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9190: Mutant polio vaccine caused outbreak in Hispaniola (fwd)
From: Greg Chamberlain <GregChamberlain@compuserve.com>
By Paul Simao
ATLANTA, Oct 4 (Reuters) - A mutant strain of the oral polio vaccine
is likely responsible for a rare but deadly outbreak of the crippling
disease in the Dominican Republic and Haiti, U.S. health officials said on
The outbreak, the first in the Western Hemisphere since 1991, has
killed two children and left 19 others paralyzed on the Caribbean island of
Hispaniola since July 2000, the U.S. Centers for Disease Control and
A further 21 possible cases are being investigated on the island,
which comprises the Dominican Republic and Haiti.
The CDC said there were strong signs that the outbreak had been caused
by a strain of the oral polio vaccine that had mutated and circulated for
about two years among people insufficiently vaccinated against the virus.
"What we observed is that the areas where this virus was found were
areas that had low vaccination coverage, at least among the youngest groups
of the population," said Dr. Patrick Zuber, an epidemiologist in the CDC's
polio eradication branch.
All those who acquired polio in the recent outbreak on the island were
14 years old or younger.
Zuber said the outbreak likely occurred through oral-fecal
transmission. Those who receive the oral polio vaccine normally reproduce
the virus in their digestive tracts and then shed it in their feces.
The United States does not use the oral polio vaccine, favoring
instead an intravenous version of the vaccine.
Polio, which once afflicted millions of children, attacks the central
nervous system, often causing paralysis, muscular atrophy and deformity.
Five to 10 percent of those infected die when their breathing muscles
The scourge largely disappeared from the Western world as a result of
vaccination programs in the 1950s, but it still exists in a handful of
nations, mostly in Africa and Asia.
Since the first polio cases emerged last year, authorities in the
Dominican Republic and Haiti have launched mass vaccination campaigns
targeted largely at children under 10 years old.
Zuber said the campaigns appeared to have been effective, though the
CDC still advised travelers not vaccinated against polio that they were at
risk of contracting the disease in the two countries.
The outbreak also raised the possibility that pockets of polio cases
could become more commonplace during the transition period toward
eradication of the disease. The World Health Organization hopes to
eradicate polio globally by 2005.