NOVA Online | Bioterror

Deer flies can carry tularemia and cause natural cases of human infection.

Agents of Bioterror
Tularemia

incubation period | symptoms | how it would spread | treatment | vaccine

The agent that causes tularemia, Francisella tularensis, is one of the most infectious bacteria known: inhaling as few as ten microscopic germs can trigger disease. A World Health Organization committee estimated that if 110 pounds of a virulent strain of the bacteria were sprayed over a city of five million, it could incapacitate 250,000 people and kill 19,000. Respiratory failure or shock would cause most fatalities.

During World War II, both the Japanese and U.S. militaries researched tularemia. In the 1990s, the Soviet Union developed antibiotic- and vaccine-resistant strains.

Tularemia occurs naturally in small mammals such as mice, squirrels, and rabbits. Human infection, which is rare, can result from insect bites or handling infected animals. It is possible that infected flies, ticks, or mosquitoes could intentionally be released as weapons, but direct spraying of the bacteria is thought to be a more likely threat.

Incubation period before symptoms
1-14 days. Following a terrorist attack, cases would likely be reported in 3-5 days.

Symptoms
Various forms of the disease all begin with the sudden onset of flu-like symptoms:

fever, chills, headache, cough, and lethargy

Additional symptoms depend on the form but include:

swollen and sore lymph nodes
skin ulcers
red and sore eyes
abdominal pain, diarrhea, and vomiting
pneumonia

How it would be spread
Aerosol or food. Human-to-human transmission has not been documented.

Treatment
Early antibiotic therapy is effective, and if started within 24 hours of exposure, may prevent disease. A variety of antibiotics can be used, although some antibiotics may be powerless against strains genetically engineered to be resistant.

Vaccine
No vaccine is available for the general public. The U.S. Food and Drug Administration is investigating a vaccine that is now available for high-risk lab workers.

Anthrax	Botulism	Cholera	Glanders

Plague	Q Fever	Smallpox	Tularemia

Chart of the 8 agents

Photo: Photo Researchers

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