NOVA Online | Bioterror

An anthrax-tainted letter, while able to kill and spread terror, is not the most dangerous anthrax weapon.

Agents of Bioterror
Anthrax

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

Anthrax gets its name from the Greek word for coal, anthrakis, because the skin form of the disease is characterized by lesions that turn jet-black. The three forms of anthrax disease (skin or cutaneous, inhalation, and gastrointestinal) are all caused by the same bacterium, Bacillus anthracis.

When sprayed as a fine aerosol mist, anthrax could be a weapon of mass destruction. An odorless, invisible cloud of anthrax could trigger thousands of cases of inhalation anthrax, the most deadly form of the disease. Bioweapons programs in the U.S., the Soviet Union, and Iraq mastered the ability to aerosolize anthrax.

Making a lethal anthrax aerosol requires access to advanced biotechnology, which some experts believe is beyond the capability of most terrorists. However, groups with substantial funding and expertise could acquire the needed materials. Aum Shinrikyo, the cult infamous for releasing sarin gas in the Tokyo subway, tried several times to disperse aerosols of anthrax. It's unclear why the attacks failed to produce illness.

In the fall of 2001, several deadly anthrax terrorist attacks took place in the U.S. All told, five people died and another 18 became infected, most from being in the vicinity of anthrax-laced letters, but at least two from completely unknown means. Experts identified the type of anthrax used in the attacks as the so-called Ames strain, which was long thought to have originated in Ames, Iowa. Then, in January 2002, investigators discovered a clerical error that revealed that the strain's origin was not Iowa but Texas, where the bacterial strain turned up in a dead cow in 1981. Authorities are still searching for the perpetrator of the attacks.

Incubation period before symptoms
12 hours - 5 days

Symptoms
Cutaneous:

Skin infections begin as itchy bumps resembling insect bites, then develop into lesions about half an inch to a little over an inch in diameter. Lesions become covered by black scabs.
swollen lymph nodes

Inhalation:

fever, chills, headache, nausea, vomiting
fluid in lungs, severe breathing difficulty
shock and respiratory failure

Gastrointestinal:

nausea, loss of appetite, vomiting, fever
abdominal pain, severe diarrhea, abdominal bleeding

How it would be spread
Letters with anthrax powder will cause only isolated cases of disease, relatively few in number. Poisoning of food is difficult to achieve with anthrax and is not considered likely. Aerosol spraying is the gravest threat. Anthrax diseases are not contagious.

Treatment
A variety of antibiotics can treat all three forms of the disease. Inhalation anthrax, however, progresses so quickly that, once symptoms are clear, it may be too late for drugs to prevent death.

Vaccine
The vaccine for anthrax used by the U.S. military is not currently available to the general public. It is given in a series of six shots over 18 months. Annual booster injections are recommended.

Anthrax	Botulism	Cholera	Glanders

Plague	Q Fever	Smallpox	Tularemia

Chart of the 8 agents

Photo: Corbis Images

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