In the United States, anthrax is a rare disease normally associated with wild and domestic animals. In humans, it most commonly occurs when people are exposed to infected animals via meat or fur processing. For this reason, anthrax is also known as woolsorters' disease.
"For anthrax to be effective as a covert agent, it must be aerosolized into very small particles. This is difficult to do, and requires a great deal of technical skill and special equipment. If these small particles are inhaled, life-threatening lung infection can occur, but prompt recognition and treatment are effective." Source: U.S. Centers for Disease Control
Anthrax is caused by the bacterial species Bacillus anthracis, which can infect humans and animals in three ways:
Of the three, skin infection is the most treatable form of the disease.
Anthrax can't be spread from routine person-to-person contact. Once a person is infected, the bacteria and the toxin it produces combine to trigger disease symptoms.
Anthrax doesn't widely disperse itself, and the respiratory form of the disease is rare and difficult to engineer and administer for covert purposes, according to the U.S. Centers for Disease Control.
The bacteria tend to die quickly in environments that don't foster their growth. The species' ability to form spores, however, allows it to remain in the environment until conditions are suitable for it to grow. When spores find themselves in the proper environment, e.g., an animal's lung, they grow into anthrax bacteria. Anthrax spores are extremely hardy, and research suggests that they can remain viable for more than 30 years.
According to the American Medical Association, there are two stages to anthrax infection. The first stage, which can last from hours to a few days, includes flu-like symptoms. In the second stage, which progresses more quickly, the infected person experiences sudden fever, extreme shortness of breath and shock.
The skin-based (cutaneous) form of the disease begins with a small pimple at the site of infection, which then becomes a black lesion. If left untreated, the disease progresses to the above symptoms.
Antibotics are commonly used to treat anthrax, and are most effective if they are taken early in the course of the disease. Anthrax infection via mouth or skin are the most treatable types of the disease.