion, the anticipated results are different. A review of the published reports of bioterroristic events in the United States shows a hundredfold increase in the reports from the early 1900s to the present time (1). The majority of these reports have been hoaxes as distinct from an actual event. The most prevalent agent threatened in these hoaxes has been Bacillus anthracis. The current episode is the first documented instance in which B. anthracis has been used successfully. In considering bioterroristic agents, one characteristic perpetrators look for is an agent known for causing morbidity, possible mortality, and perhaps a disease that is difficult to diagnosis and to treat. The more severe the morbidity and mortality the greater the fear created. Other qualities of an agent include accessibility, reproducibility, stability, and dispersibility. The organism must be available. Prior to 1996, it was not difficult to obtain most biologic agents from commercial sources, but new federal regulations were instituted that made it illegal for biologic supply companies to provide certain pathogenetic organisms. The agent, once obtained, has to be reproducible; that is, the perpetrators have to be able to produce the quantity of organisms they need. This takes knowledge, materials, and equipment. Purification may be important. Once prepared, the agent has to be stable so that the desired characteristics do not change. The infecting dose of the agent is another important consideration and will vary according to the agent and the route of dissemination as well as by the host's susceptibility. Another characteristic is the incubation period. A short incubation period makes detection before symptoms occur more difficult, a potential desirable quality to the perpetrators. Other agent qualities are difficulty in identification and in eliminating the agent once it has been released. The route of dispersion will determine the number of people exposed to the agent. Aerosol dispersion can expose the greatest number of people over time, but it is very difficult to meet the criteria necessary for widespread distribution. The agent has to be infectious by the inhalation route unless the aim is to contaminate a food or water supply by an aerosol. The airborne particles have to be less than 5 μm in size in order to be inhaled and deposited in the alveoli. If the aerosol created is colorless and odorless, it may not be detected until symptoms develop. Creating an aerosol takes a significant level of kinetic energy; this is where some perpetrators have failed in their attempts. Without an adequate energy force, a true aerosol cannot be created. Other environmental factors that can influence the success of aerosol dispersion include the direction and velocity of the wind, humidity, sunlight, radiation, and the possibility of the presence of other airborne pollutants. However, as the recent anthrax bioterroristic event demonstrated, aerosol dispersion on a smaller scale can occur with an appropriately prepared agent. Dispersion through food or water allows a greater likelihood of reaching a specific group of people, as was demonstrated in The Dalles, Oregon, bioterrorism episode (2). Other routes of dispersion that have been attempted are through medicines, medical fluids, blood, and insect vectors, but these are less efficient in meeting the perpetrators' objectives. Important host factors include susceptibility of the host and symptoms that make it difficult to arrive at a clinical diagnosis. Other factors are potential complex therapeutic measures and inadequate or no preventive measures. The agents that have been primarily considered can be categorized by their pathogenicity. Those bioterroristic agents that are considered to be the most pathogenic include Variola major (smallpox), B. anthracis (anthrax), Yersinia pestis (plague), Clostridium botulinum (botulism), Francisella tularensis (tularemia), and some hemorrhagic fever viruses such as Ebola, Lassa, and Marborg. The next level of agents includes Coxiella brunetti (Q fever), Brucella species (brucellosis), Pseudomonas mallei (glanders), and some encephalitis-causing viruses. Additionally, there are some other microorganisms of lesser toxicity that have been used in bioterroristic events such as Vibrio cholera, Salmonella, Shigella, and Staphylococcus. The Centers for Disease Control and Prevention (CDC) has developed a plan for the public health and medical response to a bioterroristic event (3). In developing this plan, CDC collaborated with an extensive group of other agencies, organizations, and persons and prepared a plan incorporating actions at all levels of responsibility. They have prepared written and website documents and have participated in meetings and training sessions to disseminate their recommended plans. Training exercises include tabletop exercises, held to educate people with responsibilities in carrying out the plan and to point out deficiencies for subsequent modification. The public health response to a bioterrorist event must be epidemiologically directed and oriented. There must be extremely close collaboration between the many different agencies at the federal, state, and local levels. The main areas involved in reacting to a bioterroristic event include planning, detection, diagnosis, investigation, treatment, communications, and training (4). In the planning phase, attention must be given to close collaboration among the multiple partners that have responsibilities for implementing the plans. The partners at the federal, state, and local levels must assist in developing the plans as well as in carrying out the responsibilities. Jurisdictions must be defined and responsibilities assigned. In the United States, the federal agencies involved comprise those in Health and Human Services, including CDC, the National Institutes of Health, the Food and Drug Administration, the Agency for Health Care Research and Quality, and the Office of Emergency Preparedness. Other federal agencies include the Department of Agriculture, the Department of Commerce, and the Justice Department. In reality, all of the federal departments may have input into the preparedness plan. Of equal importance are the state and local agencies with responsibilities similar to those at the federal level. This overlap is where problems can occur. Administrative authority and leadership must be carefully and clearly defined. All persons involved in the response plan must know what their responsibilities are, when they should initiate their activities, where they should direct them, and how to implement them. As previously indicated, it is not realistic to think that we can prevent the first case or cases in a bioterroristic event from occurring, but how we react subsequently is critical. The main objective must be to keep the quantitation of the event to a minimum. There are many disciplines that must be involved in these plans, but a critically important area is that of administration. Administrators must provide management skills that create the environment in which there can be successful accomplishment of the objectives. Other important professions include epidemiologists, laboratorian personnel, surveillance personnel, environmentalists, heath care personnel, behavior scientists, communication and public relations specialists, and support personnel. Resources, such as adequate and responsive laboratory facilities and supplies; access to computers; and other forms of communication, transportation, and finances must be available. The second area of the response plan is that of detection. A critical activity here is public health surveillance, which can be either passive or active but must be sensitive and specific. The basic, routine, passive public health surveillance system in place throughout the United States is the first level of our detection system. It is the responsibility of all health care professionals who see patients and make diagnoses to report not only reportable diseases, but also any unusual number of cases of any disease or health event that they observe. Others who should be brought into the surveillance loop for potential bioterroristic events are the 911 services, police and fire departments, medical examiners, emergency room personnel, walk-in clinics, hospitals, poison control centers, public health personnel, pharmacies, veterinarians, the media, and all citizens. It is necessary to develop among all of these groups sensitivity to an unusual situation or occurrence of a case or cases of an unusual illness so that they will report the event to the appropriate authorities. Sensitivity will be more important than specificity. It will be necessary to develop case definitions for the reporting of diseases of concern in the bioterroristic response system. Novel surveillance systems must be considered in planning for defense against bioterrorism. One such system is syndromic surveillance. Syndromic surveillance should include such syndromes as dyspnea, pneumonia, rash, nausea and/or vomiting, diarrhea, encephalitis, and other unexplained or unusual illnesses or deaths. While syndromic surveillance may be questioned, its usefulness must be evaluated. All of these data sources must be linked together with communications going from bottom to top as well as from top to can the of the surveillance system and provide support for the of data from multiple sources with and dissemination of The use of and will communications at all levels of that should a report include an unusual agent with or multiple illnesses in one or more The agent may have an unusual or or Another be a morbidity and mortality than for a known disease agent. In a number of persons with the or illness, or of in the or different areas be a There may also be an unusual of the disease an unusual population or such as a disease at an unusual time of the in the United States in unusual method of or a disease also a bioterroristic event. The to between a bioterroristic event and a is apparent in considering events over the this time, we have a number of that characteristics that those of a bioterroristic event, such as disease in the United States in the or in the in The next area of bioterrorism response is that of diagnosis. It is apparent from the current anthrax bioterrorism event that health care professionals must be diseases to which they not have been exposed their because of the or of the for health care professionals must include of diseases actual cases cannot be have to be with and to make the diagnosis of unusual It is not that laboratory be able to all for diagnosis must be at the local level and have access to a a state, or a laboratory in which more specific can be There are in the including at CDC, that can be used as the to to our ability to and identification of biologic the use of is an important for between at different and/or at different There should be of laboratory including that of so that organisms can be over are areas that are developed and throughout the The next areas in the response plan are the that should be at the local level with and support from state and federal There to be from the who has the responsibility for and the a bioterroristic event will into the more than the public health and in the of are to any response plan. They must be and and be bioterroristic The from CDC serve this with some at state health departments and at CDC or at their and on to be into the There be in at one in state health and in health departments of and must be laboratory support must be so that the either or from the can be by with reports as as This in the for a of because any one laboratory may not be able to a state of to an number of There to be a of the most preferred method of the most and to prevent the of and prevent should be as new available. The of the National developed and by CDC is a major in this There should be the in the and how can be made for of the is a major of the bioterrorism response plan not only for control and purposes but to the fear and that results from bioterroristic One cannot prevent fear and but communication and can it and its effect on the The for dissemination must be prepared for the group at which it is it be a group or the state, or The has an important responsibility to assist in the dissemination of the has become a major for The public relations should be given the responsibility for and of this for which there must be a and The but not the of the bioterroristic response is that of All of involved must be their responsibilities. This can be through written materials, and exercises, that is, of the response plan, can be very not only in the but in the deficiencies in the plans. 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bioterrorism cases were the of direct or with through the United States system it is that all of the cases be to at one the in and the other the in The first case in in which a was to the in where it was by a who developed anthrax and One other who in the room It is that B. anthracis was throughout the by this by other or by of and/or environmental was in a that for the It the or were through the at the time as the other The at into another in the in and to the of and the in in the occurrence of cases of anthrax, but no The in which the were were but no dissemination to other of the The environment of the was from these and there were and cases among in this The one to and one to were in the in The to was to in the Office and in of a number of persons in to the This in the dissemination of B. anthracis to areas the The to was as was held the was and in facilities at the Research The B. anthracis in these have been by and environmental to have the potential for widespread aerosol They 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There are aspects of this event that should for such as well as provide for other health The for a including of the or and who should do what and collaboration between agencies is more and for the public is important in order to and educate the population and to and The importance of and has been have learned a when time is of the ability to microorganisms should be as we new have also learned more the clinical of anthrax and the importance of As new and become for our response to there will be will strengthen our of public health at the federal level as well as at state and local levels. health surveillance will be as surveillance systems are will be and of communication will be at all levels. Research in many areas to the response to bioterrorism will be that will have an impact on the of public health