Since the terrorist acts of September 11, 2001, there have been many changes in our lives. From the federal government to our local communities, many efforts have been made to prevent additional attacks and to be prepared if another attack occurs. Hospitals and health care agencies provide a critical part of these preparedness efforts and as providers are expected to be prepared for victims of these attacks, whether they suffer from a traumatic injury or are infected with an exotic disease. Of these, no type of terrorist incident has the potential to generate more fear than a covert attack with a biological weapon. But no terrorist action could be hampered more by the vigilance of informed health care professionals.

Health care providers, particularly nurses, must increase their knowledge of the effects a biological attack would have on a population. With this knowledge, providers could be the first to notice an increase of consistent symptoms resulting from a covert attack. With rapid recognition and diagnosis, treatment can begin early and save many lives. Some hospitals, clinics, and physicians’ offices are connecting to regional web-based surveillance tools that will allow for even faster recognition of health syndromes that could be related to a biological attack. All health care professionals need to be armed with current knowledge. Additionally, each health care facility must have plans in place to provide isolation and personal protective equipment to ensure the safety of both their staff and facility from contamination and possible secondary infections from a contagious agent.¹

Biological weapons include bacteria, viruses, and biological toxins. Of the possible biological agents, the most likely or most hazardous include the bacteria Bacillus anthracis (anthrax) and Yersinia pestis (plague), the variola virus (smallpox), and the biological toxin botulism (Clostridium botulinum). Both the U.S. and Soviet Union participated in weaponizing these and other agents after World War II. In 1972, many countries, including the U.S. and the Soviet Union, signed an agreement at the Biological Weapons Convention prohibiting the development, production, and stockpiling of bacteriological (biological) and toxic weapons. Despite this, many countries continued their research and development. Today, several of those, including state-sponsored terrorist organizations hostile to the U.S., are suspected of proliferating biological weapons for their use.²

Biological weapons are not new. In 1346, the Tatar army hurled the corpses of soldiers who had died of the plague over the Kaffa City walls, infecting residents who were defending the city. Some of those who left Kaffa may have started the Black Death pandemic that spread throughout Europe. Russian troops used this same tactic against Sweden in 1710.² Biological warfare also occurred during the French and Indian War of 1754 to 1767 when an Englishman, Sir Jeffery Amherst, gave smallpox-laden blankets to Native Americans who were loyal to the French. The Native Americans sustained epidemic casualties as a result.²

With the possibility that such agents could be used again, heightened vigilance of health care providers is necessary. Early recognition of these illnesses could trigger earlier diagnosis and allow preventive measures that could save many lives. Caregivers need to learn the early signs and symptoms and the modes of transmission of biological agents, not only for the well-being of their patients, but also for themselves. The health of nurses who work on the front line of acute health care could be at risk. For example, those working in physicians’ offices, clinics, and EDs could be at risk of secondary infection from pathogens, such as plague and smallpox. And in the event of an attack, nursing challenges would not end with acute care. Large numbers of patients would require intensive care for weeks or even months. Entire wings of hospitals or clinics would be subject to quarantined isolation. Only education can reduce the risk.

Anthrax

After suffering through several years of anthrax letter hoaxes, real anthrax letters were mailed in 2001 to media and political offices. As a result, 22 people were infected with the bacteria. Inhalation exposure caused infection for 11 of the 22 victims, and at least the first nine were caused by exposure to anthrax found in letters.³ Although there has not been a repeated attack since then, the next episode may be right around the corner. The perpetrator of the 2001 attack has never been found, and it remains uncertain whether it was an act of domestic or international terrorism.

Bacillus anthracis is a spore-forming bacterium that causes a rapidly progressing infection. Once the infection is established, the victim is said to have anthrax. Bacillus anthracis derives its name from the Greek word for coal (anthrakis) because of the black, coal-like skin lesions it creates.⁴ Anthrax can develop from inhalation, ingestion, or exposure of nonintact skin to the bacterium. The spores are hardy and can remain viable for more than 40 years.⁵ At least 17 countries have developed an anthrax weapon program.⁴ In 1970, the World Health Organization (WHO) concluded that the release of 50 kg of aerosolized anthrax upwind of a population of 5 million could lead to an estimated 250,000 casualties and 100,000 deaths,⁶ substantiating the perceived threat from Bacillus anthracis. Because of the efficiency and durability of its spore, the bacterium’s use as a biological weapon has brought great concern to the U.S. military and, more recently, the public.

The Japanese Aum Shinriko religious sect spent millions of dollars developing an anthrax weapon and on at least eight occasions, released anthrax or botulism. Because of the difficulty encountered in the dispersion, the sect members failed to produce any infection and eventually concentrated their efforts on Sarin, a nerve agent. Sarin was used with only moderate success as a lethal agent in both Matsumoto and Tokyo.⁴

The largest incident involving inhalation anthrax occurred in 1979 in Sverdlovsk, USSR, when a military biological facility accidentally released spores into the air from a faulty laboratory ventilation system. The Soviet Ministry of Health stated that the deaths were due to contaminated meat, but in the summer of 1992, President Boris Yeltsin acknowledged that the deaths were due to an accidental release from a military microbiology facility, Compound 19. In total, 77 people developed anthrax, and 66 died.⁷ Although the majority of inhalation anthrax cases from Sverdlovsk developed between four and 14 days, cases continued to emerge up to 43 days after the release.⁴ Some argue that secondary aerosolization may be responsible for those infections that developed beyond seven days after the primary aerosolization.⁴

Cutaneous, ingested, and pulmonary anthrax

Cutaneous anthrax infection occurs when bacteria enter through cuts or breaks in the skin and cause a localized infection. In two to six days, the infection results in itching followed by papular lesions that turn vesicular and into depressed black scabs. At this point, a Gram stain and culture of vesicular fluid can confirm the diagnosis. Anthrax occurs most frequently on the head, hands, and arms of people who work with infected cows, sheep, or horses. Recent cutaneous infections have resulted from handling letters that contained anthrax spores and then touching open skin. Skin infections not promptly treated can progress into sepsis and have a mortality of 5% to 20%.⁷ Because cutaneous anthrax does not progress as rapidly as the pulmonary or gastrointestinal infection, it is usually not fatal if treatment is started before the onset of septicemia.

Ingested bacteria can also cause infection. Nonintentional infections are usually associated with the ingestion of meat from infected animals. Incubation is from one to seven days after ingestion. The bacteria invades the mucosa of the mesenteric region and infects the lymph nodes, resulting in nausea, vomiting, bloody diarrhea, abdominal pain, sepsis, and ascities. The fatality rate is 50%⁵ since it progresses to toxemia and sepsis. The only recorded case of ingested anthrax in the U.S. took place in May 2000, when an infected cow was butchered and eaten by a farm family. The infection was discovered early and treated successfully.⁸

The most dangerous form is pulmonary anthrax, also known as wool sorter’s or rag picker disease because livestock workers have inhaled spores and developed pulmonary infections from sorting hides of infected animals. The last naturally occurring case of pulmonary anthrax in the U.S. took place in 1978.⁹ An inhalation of 8,000 to 50,000 spores is needed to establish an infection.² Bacillus anthracis spores are only 3 to 5 microns in size, allowing easy implantation in fine bronchioles and alveoli. Once spores are inhaled, pulmonary macrophages carry them to the mediastinal lymph nodes, causing hemorrhaging and edema that can be seen on a chest X-ray as a symmetrically widened mediastinal area. Although blood cultures may be negative, the sputum is usually positive at this point.

In the first phase of pulmonary anthrax, victims experience flu-like symptoms, followed by a significant improvement or even apparent recovery that may stop them from seeking medical care.² Aggressive treatment with antibiotics during the initial flu phase can be successful. However, because many health care providers are unfamiliar with the disease, many patients receive supportive treatment then are discharged, subsequently dying. Providers who see unusually large numbers of normally healthy patients presenting with similar flulike symptoms should be suspicious of an intentional attack and alert local public health officials. There is no magic number that will trigger an investigation, but the astute recognition of an unusual chest X-ray combined with other consistent symptoms should be highly suspicious. Early detection is the key to saving lives.¹⁰

The second phase of pulmonary anthrax develops suddenly with severe respiratory symptoms, hypotension, and shock. The patient may have a fever and profuse sweating. Stridor and crepitant rales may also be present. Blood cultures will be positive, and bacteria may be visible on a Gram-stain smear. Specimens thought to be Bacillus anthracis should be confirmed through a state public health lab and the Centers for Disease Control and Prevention (CDC).⁵ This phase generally lasts less than 24 hours, with mortality approaching 100% even with aggressive antibiotic therapy.⁸

Health care providers must be alert for patients who present with symptoms consistent with early anthrax,¹¹ obtain appropriate diagnostic tests (e.g., blood cultures and chest radiograph),¹² and report suspicious illnesses to local or state public health authorities. Infected patients are generally no danger to health care workers. Anthrax is not contagious, and there are no known cases of person-to-person transmission. Only standard precautions for blood and body fluids should be taken. Unless a patient has had an intentional contamination with large amounts of visible spores, decontamination beyond carefully removing clothing and washing hands and other exposed skin with soap and water is not needed. Contaminated clothing should be placed in a bag for disinfecting or disposal.¹³

Prophylaxis is accomplished in two ways. First, there is a licensed vaccine that consists of a series of six doses — one given initially and others at two and four weeks, then at six, 12, and 18 months, followed by annual boosters. At least three doses are needed for prophylaxis before exposure and should be followed by an additional three doses. The vaccine is now offered to all military personnel and civilians who are at risk of exposure. The vaccine is not routinely available to members of the public unless they are thought to be in high-risk environments. The vaccine is not recommended for pregnant women or people with depressed immune systems. Thirty percent of men and 60% of women who have the vaccine experience mild local reactions, but serious events occur at one per 200,000 doses.¹⁴

A second means of prophylaxis is with antibiotics, much like the treatment of an active infection. Because laboratories have produced penicillin- and tetracycline-resistant forms of the bacteria, initial postexposure prophylaxis with oral fluoroquinolones, such as ciprofloxacin (Cipro), or doxycycline over four weeks is recommended. If available, the vaccine may also be initiated. Although diagnosis and treatment may begin at the hospital, patients undergoing prophylaxis will be sent home to continue an antibiotic regimen, especially if a large-scale exposure has taken place. Treatment for inhalation anthrax may continue for up to 60 days because inhaled spores can remain latent for extended periods.¹⁰

Bubonic and pneumonic plague

The plague has a colorful history. In A.D. 541, the first great plague began in Egypt, spreading across North Africa, Europe, and Central and Southern Asia. During a period of four years, 50% to 60% of the population died. The second plague pandemic began in 1346 and spread throughout the Middle East, killing one-third of the European population and more than 13 million in China, where it earned the name Black Death.¹⁵

A childhood nursery rhyme encapsulates the ravages of the plague: “Ring around the rosie” (describing the red ring around the infected lymph node), “pocket full of posies” (the smell of death was so overwhelming that people carried pockets full of fragrant flowers to hold under their noses), “ashes, ashes, we all fall down” (“ashes” are related to burning the bodies and “falling” to victims dying). According to some texts, another lasting impression of the disease survives in a saying used even today. Because the number of deaths from the pneumonic plague overwhelmed the ability of priests to give last rights, they gave other church members the power to issue last rights by saying, “God bless you” after the victims coughed or sneezed.¹⁶

Although much has been done to improve the living conditions that contributed to plague outbreaks, about 13 cases occur annually in the U.S., most in New Mexico, Arizona, California, and Colorado.⁵ These occurrences are usually not related to living conditions but to flea bites from infected rodents commonly found in the Western states. The animals most commonly found to carry the bacteria include rock squirrels, ground squirrels, prairie dogs, wood rats, chipmunks, and their fleas.¹⁷ In these geographic locations, the disease is endemic in the rodent population and is passed from generation to generation through flea vectors. In recent years, most of the cases of primary pneumonic plague in the U.S. have been acquired through an exposure to domestic cats with pneumonic plague, and exposure has become an occupational hazard for veterinarians in the Western U.S.⁸ Health care workers should be highly suspicious of cases of plague outside these geographical areas, specifically if pneumonic plague is the first presentation. Terrorists could pose a serious threat by using the bacteria in an attack. Local and state public health authorities should be notified immediately if a case of plague is suspected.⁸

During the 1950s and 1960s, the U.S. developed the bacterium Yersinia pestis as a biological weapon. The Soviet Union reportedly had more than 10 institutions and thousands of scientists working to develop plague-based weapons.² These weapons were based on the spread of aerosolized bacteria upwind from the targeted population. Japan even investigated using infected fleas dropped in areas of enemy troops as a way of spreading the plague. In 1970, WHO assessed a worst-case scenario of a dissemination of 50 kg of Yersinia pestis in an aerosol cloud over a city of 5 million. The agency estimated the results to be 150,000 cases of pneumonic plague, with 36,000 deaths.⁶

Exposure to Yersinia pestis can cause three forms of the plague: bubonic, septicemic, and pneumonic. Bubonic plague is usually a flea-borne disease transmitted from an infected rodent. Direct contact of open skin with infected tissue or fluids can also cause a bubonic form of the disease.⁵ The bacteria migrates to the lymph nodes, where an infection is established typically between two to eight days after exposure.¹⁵ Because infected fleas usually bite the legs of a victim, inguinal lymph nodes are most often affected (90%).⁷ As the infection develops, the lymph nodes become painful, swollen, and hot to the touch before ulcerating. If left untreated, septicemic infection results in fever, chills, prostration, abdominal pain, shock, and bleeding into the skin and other organs. The death rate is 50% to 60%.⁷ In some cases, septicemia can spread the infection to the lungs, causing the pneumonic form of the disease.

Pneumonic plague causes fever, chills, cough and difficulty breathing; rapid shock; and death. Talking, coughing, or sneezing spreads the disease in heavy droplets from person to person. The incubation period is one to four days,⁷ depending on the dose of inhaled bacteria. Pneumonic disease is characterized by overwhelming pneumonia, fever, bloody sputum, chills, and cough. The death rate is more than 50% and approaches 100% if treatment is not instituted within 24 hours of the onset of symptoms. Culturing or Gram staining lymph-node needle aspirate, sputum, or cerebrospinal fluid samples makes the diagnosis.⁵ Additionally, a complete blood count, urinalysis, and arterial blood gases (ABGs) should be obtained.

Test results that may indicate pneumonic plague are:

• A markedly elevated white blood count to levels of 20,000 or greater and a shift to the left. In late septic shock, the WBC count may be low.
• Gross hematuria, RBC casts, and proteinuria found on urinalysis.
• ABG evidence of hypoxia and/or acidosis.¹⁸
• Yersinia pestis is a nonmotile, Gram-negative bacillus that shows bipolar (looks like a safety pin) staining with Wright, Giemsa, or Wayson stain.¹⁵

Patients diagnosed with bubonic plague and a cough or those with pneumonic plague must be placed on droplet precaution in a private room or cohorted with similarly diagnosed patients.^15,19

Decontamination of these patients is not necessary, but caregivers in close contact with them must wear appropriate protective equipment, including masks and eye protection; to limit droplet production, patients should wear masks also. Patients are considered contagious until after 48 hours of antibiotic therapy.⁶ Antibiotic treatment for those exposed to the disease should continue for seven to 10 days. Streptomycin, tetracycline, chloramphenicol, gentamycin, and quinolone antibiotics are all effective.¹⁵

An attack involving infected mass casualties will rapidly deplete the pharmaceutical stocks in most hospitals. As a result, many area public health and state health agencies provide additional local stockpiles of antibiotics for treating mass casualties related to an intentional attack. The Centers for Disease Control and Prevention also maintains a stockpile program called the Strategic National Stockpile. There are currently 13 SNSs in the United States, placed in different secret locations for rapid deployment anywhere in the country. They contain antibiotics and other materials to treat mass casualties from terrorist attacks. Typically, the initial stockpiles, called a “push pack,” contain the following antibiotics:²⁰

• More than 200,000 patient days of fluoroquinolone prophylaxis.
• More than 2,000,000 patient days of doxycycline prophylaxis.
• More than 20,000 patient days of pediatric fluoroquinolone prophylaxis.
• More than 40,000 patient days of therapeutic treatment.

The push pack can be followed by a “vendor managed inventory” that is more specific for the needs of the incident. In the case of a biological attack, the VMI may contain vaccines, additional antibiotics, or extra personal protective equipment.²⁰

The occurrence of either of these diseases requires a report to be filed with local public health agencies, and the CDC subsequently investigates all cases of inhalational anthrax. The CDC maintains the Health Alert Network, an around-the-clock Internet-based network of information about evidence-based practices and procedures for health care preparedness and response. When the CDC is informed about a possible biological attack, the Health Alert Network can be used to alert public health agencies in all 50 states to heighten their awareness to the threat. The network is also used for education and information sharing. In addition, the CDC uses Epi-X to alert public health officials across jurisdictions. Epi-X is a secure, Web-based communication system to enhance bioterrorism preparedness efforts by facilitating the sharing of preliminary information about disease outbreaks. The security of this system allows public officials to share information without generating fear among the public.²¹

Unfortunately, anthrax and plague are but two of four major biological agents that bioterrorists may use. The next module will discuss smallpox and botulism, as well as measures of emergency preparedness that may counter these threats.