Anthrax: A serious bacterial infection caused by Bacillus anthracis that occurs primarily in animals. Cattle, sheep, horses, mules, and some wild animals are highly susceptible. Humans and swine are generally quite resistant to anthrax. Humans become infected when the spores of B. anthracis enter the body by contact with animals infected with B. anthracis or from contact with contaminated animal products, insect bites, ingestion, or inhalation. Aerosolized ("weaponized") spores of B. anthracis can potentially be used (misused) for biological warfare and bioterrorism. Cutaneous anthrax is the most common form of the disease and is characterized by the development of a localized skin lesion with a central eschar surrounded by marked edema (swelling). Inhalation anthrax (woolsorters' disease) typically involves hemorrhagic mediastinitis (bleeding into the mid-chest), rapidly progressive systemic (bodywide) infection, and carries a very high mortality rate. Gastrointestinal anthrax is much rarer but is also associated with a high mortality rate.
Anthrax can, as mentioned, take different forms. One is the pulmonary (lung) form of the disease. It is contracted by inhaling a large dose of the anthrax spores, typically in an enclosed space protected from direct sunlight. (The spores are quickly killed by sunlight.) If pulmonary anthrax is untreated, it is usually fatal. An intestinal form of anthrax is caused by eating meat contaminated with anthrax.
But most human anthrax comes from skin contact with animal products contaminated by anthrax. Cutaneous (skin) anthrax was once well known among people who handled infected animals (farmers, woolsorters, tanners, brushmakers and carpetmakers in the days when the brushes and carpets were animal products).
The hallmark of skin anthrax is a carbuncle, a cluster of boils, that ulcerates. Typically, the carbuncle has a hard black center surrounded by bright red inflammation. This dramatic appearance accounts for its name, "anthrax", the Greek word for "coal", a burning coal.
The pulmonary form of anthrax is an emergency and calls for early continuous IV antibiotics (such as penicillin in combination with streptomycin).
There is an anthrax vaccine for persons at high risk (such as members of the armed forces). However, the only anthrax vaccine currently made in the USA is experiencing problems with production standardization.
Bioterrorism -- The General Accounting Office (GAO), the investigative arm of the US Congress, in a 1999 report considered anthrax as a "possible" biologic threat for terrorism, but noted that a virulent strain of the bacterium is difficult to acquire and that an attack would require sophistication to manufacture and disseminate the bacteria. The GAO considered the lethal effects of anthrax to be "very high."
In the autumn of 2001, anthrax was no longer a "possible" biologic threat for terrorism. With its distribution through the mail in the US, anthrax became a 21st-century agent of bioterrorism.
Last Editorial Review: 5/13/2016