Bioterrorism

FAQs - "A" Agents

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Tularemia

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 and in Arizona?

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. Tularemia in humans is relatively rare in Arizona. There were five cases reported in Arizona over the last ten years and 28 cases over the last twenty-five years. 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 biological weapon?

Francisella tularensis is highly infectious: a small number of bacteria (10-50 organisms) can cause disease. If F. tularensis were used as a biological weapon, it would likely be spread through the air as an aerosol. Persons who inhale an infectious aerosol would generally experience severe respiratory illness, including life-threatening pneumonia and systemic disease, 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. Infected individuals have not been known to transmit the infection, 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. Forty percent 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 is often 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. Sometimes presumptive (preliminary) identification may take only a few hours, but confirmatory testing will usually take longer.

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. Other antibiotics such as streptomycin or gentamicin, are also effective, but can only be given intramuscularly or intravenously. Sensitivity testing of the tularemia bacterium can be done 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?

A vaccine for tularemia is available for use in laboratory workers, but it is not licensed for general use.

Find the PDF version of this FAQ in the Zebra Manual.