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Medical Author:

Michael C. Fishbein, MD

Michael C. Fishbein, MD

Dr. Fishbein received his undergraduate and medical degrees from the University of Illinois. He completed a residency in anatomic and clinical pathology at Harbor General Hospital/UCLA Medical Center. He is board certified in anatomic and clinical pathology.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• What is anthrax?
• What causes anthrax?
• How is anthrax contracted?
• How common is anthrax?
• How long is the incubation period with anthrax?
• What kinds of diseases does anthrax cause?
• How is the diagnosis made of anthrax?
• How is anthrax treated?
• How can anthrax be prevented?
• Anthrax At A Glance
• Anthrax Index

Anthrax is now rare in humans in the United States and developed countries. It still occurs today, largely in countries lacking public-health regulations that prevent exposure to infected goats, cattle, sheep, and horses and their products. In the last few years, there have been rare cases of anthrax in people exposed to imported animal hides used to make drums. Drum players, drum makers, and their family members have been infected in this way. The major concern for those of us in western countries (who don't play drums) is the use of anthrax as an agent of biological warfare.

The incubation period (the period between contact with anthrax and the start of symptoms) may be relatively short, from one to five days. Like other infectious diseases, the incubation period for anthrax is quite variable and it may be weeks before an infected individual feels sick.

There are three forms of disease caused by anthrax: cutaneous (skin) anthrax, inhalation anthrax, and gastrointestinal (bowel) anthrax.

CUTANEOUS ANTHRAX

The cutaneous (skin) form of anthrax starts as a red-brown raised spot that enlarges with considerable redness around it, blistering, and hardening. The center of the spot then shows an ulcer crater with blood-tinged drainage and the formation of a black crust called an eschar. There are swollen glands (lymph nodes) in the area. Symptoms include muscle aches and pain, headache, fever, nausea, and vomiting. The illness usually resolves in about six weeks, but deaths may occur if patients do not receive appropriate antibiotics.

INHALATION ANTHRAX

The first symptoms are subtle, gradual and flu-like (influenza). In a few days, however, the illness worsens and there may be severe respiratory distress. Shock, coma, and death follow. Inhalation anthrax does not cause a true pneumonia. In fact, the spores get picked in the lungs up by scavenger cells called macrophages. Most of the spores are killed. Unfortunately, some survive and are transported to glands in the chest called lymph nodes. In the lymph nodes, the spores that survive multiply, produce deadly toxins, and spread throughout the body. Severe hemorrhage and tissue death (necrosis) occurs in these lymph nodes in the chest. From there, the disease spreads to the adjacent lungs and the rest of the body. Inhalation anthrax is a very serious disease, and unfortunately, most affected individuals will die even if they get appropriate antibiotics. Why is this so? The antibiotics are effective in killing the bacteria, but they do not destroy the deadly toxins that have already been released by the anthrax bacteria.

GASTROINTESTINAL ANTHRAX

Now rare, anthrax of the bowels (gastrointestinal anthrax) is the result of eating undercooked, contaminated meat. The symptoms of this form of anthrax include nausea, loss of appetite, bloody diarrhea and fever followed by abdominal pain. The bacteria invade through the bowel wall. Then the infection spreads throughout the body through the bloodstream (septicemia) with deadly toxicity.