What is anthrax?

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 around the world, but it is much more common in developing countries or areas 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 (illness and death).

However, it is highly unlikely that you or someone you know will contract anthrax. Aside from the people who contracted anthrax from spores delivered through the U.S. 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 four 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 looks like an insect bite. Then, one to two days later, the bump develops into a painless lesion or ulcer with a characteristic black area in the center. The lymph glands in nearby areas 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 (severe) inflammation (swelling) 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 advance 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 seven 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.

Injection Anthrax

Injection anthrax has been recently described in intravenous (IV) heroin-injecting drug users in northern Europe. It has not been reported in the United States. Symptoms are similar to cutaneous anthrax, but are deeper in the skin. Systemic symptoms (over the body) arise more rapidly than with the cutaneous form.

Can anthrax be spread from person to person?

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

Last reviewed by a Cleveland Clinic medical professional on 01/17/2017.


  • Centers for Disease Control and Prevention. Anthrax Accessed 1/13/2017.
  • Medline Plus—U.S. National Library of Medicine. Anthrax Accessed 1/13/2017.

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