Anthrax is an acute infectious disease caused by the spore-forming bacteria Bacillus anthracis (B. anthracis). B. anthracis spores are highly infective and can cause inhalation, cutaneous, gastrointestinal, or injection anthrax. Inhalation anthrax results from breathing in spores and is of great concern due to its high fatality rate. You cannot catch anthrax from another person the way you might catch a cold or the flu. In rare cases, person-to-person transmission has been reported with cutaneous anthrax, where discharge from skin lesions might be infectious.
Anthrax infections occur naturally in wild and unvaccinated domestic animals in many countries including the United States. Workers can be infected if they are exposed to infected animals or to meat or products (such as wool or hides) made from infected animals.
Mail handlers and emergency response workers, including law enforcement, public health, and healthcare workers, are also at risk of exposure if B. anthracis is used as a biological weapon.
Naturally Occurring Anthrax
Workers may be exposed to B. anthracis if they work with infected animals or contaminated animal products or in environments contaminated by these products. Workers at risk include farmers, veterinarians, livestock handlers, diagnostic laboratory workers, and those who work with animal products.
Cutaneous anthrax infections may occur from skin contact with contaminated animal carcasses, wool, hides, or fur. Inhalation anthrax infections may occur from breathing in spores that may have been aerosolized either by processing or working with spore-contaminated animal products. Gastrointestinal anthrax may result from eating under-cooked meat from infected animals or from ingesting aerosolized spores. Injection anthrax infections have been reported among heroin-injecting drug users in northern Europe.
Imported animal hides have recently been associated with a number of anthrax cases (cutaneous, inhalation, or gastrointestinal anthrax) in the United States. Cases have occurred in drum makers using these hides. Cases have also occurred in people who have handled or been near the drums or in the environment where they were made.
Anthrax as a Biological Weapon
B. anthracis spores can be used as a biological weapon. A subset of select agents and toxins have been designated as Tier 1 because these biological agents and toxins present the greatest risk of deliberate misuse with significant potential for mass casualties or devastating effect to the economy, critical infrastructure, or public confidence, and pose a severe threat to public health and safety. B. anthracis is a Tier 1 agent.
B. anthracis is a select agent. The possession, use, or transfer of B. anthracis is regulated by the Division of Select Agents and Toxins (DSAT), located in CDC's Office of Public Health Preparedness and Response.
Workers may be exposed to B. anthracis either during the initial terrorist attack or when responding to the emergency event. Emergency response workers, mail handlers (if B. anthracis is sent via the mail), decontamination workers, and critical infrastructure workers may be at risk of exposure to airborne or aerosolized spores during an emergency event, depending on the method of dissemination of the spores. In 2001 B. anthracis spores were intentionally distributed through the U.S. postal system, causing 22 anthrax cases. Eleven of the 22 cases were cutaneous and 11 were inhalation; 5 of the inhalation cases were fatal.
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