Anthrax is an infection caused by a bacterium called Bacillus anthracis. Anthrax is usually a disease of animals (such as cattle, sheep, pigs, horses, goats, camels, and antelopes) but it can also occur in humans who are exposed to animals or tissues of infected animals or to Bacillus anthracis spores (a version of the bacterium in a hard shell).

Anthrax can be found worldwide, but it is much more common in developing countries or countries without veterinary public health programs, including South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East.

Why was anthrax prominent in the news?

Anthrax was prominent in the news because anthrax spores have been used in intentional acts of bioterrorism in the United States shortly after 9/11/01. Even a very tiny amount of anthrax spores can be aerosolized and inhaled by humans and result in morbidity and mortality. However, is highly unlikely that you or someone you know will contract anthrax. Aside from the people who contracted anthrax from spores delivered through the US mail in bioterrorist acts, there have been few cases of anthrax infection reported in the United States. Most were associated with handling infected animals or animal products.

What are the symptoms of anthrax?

There are three types of anthrax infections in humans.

Cutaneous (skin-derived) anthrax

Cutaneous anthrax accounts for 95 percent of anthrax cases and occurs when the bacterium enters a cut or abrasion on the skin. Typically, the infection occurs through handling the wool, hide, leather, or hair of animals infected with anthrax. The anthrax skin infection in humans begins as a raised itchy bump that resembles an insect bite. Then, 1 to 2 days later, the bump develops into a painless lesion or ulcer with a characteristic black area in the center. The lymph glands in nearby area may swell. If left untreated, about 20 percent of individuals with cutaneous anthrax die. However, deaths are rare with appropriate antimicrobial therapy.

Intestinal anthrax

Intestinal anthrax occurs after eating contaminated meat and results in an acute inflammation of the small intestinal tract. This is very uncommon in the United States. Initial symptoms include nausea, loss of appetite, and fever followed by abdominal pain, vomiting of blood, and severe diarrhea. Death occurs in 25 percent to 60 percent of individuals infected with intestinal anthrax.

Inhalational anthrax

Inhalational anthrax is extremely rare but can occur if someone breathes anthrax spores, which are kicked up into the air by mail sorting machines or released through a bioterrorist act. The anthrax spores are inhaled into the lungs. The initial symptoms may be nonspecific cold, sore throat, or flu (without the muscle aches) symptoms, but after a few days, the symptoms may progress to severe breathing problems and shock and spread into the central nervous system.. Inhalation anthrax is often fatal without early recognition and treatment.

It usually takes less than 7 days for symptoms of skin and intestinal anthrax to appear. However, symptoms can appear as early as 48 hours after the lungs have been exposed to anthrax spores.

Can anthrax be spread from person to person?

No. Anthrax is not a contagious disease. It cannot be spread from person-to-person.

How is anthrax diagnosed?

Anthrax is definitively diagnosed by isolating the bacterium, Bacillus anthracis, from the blood, skin lesions, or cerebrospinal fluid.

How is anthrax infection treated?

Several different antibiotics, (including ciprofloxacin and doxycycline) can kill Bacillus anthracis if diagnosed early. Cutaneous anthrax is often caught in an early stage because of its telltale signs. However, inhalation anthrax may be mistaken for other common illnesses and therefore, is often not diagnosed until severe symptoms appear. At this stage, antibiotic treatment is ineffective. For this reason, researchers are working on developing other effective treatments including combinations of antibiotics and antibodies and gene-based therapies. An anthrax vaccine has been available since the 1970s and is used primarily for military troops deployed in "high risk" areas.

Who should receive the anthrax vaccine?

The vaccine is currently recommended for use by those at most risk for occupational exposure to the bacteria such as:

  • military personnel (due to exposure as a biological warfare weapon)
  • laboratory workers
  • livestock handlers
  • veterinarians
  • people who work with animal hides or furs imported from areas of the world where the disease is common
  • people who handle potentially infected animal products from areas where the disease is common

Will the anthrax vaccine become more widely available to the public?

Health officials currently do not recommend the vaccine for general use by the public because of the rarity of anthrax infection. In addition, the vaccine can’t be practically given in response to a bioterrorism act due to its prolonged administration schedule – the vaccine is given as six subcutaneous injections over the course of 18 months. If diagnosed early, anthrax can be successfully treated with antibiotics. Researchers are working to develop a second generation anthrax vaccine as well as other treatment options to protect the public in the event of a bioterrorism attack.

Where can I learn more?

CDC Hotline: 800.232.4636

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.  This document was last reviewed on: 1/26/2010...#10853