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Information For Patients: Anthrax
What
is anthrax?
Anthrax is an acute infectious disease caused by the spore-forming
bacterium Bacillus anthracis. Anthrax most commonly occurs
in wild and domestic lower vertebrates (cattle, sheep, goats,
camels, antelopes, and other herbivores), but it can also occur
in humans when they are exposed to infected animals or tissue
from infected animals.
Why
has anthrax become a current issue?
Because anthrax is considered to be a potential
agent for use in biological warfare, the Department of Defense
(DoD) has begun mandatory vaccination of all active duty military
personnel who might be involved in conflict.
How
common is anthrax and who can get it?
Anthrax is most common in agricultural regions where it occurs
in animals. These include South and Central America, Southern
and Eastern Europe, Asia, Africa, the Caribbean, and the Middle
East. When anthrax affects humans, it is usually due to an occupational
exposure to infected animals or their products. Workers who are
exposed to dead animals and animal products from other countries
where anthrax is more common may become infected with B. anthracis
(industrial anthrax). Anthrax in wild livestock has occurred in
the United States.
How
is anthrax transmitted?
Anthrax infection can occur in three forms: cutaneous (skin),
inhalation, and gastrointestinal. B. anthracis spores can
live in the soil for many years, and humans can become infected
with anthrax by handling products from infected animals or by
inhaling anthrax spores from contaminated animal products. Anthrax
can also be spread by eating undercooked meat from infected animals.
It is rare to find infected animals in the United States.
What
are the symptoms of anthrax?
Symptoms of disease vary depending on how the disease was contracted,
but symptoms usually occur within 7 days.
Cutaneous: 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. Skin
infection begins as a raised itchy bump that resembles an insect
bite but within 1-2 days develops into a vesicle and then a painless
ulcer, usually 1-3 cm in diameter, with a characteristic black
necrotic (dying) area in the center. Lymph glands in the adjacent
area may swell. About 20% of untreated cases of cutaneous anthrax
will result in death. Deaths are rare with appropriate antimicrobial
therapy.
Inhalation: Initial symptoms may resemble
a common cold. After several days, the symptoms may progress to
severe breathing problems and shock. Inhalation anthrax is usually
fatal.
Intestinal: The intestinal disease
form of anthrax may follow the consumption of contaminated meat
and is characterized by an acute inflammation of the intestinal
tract. 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 25% to 60% of
cases.
Where
is anthrax usually found?
Anthrax can be found globally. It is more common in developing
countries or countries without veterinary public health programs.
Certain regions of the world (South and Central America, Southern
and Eastern Europe, Asia, Africa, the Caribbean, and the Middle
East) report more anthrax in animals than others.
Can
anthrax be spread from person-to-person?
Direct person-to-person spread of anthrax is extremely unlikely
to occur. Communicability is not a concern in managing or visiting
with patients with inhalational anthrax.
Is
there a way to prevent infection?
In countries where anthrax is common and vaccination
levels of animal herds are low, humans should avoid contact with
livestock and animal products and avoid eating meat that has not
been properly slaughtered and cooked. Also, an anthrax vaccine
has been licensed for use in humans. The vaccine is reported to
be 93% effective in protecting against anthrax.
What
is the anthrax vaccine?
The anthrax vaccine is manufactured and distributed
by BioPort, Corporation, Lansing, Michigan. The vaccine is a cell-free
filtrate vaccine, which means it contains no dead or live bacteria
in the preparation. The final product contains no more than 2.4
mg of aluminum hydroxide as adjuvant. Anthrax vaccines intended
for animals should not be used in humans.
Who
should get vaccinated against anthrax?
The Advisory Committee on Immunization Practices
has recommend anthrax vaccination for the following groups:
- Persons who work directly with the organism in the laboratory
- Persons who work with imported animal hides or furs in areas
where standards are insufficient to prevent exposure to anthrax
spores.
- Persons who handle potentially infected animal products in
high-incidence areas. (Incidence is low in the United States,
but veterinarians who travel to work in other countries where
incidence is higher should consider being vaccinated.)
- Military personnel deployed to areas with high risk for exposure
to the organism (as when it is used as a biological warfare
weapon).
The anthrax Vaccine Immunization Program in the U.S. Army Surgeon
General's Office can be reached at 1-877-GETVACC (1-877-438-8222).
http://www.anthrax.osd.mil
Pregnant women should be vaccinated only if absolutely necessary.
What is the
protocol for anthrax vaccination?
The immunization consists of three subcutaneous injections given
2 weeks apart followed by three additional subcutaneous injections
given at 6, 12, and 18 months. Annual booster injections of the
vaccine are recommended thereafter.
Are there adverse
reactions to the anthrax vaccine?
Mild local reactions occur in 30% of recipients and consist
of slight tenderness and redness at the injection site. Severe
local reactions are infrequent and consist of extensive swelling
of the forearm in addition to the local reaction. Systemic reactions
occur in fewer than 0.2% of recipients.
How
is anthrax diagnosed?
Anthrax is diagnosed by isolating B. anthracis from the
blood, skin lesions, or respiratory secretions or by measuring
specific antibodies in the blood of persons with suspected cases.
Is
there a treatment for anthrax?
Doctors can prescribe effective antibiotics. To be effective,
treatment should be initiated early. If left untreated, the disease
can be fatal.
Where
can I get more information about the recent Department of Defense
decision to require men and women in
the Armed Services to be vaccinated against anthrax?
The Department of Defense recommends that servicemen and women
contact their chain of command on questions about the vaccine
and its distribution. The anthrax Vaccine Immunization Program
in the U.S. Army Surgeon General's Office can be reached at 1-877-GETVACC
(1-877-438-8222). http://www.anthrax.osd.mil
| Clinical
Features |
Human anthrax has three major clinical
forms: cutaneous, inhalation, and gastrointestinal. Cutaneous
anthrax is a result of introduction of the spore through the
skin; inhalation anthrax, through the respiratory tract; and
gastrointestinal anthrax, by ingestion. |
| Etiologic
Agent |
Bacillus anthracis, the etiologic
agent of anthrax, is a large, gram-positive, nonmotile, spore-forming
bacterial rod. The three virulence factors of B. anthracis
are edema toxin, lethal toxin and a capsular antigen. B.
anthracis is considered to be a likely agent for use in
acts of biological terrorism. |
| Incidence |
In the United States, incidence
is extremely low. Gastrointestinal anthrax is rare but may
occur as explosive outbreaks associated with ingestion of
infected animals. Worldwide, the incidence is unknown, though
B. anthracis is present in most of the world. |
| Sequelae |
If untreated, anthrax in all forms
can lead to septicemia and death. Early treatment of cutaneous
anthrax is usually curative, and early treatment of all forms
is important for recovery. Patients with gastrointestinal
anthrax have reported case- fatality rates ranging from 25%
to 75%. Case-fatality rates for inhalational anthrax are thought
to approach 90 to 100%. |
| Transmission |
For humans, the source of infection
in naturally acquired disease is infected livestock and wild
animals or contaminated animal products. Human-to-human transmission
is extremely rare and only reported with cutaneous anthrax.
|
| Risk
Groups |
Cutaneous anthrax is the most common
manifestation of infection with B. anthracis. Inhalation
(pulmonary) anthrax occurs in persons working in certain occupations
where spores may be forced into the air from contaminated
animal products, such as animal hair processing. Occupational
risk groups include those coming into contact with livestock
or products from livestock, e.g., veterinarians, animal handlers,
abattoir workers, and laboratorians. |
| Surveillance |
For both livestock and humans, anthrax
is a notifiable disease in the United States. |
| Trends |
Among humans, there has been no
increase in naturally acquired infection in the United States.
Recently, considerable attention has been focused on the potential
for B. anthracis to be used in acts of biologic terrorism. |
| Challenges |
Because B. anthracis has
a high probability for use as an agent in biologic terrorism,
CDC is expanding epidemiologic and diagnostic laboratory capacities
and technologies. This capacity building, includes local and
state health department training. In addition, there are gaps
in our understanding of the immunology of anthrax and protection
against anthrax via vaccination. Also, post-exposure prophylaxis
against anthrax requires further investigation. |
| Opportunities |
Identify, transfer to CDC laboratories,
test, and improve as needed, rapid diagnostic technologies
developed for rapid identification of B. anthracis in
Department of Defense (DoD) laboratories. |
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MMWR Articles
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4936a1.htm
Links
Case
Definition for anthrax
Department of Defense recommends servicemen and women contact
their chain of command on questions about the vaccine and its
distribution. More information
from the Department of Defense.
Department of Defense Anthrax Vaccine Program
http://www.anthrax.osd.mil/
General information on anthrax from encyclopedia.com
References
Turnbull PCB, Bohm R et al., 1993, Guidelines for the Surveillance
and Control of Anthrax in Humans and Animals, Geneva. WHO/Zoon/93.170.
Smego R., Gebrian B., Desmangels G. Cutaneous Manifestations
of Anthrax in Rural Haiti. Clinical Infectious Diseases, 1998;
26:97-102.
Harrison L., Ezzell J., Veterinary Laboratory Investigation
Center; Abshire T., Kidd S., Kaufmann A. Evaluation of Serologic
Tests for Diagnosis of Anthrax after an Outbreak of Cutaneous
Anthrax in Paraguay. J Infect Dis 1989;160:4.
Suffin S., Carnes W., Kaufmann A. Inhalation Anthrax in a Home
Craftsman. Clinical Infectious Diseases, 1998;26:97-102.
CDC. Bioterrorism Alleging Use of Anthrax and Interim Guidelines
for Management - United States, 1998. MMWR Morb Mortal Wkly Rep
1999;48:4.
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