Anthrax is a potentially fatal disease caused by the bacterium
Bacillus anthracis. It is well known for its role in the 2001 bioterrorist attacks, in which the lethal bacteria were spread deliberately through the U.S. mail. Twenty-two people became ill, and five died.
Understanding Bacillus Anthracis
Bacillus anthracis is the bacterium that causes anthrax. It lives in soil. Bacillus anthracis is different than many other bacteria because it forms spores. In this form, the Bacillus anthracis can lie dormant, but may come to life under the right conditions. Once the Bacillus anthracis bacteria come to life, they can have deadly effects. Bacillus anthracis is an aerobic bacterium, meaning it requires oxygen to survive and grow.
Anthrax most commonly occurs in wild and domestic animals (cattle, sheep, goats, camels, antelopes, and other plant-eating animals), but it can also occur in humans. A person may develop the condition if he or she is exposed to infected animals, tissue from infected animals, or anthrax spores used as a bioterrorist weapon.
There are three major types:
Symptoms differ, depending on the type of anthrax a person has.
For all three types, symptoms can appear within seven days of coming in contact with the bacteria (
Bacillus anthracis). For
inhalation anthrax, symptoms can appear within a week, or can take up to 42 days to appear.
Anthrax is not contagious among humans -- it is not spread from one person to another. Instead, transmission occurs in one of two ways:
- From animals
- As the result of a biological weapon.
In order to make a diagnosis, the doctor will ask a number of questions, perform a physical exam, and recommend certain tests. As part of diagnosing anthrax, the doctor will also rule out other, more common medical conditions, such as the
common cold or flu.
If it is determined that a person is at high risk, the doctor may recommend certain lab tests, including:
- Specimen tests, such as blood tests
- Chest x-ray.
Treatment typically involves antibiotics, and providing relief of symptoms and complications as the body fights the bacteria (supportive care).
If a diagnosis is made early, the disease can be successfully treated with antibiotics. Unfortunately, infected people often confuse early symptoms with more common infections, such as
the flu or
common cold, and do not seek medical help until severe symptoms appear. By this time, the destructive anthrax toxins have already risen to high levels, making treatment difficult. Antibiotics can kill the bacteria, but antibiotics have no effect on anthrax toxins.
In the event that people are exposed to potentially aerosolized spores, preventive treatment involves 60 days of oral antibiotics, along with a 3-dose regimen (0 weeks, 2 weeks, and 4 weeks) of
anthrax vaccine. This combination may help to prevent the development of inhalation anthrax.
There is a vaccine to prevent the disease, but it is not yet available for the general public. Anyone who is likely to be exposed to
Bacillus anthracis may get the vaccine. These groups of people may include:
- Certain members of the U.S. Armed Forces
- Laboratory workers
- Workers who may enter or re-enter contaminated areas.
Also, in the event of an attack using anthrax as a weapon, people exposed would get the vaccine.
The Centers for Disease Control and Prevention classify agents with recognized bioterrorism potential into three priority areas (A, B, and C). Bacillus anthracis is classified as a Category A agent. Category A agents are those that:
- Pose the greatest possible threat for a bad effect on public health
- May spread across a large area, or require public awareness
- Need a great deal of planning to protect the public's health.
In an average year, the chance that any one individual in the United States will contract anthrax is extremely low, meaning about 1 in nearly 300 million. In 2001, even with the intentional release of Bacillus anthracis spores in some environments, the nationwide risk was still extremely low. There were about 23 cases in nearly 300 million people.
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