This reportdiscusses high-threat biological agents, focusing on the Centers for Disease Control and Prevention(CDC) definition for Category A pathogens (bacteria and viruses), their treatment and detection,current policies, and possible future approaches to reducing their threat. What Are High-Threat Biological Agents? Depending on what aspects of a pathogen are considered priorities, differentbiological agents are likely to be identified as high threat. (5) The CDC views CategoryA pathogens as easily disseminated ortransmitted from person to person; resulting in high mortality rates; having the potential for majorpublic health impact; potentially causing public panic and social disruption; and requiring specialaction for public health preparedness. Some anthrax strains may be less sensitive toantibiotics and therefore difficult to treat. The different forms of exposure to tularemiabacteria lead to different symptoms. Detection of Biological Agents

The detection of pathogens, especially in the case of a covert release, is a complicated process. (36) It has been suggested that the first sign of acovert pathogen release by terrorist groups may be a sudden increase in the number of hospitalpatients exhibiting symptoms. Biological Agents as Weapons of Mass Destruction Versus as Weapons of Terror

The likelihood of terrorist use of biological agents as a weapon of mass destruction is an areaof great debate. The technical feasability of terrorist groupsdisseminating biological agents is also open to question. They claim that release of small amounts of biological agent might cause alevel of panic disproportionate to the actual amount released, and point to the anxieties raised afterthe mailings of the anthrax letters of 2001 as emblematic of the type of response that can begenerated by small-scale use of biological weapons. The anthrax mailings of 2001 highlighted the vulnerability of the United States to biological attack, and reignited public interest in bioterrorism and domestic preparedness. (47)

		Research and Development

Defense against bioterrorism has spurred research and development activities. Detecting and identifying pathogens is an area of continued research. Such countermeasures include, but are not limited to,new detectors, treatments, medical prophylaxis, and physical protection from biological agents. Early treatment of theinhalation form of these diseases is essential to recovery, and a system that signaled pathogen releasebefore the appearance of symptoms in victims would be likely to increase the ability of victims toreceive medication and survive. Others have asserted that the current model will be effective in limiting casualties from a pathogen release. They claim that increases in the public health infrastructure have reduced thelikelihood that hospitals and care-providers would be overwhelmed by a bioterror event. Policymakers may ultimately determine the adequacy of current firstresponder equipment and its availability, the amount of funds that first responders should receive topurchase protective equipment, whether proper guidance has been given by the federal governmentto state and local authorities regarding this equipment, and what steps may be required, throughoversight or legislation, to properly equip first responders.
The anthrax mailings in 2001, which culminated in 5 deaths, 22 infections, and contamination of both postal and congressional buildings, intensified concerns about terrorist use of biologicalagents. This event increased Congressional interest in actions to limit the vulnerability of the UnitedStates to such attacks. High-threat biological agents, defined by the Centers for Disease Control andPrevention as Category A pathogens, are considered relatively easy to disseminate, have highmortality, and have the potential for major public health impacts.
High-threat biological agents cause different symptoms in their victims, depending on the pathogen. Since the nature of these agents differs, no single treatment can be given in the case ofa biological attack. As a result, treatment of the victims of a biological attack, especially one whichis covert, may be difficult. The identification process for many pathogens may be complicated bytheir incubation period, and the lack of distinct symptoms early in the disease's progress. Thedifficulties in treating the various high-threat agents may place strain on the resources of the medicalsystem, especially in the case of mass casualties.
Protection from biological agents is an area of active research and development. The range of protection and detection equipment available to first responders has led to questions regardingequipment standardization and state and local preparedness. Development and distribution ofvaccines continues to be a contentious issue. Attempts to detect biological releases using sensortechnologies, or through analyzing public health data, continue to be implemented, but thesetechnologies are in relatively early stages of development.
It is unclear whether terrorist groups are capable of effectively using biological agents as weapons of mass destruction, but the relatively small amounts of pathogen that may be needed toexecute a significant attack is a source of concern. Some suggest that terrorist interest in biologicalagents is increasing. However, others assert that technical difficulties would make mass casualtyattacks unlikely.
Current policies seek to reduce the proliferation of biological weapons by relying on both domestic and international controls, to increase the number of countermeasures available againstsuch pathogens through research and development activities, to improve the nation's ability to detectpathogen releases, and to increase the ability of hospitals and care providers to treat mass casualties.
Policymakers may be called upon to further address potential biological terrorism vulnerabilities, including overseeing the use of atmospheric monitoring equipment for pathogendetection; the direction of continued research and development into biological agent detectors;review of further research into protective equipment, prophylaxis and treatment against high-threatpathogens; and assessment of first responder emergency preparedness. This report will be updatedas events warrant.