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Omdat je iedere keer hetzelfde post doe ik dat ook maar
Immunizations and autism: a review of the literature.Division of Neurology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.
Because of a temporal correlation between the first notable signs and symptoms of autism and the routine childhood vaccination schedule, many parents have become increasingly concerned regarding the possible etiologic role vaccines may play in the development of autism. In particular, some have suggested an association between the Measles-Mumps-Rubella vaccine and autism. Our literature review found very few studies supporting this theory, with the overwhelming majority showing no causal association between the Measles-Mumps-Rubella vaccine and autism. The vaccine preservative thimerosal has alternatively been hypothesized to have a possible causal role in autism. Again, no convincing evidence was found to support this claim, nor for the use of chelation therapy in autism. With decreasing uptake of immunizations in children and the inevitable occurrence of measles outbreaks, it is important that clinicians be aware of the literature concerning vaccinations and autism so that they may have informed discussions with parents and caregivers.
Autism and vaccination-the current evidence.PURPOSE: The purpose of this article is to review relevant background literature regarding the evidence linking thimerosal-containing vaccine and the measles, mumps, and rubella vaccine to autism. CONCLUSIONS: Rigorous scientific studies have not identified links between autism and either thimerosal-containing vaccine or the measles, mumps, and rubella vaccine. PRACTICE IMPLICATIONS: Nurses are often in the position of providing advice regarding vaccines in their formal practice areas as well as in their daily lives. Families need current and credible evidence to make decisions for their children. Excellent vaccine information resources are available online
The MMR hypothesis was first advanced in a paper by Andrew Wakefield, in 1998. The present study suggests that Wakefield's MMR - Autism link was flawed for a number of reasons. Methodologically, the studied cohort was self selected among a large population. The MMR vaccine is given at about the same time autism is often diagnosed, exacerbating a confirmation bias effect. The MMR-Vaccine theory relies on an intestinal route for encephalopathic substances, which would be indicated by some kind of G.I. symptoms prior to the autism, but this was often not the aetiology of the disease. There are other problems with this study as well.
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Vaccines and Autism: A Tale of Shifting HypothesesThe paper examines other MMR-Vaccine link studies and finds them at fault as well.
The Thimerosal link hypothesis asserts that ethylmercury, an ingredient in Thimerosal, is the cause of autism. Thimerosal is an antibacterial that has been used for decades to preserve various vaccines, (not including MMR, which is a live vaccine). Although there are several reasons to not think that Thimerosal can cause autism, several studies have been conducted to test the relationship (probably not a bad idea given the importance of this problem) and all of these studies failed to link Thimerosal to autism. What is especially convincing are studies that show a complete discordance between Thimerosal use and autism.
In Sweden and Denmark, researchers found a relatively stable incidence of autism when thimerosal‐containing vaccines were in use (1980-1990), including years when children were exposed to as much as 200 μg of ethylmercury (concentrations similar to peak US exposures) [22]. However, in 1990, a steady increase in the incidence of autism began in both countries and continued through the end of the study period in 2000, despite the removal of thimerosal from vaccines in 1992.
The third hypothesis .... that too many vaccines stress the patient and ultimately cause autism to develop ... was also found to be flawed. Vaccines do not overwhelm the immune system. Although the infant immune system is relatively naive, it is immediately capable of generating a vast array of protective responses; even conservative estimates predict the capacity to respond to thousands of vaccines simultaneously... The immune response elicited from the vast antigen exposure of unattenuated viral replication supersedes that of even multiple, simultaneous vaccines.... Multiple vaccinations do not weaken the immune system. Vaccinated and unvaccinated children do not differ in their susceptibility to infections not prevented by vaccines ... Autism is not an immune‐mediated disease. Unlike autoimmune diseases such as multiple sclerosis, there is no evidence of immune activation or inflammatory lesions in the CNS of people with autism...
Mayo Clinic Study Suggests No Link Between Autism And ImmunizationsROCHESTER, Minn. -- Over the past 20 years, there has been speculation about a connection between immunizations and an increase in autism. However, a study by Mayo Clinic researchers published in the January issue of Archives of Pediatrics and Adolescent Medicine suggests the increase may be due to improved awareness, changes in diagnostic criteria and availability of services, not environmental factors or immunizations.
“This study is the first to measure the incidence -- the occurrence of new cases -- of autism by applying consistent, contemporary criteria for autism to a specific population over a long period of time,” says William Barbaresi, M.D., a Mayo Clinic developmental pediatrician and one of the study authors. “In doing so, the study accounts for improvements in the diagnostic criteria for autism, the medical community’s improved understanding of this disease and changes in federal special education laws.”
The study found that the increase in the incidence of autism in Olmsted County, Minn. coincided with broadening of the diagnostic criteria for autism and new federal special education laws including autism as a disability category. Both events occurred many years after immunizations were mandated for school entry. Broader, more precise diagnostic criteria for autism were introduced in 1987. Prior to these new criteria, children with autism may have been given less precise diagnoses such as “developmental delay” or “mental retardation,” and children with milder symptoms of autism may not have been identified at all. The 1991 federal special education laws improved the availability of educational services for children with autism.
The study used data from the Rochester Epidemiology Project, a database of all inpatient and outpatient records in Olmsted County, Minn. The database diagnoses are indexed for computerized retrieval, allowing researchers to identify subjects with any developmental disorder. Researchers found 3,000 children with at least one of 80 diagnoses related to autism. Of the 3,000 children, 124 actually met the current diagnostic criteria for autism. Reviewing the medical and school history of this group showed that the incidence of autism was stable until 1988-1991, then increased after new laws and new diagnostic criteria were implemented.
MMR and autism: UK database studyThe UK GP database study was impeccable. It showed no increased risk of autism or PDD with MMR, and looked at a whole range of different possible analyses to investigate whether there could be associations with age at vaccination, or type of condition. There were none.
Moreover, it also showed that while age of vaccination was 1.2 years, the age of first diagnosis was 5.4 years, a four-year gap. This is quite different from the media presentation in which a perfectly normal child begins to have behavioural problems within weeks of MMR vaccination.
And the systematic review and meta-analysis was within a whisker of having a statistically significant result that went the other way, that there was a reduced risk of autism in children who had been vaccinated with MMR. Perhaps it is too early to say, but another study like the ones we have so far would nail it down. In that case parents who did not have their children vaccinated with MMR would put them at risk of both harm from measles, and harm from being at increased risk of developing autism.
Volledige studie:
http://www.medicine.ox.ac.uk/bandolier/booth/Vaccines/MMRUK.htmlAutism and vaccination-the current evidence.Miller L, Reynolds J.
Colorado Department of Public Health and Environment, Denver, Colorado, USA. lisa.miller@state.co.us
PURPOSE: The purpose of this article is to review relevant background literature regarding the evidence linking thimerosal-containing vaccine and the measles, mumps, and rubella vaccine to autism.
CONCLUSIONS: Rigorous scientific studies have not identified links between autism and either thimerosal-containing vaccine or the measles, mumps, and rubella vaccine. PRACTICE IMPLICATIONS: Nurses are often in the position of providing advice regarding vaccines in their formal practice areas as well as in their daily lives. Families need current and credible evidence to make decisions for their children. Excellent vaccine information resources are available online.
[Lack of association between MMR vaccination and the incidence of autism in children: a case-control study]
[Article in Polish]Mrozek-Budzyn D, Kiełtyka A, Majewska R.
Zakład Epidemiologii Katedra Epidemiologii i Medycyny Zapobiegawczej Uniwersytet Jagielloński Collegium Medicum.
The matched case-control study has been undertook to investigate whether measles, mumps, and rubella (MMR) vaccine may be casually associated with autism in children. Cases were children to 14-year old with diagnosis of core autism or atypical autism. Controls were matched on age, sex and general practice. The 96 cases and 192 controls were included. The study provides strong evidence against association of autism with both MMR and a single measles individual vaccine.
Additionally children vaccinated with MMR, regardless of age of vaccination (to 18th, 24th and 36th month of life), had risk equal half of that of single measles vaccinated (for vaccinated to 18th month OR=0.41 95%PU: 0.20-0.85). Our findings confirm that MMR vaccination is not associated with an increased risk of autism in children.en zo heb je er nog wel 200-300
[ Bericht 5% gewijzigd door dramatiek op 06-11-2009 19:08:40 ]