The Facts About Anthrax
Published: January 2002
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
Anthrax is not a contagious disease and is not
transmitted from person to person. It can be Courtesy Robert Burke
acquired through three routes of entry into the
Level A protective clothing is required when the types
body: inhalation, ingestion and cutaneous.
of airborne agents are unknown, the dissemination
Inhalation anthrax occurs when spores are method is unknown or aerosol generation is still
aerosolized and breathed into the lungs. occurring.
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 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
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.
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
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 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
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
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 Courtesy Robert Burke
(CDC), �the utility and validity of these Level C protective clothing can be used when there is
assays are unknown.� The CDC has been no aerosolization of a Suspected hazardous agent or
the material is contained in a letter or package.
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
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-
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
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
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.
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)
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
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.