Anthrax is a serious, sometimes deadly disease caused by infection with anthrax bacteria. These bacteria produce spores that can spread the infection.
Anthrax in humans is rare unless the spores are spread on purpose. It became a concern in the United States in 2001, when 22 cases occurred as a result of bioterrorism. Most of those cases affected postal workers and media employees who were exposed to spores when handling mail.
Most cases of anthrax occur in livestock, such as cattle, horses, sheep, and goats. Anthrax spores in the soil can infect animals who eat plants growing in the soil. People can be exposed to spores in infected animal products or meat. This is not much of a concern in North America, because livestock are vaccinated against anthrax. But people can get anthrax from handling animal skins or products made out of animal skins from parts of the world where anthrax is more common.
Anthrax is caused by Bacillus anthracis bacteria. There are three types of infection:
The illness does not seem to spread from person to person. People who come in contact with someone who has anthrax don't need to be immunized or treated unless they were exposed to the same source of infection.
The symptoms and the incubation period—the time from exposure to anthrax until symptoms start—depend on the type of infection you have.
With cutaneous anthrax, symptoms usually appear 5 to 7 days after exposure to spores, though it may take longer.
With inhalational anthrax, symptoms usually appear 1 to 7 days after exposure. (But it can take as long as 60 days).
With gastrointestinal anthrax, symptoms usually occur within a week after exposure.
Your doctor will ask you questions about your symptoms and about any work or other activities that may have put you at risk for exposure. If the doctor suspects you may have been exposed to anthrax, testing will be done to confirm exposure or infection. Public health officials also will be notified about a possible anthrax infection.
Anthrax is confirmed when the bacteria are identified from a culture of your blood, spinal fluid, skin sores, or mucus from your nose, airways, or lungs. If results of a culture aren't clear, you may need other blood tests or a polymerase chain reaction (PCR) test. A skin ulcer may be biopsied.
Antibiotics are used to treat all types of anthrax.
Anyone who is infected needs to be treated with antibiotics as soon as possible. Starting treatment before symptoms begin may make the illness less severe and prevent death. Treatment may also include supportive care in the hospital.
Anyone who has been exposed to anthrax spores but is not infected should be treated with antibiotics and a few doses of the vaccine to prevent infection. Not everyone who has been exposed to anthrax will get sick. But because there's no way to know who will get sick and who won't, anyone who is directly exposed will get treatment. If you think that you have been exposed, call your local law enforcement agency and your doctor right away. Don't take antibiotics without talking to your doctor first.
The vaccine is not available to the general public at this time. The risk of exposure to anthrax is extremely low.
The bioterrorism attacks in 2001 made many people nervous about opening their mail. If you receive a piece of mail that contains a powdery substance or seems suspicious, the U.S. Centers for Disease Control and Prevention (CDC) recommends that you put down the piece of mail and not touch it again. Then, leave the room, wash your hands with soap and water, and call 911 to find out what to do next.
If you have concerns about anthrax, you can find the most current information through the CDC (http://emergency.cdc.gov/agent/anthrax).
Learning about anthrax:
- Southwick FS (2010). Infections due to Gram-positive bacilli. In EG Nabel, ed., ACP Medicine, section 7, chap. 4. Hamilton, ON: BC Decker.
- Inglesby TV, et al. (2002). Anthrax as a biological weapon, 2002: Updated recommendations for management. JAMA, 287(17): 2236–2252.
- Centers for Disease Control and Prevention (2001). Considerations for distinguishing influenza-like illness from inhalational anthrax. MMWR, 50(44): 985–987. Available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5044a5.htm.
Other Works Consulted
- American Public Health Association (2008). Anthrax. In DL Heymann, ed., Control of Communicable Diseases Manual, 19th ed., pp. 22–31. Washington, DC: American Public Health Association.
- Duchin J, Malone JD (2009). Anthrax section of Bioterrorism. In EG Nabel, ed., ACP Medicine, section 8, chap. 5, pp. 8–16. Hamilton, ON: BC Decker.
- Martin GJ, Friedlander AM (2010). Bacillus anthracis (anthrax). In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 2715–2725. Philadelphia: Churchill Livingstone Elsevier.
- Shadomy SV, Rosenstein NE (2008). Anthrax. In RB Wallace et al., eds., Wallace/Maxcy-Rosenau-Last Public Health and Preventive Medicine, 15th ed., pp. 1185–1194. New York: McGraw-Hill.
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Current as ofJune 4, 2014
Current as of: June 4, 2014
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