- Biological warfare experts are concerned
that countries like Iraq may be able to create forms of anthrax that can
overcome the vaccine now being given to American troops in the Persian
Gulf.
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- The concern stems from recent evidence
that the Soviet Union may have mixed together several strains of anthrax,
presumably to enhance the lethality of its germ weapons. Further questions
have been raised by separate reports that Russian scientists have produced
strains of anthrax genetically engineered to produce new toxins.
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- Any country with a modern microbiology
laboratory could perform these manipulations, although experts differ over
how effective they would be in producing a germ weapon that could thwart
the American vaccine.
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- The vaccination program, under which
all 2.4 million American military personnel are eventually to be immunized,
has been criticized by Citizen Soldier, an advocacy group for veterans,
which says the vaccine's efficacy is unproved. Given the risk of side effects,
the group argues, the vaccine should not be administered.
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- Army experts and other scientists say
the vaccine is effective, although much of the evidence is necessarily
indirect, since battlefield anthrax cannot ethically be tested on people.
They also believe that the vaccine cannot be circumvented by use of multiple
anthrax strains.
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- Anthrax is a biological weapon of choice
because the bacillus forms a sturdy, long-lasting spore and is deadly when
inhaled unless antibiotics are given immediately. It is one of the agents
Iraq is known to have had in its arsenal.
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- The American vaccine has protected people
who handle goat and sheep wool from cutaneous anthrax, the usually nonlethal
form of the disease that attacks the skin. But its efficacy against inhalation
anthrax, the form that would threaten troops on the battlefield, is harder
to assess.
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- Experts agree that the vaccine is not
perfect. "The protective efficacies of both the U.K. and U.S. vaccines
are less than ideal," a British anthrax expert, Dr. Peter C.B. Turnbull,
wrote in 1991. The vaccine was first licensed in 1970, and its design has
not changed since. But it is the only anthrax vaccine that is available
and approved by the Food and Drug Administration.
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- The vaccine's defenders say it has a
long record of safety and effectiveness. There are no permanent side effects
of any kind, and only some 2 to 4 percent of those immunized experience
significant local reactions at the injection site, said Dr. Arthur M. Friedlander,
chief bacteriologist at the Army Medical Research Institute of Infectious
Diseases, at Fort Detrick, Md.
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- Studies show that the vaccine defends
only 20 percent of guinea pigs against airborne anthrax spores, a point
emphasized by Citizen Soldier. But, Friedlander said, it protects more
than 95 percent of rhesus monkeys, which are more similar to humans. In
tests, the vaccinated monkeys survive even when given doses of anthrax
that are hundreds of times greater than the amount that kills 50 percent
of an unprotected population.
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- The only time the vaccine has been tested
against inhalation anthrax in humans was among mill workers in the early
1960s, when the disease was still common in the United States. Only five
cases of inhalation anthrax occurred among the workers during the study
period, none of them among those vaccinated. But the numbers were not large
enough to prove in a statistically meaningful way that the vaccine was
effective against inhaled anthrax spores, the authors of the study wrote.
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- Even if the vaccine is effective against
ordinary anthrax, some critics of the Army's policy are concerned that
an adversary could manipulate the bacillus so as to overwhelm the it. "One
would have to be a fool to believe Iraq could not make a strain resistant
to the vaccine," said Dr. Meryl Nass, a physician who advises Citizen
Soldier.
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- Concern that the vaccine can be sidestepped
has been fanned by recent news of Russian activities. In 1979 an accident
at a Soviet biological warfare center killed some 70 people in the city
of Sverdlovsk, now Ekaterinburg. From autopsy tissues that came into American
hands, scientists led by Dr. Paul J. Jackson of the Los Alamos National
Laboratory inferred this January that at least four strains of anthrax
had been present. The purpose of such a mixture, Jackson suggested, might
have been to overwhelm the American vaccine.
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- That vaccine works by disabling a component
of anthrax known as protective antigen, which helps the microbe's two toxins
penetrate the cells they are attacking. Friedlander said all known strains
of anthrax share the same basic form of protective antigen. For this reason,
he said, the vaccine should be equally effective against any combination
of strains.
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- It is relatively easy to make bacteria
resistant to antibiotics. But, Friedlander said, it is quite difficult
to alter the protective antigen without making the anthrax bacillus ineffective
as a weapon. So the United States' defensive strategy against anthrax has
always focused on having a good vaccine.
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- Russian scientists recently caused consternation
by reporting at a scientific conference that they had made an anthrax strain
resistant to antibiotics. But, American officials say, there was a benign
explanation for the research. Russia relies on a vaccine made from a live
but nonlethal strain of the anthrax bacterium. Making the vaccine strain
resistant to antibiotics, which would otherwise kill it, would allow physicians
to give the vaccine and antibiotics simultaneously to anyone exposed to
anthrax. (The American vaccine does not contain live bacteria.)
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- Western experts have found it harder
to find innocent explanations for a second Russian experiment, published
recently in the journal Vaccine.
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- The experiment involved inserting toxin-making
genes from a closely related and usually harmless microbe, Bacillus cereus,
into the Russian vaccine strain. The apparent purpose was to create a vaccine
effective against a natural anthrax strain that produced these toxins.
No such strain is known to exist.
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- The Russian scientists, who work at the
Obolensk State Research Center for Applied Microbiology, near Moscow, reported
that this engineered strain of anthrax killed hamsters that had received
the ordinary Russian vaccine.
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- Friedlander said there was no way of
knowing whether the American vaccine would protect against such a genetically
changed organism, which probably kills by a different mechanism.
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- But he said it was also far from clear
that this organism could be developed into a weapon that would kill people
after being inhaled. The Russian research, Friedlander said, showed only
that the engineered organism killed hamsters after injection.
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