The Facts About Anthrax

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For many years, emergency service terrorism training programs have warned about the potential use of biological materials by terrorists. Anthrax threats had become the bomb threats of the late 1990s and the new century. All of those threats had been hoaxes.

But on Oct. 2, 2001, in Palm Beach County, FL, the potential use of biological agents, in particular, anthrax became a reality. The appearance of a case of rare inhalation anthrax set off alarm bells in the minds of many in the emergency response community. Inhalation anthrax is so rare that only 18 cases occurred in the United States during the 20th century.

Anthrax is not a contagious disease and is not transmitted from person to person. It can be acquired through three routes of entry into the body: inhalation, ingestion and cutaneous. Inhalation anthrax occurs when spores are aerosolized and breathed into the lungs. Ingestion anthrax results from eating contaminated meat. Cutaneous anthrax results from spores entering the body through breaks in the skin. Approximately 95% of all accidental anthrax cases in the world are the cutaneous form.

Cutaneous anthrax occurs naturally among farmers, ranchers and veterinarians as a result of contact with infected livestock. In August 2000, some 30 head of cattle in Nevada died from anthrax. It is believed that the anthrax was contracted when ditch-clearing operations released soil-borne spores onto pasture grasses. In September 2000, a family in Minnesota was reported to have contracted ingestion anthrax from eating infected beef, which they had butchered and processed themselves.

Anthrax was one of the first diseases identified in the field of microbiology in 1876, and the first disease for which an effective live bacterial vaccine was developed, in 1881 by Louis Pasteur. Inhalation anthrax was discovered in the late 19th century. Natural outbreaks of inhalation anthrax occurred among wool sorters in England, becoming one of the first occupational respiratory infectious diseases. Processing of contaminated goat hair and alpaca wool resulted in the generation of infectious aerosols.

The largest human exposure of inhalation anthrax occurred in Sverdlovsk, Russia, in 1979. Anthrax spores were released accidentally from a military research facility upwind from the outbreak. Cases were also reported in animals located more than 30 miles from the site. There were 66 documented human deaths and 11 injuries as a result of the release, though it is believed by many that the death count may have been much higher.

Anthrax The Disease

Bacillus anthracis is a Gram-positive, spore-forming bacillus that can survive for over 100 years in the spore form. Bacteria are classified as Gram-positive or Gram-negative based on their response to the Gram staining procedure. The primary difference between Gram-negative and Gram-positive bacteria occurs in the cell wall. Gram-positive cell walls are usually much thicker and more difficult to penetrate than Gram-negative cell walls. Bacillus is a genus of bacteria that is found everywhere in nature (in soil, water and airborne dust). Spores are not formed in living tissue. When a host dies and the disease is exposed to oxygen during the decay of the corpse, the spores are formed. Development of spores is a survival system, which allows the bacteria to survive in nature until a suitable host is once again contacted.

During World War II, the British conducted tests with anthrax on Gruinard Island off the coast of Scotland. The island remained contaminated with anthrax spores and uninhabitable until 1986, when tons of topsoil were removed. The island decontaminated by soaking the remaining soil with seawater spiked with large amounts of formaldehyde.

Cutaneous Anthrax

It is not known exactly how many spores are necessary to cause cutaneous anthrax in humans. The only data available is from animal tests. Ken Alibek, a defector from the former Soviet Union’s biological weapons program, believes 10 to 15 spores could cause disease.

Once the anthrax spores enter through a break in the skin, they usually incubate for one to five days before symptoms occur, although it is possible this could take up to 60 days. The first indication of the disease is the appearance of a small papule (small, solid, raised spot on the skin). Within one to two days, a vesicle (liquid filled sack) forms on the skin, containing a bloody or thick and viscous-like serum with many organisms and a small amount of leukocytes. Leukocytes are the parts of the immune system that eat the bacteria, parasites, viruses, germs, fungus and other assorted bad characters. Vesicles may be one to two centimeters in diameter and when ruptured, leave a dead tissue ulcer. Lesions are painless and have varying degrees of fluid around them.

Fluid development can be massive in some cases, and involve the entire face or limb. Victims will have a high fever, overall sick feeling and headache. Headaches become more severe with increased fluid presence. The base of the ulcer develops a characteristic black hard plaque, indicating extensive tissue death. After two to three days, the plaque separates and may leave a scar. With treatment, the mortality rate from cutaneous anthrax is around 1%. Untreated, the rate increases to around 20%.

Inhalation Anthrax

Inhalation anthrax results from exposure to a dose of 8,000 to 10,000 aerosolized spores of a size ranging from one to five microns. The size is important to determine if spores will reach into the alveoli of the lungs to do their damage. The incubation period usually ranges from one to six days, although it is possible to take up to 60 days.

Diagnosis is difficult because of nonspecific symptoms, which include an overall feeling of sickness, fatigue, muscle aches and fever. A nonproductive cough may be present along with mild chest discomfort. Symptoms persist for two to three days, often followed by a short period of improvement. The improvement is sometimes referred to as the “anthrax eclipse.” Following the period of feeling better, there is an onset of respiratory distress with breathing discomfort, shortness of breath, noisy, crowing respiratory sounds usually upon inspiration, bluish color to skin, increased chest pain and sweating. There may also be fluid retention in the chest and neck. A chest X-ray usually reveals a characteristic widening of the space between the lungs and often, accumulation of fluid in the plural space.

Although not common, pneumonia may develop in some patients. Research suggests that people with existing pulmonary disease may have increased susceptibility to inhalation anthrax. Meningitis also occurs in as many as 50% of the cases, which may cause seizures in some patients. The onset of respiratory distress is followed by the rapid onset of shock and death with 24 to 36 hours. Inhalation anthrax is almost always fatal unless treatment is started prior to the onset of symptoms. The current treatment involves the antibiotics Cipro, doxycycline and penicillin.

Oropharyngeal And Gastrointestinal Anthrax

This form of anthrax is very rare and results from the ingestion of infected meat that has not been adequately cooked. The incubation period is usually two to five days, although it is possible to take up to 60 days.

Oropharyngeal anthrax begins with a severe sore throat or a local oral or tonsillar ulcer, associated with fever, toxicity and swelling of the neck from fluid buildup. Respiratory distress and difficulty in swallowing may also be present. Gastrointestinal anthrax begins with nonspecific symptoms of nausea, vomiting and fever, followed in many cases by severe abdominal pain.

The first signs may be an acute abdomen accompanied by, vomiting blood, massive lymph and blood plasma loss from the liver, and diarrhea. In the absence of treatment, mortality in both forms may be as high as 60%, particularly with the gastrointestinal form.

Diagnosis Of Anthrax

The diagnosis of anthrax can be extremely difficult because it is such a rare occurrence. Little data exists on human exposure after the onset of clinical signs. Symptoms in the early stages resemble colds and the flu. One major difference between anthrax and the flu is that there is no nasal involvement with anthrax. There should not be runny- or stuffy-nose symptoms associated with the colds and the flu. Because of the recent anthrax outbreak in the United States potentially related to terrorism, every case that presents flu-like symptoms should be investigated to rule out anthrax.

Meningitis caused by anthrax is clinically indistinguishable from meningitis due to other bacteria. One key test result is the presence of blood in the cerebral spinal fluid. This can occur in as many as 50% of the cases.

Until recently, the drug of choice for treatment of all forms of anthrax was penicillin. The U.S. Food and Drug Administration (FDA) has approved Cipro for treatment, and since it has become the drug of choice. Cipro has many more side effects than the other antibiotics, some of them very dangerous. Doxycycline has also been used effectively with anthrax exposure. Recent reports indicate the anthrax strain(s) found in the U.S. outbreak are sensitive to all three antibiotics.

Detection And Testing

Outside of the military, there are few options for the detection of anthrax in the field. Current and developing test technology for anthrax can be can be classified into six general categories: antibody, “ELISA,” blood, bacterial culture, microscope examination and DNA:

  • Antibody tests require a specimen from a powder, nasal swab, or surface swab. The sample is mixed with water and placed on a test strip that contains anthrax-fighting antibody. A marking on the strip indicates positive. This test takes 15 minutes, is 95% accurate, and can be conducted in the field. The drawback is that swabs may not pick up bacteria.

  • The ELISA test is similar to the test strip, but must be done in a laboratory. It takes several hours and is more accurate than the test strip.

  • Blood tests require a sample of the infected person’s blood, which is tested for anti-anthrax antibodies. The results are quick, but the test must be repeated in a week or over several weeks to check for increases in antibodies. Increases would indicate an exposure. Blood tests may miss early infection.

  • Bacterial culture requires a sample of blood, powder or swab that is placed in a culture dish with nutrients specific to anthrax bacteria. If patches of bacteria appear, the test is positive. Test results take two days and are highly accurate. Anthrax spores can also be detected.

  • Microscope examination involves samples of blood or swab being stained with a chemical. If the bacteria are boxcar shaped and turn purple, the test is positive. The test may not detect early infection and cannot detect dormant spores.

  • DNA tests require a sample from blood, powder or a swab that is mixed with a chemical that is a mirror image of anthrax DNA. If the two interact, the sample is positive for anthrax. Testing takes 24 hours or longer in an advanced laboratory setting.

Anthrax is a large bacillus-type of bacteria like many other germs that cause mild food poisoning and some that are harmless. Some quick field tests can identify if a bacillus family member is present, but do not positively identify anthrax. A negative reading would be useless because there might not be enough bacteria in a sample to register.

The use of nasal swabs that was widely reported on TV is not a medically important test. It is merely an investigative tool to determine how many people might have been exposed and where. Spores might disappear by the time the swab test is conducted. Those prescribed antibiotics should not stop taking them just because a nasal swab is negative.

Several companies have developed handheld assay field tests, but according to the U.S. Centers for Disease Control and Prevention (CDC), “the utility and validity of these assays are unknown.” The CDC has been asked to evaluate the sensitivity and specificity of the commercially available rapid, hand-held assays for B. anthracis. When the study is completed, results will be made available. Because of all the current activity, conclusions from this study are not expected in the near future.

One company has a system that it claims can detect anthrax in the field, but the amount of spores present must be 10,000 or greater. At this level, the sample would be visible. In instances where there is no visible product, the test would be below the sensitivity of the product. Officials of the company say the CDC advisory was not directed at its product. The company claims the technology used in their product is also used by the military and FBI, so if the CDC finds the product is unreliable, then so would be the tests conducted by the military and FBI.

Research is underway on several fronts to develop technology for the field detection of anthrax. Some research is focusing on technology to allow for air monitoring of at-risk spaces such as subway systems. Those close to the research indicate it is still at least two years away from general use. These devices would be fully automated and behave similar to smoke detectors.

Other technology under investigation involves the use of DNA analysis in the field to identify anthrax. As recently as Nov. 5, 2001, the Mayo Clinic announced it had a new DNA test that can detect the presence of anthrax in less than an hour. The device has not been approved by the Food and Drug Administration (FDA), because the number of anthrax cases has been too small for clinical trials to be conducted.

Any tests conducted in the field should be followed up immediately by laboratory testing for confirmation. No actions should be taken concerning those exposed based solely on field-testing.


According to an article in the Journal of the American Medical Association in January 2000, the best decontamination solution for people is soap and water. Chlorine bleach solutions do not come without hazards. Getting bleach solutions in your eyes can cause damage or blindness. They can also damage wounds and the skin in certain concentrations.

In order for bleach to kill anthrax, it must contact the bacteria for a specified time. Leaving a bleach solution on a person long enough for the solution to kill the bacteria would likely damage the skin. A safer and more effective way to decontaminate might be to use soap and water on people and use the bleach solutions to kill the anthrax in the runoff. Anthrax spores are solid materials and should be easily removed from the body with soap and water.

Decontamination for equipment and other surfaces can be accomplished with four materials. They are Sandia foam, Nanoemulsion, formaldehyde fumigation, and sodium hypochlorite (bleach):

  • Sandia foam was developed by Sandia National Laboratories. It is made from a cocktail of oxidizing agents. The foam is non-toxic and non-corrosive, and does not contaminate the environment. Foam is sprayed on affected surfaces, filling in crevices in several hours. The foam collapses back to its compact liquid state and can be rinsed away. Sandia foam works by poking holes in the protective outer cover of the anthrax spores. It attacks the genetic material inside. During laboratory testing, only one in 10 million anthrax spores survived treatment with the foam.

  • Nanoemulsion is a non-toxic, non-corrosive material that can be applied to porous objects and surfaces. It is mixed with water and then sprayed onto surfaces to be decontaminated. The material destabilizes the spores within minutes. Nanoemulsion is safe to use and leaves no residual toxic effects.

  • Formaldehyde fumigation is a dangerous procedure and should only be used in ventilation systems. The area to be treated should be sealed off from other areas. Crystallized formaldehyde is heated, which generates a vapor. The vapor is extremely toxic and proper ventilation must be used along with appropriate protective equipment. Formaldehyde functions by fixing the proteins in the anthrax and renders the spore inactive.

  • Sodium hypochlorite is used to make chlorine bleach solutions. It is used to decontaminate surfaces, such as walls, floors and furniture. Bleach solutions are usually sprayed or wiped onto surfaces. The bleach solution poisons the bacteria.

Protective Equipment

The National Institute for Occupational Safety and Health (NIOSH) recently released Interim Recommendations for the Selection and use of Protective Clothing and Respirators Against Biological Agents. First and foremost, every agency responding to a suspected biohazard incident should do so with a plan. Elements should include assessment of the hazard, respiratory protection needs, and decontamination strategies.

Plans should be developed based upon recommendations by the CDC and other recognized expert agencies. Biological agents are particulate materials. They will not penetrate proper respirators and appropriate protective clothing. Based on the following response situations, the protective equipment recommended by the CDC and NIOSH is listed:

1. NIOSH-approved, pressure-demand self-contained breathing apparatus (SCBA) and full Level A protective suits should be used where the following information is unknown or the event is uncontrolled.

  • Type(s) of airborne agent(s)
  • Dissemination method
  • If dissemination via an aerosol-generating device is still occurring or it has stopped, but there is no information on the duration of dissemination or what the exposure concentration might be.

2. NIOSH-approved, pressure-demand SCBA and full Level B protective suits should be used if it is confirmed that:

  • The suspected biological aerosol is no longer being generated.
  • Other conditions may present a splash hazard.

3. Response personnel may use a full facepiece respirator with a P100 filter of a powered air-purifying respirator (PAPR) with high-efficiency particulate air (HEPA) filters when it can be confirmed that:

  • An aerosol-generating device was not used to create high airborne concentration.
  • Dissemination was by a letter or package that can be easily bagged.

Procedures and equipment development are constantly changing, sometimes on a daily basis. It is critical that emergency response personnel keep up with the latest information being disseminated by the FBI, CDC, NIOSH, local and state health departments, and others. If you are unsure about information available, then confirm it with the appropriate organizations.

Keep in mind that it is likely emergency responders will not respond to scenes of biological releases. They will become involved as patients become ill or as investigations of illness develops in an attempt to locate the source of the infection. It is most important that emergency responders and the local medical system are trained to recognize biological agent symptoms and have the proper protective equipment available for their use.

Robert Burke, a Firehouse® Magazine contributing editor, is the fire marshal for the University of Maryland. He is a Certified Fire Protection Specialist (CFSP), Fire Inspector II, Fire Inspector III, Fire Investigator and Hazardous Materials Specialist, and has served on state and county hazardous materials response teams. Burke is a veteran of 24 years in fire and emergency services, with experience in career and volunteer departments. He has attained the rank of lieutenant, assistant chief and deputy state fire marshal. Burke is an adjunct instructor at the National Fire Academy and the Community College of Baltimore, Catonsville Campus, and the author of the textbooks Hazardous Materials Chemistry for Emergency Responders and Counter-Terrorism for Emergency Responders. He can be reached in the Internet at