Day 1 12:00 am — It is a warm summer evening in the city of Anywhere, USA, population 2.6 million. People are sleeping with their windows open to let in the gentle breeze blowing from the north. About 10 miles north of the city, a small plane flies over farmland in a roughly west to east direction. The noise of the plane does not disturb the handful of residents who hear it because there are several farms in the area and farmers often have their crops dusted at night. The plane, a commercial crop duster with customized spraying equipment, releases a misty spray over a distance of 27 miles. The spray is actually an aerosol of wet droplets carrying anthrax spores that are being delivered by a terrorist group in a biological attack.

Day 1 3:00 am — By this time, the plane has landed at a rural landing strip and its pilot is driving his pickup truck on a long journey to the Canadian border; once there, he will make his way overseas. The breeze, now a little stronger, has begun to disperse the cloud of microscopic anthrax droplets towards the south. The cloud is already almost 9 miles long and is just beginning to reach the outskirts of the city. Slowly, the droplets containing the anthrax spores will float towards the earth, settling on roads, gardens, and the roofs of buildings, where they may be swept into air intake vents. A large number of spores will even ride the breeze through the open bedroom windows to the sleeping citizens of Anywhere.

Day 1 6:00 am — The cloud, with its deadly load of anthrax spores, has now traveled about 14 miles and many of the spores have settled onto the ground, while others are still floating in the air. People begin to get up and leave for work, unaware that they may have inhaled anthrax spores while they slept, or when settled spores are disturbed and propelled back into the air while running to their buses, or opening their car doors. The city of Anywhere and its surrounding districts are home to 2.6 million people. About 1.5 million of these live in the area over which the spores were dispersed and within this area, approximately 624,000 people were actually exposed to anthrax spores during the night and morning. The diagram shows the concentration of anthrax bacterial spores in various zones; the higher the concentration, the more chance that individuals will develop the disease if exposed. In the red-colored zone, 90% of those exposed will contract inhalation anthrax disease. In the orange zone, 50% of those exposed will develop the disease, and in the yellow zone, 20%. The 624,000 people exposed to the spores are distributed amongst the zones as follows: about 700 live in the red zone, 118,000 in the orange zone, and the remaining 505,300 in the yellow zone. This means that in the red zone, 630 people will develop anthrax disease (90% of 700), in the orange zone, 59,000 people will develop the disease (50% of 118,000), and in the yellow zone, 101,060 (20% of 505,300).

Day 1 The outcome of the bioterrorist attack and the number of people who will ultimately lose their lives depends largely on how well prepared the city of Anywhere is to deal with an attack's aftermath. Two examples are discussed here: the worst-case scenario in which the city is totally unprepared for an attack, and the best-case scenario, in which the city has detailed, efficient procedures in place and coordinates effectively with state and federal resources to deal with the attack. orange zone, 59,000 people will develop the disease (50% of 118,000), and in the yellow zone, 101,060 (20% of 505,300).

Worst Case Scenario — Day 2 Beginning with Day 2 and continuing over the next several days, roughly 160,000 citizens of Anywhere will begin showing signs of fever, coughing, mild chest pains, and other flu-like symptoms. Many will be sick enough to visit their family doctors or emergency clinics. Physicians, most of whom do not even suspect anthrax, believe that this is just an outbreak of the flu and therefore send their patients home for bed rest.

Worst Case Scenario — Day 3 Some patients are beginning to display severe symptoms and are admitted to hospitals. Hospital laboratories, not knowing the seriousness of the situation, follow normal procedures for identifying the source of the disease and, when they come up with unusual findings, make arrangements to send samples off to county and state reference laboratories for confirmatory tests. This identification process may take anywhere from two to four days. Because Anywhere's various hospitals and clinics are not in communication with each other, no one realizes that a large number of patients over a wide area are showing similar symptoms.

Worst Case Scenario — Day 4 Anywhere has 36 hospitals and 12,000 hospital beds, and all available beds are soon occupied. Thousands of patients are now ill and hundreds are beginning to die. A preliminary diagnosis of anthrax is made. A citywide emergency is declared, local health officials scramble to coordinate, and the mayor makes an announcement asking the public to remain calm and assuring them that anthrax is not contagious. The number of ill individuals arriving at hospitals rises dramatically, inflated by many uninfected residents who have panicked after the news broadcast and now are demanding treatment of imagined illness. By the end of Day 4, more than 1,000 people have died and hospital workers, either fearing for their own safety or unable to cope with the influx of new patients, begin abandoning their posts.

Worst Case Scenario — Day 5 Public health officials announce that antibiotics will be distributed at various schools, hospitals, and police stations around the city. Nevertheless, there is much confusion among Anywhere's population about where to go for treatment and who gets priority. Many members of the public are unaware that several antibiotics are effective against anthrax and panic when supplies of Ciprofloxacin, considered by many to be the antibiotic of first choice, run out and authorities substitute other antibiotics. Meanwhile, the city transit system has shut down, and people begin to flee the northern areas of the city, where most of the sick people live. Miscommunication and poor coordination mean that shipments of additional antibiotics from the federal government are delayed. By the end of Day 5, hospitals have run out of room, so they can no longer admit patients. Triage is undertaken in the street, and the ill are either being sent home or are diverted to local schools and sports centers that are serving as makeshift treatment areas. As medical supplies in the city become exhausted and as the number of medical personnel attending to the sick and dying diminishes, the quality of treatment drops drastically. As the number of dead reaches the 5,000 mark, city mortuaries are unable to store corpses and are forced to close down.

Worst Case Scenario — Day 6 The large-scale distribution of antibiotics begins, as federal supplies and the National Guard arrive. However, it is too late for many of the victims since antibiotic treatment of anthrax must begin soon after the infection is contracted. The city has almost ceased to function; evacuation and illness mean that most of the residents have abandoned their homes and officials have left their posts. Anywhere has become Nowhere.

Worst Case Scenario — Day 22 The final death toll is 125,000.

Best Case Scenario — Day 2 Veterinarians begin seeing several sick and dying livestock in the area to the north of the city. They inform the city health department, which notes the information. Meanwhile, the first patients begin to show signs of illness and visit their doctors and emergency clinics. The doctors at first diagnose these isolated cases as a non-specific flu-like illness. However, as the number of cases increases, a few doctors begin to suspect that a more dangerous epidemic is underway. Knowing that anthrax is one possible cause of this epidemic, these doctors immediately send away samples for urgent testing and inform the city health department of their suspicions. The city health department sends out an alert to all hospitals and clinics to be on the lookout for unusual diseases or numbers of ill persons. Meanwhile, city laboratories discover that the submitted samples contain bacteria of the Bacillus family, which includes anthrax bacteria, and immediately send the samples to the closest laboratory that is part of the national Laboratory Response Network for bioterrorism. Using advanced techniques, this specially equipped laboratory makes a provisional identification of anthrax by 10 p.m. on Day 2. All of the city's hospitals are informed of these results and immediately start patients on courses of antibiotics.

Best Case Scenario — Day 3 In the early hours of Day 3, disaster management plans at the local, state, and federal level are put into effect. The Centers for Disease Control and Prevention (CDC), the Federal Bureau of Investigation (FBI), and the Federal Emergency Management Agency (FEMA) are informed of the epidemic, the National Pharmaceutical Stockpile is activated, and various other biological response units are mobilized, including the Department of Defense Weapons of Mass Destruction Civil Support Teams and units of the Metropolitan Medical Response System and the National Disaster Medical System. Local health authorities begin an epidemiological investigation. At 9 a.m., an announcement is made directing anyone who had been present in the northern half of the city two days prior to assemble at local treatment centers to receive antibiotics. By 10 a.m., a wide-ranging antibiotic distribution network has been established and staffed. Federal assistance and supplies begin arriving at midday, enabling fresh medical personnel to relieve tired local personnel by evening. A massive public information campaign is conducted to encourage the public to remain calm and to ensure that only those at most risk show up at the distribution centers. Officials assure the public that they have more than enough antibiotics to treat everyone. Although there are sporadic incidents of looting of pharmacies and some cases of panic, in general, the coordinated official response means that public order is maintained.

Best Case Scenario — Day 4 By 10 a.m., more than 400,000 people have received antibiotics at 22 treatment centers located throughout the city. This figure includes most of those displaying initial symptoms. Sports stadiums and schools have been converted into temporary treatment centers in order to supplement hospital care for those already displaying more severe symptoms of the disease. Efficient coordination between local, state, and federal officials makes these measures possible. An investigation is launched by the FBI to gather evidence, and environmental testing by CDC and Environmental Protection Agency (EPA) officials has begun to determine the extent of contamination.

Best Case Scenario — Day 22 It has been a harrowing time for the city of Anywhere. It has suffered its worst disaster in history and lost 38,000 of its citizens to anthrax. However, the city has managed to continue to function, and the majority of those who were initially infected are now either non-symptomatic or on the road to recovery, though they will have to continue taking antibiotics for the next two months. It is now possible for the long process of decontamination and rebuilding to begin.

Conclusion Although it may seem frightening, this scenario is a realistic description of a bioterrorist attack on a large U.S. city. It shows that a single release of aerosolized pathogens by terrorists could have catastrophic consequences. It also highlights how vital it is that local, state, and federal authorities be well prepared, well trained, and have coordinated plans to deal with the consequences of a large-scale chemical or biological terrorist event. Starting the efficient distribution of antibiotics on Day 3 as opposed to Day 5 cut the number of deaths from anthrax by two-thirds (38,000 as opposed to 125,000 deaths out of 160,000 infected). There are other measures that, while not available at present, could further reduce the number of fatalities. The first is reliable biological agent detectors that are currently being developed. These would alert authorities soon after the release of the anthrax in our scenario; treatment could then begin hours after the attacks and, in the current best-case scenario, would cut the number of deaths to approximately 8,000 people. In addition, large-scale vaccination of the public against anthrax before the event would make most people immune, but because of several issues with the vaccine, including logistics, authorities have not seriously considered this option. Obtaining a strain of pathogenic anthrax bacterium, processing it, and spraying it effectively are not easy tasks and beyond the technical capabilities of most of today's terrorist groups. On the other hand, the attacks in September-October 2001 that utilized letters laden with anthrax spores show that at least some terrorists have the capability to carry out a biological attack-and that governments must be prepared to protect their citizens from this threat.