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Anthrax Q & A: Signs and Symptoms

What are the types of anthrax infection?
Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal.

Cutaneous anthrax: Most (about 95%) anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animals. Skin infection begins as a raised itchy bump that resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Lymph glands in the adjacent area may swell. About 20% of untreated cases of cutaneous anthrax will result in death. Deaths are rare with appropriate antimicrobial therapy.

Inhalation anthrax: Initial symptoms may resemble a common cold – sore throat, mild fever, muscle aches and malaise. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.

Gastrointestinal anthrax: The intestinal disease form of anthrax may follow the consumption of contaminated meat and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Intestinal anthrax results in death in 25% to 60% of cases.

What are the symptoms for anthrax?
These symptoms can occur within 7 days of infection:

See also Notice to Readers: Considerations for Distinguishing Influenza-Like Illness from Inhalational Anthrax.

Is anthrax contagious?
No. Anthrax is not contagious; the illness cannot be transmitted from person to person.

What are the case fatality rates for the various forms of anthrax?
Early treatment of cutaneous anthrax is usually curative, and early treatment of all forms is important for recovery. Patients with cutaneous anthrax have reported case fatality rates of 20% without antibiotic treatment and less than 1% with it. Although case-fatality estimates for inhalation anthrax are based on incomplete information, the rate is extremely high, approximately 75%, even with all possible supportive care including appropriate antibiotics. Estimates of the impact of the delay in postexposure prophylaxis or treatment on survival are not known. For gastrointestinal anthrax, the case-fatality rate is estimated to be 25%-60% and the effect of early antibiotic treatment on that case-fatality rate is not defined.

Can the presence of Bacillus anthracis spores be detected by a characteristic appearance, odor, or taste?
Bacillus anthracis spores do not have a characteristic appearance (e.g., color), smell, or taste. Spores themselves are too small to be seen by the naked eye, but have been mixed with powder to transport them. The U.S. Postal Service advises that individuals be suspicious of letters or packages with any powdery substance on them, regardless of color. (See

What would be the approximate size of enough Bacillus anthracis spores to cause infection?
They could not be seen by the naked eye but could be seen under a microscope.

How can I know my cold or flu is not anthrax?
Many human illnesses begin with what are commonly referred to as “flu-like” symptoms, such as fever and muscle aches. However, in most cases anthrax can be distinguished from the flu because the flu has additional symptoms. In previous reports of anthrax cases, early symptoms usually did not include a runny nose, which is typical of the flu and common cold.

If I have the flu, can I still get anthrax?
Yes, a person could theoretically get both the flu and anthrax, either at the same time or at different times.

Page last modified June 2, 2003

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