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What
is tularemia?
Tularemia is an infectious disease caused by a hardy bacterium,
Francisella tularensis, found in animals (especially rodents, rabbits,
and hares).
How
do people become infected with the tularemia bacteria?
Typically, persons become infected through the bites of arthropods
(most commonly, ticks and deerflies) that have fed on an infected
animal, by handling infected animal carcasses, by eating or drinking
contaminated food or water, or by inhaling infected aerosols.
Does
tularemia occur naturally in the United States?
Yes. It is a widespread disease of animals. Approximately 200 cases
of tularemia in humans are reported annually in the United States,
mostly in persons living in the south-central and western states.
Nearly all cases occur in rural areas and are associated with the
bites of infective ticks and biting flies or with the handling of
infected rodents, rabbits, or hares. Occasional cases result from
inhaling infectious aerosols and from laboratory accidents.
Why
are we concerned about tularemia as a bioweapon?
Francisella tularensis is highly infectious: a small number of bacteria
(10-50 organisms) can cause disease. If F. tularensis were used
as a bioweapon, the bacteria would likely be made airborne for exposure
by inhalation. Persons who inhale an infectious aerosol would generally
experience severe respiratory illness, including life-threatening
pneumonia and systemic infection, if they were not treated. The
bacteria that cause tularemia occur widely in nature and could be
isolated and grown in quantity in a laboratory, although manufacturing
an effective aerosol weapon would require considerable sophistication.
Can
someone become infected with the tularemia bacteria from another
person?
No. People have not been known to transmit the infection to others,
so infected persons do not need to be isolated.
How
quickly would someone become sick if they were exposed to the tularemia
bacteria?
The incubation period for tularemia is typically 3 to 5 days, with
a range of 1 to 14 days.
What
are the signs and symptoms of tularemia?
Depending on the route of exposure, the tularemia bacteria may cause
skin ulcers, swollen and painful lymph glands, inflamed eyes, sore
throat, oral ulcers, or pneumonia. If the bacteria were inhaled,
symptoms would include the abrupt onset of fever, chills, headache,
muscle aches, joint pain, dry cough, and progressive weakness. Persons
with pneumonia can develop chest pain, difficulty breathing, bloody
sputum, and respiratory failure. 40% or more of persons with the
lung and systemic forms of the disease may die if they are not treated
with appropriate antibiotics.
What
should someone do if they suspect they or others have been exposed
to the tularemia bacteria?
Seek prompt medical attention. If a person has been exposed to Francisella
tularensis, treatment with tetracycline antibiotics for 14 days
after exposure may be recommended.
Local
and state health departments should be immediately notified so an
investigation and control activities can begin quickly. If the exposure
is thought to be due to criminal activity (bioterrorism), local
and state health departments will notify CDC, the FBI, and other
appropriate authorities.
How
is tularemia diagnosed?
When tularemia is clinically suspected, the healthcare worker will
collect specimens, such as blood or sputum, from the patient for
testing in a diagnostic or reference laboratory. Laboratory test
results for tularemia may be presumptive or confirmatory.
Presumptive
(preliminary) identification may take less than 2 hours, but confirmatory
testing will take longer, usually 24 to 48 hours.
Can
tularemia be effectively treated with antibiotics?
Yes. After potential exposure or diagnosis, early treatment is recommended
with an antibiotic from the tetracycline (such as doxycycline) or
fluoroquinolone (such as ciprofloxacin) class, which are taken orally,
or the antibiotics streptomycin or gentamicin, which are given intramuscularly
or intravenously. Sensitivity testing of the tularemia bacterium
can be done in the early stages of a response to determine which
antibiotics would be most effective.
How
long can Francisella tularensis exist in the environment?
Francisella tularensis can remain alive for weeks in water and soil.
Is
there a vaccine available for tularemia?
In the past, a vaccine for tularemia has been used to protect laboratory
workers, but it is currently under review by the Food and Drug Administration.
All information obtained from the CDC
(Center for Disease Control and Prevention)
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