Aerosolized Anthrax Scenario

• Overview
• Planning Considerations
• Mission Areas Activated
• Implications

Overview

For years, the UA has been growing and gaining political strength in a region of the world historically unfriendly to the West, especially the U.S.  A series of small, but somewhat successful, conventional attacks against Western targets in the area has aided UA recruiting efforts and also resulted in increased financial resources provided through large donations by wealthy, sympathetic followers.  Several years ago, using their newfound popularity among several Western educated scientists and physicians in the area and their increasing financial resources, UA leaders decided to begin development of a biological weapons program.  After observing the impact of the attacks in 2001, they determined that a biological attack using anthrax could be successful if properly planned and resourced.  Biological warfare experts working for UA have determined that an aerosolized anthrax attack in a major city or multiple cities in the United States would cause catastrophic damage, killing thousands, exposing hundreds of thousands, and sending the country into a panic.  Leaders of the UA feel this type of attack would support their ultimate objective, the removal of U.S. forces in that region of the world, by embarrassing the U.S. government on homeland security issues and forcing them to abandon current policies.   The UA planners, along with several members of the organization with extensive science backgrounds, began the development of an operational plan that if successful would ultimately result in the release of aerosolized anthrax in several major U.S. cities.  Twenty-four months ago, the UA began executing their plan, developing the capability to weaponize Bacillus anthracis and infiltrating the necessary personnel and equipment into the U.S. 

Over the course of the last several months, UA cells within the U.S. have obtained the necessary equipment and supplies to conduct the attack, have performed all of the intelligence activities required, and have produced the necessary anthrax slurry to conduct the attack.  The only problem currently identified by the UA scientists is the inefficiency of the dissemination method, which results in a lower percentage of aerosolization than desired by the UA planners.  Ten days prior to the scheduled attack date, chosen to coincide with an upcoming major conference in the target city, the UA leadership decides to dispatch a new member of the organization who has designed a new type of spraying device that increases the efficiency of the aerosolization process.  Arrangements are made to smuggle the individual over the border approximately 1 week prior to the attack.

Unknown to the UA, the member being sent to the U.S. to modify the delivery system has been under surveillance by the intelligence agency of a friendly government in the area.  In an operation coordinated between intelligence agencies, border agents, and law enforcement officials, the UA operative is arrested while crossing the border into the United States.  An examination of the background information on the individual provided by friendly intelligence organizations provides US intelligence officials with enough information to determine the operative may be involved in a terrorist attack on the United States, mostly likely some form of bioterrorism.  A search of the operative’s overseas apartment discovers several detailed maps of U.S. cities, marked with multiple routes into and out of the cities, as well as detailed meteorological information on each of the cities.  Under intense interrogation, the UA member identifies that he is part of a group planning an attack on U.S. cities.  The UA member is able to provide some information on the names and countries of origin for other members of the group as well as the first target city.  He also states he expects the attack to occur within the next 2 weeks.  Information obtained from the prisoner is provided to other agencies in the U.S. and overseas in an attempt to locate and apprehend the other members of the terrorist organization.   Provided with this intelligence, which is regarded as highly credible, the Department of Homeland Security National Operations Center (NOC) notifies the Secretary of the Department of Homeland Security (DHS), who, after consultation with the President, decides to raise the Terror Alert Level from Yellow to Orange.  As a result, HHS takes the following steps: 

• Place the U.S. Public Health Service Commissioned Corps (PHS CC) on alert status
• Alert emergency support and management teams for potential deployment
• Increase operational hours at all HHS Emergency Operations Centers (EOCs) to 24 hours a day, seven days a week.

The NOC, in collaboration with the Federal Bureau of Investigation’s Strategic Information and Operations Center (SIOC) and appropriate Joint Terrorism Task Forces (JTTFs), continues actions in an attempt to gain further intelligence on an imminent attack, which includes conducting security operations, tactical operations, and other prevention activities.  The UA cell conducting the attack, noting the increase in the Terror Alert Level and suspecting their operation may have been compromised by the capture of the new operative, push up their attack date.  Three days after the capture of the operative, a specially fitted box truck turns onto a busy street and enters the morning rush hour traffic that is slowly moving through the downtown area.  A large number of people are exiting the Convention Center/Downtown subway station, having just arrived on an incoming train.  A large group of construction and maintenance workers are completing projects on the newly renovated convention center, readying it for an upcoming event.  As the truck drives south past the convention center, the driver’s companion turns on a concealed improvised spraying device with a conventional nozzle that rapidly aerosolizes and disperses approximately 100 liters of wet-fill Bacillus anthracis slurry, or 109 colony-forming units per milliliter (cfu/mL).  For the most part, the dissemination goes unnoticed by the people on the street.  Several people report an unpleasant smell to city officials, but the odor is attributed to repair work that is being done on underground pipes in the downtown area. The dissemination efficiency achieved in this operation (less than 1%) is comparatively modest. Nonetheless, it is sufficient to result in the potential exposure of approximately 330,000 persons. Assuming that winds are southeasterly, the majority of the population exposed will be in an area extending northwest from the city, an area which includes several large suburbs and a small city just across the border with another State.  Among those exposed, more than 13,000 cases of inhalation anthrax would be expected.

In 2004, DHS, in collaboration with HHS and EPA, placed a series of BioWatch sensors in the city, to include several in the vicinity of the convention center.  A significant number of spores from the aerosolized Anthrax attack are collected by the Dry Filter Unit (DFU) BioWatch sensor over the span of the next four hours.  Four rotating filters within the BioWatch unit collect spores, with the numbers of spores collected on the filters gradually decreasing over time.  Over the course of the day, the BioWatch filters randomly collect samples containing additional anthrax spores, but at substantially lower concentrations than earlier in the day.  Sixteen hours after the attack, workers from the EPA collect the filters and send them to the Region, Tribe, Territory, State public health laboratory for analysis. The Region, Tribe, Territory, State public health laboratory, a part of the Laboratory Response Network (LRN), performs the primary testing.  Through Polymerase Chain Reaction (PCR) testing, initial results indicate the samples taken from many of the filters are PCR Reactive.  Confirmatory tests also come back PCR Reactive.  Upon confirmed detection of DNA of Bacillus anthracis, additional sampling, communications and risk management mechanisms and protocols in place at DHS, HHS/CDC, HHS/ASPR, EPA, and DOJ/FBI are carried out.  The FBI-WMD Coordinator, local, Region, Tribe, Territory, State and Federal emergency management and public health officials are all rapidly notified.  The HHS Secretary’s Operations Center (SOC) coordinates with the CDC to ensure all appropriate Region, Tribe, Territory, State and local Public Health officials are notified and to republish guidance on the appropriate diagnosis and treatment of patients that present at healthcare facilities with symptoms of anthrax exposure.

Meanwhile, emergency departments (EDs) and doctors’ offices are beginning to experience an increase in the number of individuals seeking evaluation and treatment for conditions such as fever, malaise, nausea, vomiting (typical influenza type symptoms).  These patients are presumably those who were along the street outside the convention center and were exposed to the highest concentrations of Anthrax spores.  Due to the recent public health alerts generated after the BAR, patient workups include testing for inhalation anthrax, and for patients that present with the appropriate symptoms and meet the additional diagnosis guidelines published by the Public Health Office, immediate treatment begins. 

Three days following the release, the Region, Tribe, Territory, State health department is notified by four separate clinicians that patients have been admitted to different hospitals with severe respiratory symptoms that are now growing gram-positive rods from blood cultures.  Samples are sent to the appropriate Public Health lab for confirmation and the CDC and other appropriate Region, Tribe, Territory, State and Federal Agencies are notified.  Local and Region, Tribe, Territory, State emergency management officials begin immediate implementation of their consequence management plans.

At the NOC, a recommendation is made to the Secretary of Homeland Security, based upon credible intelligence, a BioWatch Actionable Result, and multiple patients diagnosed with inhalation anthrax, to declare an Incident of National Significance and activate the National Response Plan.  After immediate consultation with other high-level government officials, the Secretary makes the declaration.  In accordance with the National Response Plan, the Emergency Alert System, Incident Communications Emergency Plan, and National Incident Communications Conference Line are all activated.  The National Response Coordination Center (NRCC) and relevant Regional Response Coordination Center (RRCC), are activated at full staffing levels and all Emergency Support Functions (ESFs) are alerted.  HHS forms an Incident Response Coordination Team (IRCT) and directs CDC to prepare to deploy the appropriate antibiotics and medical supplies from the SNS to respond to the incident.  Guidance on inhalation anthrax is also prepared for and distributed to Region, Tribe, Territory, State and local public health officials.   

Over the course of the next week, many more patients are diagnosed with inhalation anthrax.  Many additional people seek treatment at local hospitals and physician office’s, but are determined not to require antibiotics.  Even hospitals well outside the impacted region report increases in patients presenting with influenza type symptoms – many of whom were in the impacted city the week before and simply suspect they may have been exposed.  After an appropriate workup and determining the risk of exposure based upon epidemiological investigations, many of these patients begin the prophylaxis protocol. 

Planning Considerations[1]

Geographical Considerations/Description:

Dispersal of the anthrax takes place in a densely populated urban city with a significant commuter workforce. Various businesses in the downtown area are regularly visited by individuals from regions across the country.  Overall, the exposed population will disperse widely before the incident is detected.  A major fraction (perhaps up to 50 % of persons in the city) may reside a significant distance from the city and would probably seek health care close to their residence.  A significant but smaller fraction of persons in the city may be from other states and nations, complicating risk communication and other response issues.  The direction of the plume and levels of exposure at various distances from the point of release will be extremely difficult to determine.

Timeline/Event Dynamics:

Because the incubation period range for inhalation anthrax is not well defined, cases may begin to present to EDs as soon as 1-3 days post-release.  The widely ranging (1-41 days based on multiple research statistics) incubation period is due to a variety of host factors as well as dose and characteristics of the infecting strain.  Higher doses (such as to those people who were immediately outside the convention center during the attack), based on animal data, are likely to result in shorter incubation periods.  Determining when the period of risk is over will also be problematic and will entail a considerable environmental evaluation effort. 

The first cases who received relatively high doses may show rapid progression of symptoms and a higher mortality rate. In the absence of a PCR-verified confirmation of the incident, the rapidly escalating number of previously healthy persons with severe respiratory symptoms would quickly trigger alarms within hospitals and at the Department of Public Health (DPH).

Based on crude estimates developed for determining hospital capacities following 9/11, it is thought that by expediting discharges and by canceling elective and semi-elective surgical procedures in the 100-plus hospitals around the city, rooms would be available to accommodate as many as 3,000 additional patients on fairly short notice. It is not precisely known how many patients requiring intensive care could be absorbed, but the number would be significantly less than 3,000, possibly on the order of a couple of hundred. There is a possibility that hospitals may be able to increase intensive care bed capacity by 15-20% by temporarily lodging patients with inhalation anthrax in post-anesthesia care units.

The situation in the hospitals will be complicated by the following facts: The release has occurred at the beginning of an unusually early influenza season and the prodromal symptoms of inhalation anthrax are relatively non-specific. It should be expected that large numbers of worried patients, including many with fever and upper respiratory symptoms, would crowd EDs for evaluation and treatment. Discriminating patients with anthrax from those with more benign illnesses will require the promulgation of clear-case definitions and guidance. Physician uncertainty will result in low thresholds for admission and administration of available countermeasures (e.g., antibiotics), producing severe strains on commercially available supplies of such medications such as ciprofloxacin and doxycycline, and exacerbating the surge capacity problem.

Assumptions:

• Wet-fill anthrax supply 100 liters of 10⁹ cfu/mL
• Length of line source 1,000 meters
• Initial buoyancy of plume None
• Meteorological conditions Mid-range
• Dissemination efficiency 1%[2]
• Human ID₅₀/ID₁ 10,000 cfu/530 cfu
• Untreated case-fatality rate 99%
• Treated case-fatality rate 45%
• Protection factor of buildings 50%
• Percentage of population outside 15%

Mission Areas Activated

Prevention/Deterrence:

The ability to prevent further releases of anthrax lies with law enforcement and may include: selection of agent registration and control; knowledge of persons with laboratory skills to grow and aerosolize anthrax; reconnaissance of purchase and shipment of critical laboratory and dispersion supplies; reconnaissance of mobile or temporary laboratories; and public health protection measures at the site before and during the attack. Forensic studies such as DNA “fingerprinting” may have value in determining the source if the UA obtained the strain in-country. 

Emergency Assessment/Diagnosis:

Surveillance systems will be used to monitor the impact of the attack, determine resource needs, classify the type of incident, and determine whether additional events have taken place. Additional environmental sampling, both inside and outside buildings, may be warranted in order to assess the risk for continued exposure from contaminated environments. ED physicians, local hospital personnel, infectious disease physicians, medical examiners, epidemiologists, and other public health officials should immediately recognize the seriousness of the incident. Laboratory methods such as performing a Gram stain and observing Gram-positive rods (consistent with Bacillus species) are available at all local public and private laboratories; however, there may be a delay in the recognition of anthrax since most hospital ED and laboratory personnel in the city and elsewhere have limited or no experience in identifying and/or treating this disease. Supplemental testing and confirmation for anthrax is available through the CDC’s Laboratory Response Network (LRN).  A rapid onset with large numbers of persons presenting at EDs with respiratory distress and fevers should create high suspicion of a terrorist event utilizing anthrax or other agents of bioterrorism. Detection of anthrax also should initiate laboratory identification of the strain and a determination of any antimicrobial drug resistance.  Actions of incident-site and Emergency Operations

Actions of incident-site and Emergency Operations Center (EOC) personnel tested during and after the attack include dispatch, agent detection, hazard assessment and prediction, monitoring and sampling, and tracing origin of the initial contamination back to its source.

Emergency Management/Response:

The National Incident Management System (NIMS), the EOC, and the Joint Information Center (JIC) will be used to manage and respond to the attack. This is a large-scale incident with thousands of potential exposures. Actions of incident-site EOC and JIC personnel tested after the attack include public alerts, mobilization of the SNS, activation of PODs, traffic and access control, protection of special populations, potential protective measures including shelter-in-place recommendations, requests for resources and assistance, and public information activities.

Hazard Mitigation:

Efforts to mitigate the impact of the attack include the provision of Pre-positioned Equipment Pods, environmental testing and decontamination, and care of ill persons. Persons with primary aerosol exposure to anthrax need to receive antibiotic therapy prior to the onset of symptoms in order to prevent inhalation anthrax – this is an illness with an exceptionally high mortality rate (approximately 40% to 50%) even when met with aggressive medical care. Person-to-person spread does not occur. Actions of incident-site personnel tested after the attack include hazard identification, site control, establishment and operation of ICS, treatment of exposed victims, mitigation efforts, distibution of personal protective equipment (PPE) and prophylaxis for responders, site remediation and monitoring, provision of public information, and effective coordination with national and international public health and governmental agencies.

Environmental sampling will be important due to contamination associated with the low efficiency dispersal device.  A major issue will be safety in continued use and occupancy of buildings and other structures in the contamination zone. Prioritization of environmental sampling will be a problem, particularly in face of laboratory limitations.  Adequacy of sampling will also be an issue.

Evacuation/Shelter:

The JIC will coordinate efforts to provide warnings to the population-at-large and the population-at-risk, and will notify people to shelter-in-place and/or evacuate. The ICS will be used to provide resources for managing traffic flow and accessing affected areas and PEP distribution centers. Evacuation and treatment of victims will be required, as will prompt antimicrobial prophylaxis of exposed persons, responders, and pertinent health care workers.

Victim Care:

State and local Public health departments will take the lead in providing care to ill persons, disbursement of post-exposure prophylaxis, and vaccination, if indicated. Tens of thousands of persons will require treatment or prophylaxis with ventilators and antibiotics. Thousands of persons will seek care at hospitals, with many needing advanced critical care due to inhalation anthrax. Exposed persons also will need to be informed of the signs and symptoms suggestive of inhalation anthrax. Mobilization of the SNS for additional critical supplies and countermeasures will be necessary. Public information activities will be needed to promote awareness of potential signs and symptoms of anthrax exposure/inhalation. Actions of incident personnel after the attack include emergency response, protective action decisions and communication, recognition of the hazard and scope, victim treatment, need for additional ventilators at hospitals, non-hospital patient screening clinics, and establishment of treatment or drug distribution centers for prophylactic antibiotics, veterinary services (as animal carcasses will be present across the region), and mortuary considerations.

Investigation/Apprehension:

Law enforcement will take the lead in investigating the attack. It will be done in collaboration with the public health officials who will be working to identify populations at risk of disease. Epidemiological trace-back of victims and parallel criminal investigations to determine the location of point-source exposures will be needed. Laboratory analyses will be required in order to determine the implicated anthrax strain. Actions of incident-site personnel tested after the attack include dispatch, site containment and control, criminal investigation, tactical deployment, and apprehension.

Recovery/Remediation:

Decontamination/Cleanup: Decontamination/cleanup efforts will be coordinated by the Environmental Protection Agency (EPA) with input from HHS/CDC. Anthrax in its spore form (the probable form for dissemination as a biological terrorism agent) would not be rapidly inactivated by environmental conditions (i.e., ultraviolet exposure or desiccation). Anthrax is hardy and resistant to environmental extremes – it is therefore long-lived in the environment. Extensive decontamination and cleanup likely will be necessary. Human and animal health implications will require considerable consultation between EPA, HHS/CDC and USDA.  Environmental clearance standards will have to be developed. Actions of incident-site personnel include environmental testing, identification and closure of highly contaminated areas, and provision of public information. The economic costs associated with the closure and decontamination of affected areas may run in the billions of dollars.

Site Restoration: The EPA will coordinate site restoration efforts with input from the HHS/CDC. Costs are scenario-dependent and therefore difficult to predict, but they will likely be enormous.

Implications

Secondary Hazards/Events:

Social order questions will arise. The public will want to know very quickly if it is safe to remain in the affected city and surrounding regions. Many persons will flee regardless of the public health guidance that is provided – some fearing additional anthrax releases and some fearing perceived continued risk of exposure from the “contaminated” area. Pressure may be placed directly on pharmacies to dispense medical countermeasures directly, particularly if there are delays in setting up official points of distribution. It will be necessary to provide public health guidance in more than a dozen languages. The number of visitors and commuters working in the city on the morning of the attack will complicate the identification of patients and distribution of antibiotics, as cases will present over a wide geographic area, and many commuters will be reluctant to reenter the city because of perceived risk and their desire to remain in their city of residence for treatment.

As always with a bioterrorism event, the public health and law enforcement communities will be attempting to determine whether any other agents were released at the same time as the anthrax attack

Deaths/Injuries/Illnesses:

Exposures 328,484

Untreated fatalities 13,208

Total casualties 13,342 

Property Damage:

Based on the experience with postal anthrax, property damage would be due to contaminated building contents and remediation approaches.  Substantial cleanup would be required in buildings where air-intakes absorbed Anthrax spores. 

Service Disruption:

City services will be hampered by concerns regarding the safety of remaining in the city, going outdoors, and returning to the city from surrounding States.

Economic Impact:

There is the potential for a sell-off in the economic markets; moreover, the stock exchange and large businesses may be directly affected by the attack. Depending on the success of the dissemination techniques and virulence of the biological agent, fatalities could be considerable. Therefore, the expected earnings during a victim’s life will be lost, resulting in a decline in consumer spending and a loss of revenue for the metropolitan area. Business disruption in the area will be long-lasting.  An overall national economic downturn is possible in the wake of the attack due to loss of consumer confidence. The costs of the closure of a large section of the city and the decrease in revenue from tourism for an indeterminate period would be enormous, as would the costs of remediation and decontamination. Persons from other areas may chose to not enter the impacted city for years.

Long-Term Health Issues:

HHS/CDC will be involved in the assessment of the long-term health impacts of the attack, as well as the measures that will be taken to prevent disease (e.g., post-exposure prophylaxis and vaccinations). Many persons will be killed, permanently disabled, or sick due to anthrax. The long-term sequelae of inhalation anthrax in survivors are not well understood but may be significant. The long-term effects of longer duration antimicrobial prophylaxis regimens for large numbers of persons also will need follow-up study. The associated mental health issues relating to the attack will be significant.

Risk Communications:

Depending on the size and location of the attack, it may be necessary to notify and involve foreign governments and agencies.  International notification in accordance with the International Health Regulations (IHRs) to the World Health Organization (WHO) Contact Point may be required, especially if the event occurs at a location along an international border or if foreign nationals are involved.