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- After centuries of obscurity when it worried only people
who worked with cattle or wild animals, anthrax has emerged to become one
of modern society's "agents of doom" - an ultimate weapon of
mass destruction.
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- How did this bacteria, which had an honored role in medical
history, become the 100-megaton bomb in the arsenal of bioterrorism and
biological warfare?
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- Blame twisted human ingenuity exploiting the weird way
that anthrax and certain other living things reproduce - without sex.
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- Just 220 pounds of powdered anthrax material, seeded
into the air of a city, could kill more than 1 million people, one study
estimated. In contrast, 80,000 would die in the explosion of a 12.5-kiloton
atomic bomb.
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- Iraq, North Korea, Russia, and other countries can deliver
anthrax in artillery shells, bombs, and missiles. U.S. military forces
are being vaccinated against anthrax. Terrorist threats involving anthrax
have occurred in the United States and elsewhere. More than 70 Russians
died in a 1979 anthrax-release accident at a germ warfare production facility.
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- Anthrax is an international concern because it reproduces
oddly. Animals and many plants reproduce from "gametes," reproductive
cells like sperm and eggs. A gamete from one parent combines with a gamete
from the other to form a new individual. That's sexual reproduction.
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- Some, however, reproduce without sex, or "asexually,"
often by forming "spores." These tiny ball-like structures consist
of an outer wall surrounding a nucleus and other cell material. A spore
can grow into a new individual without uniting with another reproductive
cell.
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- Asexual reproduction occurs in microscopic organisms
like bacteria; fungi like molds and mushrooms, and flowerless plants like
ferns and mosses. Some have alternate cycles of sexual and asexual reproduction.
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- Bacillus anthracis (B. anthracis), the anthrax bacterium,
produces "super" spores with such a thick outer wall that they
can survive in the environment for decades. Anthrax spores make a nearly
perfect biological weapon because they withstand extreme dryness, heat,
ultraviolet light, radiation, and many disinfectants.
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- They also are relatively easy to make and transport;
can be "delivered" like dust through the air, and are very lethal.
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- Most cases of anthrax occur in cattle and other grazing
animals. Rare in the United States, anthrax still is a problem in parts
of Africa, Asia, the Middle East, and some other places. People get infected
from contact with infected animals, animal products, or con-taminated soil.
Anthrax once was called "woolsorters" disease because it was
a special risk for workers who handled fresh animal hides.
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- Once inside a person, anthrax spores grow into full-fledged
bacteria, which spread throughout the body and produce toxins. These poisonous
chemical compounds can cause terrible illness and kill within three days.
Anthrax can be prevented with a vaccine and treated with antibiotics. Even
with treatment, death rates in inhalational and gastrointestinal anthrax
are high.
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- Anthrax once played another role - as a star in the advance
of medical science. In 1876, German physician Robert Koch used B. anthracis
to develop rules still used to prove that a specific microbe causes a disease.
Anthrax was the first microbe proven to cause a human disease. French scientist
Louis Pasteur later used anthrax to make new vaccines. It also served as
a research tool in pioneering studies of the immune system.
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- B. anthracis's final role could be mass murderer, as
human ingenuity produces even-deadlier genetically engineered strains of
B. anthracis resistant to vaccines and antibiotics.
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