Anthrax is a life-threatening infectious disease that normally affects animals, especially ruminants (such as goats, cattle, sheep, and horses). Anthrax can be transmitted to humans by contact with infected animals or their products. In recent years, anthrax has received a great deal of attention as it has become clear that the infection can also be spread by a bioterrorist attack or by biological warfare. Anthrax does not spread from person to person.


Anthrax can infect humans in three ways. The most common is infection through the skin, which causes an ugly sore that usually goes away without treatment. Humans and animals can ingest anthrax from carcasses of dead animals that have been contaminated with anthrax. Ingestion of anthrax can cause serious, sometimes fatal disease.


The most deadly form is inhalation anthrax. If the spores of anthrax are inhaled, they migrate to lymph glands in the chest where they proliferate, spread, and produce toxins that often cause death.


Cutaneous (skin) anthrax


  1. Cutaneous anthrax occurs 1-7 days (usually 2-5) after spores enter the body through breaks in the skin.
  2. This form most commonly affects the exposed areas of the arms and, to a lesser extent, the head and neck.
  3. The infection may spread throughout the body in up to 20% of untreated cases.
  4. Cutaneous anthrax begins as a small pimplelike lesion (a sore) that enlarges in 24-48 hours to form a "malignantpustule" at the site of the infection. This sore (about 2-3 cm or about an inch) is round with a raised edge. The sore is not painful. The central area of infection is surrounded by small blisters filled with bloody or clear fluid containing many bacteria. A black scab forms at the site of the sore in 7-10 days and lasts for 7-14 days before separating. The surrounding area may be swollen and painful and may last long after the scab forms.
  5. Sores that affect the neck may cause swelling that could affect breathing.


Inhalational anthrax


  1. Inhalational anthrax begins abruptly, 1-60 days (usually 1-3 days) after inhaling large amounts of anthrax spores. The size of the spores is extremely important when it comes to causing disease, and this depends upon the techniques of the person producing the spores. Spores that are too small are inhaled but then immediately exhaled and do not remain in the lungs to cause disease. Spores that are made too large do not remain suspended in the air when released and drop to the ground and are thus never inhaled in the first place. Optimal sized spores for an anthrax biological weapon measure 1-5 micrograms in diameter.
  2. A person may initially have no specific respiratory or breathing symptoms but might have a low-grade fever and a nonproductive cough. An exposed person may feel chest pain early in the illness and improve temporarily before rapidly progressing to having severe breathing problems.
  3. Inhalational anthrax progresses rapidly with high fever, severe shortness of breath, rapid breathing, bluish color to the skin, a great deal ofsweating, vomiting blood, and chest pain that may be so severe as to seem like a heart attack.
  4. Inhalational anthrax usually causes death when the poisonous toxins produced by the bacteria overwhelm the body systems.


Intestinal anthrax


  1. Swallowing spores may cause intestinal anthrax 2-5 days later.
  2. People with intestinal anthrax may have nausea, vomiting (also vomitblood), tiredness, no appetite, abdominal pain, and bloody diarrhea, plus a fever.
  3. Intestinal anthrax is difficult to recognize. Shock and death may occur 2-5 days after it begins.


Oropharyngeal (mouth and throat) anthrax


  1. Swallowing of spores may result in anthrax appearing in the mouth and throat 2-7 days after exposure.
  2. People with this type of anthrax may have a sore throat on one side or difficulty swallowing.
  3. Death may occur because the person's throat may swell and cause difficulty breathing.


Septicemic (bloodstream) anthrax


  1. Septicemic anthrax refers to an overwhelming blood infection by anthrax. This can be a complication of inhalational anthrax.
  2. Internal organs may become darkly colored with widespread bleeding. The bacteria multiply in the blood and overwhelm the red blood cells. The term anthrax is derived from the Greek word for coal and was descriptive in that the lesions produced turned black.
  3. Most cases of septicemic anthrax occur following inhalational anthrax. The number of organisms released from the liver or spleen into the bloodstream overwhelm the body's defenses and produce massive amounts of lethal toxin that result in shock and death.


Anthrax meningitis


  1. This type of anthrax may complicate any form of anthrax and spread throughout the central nervous system and to the brain. 


The agent of anthrax is a bacterium called Bacillus anthracis. While other investigators discovered the anthrax bacillus, it was a German physician and scientist, Dr. Robert Koch, who proved that the anthrax bacterium was the cause of a disease that affected farm animals in his community.


Under the microscope, the bacteria look like large rods. However, in the soil, where they live, anthrax organisms exist in a dormant form called spores. These spores are very hardy and difficult to destroy. The spores have been known to survive in the soil for as long as 48 years.


The inhaled form of anthrax (pulmonary anthrax) is rare and extremely deadly. Studies of previous cases indicate that a dose of 2,500 to 55,000 anthrax spores is lethal to about half of the people who inhale them. The first stage of anthrax infection, lasting from hours to a few days, involves flu-like symptoms, including fever, coughing, weakness and chest pains.


The second stage usually ends in death within days. Lung damage deprives the body of oxygen. The victim then goes into shock. Brain infection may also occur.


Antibiotics only prove helpful at the earliest stages of the disease because they fight bacteria, not the toxins the bacteria produce in abundance.


The cutaneous form of anthrax is caused by the same germ but is contracted through the skin. Three to five days after infection, a painless blister appears. A day or two later, this becomes a black, open sore. Cutaneous anthrax accounts for 95 percent of anthrax cases in the United States, and is easily treated with antibiotics. Left untreated, perhaps 5 percent of cases progress to a dangerous bloodstream infection, which is almost always fatal.


In most cases, early treatment can cure anthrax. The cutaneous (skin) form of anthrax can be treated with common antibiotics such as penicillin, tetracycline, erythromycin, and ciprofloxacin (Cipro). The pulmonary form of anthrax is a medical emergency. Early and continuous intravenous therapy with antibiotics may be lifesaving. In a bioterrorism attack, individuals exposed to anthrax will be given antibiotics before they become sick.


A vaccine exists but is not yet available to the general public. Most experts think that the vaccine will also be given to exposed individuals who are victims of a bioterrorist attack. Of note, anthrax is a reportable disease. That means that local or state health agencies must be notified if a case of anthrax is diagnosed. These agencies can better characterize the anthrax so that the affected individual can receive the most effective treatment for that particular organism.

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