6187: Caribbean polio cases linked to vaccine mutation (fwd)

[Bob Corbett <corbetre@webster.edu>]

From: Greg Chamberlain <GregChamberlain@compuserve.com>

ATLANTA, Dec. 7 (UPI) -- Seven children in Haiti and the Dominican Republic
have been paralyzed by a mutated polio strain linked to the oral polio
vaccine given out in those countries, reported U.S. health experts.
   The Centers for Disease Control and Prevention, Atlanta, said laboratory
tests have confirmed polio in six children in the Dominican Republic and
one in Haiti, collectively defined as Hispaniola. The mutant strain is
suspected in another 13 cases of paralysis in the Dominican Republic.
   Most of the patients are under six years of age, though their ages
ranged from nine months to 21 years.
   Dr. Roland Sutter, chief of the CDC's polio-eradication branch, said
mutations in the virus used in oral polio vaccine occur regularly without
causing illness, but the Hispaniola strain was able to mutate and spread
because so few people have been vaccinated.
   "It both acquired the ability to cause paralytic disease and the
wild-type transmissibility characteristics which allowed it to be
transmitted quite widely," Sutter said, adding that vaccination coverage
was as low as 20 or 30 percent in the affected areas.
   Researchers traced the virus to the one used in oral polio vaccine and
found the two strains were 97 percent genetically similar. They believe the
mutated virus has been circulating for about two years.
   While seven cases of paralysis have been linked to the mutant strain,
Sutter said this does not suggest that the strain is more likely to cause
paralytic illness.
   "At this point, we certainly don't have any evidence that this virus has
a greater ability to cause paralysis than other wild viruses," he said.
   No wild polio cases have been detected in the Western Hemisphere since
1991, but vaccination efforts are important in the United States and
elsewhere because infected travelers from other regions can spread the
virus.
   Sutter noted that the polio vaccine injection now administered in the
United States uses an inactivated form of the virus. The oral vaccine made
from a live virus that had been used for U.S. childhood vaccination since
1965 caused a small number of polio cases -- about 1 for every 2.4 million
doses, the CDC said.
   "In most countries of the world, and certainly in all countries where
there is still polio, we still need to use the oral vaccine until the job
of full eradication is finished," Sutter said, because it is much easier to
dispense than the injected version.
   The Dominican Republic and Haiti have launched new mass vaccination
efforts in response to the outbreak.
   More than 30 cases of polio occurred in Egypt when a similar mutation
circulated between 1983 and 1993.