artikel sejenis bisa didapatkan di
http://www.medscape.com/viewarticle/540205
Dr. Kristianto Budi Wibowo
Adam & Hanni Armansyah <[EMAIL PROTECTED]> wrote:
Original page:
http://www.webmd.com/content/Article/124/115706.htm
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MMR, Thimerosal-Exposure Not Linked to Incidence By Salynn Boyles
WebMD Medical News Reviewed By Louise Chang, MD
on Thursday, July 06, 2006
July 6, 2006 -- New research from Canada may not end the debate about
childhood vaccines and autism, but it offers more evidence that vaccines are
not to blame for the dramatic rise in reported cases of the developmental
disorder.
The study examined outcomes among 28,000 children in Quebec, exposed to
different dosages of the measlesmeasles, mumpsmumps, rubella (MMR) vaccine
and vaccines containing the mercury-based preservative thimerosal.
Researchers found no relationship between MMR vaccine exposure, thimerosal
exposure and autism rates.
In fact, a higher incidence of autism was seen in Canadian children
vaccinated after thimerosal was eliminated from vaccines than among children
who received thimerosal-containing immunizations.
The study is published in the July issue of the journal Pediatrics.
"We found that the prevalence of autism and other pervasive developmental
disorders was higher among kids who had zero exposure to mercury than among
kids with what would be considered medium and even high exposures," says
researcher Eric Fombonne, MD, who directs the department of pediatric
psychiatry at The Montreal Children's Hospital.
Unique Opportunity
Fombonne is a long-time autism researcher who documented the rise in cases
in the U.K. before joining the faculty of Canada's McGill University. His
latest study shows that autism rates increased steadily in Canada among
children born in the study period between 1987 and 1998. The increase was
similar to that which has been reported in the U.S. and the U.K., he tells
WebMD.
Canadian health officials added a second MMR vaccine prior to age 2 in
children vaccinated after 1995, so children immunized prior to this received
half the dosage of the vaccine as children vaccinated later.
MMR vaccines have never contained mercury, but it has still been believed by
some to be a possible cause of autism. After reviewing the clinical
evidence, a panel convened by the independent Institute of Medicine rejected
this idea in its 2004 report on vaccine safety. The panel also found no link
between thimerosal and autism.
The increase in autism or autism-related disorders seen among the children
in the study remained steady before and after 1996, suggesting that
increasing the MMR dosage had no impact on the developmental disorder.
"Our study once again rules out MMR as a cause for autism," Fombonne tells
WebMD. "Because both doses were given prior to age 2, this was a unique
opportunity to study this vaccine at the time in which these disorders are
usually first seen."
Fombonne and colleagues also had a unique opportunity to study the impact of
thimerosal dosage, because children born at different times during the study
period had very different exposures.
Those born between 1987 and 1991 had what Fombonne called medium cumulative
exposures to thimerosal, while those born between 1992 and 1995 had higher
levels because the Hib vaccine was added to the immunization schedule. Hib
vaccine protects against a type of bacteria which can cause serious
infections in children (such as meningitis, pneumonia, and infections of the
bones, blood, and joints). Thimerosal was removed from vaccines given to
Canadian children in 1996, so children immunized after this time had no
exposure.
Despite the changes in exposure, the incidence of autism and autism-related
disorders continued to increase in a linear manner during the study period,
leading the researchers to conclude that thimerosal exposure did not affect
autism rates.
The Search for Answers
So if vaccines are not contributing to the rise in reported autismautism
cases, what is? Fombonne says the increase can be explained by a broadening
of what is considered autism and related disorders, increased awareness of
these disorders, and a greater emphasis on early diagnosis.
American Academy of Pediatrics spokesman Joseph Bocchini, MD, tells WebMD
that while it is clear that these are important contributors to the increase
in diagnosed cases, other unidentified contributors may also be playing a
role.
Bocchini is chief of pediatric infectious diseases at Louisiana State
University Health Sciences Center in Shreveport."We don't know if there is
an actual increase in incidence, but we are working to find that out," he
says.
He adds that the Canadian study supports a "large body of data" showing no
association between MMR vaccines or thimerosal exposure and pervasive
developmental disorders like autism.
"It is understandable that parents of children with these disorders would
want to find something that they can point to as a cause, and it is also
understandable that they would look at vaccines. But when you look at the
evidence in an objective way there is simply nothing to link vaccines with
these disorders."
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SOURCES: Fombonne, E. Pediatrics, July, 2006; vol 118: online edition. Eric
Fombonne, MD, director, pediatric psychiatry, Montreal Children's Hospital,
McGill University, Montreal, Quebec, Canada. Joseph Bocchini, MD, chief,
pediatric infectious diseases, Louisiana State University Health Sciences
Centers, Shreveport, La.; and spokesman, American Academy of Pediatrics.
WebMD Medical News: "New Intensity to Debate Over Autism Causes."
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