Terrorists could select from a long list
of organisms to employ as bioweapons, but five biological
agents cause the most concern. They are widely known and have
the potential to pose the most serious threats to civilian
An acute infectious disease caused by the spore-forming bacterium
Symptoms: Cutaneous anthrax: starts
with a welt or swelling that progresses from a fluid-filled
blister to a black, ulcerous lesion. Inhalation anthrax: resembles
a common cold and develops into severe breathing problems
Time Frame: Symptoms usually occur
within 7 days of exposure; sometimes as late as 6 to 8 weeks
Infection: It does not transmit person
to person. Anthrax infection follows contact with infected
animals or contaminated animal products. Inhalation anthrax,
the deadliest form, results from exposure to airborne spores.
Cutaneous anthrax, caused by exposure of the skin to anthrax
spores, is the most common form. Gastrointestinal anthrax
also occurs, though rarely.
Fatality without Treatment: Inhalation
anthrax is estimated to be 70 to 90 percent fatal. About 20
percent of cutaneous anthrax is fatal without
Botulism is a muscle-paralyzing disease caused by a toxin
made by a bacterium called Clostridium botulinum.
Symptoms: Double vision, blurred
vision, drooping eyelids, slurred speech, difficulty swallowing,
dry mouth, and muscle weakness.
Time Frame: Symptoms begin within 2 hours to 8 days.
Infection: Botulinum toxin can spread
through the air or food supply. It does not transmit person
Fatality without Treatment: About
This highly contagious bacterium, Yersinia pestis,
is found in rodents and fleas and can be easily grown and
disseminated by aerosol.
Symptoms: Fever, headache, weakness,
and cough productive of bloody or watery sputum.
Time Frame: Symptoms within 1 to
6 days of exposure. Without treatment, death occurs within
2 to 4 days after onset of symptoms.
Infection: Person-to-person transmission
of pneumonic plague occurs through respiratory droplets, which
can only infect those who have face-to-face contact with the
ill patient. The most common infection occurs by plague-infected
fleas biting humans, who then develop bubonic plague.
Fatality without Treatment: Nearly
Smallpox, caused by the Variola virus, is seen as one
of the most serious bioterrorist threats because of its high
case-fatality rates and transmissibility.
Symptoms: Fever, fatigue, headaches,
and backaches followed by rashes and lesions.
Time Frame: First symptoms present
7 to 17 days after exposure. Death can occur within 2 weeks
Infection: Smallpox is spread from
one person to another by infected saliva droplets that expose
a susceptible person having face-to-face contact with the
Fatality without Treatment: About 30 percent.
Francisella tularenis, the organism that causes tularemia,
is one of the most infectious pathogenic bacteria known
inhalation of as few as 10 organisms can cause disease.
Symptoms: Fever, fatigue, chills,
swollen lymph nodes, and pneumonia.
Time Frame: Onset of symptoms begins
in 1 to 14 days.
Infection: Human infection occurs
through handling infectious animal tissues or fluids; direct
contact or ingestion of contaminated water, food, or soil;
and bites by infected insects, arachnids, or crustaceans.
Fatality without Treatment: 5 to
15 percent for severe Type A strains; 30 to 60 percent if
infection in lung or bloodstream.
Fighting Bioterror for treatment and vaccine information.
Sources: CDC; Johns Hopkins Center for Civilian