"Rather than invading our beaches or launching bombers, adversaries may … deploy compact and relatively cheap weapons of mass destruction—not just nuclear, but also chemical or biological, to use disease as a weapon of war." President William J. Clinton, May 22, 1998
A bioterrorism incident may occur quietly with no explosion and no forewarning. In one possible situation, the emergency physician on shift slowly becomes aware of an unusually large number of patients in the ED with nonspecific complaints. At the end of his or her shift, hours after discharging the first young man with those vague symptoms, the patient returns acutely short of breath, cyanotic, and hypotensive.
Biological weapons (BWs) are the terrorist's perfect weapon; they are relatively easy to make, difficult to detect, and a significant threat of morbidity and mortality. A terrorist needs to go no further than an Internet connection to download the appropriate "recipe" with easily obtainable ingredients.
It is sobering. The question no longer is "What if?" Rather, the question is "When?" As emergency medicine physicians providing acute health care for the nation, the next question, without hesitation, should be "What are we going to do about it?"
Primary Routes of Exposure of Biological Agents
Potentially more lethal than chemical agents, because they are obtained from nature, more accessible, and easy to produce, biological agents (bacteria, viruses, bacterial toxins) pose a significant threat as weapons of mass destruction. [1, 2, 3, 4, 5, 6]
BWs are devices composed of 4 major components as follows: payload (biological agent), munition (container that keeps the payload intact and virulent during delivery), delivery system (eg, missile, artillery shell, aircraft), and a dispersal mechanism. The two most likely potential methods of dissemination are a line source and a point source.
A line source technique is the most effective dispersal means for biological agents. For example, this may involve a truck or air sprayer moving perpendicular to the wind during an inversion (when air temperature increases with altitude and holds surface air and pollutants down). Inversions normally occur at dawn, dusk, or night.
The point source technique uses small bomblets deployed in a saturation mode. The saturation technique overcomes the meteorologic requirements for line source dissemination. Agents may be introduced into buildings' heating-ventilation-air conditioning systems or via food or water contamination. Small packages or envelopes may contain biological agents, but unless they also contain a dispersal device, they are not likely to pose an inhalational threat.
Regardless of the type of dispersal method used, victims are contaminated via 3 potential routes: skin, gastrointestinal (GI), and pulmonary. Cutaneous exposure provides the least potential for significant morbidity and mortality, since intact skin provides an excellent barrier against most of these agents except mycotoxins. However, mucous membranes, abrasions, or other lesions may provide a portal of entry for bacteria, viruses, or toxins.
Contamination of food or water supplies allows for a potentially significant GI exposure. This type of exposure is limited by the direct effects of water dilution and treatment, which inactivates or significantly weakens most microbes and toxins. For this to be a viable method for contamination, the agent must be introduced near the end user and is less likely to result in mass casualties. Exposure via the inhalational route is the most effective mode of delivery for BW agents. Aerosol clouds with droplet or particle diameters of 1-5 µm containing microbes or toxins are not detectable by the senses. Although limited by environmental constraints (wind, sunlight, temperature, desiccation), the potential impact of widespread illness and death may be catastrophic.
Table. Potential Agents and Routes of Primary Exposure* (Open Table in a new window)
|Bacteria||Plague||Percutaneous (flea), pulmonary|
|Anthrax||Percutaneous, GI, pulmonary|
|Tularemia||Percutaneous, GI, pulmonary|
|Viral equine encephalitis (VEE)||Percutaneous (mosquito), pulmonary|
|Viral hemorrhagic fevers (VHF)||Mucous membranes, pulmonary|
|Ricin||Percutaneous, GI, pulmonary|
|Staphylococcal enterotoxin B (SEB)||GI, pulmonary|
|* Specific and additional agents are discussed at length in other articles.|
As described in the introductory scenario, the symptoms that develop after a biological attack are likely to be nonspecific initially, making diagnosis difficult. Early diagnosis is key, and emergency medicine physicians should attempt to recognize a number of potential clues that may suggest release of a BW. Rapid realization of a bioterrorist attack affords greater potential for prophylaxis, appropriate treatment, and prevention of secondary spread. 
Suspect a BW attack if any of the following are present:
Large epidemic with unprecedented number of ill or dying
Immunocompromised individuals demonstrating first susceptibility and rapid progression of disease (although equal affliction of previously healthy individuals also may be a clue)
Particularly high volumes of patients complaining primarily of similar symptoms that are associated with an escalating mortality rate
Unusual or impossible vector for transmission for that particular region
Multiple simultaneous outbreaks
Epidemic caused by a multidrug-resistant pathogen
Reports of sick or dying animals or plants
Single case of disease by an uncommon agent (smallpox, inhalational anthrax, some VHFs) 
Containment and Decontamination
Unlike a chemical terrorism event, where a hazardous materials (HAZMAT) team and local first responders may have the opportunity to decontaminate a significant number of victims prior to their arrival at the hospital, a biological event may be unannounced.  As such, the first indication of a release may be the presentation of multiple ill patients to the ED. Decontamination of patients to avoid contaminating unexposed patients and staff only is considered immediately after an announced release of a biological agent and is carried out adequately with soap and water. In the more likely scenario in which the release is unannounced and patients present already ill, the emphasis is not decontamination but rather respiratory isolation of the patient with employment of standard precautions until the agent is known.
To render agents completely harmless on instruments, dry heat requires 2 hours of treatment at 160°C. Using steam at 121°C and 1 atm of pressure can reduce the time to 20 minutes (autoclaving).
When a biological attack is suspected, immediately employ necessary steps to ensure the safety of hospital personnel, existing patients, and the facility, thereby maximizing the ability to care for victims (see CBRNE - Biological Warfare Mass Casualty Management). [10, 9, 11, 12, 13]
One relatively simple triage method relies on a formal color-coded tagging system. For example, black stands for expectant, red for immediate, yellow for delayed, and green for healthy. When the need to triage multiple casualties in a rapid manner presents itself, simplicity is crucial. Additionally, the importance of practicing a triage method to ensure staff familiarity cannot be overstated.
A mass casualty incident (MCI) requires constant retriage of patients and resources. Effective response to an MCI requires that staffing and equipment supplies balance patient care demands, a potentially difficult equilibrium to establish. Nonetheless, this provides the opportunity to maximize the greatest good for the greatest number.
Many difficult decisions must be made under extremely stressful conditions, and using a simple system for evaluation and classification eases the burden of dealing with a BW event. Different triage systems exist and vary by local protocol. The ED physician must become familiar with his or her role within the local system, since the ED likely will serve as the center for medical care for the community during the early hours or days following a biological incident.
Although not traditionally viewed as a medical priority, securing hospital staff and resources is paramount to the successful delivery of medical care during an MCI. The ED staff, patients, and facility potentially are placed at risk by contaminated casualties seeking medical attention or family members seeking information. In addition, the ED may become a terrorist target through secondary devices, the deployment of which would halt medical care. Hospital entrances should be locked and guarded to prevent the public and injured from entering the facility unnoticed.
Hospital security must be trained to handle the initial moments of an MCI prior to the arrival of the local authorities, whose delay likely is based on the nature of the event. Hospital security personnel have direct exposure to the public. This potential risk mandates that they are trained adequately regarding personal protective equipment and have an understanding of medical triage dynamics. Additionally, they may require training in the areas of public reassurance and guidance; however, a predesignated information officer is essential.
Depending on the agent, prophylactic antibiotics and vaccines may be available for treatment of victims of a bioterrorism incident. Early notification of appropriate authorities (eg, Federal Bureau of Investigation [FBI], local health department, emergency management) and mobilization of resources (first responders, hospitals, health care providers, poison centers, police, fire, media) serve to minimize the number of casualties.
Appropriate Resources and Conclusion
See the list below:
The Centers for Disease Control and Prevention (CDC): CDC capabilities are epidemiologic surveillance, biological agent identification, and public health consultation and response.
US Army Medical Research Institute of Infectious Diseases (USAMRIID): As the Department of Defense's lead laboratory for medical aspects of biological warfare defense, USAMRIID conducts research to develop vaccines, drugs, and diagnostics for laboratory and field use. In addition to developing medical countermeasures, USAMRIID formulates strategies, information, procedures, and training programs for medical defense against biological threats. This web site also provides numerous links to other sites involved in biological warfare defense.
Although the likelihood of involvement in a bioterrorist incident is low for any given emergency physician, the consequences of unpreparedness are potentially catastrophic. Therefore, it is important that each physician understands his or her role within the hospital and community bioterrorist response plans. The greatest potential to save lives rests on the early recognition of the incident, accurate clinical diagnoses, and the expedient mobilization of appropriate hospital, local, and federal resources. 
eMedicineHealth's First Aid and Injuries Center provides excellent patient education resources. Also, see eMedicineHealth's patient education articles Biological Warfare and Personal Protective Equipment.