5 Feared Biological Agents

Anthrax

An acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. 

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 and shock. 

Time Frame: Symptoms usually occur within 7 days of exposure; sometimes as late as 6 to 8 weeks after exposure.

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 treatment.

BOTULINUM TOXIN

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 to person.

Fatality without Treatment: About 8 percent.

PLAGUE

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 100 percent.

SMALLPOX

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 of symptoms.

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 ill person.

Fatality without Treatment: About 30 percent.

TULAREMIA

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.

Sources: CDC; Johns Hopkins Center for Civilian Biodefense Studies