Anthrax is an infection caused by the bacterium Bacillus anthracis that primarily affects livestock but that can occasionally spread to humans, affecting either the skin, intestines, or lungs. During the 1800s, in England and Germany, anthrax was known either as ‘‘wool-sorter’s’’ or ‘‘ragpicker’s’’ disease because workers contracted the disease from bacterial spores present on hides and in wool or fabric fibers. The first anthrax vaccine was perfected in 1881 by Louis Pasteur.
Anthrax as a weapon
The bacteria that cause anthrax may be used as a type of biological warfare, since it is possible to become infected simply by inhaling the spores, and inhaled anthrax is the most serious form of the disease. The largest-ever documented outbreak of human anthrax contracted through spore inhalation occurred in Russia in 1979, when anthrax spores were accidentally released from a military laboratory, causing a regional epidemic that killed 69 of its 77 victims. In the United States in 2001, terrorists converted anthrax spores into a powder that could be inhaled and mailed it to intended targets, including news agencies and prominent individuals in the government.
Causes of Anthrax infection
The naturally occurring bacterium Bacillus anthracis produces spores that can remain dormant for years in soil and on animal products, such as hides, wool, hair, or bones. The disease is often fatal to cattle, sheep, and goats, and their hides, wool, and bones are often heavily contaminated. The bacteria are found in many types of soil, all over the world, and usually do not pose a problem to humans because the spores stay in the ground. They can enter the body through a cut in the skin, through consuming contaminated meat, or through inhaling the spores.
Symptoms of Anthrax Infection
- In humans, anthrax usually occurs when the spores enter a cut or abrasion, causing a skin (cutaneous) infection at the site. At first, the bacteria cause an itchy, raised area like an insect bite. Within one to two days, inflammation occurs around the raised area,and a blister forms around an area of dying tissue that becomes black in the center. Other symptoms may include shivering and chills. In most cases, the bacteria remain within the sore. If, however, they spread to the nearest lymph node (or, in rare cases, escape into the bloodstream), the bacteria can cause a form of blood poisoning that rapidly proves fatal.
- Inhalation anthrax begins with flu-like symptoms, namely fever, fatigue, headache, muscle aches, and shortness of breath. As early as one day after these initial symptoms appear, and as long as two weeks later, the symptoms suddenly worsen and progress to bronchitis. The patient experiences difficulty breathing, and finally, the patient enters a state of shock. This rare form of anthrax is often fatal, even if treated within one or two days after the symptoms appear.
- Intestinal anthrax is a rare, often-fatal form of the disease, caused by eating meat from an animal that died of anthrax. Intestinal anthrax causes stomach and intestinal inflammation and sores or lesions (ulcers), much like the sores that appear on the skin. The first signs of the disease are nausea and vomiting, loss of appetite, and fever, followed by abdominal pain, vomiting of blood, and severe bloody diarrhea.
Diagnosis of Anthrax Infection
Anthrax is diagnosed by detecting B. anthracis in samples taken from blood,spinal fluid,skin lesions,or respiratory secretions. Blood samples will also indicate elevated antibody levels or increased amounts of a protein produced directly in response to infection with the anthrax bacterium. Polymerase chain reaction (PCR) tests amplify trace amounts of DNA to show that the anthrax bacteria are present. Additional DNA-based tests are also currently being perfected.
Treatment of Anthrax Infection
In the early stages, anthrax is curable by administering high doses of antibiotics, but in the advanced stages, it can be fatal. The antibiotics used include penicillin, doxycycline, and ciprofloxacin. Because inhaled spores can remain in the body for a long time, antibiotic treatment for inhalation anthrax should continue for 60 days. In the case of cutaneous anthrax, the infection may be cured following a single dose of antibiotic, but it is important to continue treatment so as to avoid potential serious complications, such as inflammation of the membranes covering the brain and spinal cord (meningitis).