Questions & Answers
Anthrax - Countering the Threat
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Anthrax Weapons -- The Threat

  1. Why is anthrax vaccination needed?
    Anthrax is highly lethal and relatively easy to produce in large quantities for use as a weapon. Anthrax spores are easily spread in the air over a large area and can be stored and remain viable for a long time. For this reason, anthrax may be the most important biological warfare threat facing U.S. forces. The intelligence community believes several countries currently have or are developing an offensive biological warfare capability using anthrax. However, given the ease with which anthrax can be produced, the threat could come from anywhere. For that reason, U.S. Forces may have little or no warning before an anthrax attack, which could be delivered by unconventional means. As a result, U.S. military forces around the world face a very real threat of a surprise anthrax attack. On February 24, 2004, CIA Director George Tenet told the Senate Select Intelligence Committee: "Although gaps in our understanding remain, we see al-Qaeda's program to produce anthrax as one of the most immediate terrorist CBRN [chemical, biological, radiological, nuclear] threats we are likely to face."

  2. Has any country ever used anthrax as a weapon?

    There is some evidence that the Japanese used anthrax as a biological weapon (BW) in China during World War II (Christopher GW, et al. Biological warfare: A historical perspective. JAMA 1997; 278 (Aug 6): 412-17).

    Since then, several countries are believed to have incorporated anthrax spores into biological weapons. Intelligence analysts believe that at least seven potential adversaries have an offensive BW capability to deliver anthrax -- twice the number of countries when the 1972 Biological and Toxin Weapons Convention (BTWC) took effect. The BTWC was designed to prohibit such activity.

    Iraq admitted to the United Nations in 1995 that it loaded anthrax spores into warheads during the Gulf War. In the post-cold war era, the former Soviet Union admitted to having enough anthrax on hand to kill every person on the planet several times over. The accidental aerosolized release of anthrax spores from a military microbiology facility in the former Soviet Union city of Sverdlovsk in 1979 resulted in at least 79 cases of anthrax infection and 68 human deaths and demonstrated the lethal potential of anthrax aerosols. Members of Aum Shinrikyo, the group responsible for the 1995 Tokyo sarin attack, reportedly experimented with biological agents in Japan before resorting to chemical agents. A lengthy article in the May 26, 1998, edition of the New York Times reported that members of Aum Shinrikyo released anthrax spores and botulinum toxin in Tokyo, Yokohama, and Yokosuka in 1990, targeting Japanese government and U.S. Navy facilities. Fortunately, no one was injured in these events.

    Anthrax spores have also been used as a weapon inside the United States by unknown terrorists in the Fall of 2001. The attack killed 5 people and infected at least 17 others.

  3. Has anthrax vaccine ever been used in the past? How often?
    Yes, since licensure in November 1970, anthrax vaccine has been administered to people at risk (both civilian and military) -- veterinarians, laboratory workers, and some people working with livestock for several decades. The manufacturer and FDA report that about 68,000 doses of anthrax vaccine were distributed between 1974 and 1989. The Army has purchased anthrax vaccine since its approval by the FDA in 1970, for use by about 1,500 at-risk laboratory workers. Anthrax vaccine was administered during the Gulf War to about 150,000 Service members, to protect U.S. forces against the threat of Iraq's biological weapons. The DoD vaccinated over 1.5 million DoD personnel with over 5.9 million doses since the beginning of the AVIP in March 1998.

  4. How are biological agents deployed?
    Biological agents can be dispersed in many ways, ranging from mailed envelopes, intentional human vectors, spray devices, bombs, to ballistic missiles. Biological agents are often hard to detect. Symptoms are delayed. Without preventive medical efforts, such as vaccination, the results can be devastating and widespread. A 1993 report by the U.S. Congressional Office of Technology Assessment estimated that between 130,000 and 3 million deaths could follow the aerosolized release of 100 kg of anthrax spores upwind of the Washington, DC area -- truly a weapon of mass destruction. An anthrax aerosol would be odorless, invisible, and capable of traveling many miles.

  5. Has the threat of biological warfare changed?
    The threat of biological warfare has been a risk to U.S. forces for many years. The threat of anthrax weapons in the hands of adversarial countries remains. But anthrax was used as a biological weapon in the United States in fall 2001 by unknown terrorists. Delivering anthrax was as simple as putting it in an envelope and dropping it in a mailbox. DoD analysts maintain an updated evaluation of the level of threat, adjusting the information as necessary to reflect the risk to U.S. operations. Assessment of the potential offensive biological threat facing American Service members indicates it is necessary to have a robust biological defense program today. The threat is real and the consequences are grave. On 16 October, 2006, Assistant Secretary of Defense for Health Affairs William Winkenwerder said, "...anthrax remains a deadly infection that's been used as a bioterrorism weapon against our own population. The threat environment and unpredictable nature of terrorism makes it necessary to include biological warfare defense as part of our force protection measures."

  6. Who is at greater risk from a biological attack? Soldiers? Sailors? Airmen? Marines? Front line? Rear area? Logistical units?
    Anthrax weapons have the potential to contaminate wide areas of the battlefield. It is difficult to determine who would be at a greater risk from a biological threat. All Service members meeting the criteria to receive the vaccine need to be protected, regardless of Service, specialty, or location within higher threat areas.

  7. What preparations have been made to respond to an anthrax release in a high-threat area?
    We are taking necessary steps to develop optimal protection against the threat of anthrax and other potential bio-weapon agents, including improved intelligence, detection, surveillance capabilities, protective clothing and equipment, new generation vaccines, and other medical countermeasures. In addition, we have stockpiled antibiotics in pre-positioned locations and medical personnel are better educated in the treatment of anthrax.

  8. If we vaccinate against anthrax, couldn't our adversaries just switch to a different biological weapon?
    If the DoD anthrax vaccination program causes adversaries to switch to a different weapon, it can be considered a success. Other biological weapons are less stable, less predictable, or less effective than anthrax weapons.

  9. Are vaccines being developed for other biological agents?
    Yes. As potential biological warfare threats are identified, DoD works with other government agencies and industry partners to develop medical countermeasures. Vaccines are being developed, whenever appropriate, for all validated biological threat agents. More information is provided in the specific Q & A section entitled -- Biological Warfare - Overview.

Anthrax -- The Disease

  1. What is anthrax?

    Anthrax is a rapidly progressing acute infection caused by spore-forming bacteria called Bacillus anthracis. Anthrax most commonly occurs in warm-blooded animals, especially goats, cattle, and sheep, but it can also infect humans. Anthrax spores can be easily produced in a dry form for biological weapons. Spores can survive many years in adverse conditions and still remain capable of causing disease. When inhaled by humans, these spores cause respiratory failure that can lead to death within a week.

    Anthrax can make an excellent weapon of mass destruction. The spores may be used as a weapon in a variety of delivery systems. They can be produced in large quantities without sophisticated equipment. All it takes is a single breath of aerosolized anthrax to inhale enough spores to cause the disease. Then, if serious symptoms occur, it kills 99% of unprotected people. Even if a person with symptoms receives antibiotics, the death rate is still about 50%. Anthrax spores are odorless, colorless, and tasteless.

  2. Who gets infected with anthrax?
    Animals and people can get anthrax disease. Anthrax is most commonly found in agricultural regions where goats, sheep, cattle or other plant-eating animals have not been vaccinated. When anthrax infects humans, it is usually due to an occupational exposure to infected animals or their products, especially hides, hair, wool, bones or bone products. Less commonly, ingesting undercooked, contaminated meat can infect humans.

  3. What are the symptoms of anthrax?
    • Fever (over 100 degrees F). The fever may be accompanied by chills or night sweats.
    • Flu-like symptoms.
    • Cough, usually a non-productive cough, chest discomfort, shortness of breath, fatigue, muscle aches, sore throat followed by difficulty swallowing, enlarged lymph nodes, headache, nausea, loss of appetite, abdominal distress, vomiting or diarrhea.
    • A sore, especially on the face, arms or hands, that starts as a raised bump and develops into a painless ulcer with a black area in the center.

  4. How can I know my cold or flu is not anthrax?
    Many human illnesses begin with what are commonly referred to as “flu-like” symptoms, such as fever and muscle aches. However, in most cases anthrax can be distinguished from the flu because the flu has additional symptoms. In previous reports of anthrax cases, early symptoms usually did not include a runny nose, which is typical of the flu and common cold.

  5. Where is anthrax usually found?
    Anthrax is found around the globe. It is more often a risk in countries that do not vaccinate their livestock, or that have substandard or ineffective public-health programs.

  6. What are the types of anthrax infection? How is anthrax transmitted?
    There are three forms of anthrax disease, varying by the route of infection. People can get anthrax in the following three ways:
    1. Through a break in the skin (cutaneous anthrax). Most (about 95%) anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather, or hair products (especially goat hair) of infected animals. About 20% of untreated cases of cutaneous anthrax will result in death and less than 1% resulting in death with antibiotic treatment
    2. By eating inadequately cooked contaminated meat (gastrointestinal anthrax). Initial signs of nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Intestinal anthrax results in death in about 25% to 60% of cases.
    3. By breathing in bacteria or spores (inhalational anthrax). Inhalational anthrax does not typically spread from person to person. Inhalational anthrax is usually fatal. Although case-fatality estimates for inhalational anthrax are based on incomplete information, the rate is extremely high even with all possible supportive care including appropriate antibiotics.
    Because anthrax spores can live in the soil for many years, animals can get anthrax by grazing or drinking water in contaminated areas. Weaponized anthrax could be used against people in almost any location, and in many different ways. The greatest threat with the most deadly consequences comes from inhaled anthrax.

  7. Can people spread anthrax to each other?
    Direct person-to-person spread of inhalational anthrax is "very rare," according to the American Public Health Association’s Control of Communicable Diseases Manual. Presumably, person-toperson spread would require contact with contaminated skin lesions.

  8. Can anthrax be transmitted by insects?
    One report suggested that black flies may have transmitted anthrax from animals to humans, where there was a large outbreak in the animal population. Insects are not a major factor in the spread of anthrax.

  9. How is anthrax diagnosed?
    Anthrax is diagnosed by isolating the bacteria, Bacillus anthracis, from the blood, skin, or cerebral spinal fluid, or by measuring specific antibodies in the blood of suspected cases. Generally, diagnosis by antibodies is done weeks or months after the infection occurs, too late to aid in treatment. The best protection is vaccination before exposure, combined with the appropriate Mission-Oriented Protective Posture (MOPP), including protective clothing and detection equipment.

  10. Can I get screened or tested to find out whether I have been exposed to anthrax?
    There is no screening test for anthrax; there is no test that a doctor can do for you that says you have been exposed to or carry it. The only way exposure can be determined is through a public health investigation.

  11. What is a nasal swab test?

    A nasal swab involves placing a swab inside the nostrils and taking a culture. The CDC and the U.S. Department of Health and Human Services do not recommend the use of nasal swab testing by clinicians to determine whether a person has been exposed to Bacillus anthracis, the bacteria responsible for anthrax, or as a means of diagnosing anthrax. At best, a positive result may be interpreted only to indicate exposure; a negative result does not exclude the possibility of exposure. Also, the presence of spores in the nose does not mean that the person has inhalational anthrax. The nose naturally filters out many things that a person breathes, including bacterial spores. To have inhalational anthrax, a person must have the bacteria deep in the lungs, and also have symptoms of the disease.

    Another reason not to use nasal swabs is that most hospital laboratories cannot fully identify anthrax spores from nasal swabs. They are only able to tell that bacteria that resemble anthrax bacteria are present.

  12. If patients are suspected of being exposed to anthrax, should they be quarantined or should other family members be tested?
    Anthrax is not known to spread from one person to another person. Therefore, there is no need to quarantine individuals suspected of being exposed to anthrax or to immunize or treat contacts of persons ill with anthrax, such as household contacts, friends, or coworkers, unless they also were also exposed to the same source of infection. For more information on laboratory testing, go to

  13. Why vaccinate at all? Why not treat with antibiotics after exposure?
    There is no better round-the-clock protection against anthrax infection than the anthrax vaccine. Antibiotics are effective when started immediately or very soon after exposure. However, not all exposures can be predicted in advance or even determined in very early stages, particularly in certain military situations. In such situations, the consequences for military personnel and their mission could be very unfavorable. This is not a risk we can afford to take.

  14. For More Information:
    Advisory Committee on Immunization Practices. Use of anthrax vaccine in the United States. MMWR-Morbidity & Mortality Weekly Report 2000;49(RR-15, Dec 15):1-20.

    Brachman PS. Anthrax. Annals of the NY Academy of Sciences 1970;46:577-82.

    Brachman PS. Inhalation anthrax. Ann NY Acad Sci 1980;56:83-93.

    Brachman PS, Friedlander AM, Grabenstein JD. Anthrax. In: Plotkin SA, Orenstein WA, ed. Vaccines, 4th ed. Philadelphia: W. B. Saunders, 2003.

    Brachman PS, Gold H, Plotkin SA, Fekety FR, Werrin M, Ingraham NR. Field evaluation of a human anthrax vaccine. American Journal of Public Health 1962;52:432-45.

    Emerging Infectious Diseases specialty issue, Proceedings of the Symposium on Bioterrorism: July/August 1999.

    Food and Drug Administration. Biological products; Bacterial vaccines and toxoids; Implementation of efficacy review. Federal Register 1985;50:51002-117.

    Food and Drug Administration. Biological products; Bacterial vaccines and toxoids; Implementation of efficacy review. Federal Register 2004;29:78281-93.

    Franz DR, Jahrling PB, Friedlander AM, McClain DJ, Hoover DL, Bryne WR, Pavlin JA, Christopher GW, Eitzen EM Jr. Clinical recognition and management of patients exposed to biological warfare agents. Journal of the American Medical Association 1997;278(Aug 6):399-411.

    Hambleton P, Carman JA, Melling J. Anthrax: The disease in relation to vaccines. Vaccine 1984;2:125-32.

    Inglesby TV, O'Toole T, Henderson DA, Bartlett JG, Ascher MS, Eitzen E, Friedlander AM, Gerberding J, Hauer J, Hughes J, McDade J, Osterholm MT, , Parker G, Perl TM, Russell PK, Tonat K, Working Group on Civilian Bio-defense. Anthrax as a biological weapon, 2002: Updated recommendations for management.

    Journal of the American Medical Association 2002;287:2236-52.

    Journal of the American Medical Association specialty issue on biological warfare and biological terrorism: August 6, 1997.

    Sidell FR, Takafuji ET, Franz DR. Medical Aspects of Chemical & Biological Warfare. Washington, DC: Department of the Army, 1997.

    Turnbull PCB. Guidelines for the Surveillance and Control of Anthrax in Humans and Animals, 3rd ed., WHO Report WHO/EMC/ZDI/98.6.;jsessionid=FRZCbn15JMK9npLt12pBYDyZHTbdLSmz7Msn3Kvn1s1x75nCS8YR!736553971!-949856145!8091!-1