FOCUSING PREPAREDNESS ACTIVITIES | Terrorism and Disaster Management

Preparedness for terrorist-caused outbreaks and injuries is an essential component of the U.S. public health system, which is designed to protect the population against any unusual public health event (e.g., influenza pandemics; contaminated municipal water supplies; intentional dissemination of Yersinia pestis, the causative agent of plague) (Janofsky 1995).

Early detection of and response to biological or chemical terrorism are just as crucial for state and local organizations. Without special preparation at these levels, a large-scale attack with variola virus, aerosolized anthrax spores, a nerve gas, or a food-borne biological or chemical agent could overwhelm the local, and then perhaps the national, public health infrastructure. Large numbers of patients, including both infected persons and the “worried well,” would seek medical attention, with a corresponding need for medical supplies, diagnostic tests, and hospital beds. Emergency responders, healthcare workers, and public health officials could be at special risk.

Prepare for Unique Attacks

The epidemiologic skills, surveillance methods, diagnostic techniques, and physical resources required to detect and investigate unusual or unknown diseases, as well as syndromes or injuries caused by chemical accidents, are similar to those needed to identify and respond to an attack with a biological or chemical agent. However, public health agencies must also prepare for the special features a terrorist attack probably would have, including mass casualties or the use of rare agents.

Terrorists might use combinations of chemical and biological agents, attack in more than one location simultaneously, use new agents, or use organisms that are not on the critical list (e.g., common, drug-resistant, or genetically engineered pathogens).

Focus on Agents of Greatest Impact

Potential biological and chemical agents are numerous, and the public health, hospital, and healthcare organization infrastructure must be equipped to quickly resolve crises that would arise from a biological or chemical attack. Because of the hundreds of new chemicals introduced internationally each month, treating exposed persons by clinical syndrome rather than by specific agent is more useful for public health planning and emergency medical response purposes. Public health agencies and first responders might render the most aggressive, timely, and clinically relevant treatment possible by using treatment modalities based on syndromic categories (e.g., burns and trauma, cardiorespiratory failure, neurologic damage, and shock). These activities must be linked with authorities responsible for environmental sampling and decontamination.

To best protect the public, preparedness efforts must be focused on agents that might have the greatest impact on U.S. health and security, especially agents that are highly contagious or that can be engineered for widespread dissemination via small-particle aerosols (as we are planning now for mass smallpox vaccination of the U.S. population). Preparing the nation to address these dangers is a major challenge to U.S. public health systems and healthcare providers.

Focus on Early Detection

Early detection requires increased biological and chemical terrorism awareness among frontline healthcare providers because they are in the best position to report suspicious illnesses and injuries. Also, early detection will require improved communications systems between those providers and public health officials. State and local healthcare agencies must have enhanced capability to investigate unusual events and unexplained illnesses, and diagnostic laboratories must be equipped to identify biological and chemical agents that are rarely seen in the United States.

Fundamental to these efforts is comprehensive, integrated training designed to ensure core competency in public health preparedness and the highest levels of scientific expertise among local, state, and federal partners.

OVERT VERSUS COVERT TERRORIST ATTACKS

Terrorist incidents in the United States and elsewhere involving bacterial pathogens (Török et al. 1997), nerve gas (Okumura et al. 1998), and a lethal plant toxin (i.e., ricin) (Tucker 1996) have demonstrated that the United States is vulnerable to biological and chemical threats as well as traditional explosive weapons. Recipes for preparing “homemade” agents are readily available (Fester 1997), and reports of arsenals of military bioweapons (Davis 1999) raise the possibility that terrorists might have access to highly dangerous agents that have been engineered for mass dissemination as small-particle aerosols. Agents such as the variola virus, the causative agent of smallpox, are highly contagious and often fatal. Responding to large-scale outbreaks caused by these agents will require the rapid mobilization of public health workers, emergency responders, and private healthcare providers. Large-scale outbreaks will also require rapid procurement and distribution of large quantities of drugs and vaccines, which must be immediately available.

In the past, most planning for emergency response to terrorism has been concerned with overt attacks, such as bombings. Chemical terrorism acts are also likely to be overt because the effects of chemical agents absorbed through inhalation or through the skin or mucous membranes are usually immediate and obvious. Such attacks elicit immediate response from police, fire, and emergency medical services (EMS) personnel.

In contrast, attacks with biological agents are more likely to be covert. They present different challenges and require an additional dimension of emergency planning that involves the public health infrastructure. Because the initial detection of and response to a covert biological or chemical attack will probably occur at the local level, disease surveillance systems at local hospitals and state and local health agencies must be capable of detecting unusual patterns of disease or injury, including those caused by unusual or unknown threat agents. Epidemiologists at state and local health agencies must have expertise and resources for responding to reports of clusters of rare, unusual, or unexplained illnesses.

Covert dissemination of a biological agent in a public place will not have an immediate impact because of the delay between exposure and onset of illness (i.e., the incubation period). Consequently, the first casualties of a covert attack will most likely be identified by physicians or other primary healthcare providers. For example, in the event of a covert release of the contagious variola virus, patients will appear in doctors’ offices, clinics, and emergency rooms during the first or second week after release, complaining of fever, back pain, headache, nausea, and other symptoms of what initially might appear to be an ordinary viral infection. As the disease progresses, these persons will develop the papular rash characteristic of early-stage smallpox, a rash that physicians might not recognize immediately. By the time the rash becomes pustular and patients begin to die, the terrorists would be far away and the disease disseminated through the population by person-to-person contact.

Only a short window of opportunity will exist between the time the first cases are identified and a second wave of the population becomes ill. During that brief period, public health officials will need to determine that an attack has occurred, identify the organism, and avoid more casualties through prevention strategies (e.g., mass vaccination in the case of smallpox or prophylactic treatment in the case of anthrax). In the case of smallpox, as person-to-person contact continues, successive waves of transmission could carry infection to other worldwide localities, similar to what occurred in the SARS (severe acute respiratory syndrome) outbreak in spring 2003. These issues might also be relevant for other person-to-person transmissible etiologic agents (e.g., plague or certain viral hemorrhagic fevers).

Certain chemical agents can also be delivered covertly through contaminated food or water. In 1999, the vulnerability of the food supply was illustrated in Belgium, when chickens were unintentionally exposed to dioxin-contaminated fat used to make animal feed (Ashraf 1999). Dioxin, a cancer-causing chemical that does not result in immediate symptoms in humans, was probably present in chicken meat and eggs sold in Europe as early as 1999, because the contamination was not discovered for months. This incident underscores the need for prompt diagnoses of unusual or suspicious health problems in animals as well as humans, a lesson that was also demonstrated in New York City by the winter 1999 outbreak of mosquito-borne West Nile virus first diagnosed in birds and humans. The dioxin episode also demonstrates how a covert act of food-borne biological or chemical terrorism could affect commerce and human or animal health.