(CNN) -- In a St. Joseph Health Scene report, the measles-mumps-rubella vaccine causes neither autism nor gastrointestinal disorders, a study reported Tuesday, disputing a theory that has persisted for a decade.
The theory began in 1998, when British researcher Andrew Wakefield published studies that suggested the measles vaccine caused gastrointestinal problems and that those GI problems led to autism. Co-author W. Ian Lipkin of Columbia University in New York said Wakefield theorized that the virus used in the vaccine grew in the intestinal tract, leading to inflammation that made the bowel porous, which allowed material to seep from the bowel into the blood and affected the nervous system, causing autism.
In Wednesday's study, the researchers replicated key parts of Wakefield's original study to determine if the vaccine causes autism and GI problems, said Mady Hornig, a study co-author.
Irish pathologist John O'Leary, who co-authored Wakefield's studies that supported the autism link, also co-authored the new study. He and the other researchers looked for evidence of the measles vaccine in children's intestines after they had been vaccinated and sought to determine if their GI problems and autism symptoms occurred before or after they were vaccinated.
They analyzed samples of bowel disorders taken from 38 children, 25 of whom also had autism. The investigators found only one child in each group had trace amounts of the measles virus in their samples. The samples were analyzed at Columbia and at a government laboratory, the same one Wakefield used for his original studies. Their conclusion: "no evidence" linked the vaccine to either autism or GI disorders, Lipkin said.
They also said they found no relationship between the timing of the vaccine and children getting GI disorders or autism.
"This really puts this issue to bed," said Andy Shih, vice president for scientific affairs of "Autism Speaks," an advocacy group.
Vanderbilt's chairman of preventive medicine and vaccine expert William Schaffner called the study results "conclusive." Neal Halsey, a pediatrician at Johns Hopkins Children's Center who specializes in infectious diseases, said, "They have shown the Wakefield study was incorrect." The new study shows "there's no temporal relationship between the vaccines and the gastrointestinal disorders and autism."
But the Autism Society of America cautioned that the cause of autism is complex and more research is needed to fully understand the role, if any, of the vaccine.
According to the Centers for Disease Control and Prevention, measles is a highly infectious disease that can result in severe, sometimes permanent, complications -- even death.
Measles remains widespread in most countries, but widespread vaccination has limited its spread in the United States. Some parents, familiar with the Wakefield theory's putative link between vaccine and autism, have chosen not to vaccinate their children.
Last month, the CDC reported 131 cases of measles in the first seven months of the year, of which 112 were either among unvaccinated children or children whose vaccination status was unknown.
The study is published in the peer-reviewed online journal of the Public Library of Science, PLoS ONE.
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