Bioterror Related Diseases

Bioterror-related illnesses

Bioterror-related diseases are medical conditions that may be caused by the deliberate release of biological agents such as bacteria, viruses and toxins. Many of these diseases have the potential to spread quickly, causing widespread infection, illness and death. They may be contracted through inhalation, ingestion and contact with the skin or eyes. Some are communicable diseases, easily transmitted through close person-to-person contact (e.g., sharing body fluids) or exposure to surfaces (handrails, doorknobs) touched by infected persons. Others are not easily spread among people but cause severe illness or death.

Biological warfare is not new. For thousands of years, warring parties have sent (or flung) sickened cattle or people into the enemy's camp to spread disease. Biological terror has become more of a publicized threat in recent years as terrorism-related acts have increased globally. In 2001, anthrax spores sent through the postal system caused 22 cases of anthrax, resulting in five deaths. Other bioterror incidents have occurred in Japan and the Middle East.

Some of the diseases that have been linked to potential acts of bioterrorism (such as botulism and viral hemorrhagic fever) occur each year in the United States but involve relatively small, isolated cases. This is because many of the bacteria and viruses that cause these diseases are found naturally in the environment. For this reason, incidents of bioterrorism have sometimes been mistaken for naturally occurring outbreaks of a disease. For example, in 1984 cult members in Oregon deliberately released salmonella bacteria into the community to stop people from participating in local elections. Although the incident, which caused over 700 cases of salmonella, was first thought to be a natural outbreak, it was later discovered to be a case of bioterrorism.

Biological agents can be used as weapons for many reasons. Microscopic bacteria and viruses are difficult to detect, making them easy to transport and release without causing suspicion. Also, many bioterror-related diseases are easily transmitted from person to person, which means that only a few people need to be initially infected for the disease to spread throughout the population. This is further complicated by the fact that some diseases have long incubation periods – the period of time that a disease-causing microbe is in the body without causing any symptoms. During that time, it may be possible to transmit the disease, so hundreds or thousands of people could become infected before it becomes apparent that an outbreak has occurred.

The U.S. Centers for Disease Control and Prevention (CDC) monitors public health through a national surveillance system, which is designed to signal when disease outbreaks occur at higher-than-normal levels. Physicians and hospitals are required to report cases of communicable diseases to state and federal public health officials. Law enforcement officials then investigate whether the epidemics may be related to deliberate acts of bioterrorism.

The CDC classifies bioterrorism agents into three categories (A, B and C) based on the potential threat to public health (e.g., how easily they spread and severity of the disease or illness).

Category A diseases (e.g., anthrax, botulism, smallpox and the plague) pose the highest threat to public health and national security because they can be easily transmitted and can result in high death tolls.

Category B diseases (e.g., salmonella, typhoid fever, viral encephalitis and cholera) are moderately easy to spread and may have moderate illness rates and low death toll. Category C diseases are emerging infections (such as Nipah virus and hantavirus) that can be altered or engineered in a laboratory for mass distribution and dissemination.

Category C agents have the potential for causing high disease and death rates and a major impact on public health.

Since the turn of the 20th century, there have only been two confirmed instances of bioterrorism in the United States. Some analysts explain that the aim of most bioterrorists is to disrupt lives and societies rather than destroy large segments of the population.

Types and differences

The U.S. Centers for Disease Control and Prevention (CDC) classifies bioterror-related diseases into three categories based on the potential threat to public health and safety. These categories are as follows:

  • Category A (highest priority): These diseases can be easily disseminated or transmitted from person to person. They may also result in high death tolls and have the potential for major public health impact. They may also cause mass panic and disruption and require special precautions and preparedness planning on the part of national security and public health officials.
  • Category B (moderate priority): These diseases are moderately easy to transmit, can lead to moderate to low disease and death toll rates and require the CDC to use enhanced laboratory testing and surveillance to monitor outbreaks.
  • Category C: These are diseases that result from emerging pathogens (harmful bacteria and other microorganisms) that could be engineered for mass dissemination in the future because of availability, ease of production and distribution potential for high disease and death toll rates.

The category A diseases include:

  • Anthrax. Caused by the bacteria Bacillus anthracis. Anthrax bacteria are very resilient and can survive for many years in a form called a spore. After anthrax enters the body, the bacteria form toxins that can be deadly. Anthrax spores can be inhaled, ingested or passed through broken skin. Anthrax cannot be transmitted from one person to another. Symptoms of anthrax poisoning include fever, muscle aches and fatigue. The different types of anthrax produce specific symptoms in the lungs (inhalation anthrax), skin, (cutaneous anthrax) or digestive system (gastrointestinal anthrax).
  • Botulism. Caused by the toxin produced by the Clostridium botulinum bacteria. This toxin is among the most poisonous substances known to humans. Symptoms of foodborne botulism typically appear within 12 to 36 hours of exposure to C. botulinum. Among other symptoms, patients experience muscle weakness that begins in the shoulders and then moves down the body. This paralysis can prevent breathing muscles from functioning, resulting in death unless the patient receives mechanical ventilation.
  • Plague. Caused by the bacterium Yersinia pestis. There are three types of plague: pneumonic, septicemic and bubonic. Plague is spread by infected rodents and fleas, although there is concern that terrorist organizations could disperse plague bacteria by spraying it into the air. Symptoms of plague may vary depending on the type of infection. For example, patients with bubonic plague may experience painful, swollen lymph nodes known as buboes. Patients with septicemic plague may experience bleeding from the mouth, nose, rectum or under the skin. Meanwhile, patients with pneumonic plague may have symptoms that resemble those of pneumonia, including bloody sputum, breathing difficulties and chest pain.
  • Smallpox. Caused by the variola virus, smallpox killed millions of people worldwide in the past. It was eradicated by 1978 due to an immunization program administered by the World Health Organization. Smallpox usually starts with flu-like symptoms, such as a high fever and headache. A rash develops on the face and then spreads to the arms, legs, hands and feet. Blisters and pustules form on the skin in later stages of the disease.
  • Tularemia. Caused by the bacterium Francisella tularensis. Tularemia is a fairly common infection in wild rodents and can be spread to humans from flea and tick bites. Symptoms of human infection of tularemia can include fever, headaches, diarrhea and pneumonia. Tularemia can not be spread from person to person and it can be effectively treated with antibiotics. It is classed as a category A bioterror agent because it is highly infectious, easy to produce and can cause severe respiratory illness in people who inhale the bacteria.
  • Viral hemorrhagic fevers. Refers to a number of viral diseases that are endemic to much of the tropics and subtropics. In addition to the bleeding and fever for which they are named, they affect multiple organ systems and cause a wide range of symptoms. Some progress slowly, while others are characterized by a sudden onset and quickly become life threatening. Hemorrhagic fevers are usually caused by insect or animal bites. However, people can also become infected by breathing in aerosolized virus particles. Some types of hemorrhagic fever, such as Ebola and yellow fever, can be transmitted from person to person. There is no cure for the hemorrhagic fevers and, without supportive therapy, the diseases are often fatal.

Some other possible agents of bioterror include:

DiseaseCaused byTransmission MethodPerson to Person
BrucellosisBacteriaAnimal-borne (domestic and wild animals)Yes (rare)
Foodborne illnessesBacteriaFood-borneGenerally, no
GlandersBacteriaAnimal-borne (domestic animals)Yes
MelioidosisBacteriaAnimal-borne (domestic animals)Yes
Q feverBacteriaAnimal-borne (domestic animals)Yes (rare)
RicinToxinPoison that can be ingested or inhaledNo
Nipah virusVirusAnimal-borne (bats)No
Hantavirus Pulmonary SyndromeVirusAnimal-borne (rodents)No

Causes and risk factors

The risk factors for bioterror-related diseases vary depending on the biological agent used and the way in which the disease is transmitted. In the case of some bioterror agents, certain occupations are more at risk than others because people working at these occupations are more likely to come into contact with the agent first.

For example, during the 2001 bioterrorist attacks, the majority of people affected were those who worked for the postal service. Anthrax used as an agent of bioterrorism may be sent through the mail in a powdered form, so postal and mailroom workers are often the first people who come into contact with the substances. The U.S. Centers for Disease Control and Prevention (CDC) has implemented numerous guidelines for postal workers to prevent infection should an anthrax attack occur again. CDC guidelines suggest wearing protective gloves and having access to respirators if working with a machine that might generate airborne anthrax particles. Other groups that may be more at risk from bioterrorism are hospital workers and emergency response staff, such as firefighters and police officers.

People who are serving in the military overseas, especially in South Korea and the Middle East, are also more at risk for bioterror-related diseases. Currently, military personnel serving in the Middle East or South Korea are among the only groups who are routinely vaccinated against anthrax and smallpox. Biological weapons are a particular threat to the military personnel serving in these areas.

Signs and symptoms

Signs and symptoms of bioterror-related diseases vary depending on the biological agent (bacteria, virus) used and the resulting disease or illness. It also depends on the site of the infection. One of the first symptoms of almost every bioterror-related disease is fever, fatigue and body aches as the body’s immune system struggles to fight the disease. Some general classification of diseases and potential signs and symptoms include:

Respiratory infections

Diseases that are airborne or transmitted through respiratory secretions (e.g., pneumonic plague, inhalation anthrax):

  • Persistent cough
  • Trouble breathing
  • Green or rust-colored sputum (a symptom of pneumonia)

Gastrointestinal infections

Diseases that are foodborne or sometimes animal-borne and that infect the gastrointestinal system (e.g., botulism and foodborne diseases):

  • Vomiting
  • Diarrhea
  • Blood in the stool
  • Abdominal pain

Cutaneous (skin) infections

Diseases that affect the skin (e.g. smallpox) or that may be transmitted through open cuts or sores (e.g. cutaneous anthrax, glanders):

  • Lesions
  • Open sores
  • Rashes

Other infections

Most bioterror-related diseases can cause multiple symptoms. This is especially the case if the virus or bacteria enter the bloodstream or lymph nodes, where they can then spread throughout the body, causing varying symptoms, such as:

  • Confusion or dementia
  • Hemorrhagic bleeding
  • Meningitis

Diagnosis methods

Unless there is a documented outbreak, medical personnel may not recognize that a patient experiencing fever and pneumonia-like symptoms or severe gastrointestinal symptoms is the victim of a bioterror-related disease. Many bioterror-related diseases have symptoms that are similar to more common diseases such as influenza or salmonella, so bioterror-related diseases may not be diagnosed until it becomes apparent that one patient’s case is not isolated. Incidences of diseases occurring in people with no known risk factors, such as travel to a region where the disease is endemic, may also help to alert medical professionals.

The first step in diagnosing many diseases, including those that could be related to bioterror, is conducting a medical history and a physical examination. If a bioterror-related disease is suspected, the physician may ask questions about the places that the patient may have visited recently or any suspicious material that may have been handled. If an outbreak of the disease has been confirmed, the physician may conduct a rapid test such as a nasal swab or blood test to make a quicker diagnosis. This is especially the case if the disease requires the immediate treatment or quarantine of the infected person.

Diagnosis methods for bioterror-related diseases could include:

Blood tests

There are several blood tests that may be conducted to test for signs of bioterror-related diseases. Some tests examine the blood for signs of bacteria, viruses or toxins and some tests look at the blood serum for signs of antibodies to diseases. Certain tests may not be accurate until several weeks after the initial infection, because the antibodies may take one to two weeks to develop.

Sputum culture

If the disease infects the respiratory system, a sample of sputum (discolored phlegm) may be taken to examine it for signs of bacteria or viruses.

Stool sample

In diseases that infect the gastrointestinal system, physicians may request a stool sample and examine it for signs of the disease.

Urine tests

Urine tests can be used to help diagnose a range of infections, especially those that may affect the kidneys, bladder or urinary tract.

Skin test

A physician may take a sample of a lesion or ulcer that is suspected to be the result of a cutaneous (skin) infection. It will be examined under a microscope for signs of disease.

Chest x-ray

A chest x-ray is one of the most accurate ways to diagnose pneumonia and other diseases of the respiratory system that may be the result of a bioterror agent. Diseases such as inhalation anthrax may produce characteristic results during an x-ray exam. A chest x-ray may also be used to rule out diseases such as influenza, which may produce similar symptoms to many other respiratory diseases.

Spinal tap

In some cases, bioterror-related diseases may spread to the brain and spinal cord and cause meningitis. This can be diagnosed by inserting a needle into the spinal canal and withdrawing the fluid. Blood in the spinal fluid may be a sign of hemorrhagic meningitis.

Treatment and prevention

Treatment of bioterror-related diseases varies depending on the disease contracted. Diseases that are caused by bacteria can usually be treated with antibiotics. Antibiotics can even be used to treat potentially fatal diseases such as anthrax and plague. However, in many cases, antibiotics must be given within 24 hours of symptoms first appearing for them to be effective. This may not always be possible, especially when the symptoms of the bioterror-related disease are similar to those of diseases that do not require antibiotics (e.g., influenza). Antitoxin along with antibiotics is used to treat cases of botulism.

Bioterror-related diseases that are caused by viruses are more problematic. Although some viral diseases (e.g., certain viral hemorrhagic fevers) can be treated with antiviral medication, there is no approved medication for the treatment of the majority of bioterror-related viral diseases. Instead, other treatment methods may be used. One method of treatment for viral diseases is supportive therapy. Supportive therapy may include replacing lost fluids through an intravenous drip or providing the patient with medication to control pain and fever. Although these treatment methods may not treat the infection directly, they enable the body to remain strong enough to fight the disease. Sometimes physicians may also prescribe antibiotics for a viral disease to treat any bacterial infection that may occur.

Vaccination may be one of the most effective ways to prevent bioterror-related diseases. However, because the risk of an outbreak of bioterror-related disease is fairly low, vaccines may not be given to everyone on a preventative basis. Because of their increased risk, the following groups may be vaccinated against certain bioterror-related diseases:

  • Military personnel, especially those who may serve in the Middle East or South Korea where there is a greater risk of biological weapons.
  • Laboratory workers who work with bioterror agents.
  • Healthcare workers and emergency response workers.
  • Veterinarians and others who may handle infected animals.

In the event of an outbreak of a bioterror-related disease, vaccinations may be given to those who have been exposed, or are at a high risk of being exposed to the bioterror agent. Vaccination can be used to reduce the chances of an infection turning into disease even after exposure to the virus or bacteria. This is one of the key methods of treatment for certain diseases, such as anthrax and smallpox.

For example, vaccination with the smallpox vaccine within three days of exposure to the smallpox virus has been shown to completely prevent illness or severely weaken the infection. If the vaccine is administered between four to seven days of exposure, it may not prevent the disease, but it usually modifies the infection in such a way that the resulting disease is mild. Most vaccines for bioterror-related diseases can produce side effects that may be unpleasant, such as itching and swelling at the injection site and flu-like symptoms. However, in the event of a bioterror attack, the benefits of vaccination far outweigh the potential side effects.

Some people feel that the best way to prepare for a bioterror attack is to build a stockpile of antibiotics for use in the event of an attack. However, this method of prevention could have serious consequences for the health of the individual and the community. Not all types of antibiotics are effective against all diseases and the inappropriate use of antibiotics can cause diseases to develop antibiotic resistance.

This can make the disease stronger and more difficult to treat and can have devastating results for the management of the disease. The U.S. Centers for Disease Control and Prevention (CDC) maintains a strategic national stockpile of antibiotics and vaccines. This resource is designed to be able to provide quick and efficient treatment to any affected area in the United States within one to two hours of a reported outbreak. For example, the stockpile has enough smallpox vaccine to treat every person in the United States.

There may be little that individuals can do to prevent exposure to a bioterror agent in the event of an attack. Most times, it is simply a case of being in the wrong place at the wrong time. However, there are some precautions that people can take to prevent infection or reduce the risk of serious illness following exposure. These precautions include:

Personal hygiene

The most efficient way to prevent the transmission of many types of diseases is to practice good personal hygiene. It is important that people wash their hands regularly, especially after visiting the bathroom and before eating or preparing food. Ideally, hands should be washed with warm water and soap, although an alcohol-based sanitizer is an alternative if water is not available.

People who have been diagnosed with an infectious disease and those who are caring for people with infectious diseases should take extra precautions to prevent transmission. This includes washing clothing and bedding thoroughly and using latex gloves and washing the hands after handling anything that may have been in contact with the blood, urine, stool and other bodily fluids of the infected person. In cases where the disease may be spread by respiratory secretions, infected people and their caregivers may be encouraged to wear protective surgical masks when interacting.

Sanitary preparation of food

Many cases of foodborne diseases can be prevented by taking suitable precautions during the preparation and cooking of food. Meat and poultry should be thoroughly cooked to an internal temperature of 165 to 185 degrees Fahrenheit (74 to 85 degrees Celsius). Fruits and vegetables should be washed in warm water before consumption. Additionally, surfaces and utensils that have come into contact with raw meat should be disinfected before they are used again.

Healthy immune system

One of the keys to effectively fighting infection is to maintain a healthy immune system. This can be achieved by eating a balanced diet that is rich in essential nutrients. Another important element of maintaining a healthy immune system relates to the use of antibiotics. Antibiotics should only be prescribed for bacterial infections and should not be taken for a viral infection. If antibiotics are prescribed, it is essential that they are taken as recommended because pathogens may become resistant to antibiotics that are stopped prematurely.

In the wake of the 2001 anthrax attacks on the United States, some people purchased gas masks in an attempt to protect themselves from exposure to potential bioterror agents. When used correctly, gas masks and other respirators may provide some protection.

However, purchasing, using and storing gas masks and respirators requires training that is not always available to the general public. Members of the public who have no experience with gas masks or respirators will probably remain unprotected and may even end up harming themselves by using ill-fitting and unsuitable masks. The CDC does not recommend that people purchase gas masks or respirators as a method of protection.

Lifestyle changes and considerations

One of the most profound lifestyle changes that may come about following a bioterror attack is the implementation of quarantine regulations. Quarantine is a legal procedure that restricts the freedom and movement of people in the interests of public safety. The restrictions are intended to isolate the infected person or persons to a geographic area (a hospital ward, their homes or the place where the infection is discovered) to prevent further spread of communicable diseases. The decision to enforce quarantine measures is made by individual states, although there are other authorities in the United States that have the power to quarantine people, including the Centers for Disease Control and Prevention (CDC). The nature of the quarantine regulations depends on the extent of the outbreak.

Individuals under quarantine cannot see family members or loved ones (unless they too are infected) nor carry on their normal lifestyles. Even if they show no signs of illness, those who come in contact with infected persons may be quarantined as well. In some cases, such as with anthrax spores, the entire building where a biological agent has been discovered may have to be shut down until hazardous materials crews can determine clean-up procedures.

After a bioterror attack, people may experience psychological problems, whether or not they were directly affected. In most cases, symptoms are mild and may include:

  • Difficulty sleeping
  • Feelings of fear or grief
  • Depression
  • Nausea
  • Changes in appetite

Studies have shown that this pattern of psychological change is usually temporary and may resolve itself within three weeks of the traumatic event. However, some people experience problems that last longer and can interfere with their daily life. This is called post-traumatic stress disorder (PSTD). PSTD is an anxiety disorder that involves feelings of intense fear, helplessness or horror brought on by experiencing or witnessing an especially traumatic or terrifying event. Signs and symptoms of PSTD may include:

  • Emotional numbness to people or activities
  • Memory loss
  • Headaches and gastrointestinal problems
  • Substance abuse
  • Eating disorders
  • Suicidal feelings

It is important to realize that feelings of fear and stress following a traumatic experience are normal and are part of the body’s coping system. Returning to a regular routine and relying on support systems (e.g., friends, family, support groups) are important steps to recovering from the stress of a bioterror attack. People who feel they may be experiencing unmanageable trauma after a bioterror attack should consult their physician about possible treatment methods.

Questions for your doctor

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to bioterror-related diseases:

  • Am I in a group (e.g., a first-responder, lab worker) that should be vaccinated against potential bioterror agent?
  • How long will a vaccine protect me against infection?
  • What precautions can I take to prevent infection?
  • If I am a first-responder, are my close family members at risk of infection from me in the event of an attack?
  • What should I do if I suspect I have been infected with a bioterror-related disease?
  • Will I need to be quarantined? If so, for how long?
  • What are my chances of survival from the disease?
  • How long should I expect to be hospitalized with this condition?
  • What should I do if I experience depression after a bioterror attack?