Anthrax!
Anthrax!
Anthrax General Information Exposure and mode of infection. Signs and Symptoms Diagnosis Prevention Treatment Use as a Biological Warfare Agent both in Military and Bioterrorism.
Anthrax is an acute
disease
caused by the bacterium Bacillus
anthracis. Most forms of the disease are lethal, and it affects both
humans and other animals.
Like
many other members of the genus
Bacillus,
Bacillus anthracis can form dormant endospores
(often referred to as "spores" for short, but not to be confused with fungal
spores) that are able to survive in harsh conditions for decades or even
centuries. Such spores can be found on all continents, even Antarctica.
When spores are inhaled, ingested, or come into contact with a skin lesion on a
host they may reactivate and multiply rapidly.
Anthrax
commonly infects wild and domesticated herbivorous mammals that ingest or inhale
the spores while grazing. Ingestion is thought to be the most common route by
which herbivores contract anthrax. Carnivores living in the same environment may
become infected by consuming infected animals. Diseased animals can spread
anthrax to humans, either by direct contact (e.g., inoculation of infected blood
to broken skin) or by consumption of a diseased animal's flesh.
Anthrax
spores can be produced in
vitro (in the lab) and used as a biological
weapon. Anthrax does not spread directly from one infected animal or
person to another; it is spread by spores. These spores can be transported by
clothing or shoes. The body of an animal that had active anthrax at the time of
death can also be a source of anthrax spores.
Exposure
Occupational
exposure to infected animals or their products (such as skin, wool, and meat) is
the usual pathway of exposure for humans. Workers who are exposed to dead
animals and animal products are at the highest risk, especially in countries
where anthrax is more common. Anthrax in livestock grazing on open range where
they mix with wild animals still occasionally occurs in the United States and
elsewhere. Many workers who deal with wool and animal hides are routinely
exposed to low levels of anthrax spores but most exposures are not sufficient to
develop anthrax infections. It is presumed that the body's natural defenses can
destroy low levels of exposure. These people usually contract cutaneous anthrax
if they catch anything. Throughout history, the most dangerous form of
inhalational anthrax was called Woolsorters' disease because it was an
occupational hazard for people who sorted wool. Today this form of infection is
extremely rare, as almost no infected animals remain. The last fatal case of
natural inhalational anthrax in the United States occurred in California in
1976, when a home weaver died after working with infected wool imported from
Pakistan. The autopsy was done at UCLA hospital. To minimize the chance of
spreading the disease, the deceased was transported to UCLA in a sealed plastic
body bag within a sealed metal container.
In
November 2008, a drum maker in the United Kingdom who worked with untreated
animal skins died from anthrax. In December 2009 an outbreak of anthrax occurred
amongst heroin addicts in Glasgow,
Scotland, resulting in ten deaths. The source of the anthrax is believed to be
dilution of the heroin with bone meal in Afghanistan. Also during
December 2009, The New Hampshire Department of Health and Human Services
confirmed a case of gastrointestinal anthrax in an adult female. The CDC
(Center for Disease Control) investigated the source and the possibility that it
was contracted from an African drum recently used by the woman taking part in a
drumming circle. The woman apparently inhaled anthrax [in spore form] from
the hide of the drum. She became critically ill, but with gastrointestinal
anthrax rather than inhaled anthrax, which made her unique in American medical
history. The building where the infection took place was cleaned and reopened to
the public and the woman recovered. Jodie Dionne-Odom, New Hampshire state
epidemiologist, states, "It is a mystery. We really don't know why it
happened."
Anthrax can
enter the human body through the intestines (ingestion), lungs (inhalation), or
skin (cutaneous) and causes distinct clinical symptoms based on its site of
entry. In general, an infected human will be quarantined. However, anthrax does
not usually spread from an infected human to a non- infected human. But, if the
disease is fatal to the person's body, its mass of anthrax bacilli becomes a
potential source of infection to others and special precautions should be used
to prevent further contamination. Inhalational anthrax, if left untreated until
obvious symptoms occur, may be fatal.
Anthrax can
be contracted in laboratory accidents or by handling infected animals or their
wool or hides. It has also been used in biological
warfare agents and by terrorists
to intentionally infect as exemplified by the 2001
anthrax attacks.
Pulmonary
Respiratory
infection in humans initially presents with cold or flu-like
symptoms for several days, followed by severe (and often fatal)
respiratory collapse. Historical mortality was 92%, but, when treated early
(seen in the 2001 anthrax
attacks), observed mortality was 45%.[Distinguishing
pulmonary anthrax from more common causes of respiratory illness is essential to
avoiding delays in diagnosis and thereby improving outcomes. An algorithm for
this purpose has been developed. Illness progressing to the fulminant phase has
a 97% mortality regardless of treatment.
A lethal
infection is reported to result from inhalation of about 10,000–20,000 spores,
though this dose varies among host species. As with all diseases, it is presumed
that there is a wide variation to susceptibility with evidence that some people
may die from much lower exposures; there is little documented evidence to verify
the exact or average number of spores needed for infection. Inhalational anthrax
is also known as Woolsorters' or Ragpickers' disease as these professions were
more susceptible to the disease due to their exposure to infected animal
products. Other practices associated with exposure include the slicing up of
animal horns for the manufacture of buttons, the handling of hair bristles used
for the manufacturing of brushes, and the handling of animal skins. Whether
these animal skins came from animals that died of the disease or from animals
that had simply laid on ground that had spores on it is unknown. This mode of
infection is the type used weaponization in biological warfare..
Gastrointestinal
Gastrointestinal
infection in humans is most often caused by eating anthrax-infected meat and is
characterized by serious gastrointestinal difficulty, vomiting
of blood, severe diarrhea, acute inflammation of the intestinal tract,
and loss of appetite. Some lesions have been found in the intestines and in the
mouth and throat. After the bacterium invades the bowel system, it spreads
through the bloodstream throughout the body, making even more toxins on the way.
Gastrointestinal infections can be treated but usually result in fatality rates
of 25% to 60%, depending upon how soon treatment commences. This form of anthrax
is the rarest form. In the United States, there is only one official case
reported in 1942 by the CDC.
Cutaneous
Anthrax skin lesion
Cutaneous
(on the skin) anthrax infection in humans shows up as a boil-like skin lesion
that eventually forms an ulcer with a black center (lesion). The black lesion often shows up as a large, painless necrotic
ulcer (beginning as an irritating and itchy skin lesion or blister that is dark
and usually concentrated as a black dot, somewhat resembling bread mold) at the
site of infection. In general, cutaneous infections form within the site of
spore penetration between 2 and 5 days after exposure. Unlike bruises or most
other lesions, cutaneous anthrax infections normally do not cause pain.
Cutaneous
anthrax is typically caused when bacillus anthracis spores enter through cuts on
the skin. This form of Anthrax is found most commonly when humans handle
infected animals and/or animal products (e.g., the hide of an animal used to
make drums).
Cutaneous
anthrax is rarely fatal if treated, because the infection area is limited to the
skin, preventing the Lethal Factor, Edema Factor, and Protective Antigen from
entering and destroying a vital organ. Without treatment about 20% of cutaneous
skin infection cases progress to toxemia
and death.
Other than Gram
stain of specimens, there are no specific direct identification
techniques for identification of Bacillus species in clinical material.
These organisms are Gram-positive but with age can be Gram-variable to
Gram-negative. A specific feature of Bacillus species that makes it
unique from other aerobic microorganisms is its ability to produce spores.
Although spores are not always evident on a Gram stain of this organism, the
presence of spores confirms that the organism is of the genus Bacillus.
All Bacillus
species grow well on 5% Sheep blood agar and other routine culture media.
PLET (polymyxin-lysozyme-EDTA-thallous acetate) can be used to isolate B.anthracis
from contaminated specimens, and bicarbonate agar is used as an identification
method to induce capsule formation.
Vaccines
An anthrax
vaccine (BioThrax or Anthrax Vaccine Adsorbed) licensed by the U.S. Food and Drug Administration (FDA) and
produced from one non-virulent strain of the anthrax bacterium was formerly
administered in a six-dose primary series at 0, 2, 4 weeks and 6, 12, 18 months,
with annual boosters to maintain immunity. On December 11, 2008, the FDA
approved omitting the week 2 dose, resulting in the currently recommended
five-dose series.
Anthrax
cannot be spread directly from person to person, but a peoples clothing and body
may be contaminated with anthrax spores. Effective decontamination of people can
be accomplished by a thorough wash-down withantimicrobial
effective soap and water. Waste water should be treated with bleach or other
anti-microbial agent. Effective decontamination of articles can be accomplished
by boiling contaminated articles in water for 30 minutes or longer. Chlorine
bleach is ineffective in destroying spores and vegetative cells on surfaces,
though formaldehyde is effective. Burning clothing is very effective in
destroying spores. After decontamination, there is no need to immunize, treat or
isolate contacts of persons ill with anthrax unless they were also exposed to
the same source of infection.
Antibiotics
Early
antibiotic treatment of anthrax is essential—delay significantly lessens
chances for survival.
Treatment
for anthrax infection and other bacterial infections includes large doses of
intravenous and oral antibiotics,
such as fluoroquinolones
like ciprofloxacin,
or doxycycline,
erythromycin, vancomycin
or penicillin.
FDA-approved agents include ciprofloxacin, doxycycline and penicillin.
In possible
cases of inhalation anthrax, early antibiotic
prophylaxis treatment is crucial to prevent possible death.
In May 2009,
Human Genome Sciences
submitted a Biologic License Application (BLA, permission to market) for
its new drug,raxibacumab (brand name ABthrax) intended for emergency treatment of inhaled
anthrax. If death occurs from anthrax the body should be isolated to prevent possible
spread of anthrax germs. Burial does not kill anthrax spores.
In recent
years there have been many attempts to develop new drugs against anthrax, but
existing drugs are effective if treatment is started soon enough.
Anthrax in bioterrorism and biological warfare.
The virulent
Ames strain, which
was used in the 2001
anthrax attacks in the United States, has received the most news coverage
of any anthrax outbreak. The Ames strain contains two virulence plasmids,
which separately encode for a three-protein toxin, called anthrax
toxin, and a poly-glutamic acid capsule.
Nonetheless, the Vollum strain, developed but never used as a biological
weapon during the Second World War, is much more dangerous. The Vollum
(also incorrectly referred to as Vellum) strain was isolated in 1935 from
a cow in Oxfordshire,
UK. This is the same strain that was used during the Gruinard
bioweapons trials. A variation of Vollum known as "Vollum 1B" was used
during the 1960s in the US and UK bioweapon programs. Vollum 1B is widely
believe
to have been isolated from William A. Boyles, a 46-year-old scientist at the
U.S. Army Biological Warfare Laboratories at Camp (later Fort) Detrick
(precursor to USAMRIID)
who died in 1951 after being accidentally infected with the Vollum strain. The Sterne
strain, named after the Trieste-born immunologist Max Sterne, is an attenuated
strain used as a vaccine, which contains only the anthrax
toxin virulence plasmid and not the poly-glutamic acid capsule
expressing plasmid.
Site
cleanup
Anthrax
spores can survive for very long periods of time in the environment after
release. Methods for cleaning anthrax-contaminated sites commonly use oxidizing
agents such as peroxides,
ethylene oxide,
Sandia Foam, chlorine dioxide (used in the Hart Senate Office Building), and liquid bleach products
containing sodium hypochlorite. These agents slowly destroy bacterial spores. A
bleach solution for treating hard surfaces has been approved by the EPA.]Bleach
and vinegar must not be combined together directly, as doing so could produce chlorine
gas. Rather some water must first be added to the bleach (e.g., two cups water
to one cup of bleach), then vinegar (e.g., one cup), and then the rest of the
water (e.g., six cups). The pH of the solution should be tested with a paper
test strip; and treated surfaces must remain in contact with the bleach solution
for 60 minutes (repeated applications will be necessary to keep the surfaces
wet).
Chlorine
dioxide has emerged as the preferred biocide against anthrax-contaminated
sites, having been employed in the treatment of numerous government buildings
over the past decade. Its chief drawback is the need for in
situ processes to have the reactant on demand.
To speed the
process, trace amounts of a non-toxic catalyst
composed of iron
and tetro-amido macrocyclicligands
are combined with sodium
carbonate and bicarbonate
and converted into a spray. The spray formula is applied to an infested area and
is followed by another spray containing tert-Butyl
hydroperoxide.
Using the
catalyst method, a complete destruction of all anthrax spores can be achieved in
under 30 minutes. A standard catalyst-free spray destroys fewer than half the
spores in the same amount of time. They can be heated, exposed to the harshest
chemicals, and they do not easily die.]
Cleanups at
a Senate office building, several contaminated postal facilities and other U.S.
government and private office buildings showed that decontamination is possible,
but it is time-consuming and costly. Clearing the Senate office building of
anthrax spores cost $27 million, according to the Government Accountability
Office. Cleaning the Brentwood postal facility outside Washington cost $130 million
and took 26 months. Since then newer and less costly methods have been
developed.
Clean up of
anthrax-contaminated areas on ranches and in the wild is much more problematic.
Carcasses may be burned, though it often takes up to three days to burn a large
carcass and this is not feasible in areas with little wood. Carcasses may also
be buried, though the burying of large animals deeply enough to prevent
resurfacing of spores requires much manpower and expensive tools. Carcasses have
been soaked in formaldehyde to kill spores, though this has environmental
contamination issues. Block burning of vegetation in large areas enclosing an
anthrax outbreak has been tried; this, while environmentally destructive, causes
healthy animals to move away from an area with carcasses in search of fresh
graze and browse. Some wildlife workers have experimented with covering fresh
anthrax carcasses with shade cloth and heavy objects. This prevents some
scavengers from opening the carcasses, thus allowing the putrefactive bacteria
within the carcass to kill the vegetative B. anthracis cells and preventing
sporulation. This method also has drawbacks, as scavengers such as hyenas are
capable of infiltrating almost any exclosure. The occurrence of previously
dormant anthrax, stirred up from below the ground surface by wind movement in a
drought-stricken region with depleted grazing and browsing, may be seen as a
form of natural culling and a first step in rehabilitation of the area.
Biological
warfare
Anthrax was first tested as a biological warfare agent by Unit 731 of the Japanese Kwantung Army in Manchuria during the 1930s; some of this testing involved intentional infection of prisoners of war, thousands of whom died. Anthrax, designated at the time as Agent N, was also investigated by the allies in the 1940s. Weaponised anthrax was part of the U.S. stockpile prior to 1972, when the United States signed the Biological Weapons Convention.
Anthrax
spores can and have been used as a biological
warfare weapon. Its first modern incidence occurred when Scandinavian
freedom fighters ("the rebel groups") supplied by the German General
Staff used anthrax with unknown results against the Imperial Russian Army in
Finland in 1916.There is a long history of practical bioweapons
research in this area. For example, in 1942 British bioweapons trials
severely contaminated Gruinard
Island in Scotland with anthrax spores of the Vollum-14578 strain,
making it a no-go area until it was decontaminated in 1990.The Gruinard trials
involved testing the effectiveness of a submunition
of an "N-bomb"—a biological weapon. Additionally, five million
"cattle cakes" impregnated with anthrax were prepared and stored at Porton
Down for "Operation
Vegetarian"—an anti-livestock weapon intended for attacks on
Germany by the Royal Air
Force. The infected cattle cakes were to be dropped on Germany in 1944.
However neither the cakes nor the bomb was used; the cattle cakes were
incinerated in late 1945.
More recently, the Rhodesian government used anthrax against cattle and humans in the period 1978–1979 during its war with black nationalists.
American military and British
Army personnel are routinely vaccinated against anthrax prior to active
service in places where biological attacks are considered a threat. The anthrax
vaccine, produced by BioPort
Corporation, contains non-living bacteria, and is approximately 93%
effective in preventing infection.
Weaponised
stocks of anthrax in the US were destroyed in 1971–72 after President Nixon
ordered the dismantling of US biowarfare programs in 1969 and the destruction
of all existing stockpiles of bioweapons.
The Soviet
Union created and stored 100 to 200 tons of anthrax spores at Kantubek
on Vozrozhdeniya Island.
They were abandoned in 1992 and destroyed in 2002.
Sverdlovsk incident
2 April 1979
Main article: Sverdlovsk
anthrax leak
Despite
signing the 1972 agreement to end bioweapon production the government of the
Soviet Union had an active bioweapons program that included the production of
hundreds of tons of weapons-grade anthrax after this period. On 2 April 1979,
some of the over one million people living in Sverdlovsk (now called Ekaterinburg,
Russia), about 850 miles east of Moscow, were exposed to an accidental
release of anthrax from a biological weapons complex located near there.
At least 94 people were infected, of whom at least 68 died. One victim died four
days after the release, ten over an eight-day period at the peak of the deaths,
and the last six weeks later. Extensive cleanup, vaccinations and medical
interventions managed to save about 30 of the victims. Extensive cover-ups and
destruction of records by the KGB continued from 1979 until Russian
President Boris Yeltsin
admitted this anthrax accident in 1992. Jeanne Guillemin reported in 1999 that
a combined Russian and United States team investigated the accident in 1992.
Nearly all
of the night shift workers of a ceramics plant directly across the street from
the biological facility (compound 19) became infected, and most died. Since most
were men, there were suspicions by NATO
governments that the Soviet Union had developed a sex-specific weapon. The government blamed the outbreak on the consumption of anthrax-tainted meat and
ordered the confiscation of all uninspected meat that entered the city. They
also ordered that all stray
dogs be shot and that people not have contact with sick animals. There
was also a voluntary evacuation and anthrax vaccination program established for
people from 18–55.
To support
the cover-up story
Soviet medical and legal journals published articles about an outbreak in
livestock that caused GI anthrax in people having consumed infected meat, and
cutaneous anthrax in people having come into contact with the animals. All
medical and public health records were confiscated by the KGB. In addition to
the medical problems that the outbreak caused, it also prompted Western
countries to be more suspicious of a covert Soviet Bioweapons program and to
increase their surveillance of suspected sites. In 1986, the US government was
allowed to investigate the incident, and concluded that the exposure was from
aerosol anthrax from a military weapons facility. In 1992, President Yeltsin
admitted that he was "absolutely certain" that "rumors"
about the Soviet Union violating the 1972 Bioweapons Treaty were true. The
Soviet Union, like the US and UK, had agreed to submit information to the UN
about their bioweapons programs but omitted known facilities and never
acknowledged their weapons program.
Anthrax bioterrorism
In theory,
anthrax spores can be cultivated with minimal special equipment and a first-year
collegiate microbiological
education, but in practice the procedure is difficult and dangerous. To make
large amounts of an aerosol
form of anthrax suitable for biological warfare requires extensive practical
knowledge, training, and highly advanced equipment.
Concentrated
anthrax spores were used for bioterrorism
in the 2001 anthrax attacks
in the United States, delivered by mailing postal letters containing the
spores. The letters were sent to several news media offices as well as to two
Democratic senators: Tom Daschle
of South Dakota and Patrick
Leahy of Vermont. As a result, 22 were infected and five died.
Only a few grams of material were used in these attacks and in August 2008 the
US Department of Justice announced they believed that Dr.
Bruce Ivins, a senior biodefense researcher employed by the United States
government, was responsible. These events also spawned many anthrax
hoaxes.
Due to these
events, the U.S. Postal
Service installed biohazard detection systems at its major distribution
centers to actively scan for anthrax being transported through the mail.
Decontaminating mail
In response
to the postal anthrax attacks and hoaxes the US
Postal Service sterilized some mail using a process of gamma irradiation
and treatment with a proprietary enzyme
formula supplied by Sipco
Industries Ltd.
A scientific
experiment performed by a high school student, later published in The Journal of
Medical Toxicology, suggested that a domestic electric
iron at its hottest setting (at least 400 °F (204 °C)) used for at
least 5 minutes should destroy all anthrax spores in a common postal envelope.
