Anthrax

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Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention | Organizations

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Definition

Anthrax is a life-threatening bacterial infection. The disease usually occurs in hoofed animals, like cattle and goats. Although it is rare, people can contract anthrax from exposure to infected animals or anthrax spores. The bacteria produce spores that can survive in the environment for decades.

There are three forms of human anthrax, depending on where spores enter the body:

• Inhalation – from breathing airborne spores into the lungs (about 5% of cases)
• Cutaneous (or skin) – due to spores entering a cut or break in the skin (about 95% of cases)
• Gastrointestinal – from ingesting spores in raw or undercooked food (extremely rare)

Causes

Bacillus anthracis bacteria cause anthrax. Human-to-human transfer of anthrax has not been documented and is considered extremely unlikely to occur. Anthrax occurs after exposure to infected animals, their products, or spores. The bacteria do not form spores in living tissue. Once in the body, the spores germinate, or change to the active bacterial form. The bacteria multiply and release toxins that lead to swelling, bleeding, and tissue death. All forms of anthrax can cause death. Whereas only 10-20% of untreated cutaneous cases are lethal, inhalation anthrax is almost always fatal once symptoms develop. Death can occur within a few days.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

• Working in a laboratory with Bacillus anthracis
• Working with anthrax-infected animals or their products
• Criminal acts or biologic terrorism

Symptoms

Symptoms usually start within a few days of exposure and vary depending on the type of disease:

Inhalation anthrax symptoms occur in stages over several days and include:

• Cold or flu symptoms:
  • Cough
  • Fatigue
  • Weakness
  • Fever
  • Chills
  • Headache
  • Muscle aches
• Sometimes a brief period of seeming recovery
• Rapid onset of:
  • Severe difficulty breathing
  • Chest pain
  • Sweating
  • Shock
  • Delirium
  • Death

Cutaneous or skin symptoms occur in stages:

• Raised bump, like an insect bite, that is itchy and round
• Raised area opens, forming an ulcer with a black area in the center and producing drainage of clear or pinkish fluid
• Swelling around the wound
• Swollen, painful lymph nodes

Gastrointestinal lesions can occur in:

• Mouth and throat:
  • Sores in the mouth or esophagus
  • Swelling in throat
  • Swollen lymph nodes
  • Sore throat
• Intestines:
  • Nausea
  • Vomiting
  • Fever
  • Abdominal pain
  • Bloody diarrhea

Diagnosis

The doctor will ask about your symptoms, medical history and possible source of exposure, and perform a physical exam.

Test may include:

• Chest X-ray for inhalation anthrax
• Culture of wounds, mucosal membranes, and body fluids to check for bacteria
• Blood test to detect antibodies to anthrax

Treatment

Starting antibiotics early is essential. Any delay greatly increases the risk of death for inhalation anthrax. Treatment is begun intravenously, followed by oral antibiotics for several weeks. Skin lesions are carefully cleaned and dressed with bandages.

Medications

You may be prescribed:

• Ciprofloxacin (Cipro)
• Penicillin
• Doxycycline

Public Health Measures

Finding the source of the anthrax is very important. Public health officials will check places where a patient lives and works. Contaminated surfaces should be disinfected. Other people who may have been exposed will be tested and may be given antibiotics. Additional post-exposure therapies are under investigation.

Prevention

It is difficult to tell if you have been exposed. Anthrax is colorless and has no smell or taste. One case leads to fears that others in the same environment may have encountered the spores. Seek medical care if you suspect you have had contact with anthrax. Antibiotics may be able to prevent infection following exposure. A vaccine exists to prevent anthrax. It requires multiple shots and is only partially effective. The vaccine is not available in the U.S. at this time and is not recommended for the general population.

Strategies to prevent exposure to anthrax include:

• Avoid contact with infected animals or animal products.
• Do not touch fluid draining from an anthrax wound.
• Proper handling of suspicious mail:
  • Do not open mail from an unknown source.
  • Do not shake packages.
  • Do not smell or taste contents.
  • Put the parcel down and immediately wash your hands with soap and warm water.
  • Call local law enforcement.

Organizations

Centers for Disease Control and Prevention
http://www.cdc.gov

U.S. Army Surgeon General's OfficeAnthrax Vaccine Information Program
http://www.anthrax.osd.mil

U.S. Department of Health and Human Services
http://www.hhs.gov

SOURCES:

Cecil Textbook of Medicine, 21st ed. W.B. Saunders Company, 2000.

AAP 2000 Red Book: Report of the Committee on Infectious Diseases, 25th ed. American Academy of Pediatrics, 2000.

Principles and Practice of Infectious Diseases, 5th ed. Churchill Livingstone Inc., 2000.

"Consensus Statement, Anthrax as a Biological Weapon: Medical and Public Health Management," Journal of the American Medical Association, May 12, 1999.

"Use of Anthrax Vaccine in the United States: Recommendations of the Advisory Committee on Immunization Practices (ACIP)," Morbidity and Mortality Weekly Report, December 15, 2000.

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Last reviewed October 2001 by Medical Review Board