الأحد، 5 فبراير 2012

Anthrax

Anthrax is a zoonotic infection caused by Bacillus anthracis (see the image below) . Most anthrax is cutaneous (95%). The remaining cases of the disease are inhalational (5%) and gastrointestinal (< 1%). Cutaneous anthrax results from exposure to the spores of B anthracis while handling sick animals or contaminated wool, hair, or animal hides. Pulmonary anthrax results from inhaling anthrax spores. GI anthrax results from ingesting meat products that contain anthrax. Anthrax is present in areas where animals, particularly herbivores, graze. Anthrax caused by inhalation is usually fatal, and symptoms usually begin days after exposure. This delay makes the initial exposure to B anthracis difficult to track.
Polychrome methylene blue stain of Bacillus anthraPolychrome methylene blue stain of Bacillus anthracis. Image courtesy of Anthrax Vaccine Immunization Program Agency, Office of the Army Surgeon General, United States. Anthrax was described in the early literature of the Greeks, Romans, Egyptians, and Hindus. The term anthrakis means coal in Greek, and the disease is named after the black appearance of its cutaneous form.[1] The fifth plague described in the Old Testament book of Genesis may be among the earliest descriptions of anthrax. At the end of the 19th century, Robert Koch's experiments with anthrax led to the original theory of bacteria and disease. John Bell's work in inhalational anthrax led to wool disinfection processes and the term woolsorter's disease.
A modern concern is use of anthrax as a biologic warfare agent. During the first Gulf War, Iraq reportedly produced 8500 L of anthrax. A total of 150,000 US troops were vaccinated with anthrax toxoid. In the weeks following the terrorist attacks of September 11, 2001, 22 confirmed or suspected cases of anthrax infection were disseminated via the US postal system; the spores mailed in these letters were ultimately traced to a US army medical research institute. Since there have been no cases of naturally occurring inhalational anthrax in the US since 1976, alarm should be raised for the occurrence of even a single infection.

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