Sept. 4 (Bloomberg) -- The measles, mumps and rubella vaccine doesn't raise a child's risk for autism, according to a new study researchers say they hope will reduce fears among parents who have avoided giving the shots to their children.

The new analysis was meant to replicate a 1998 report that first suggested the MMR vaccine caused bowel ailments in children that led to autism. Using molecular technology to detect genetic material from the vaccine in bowel tissue, researchers from the U.S. and Ireland found no connection between the vaccine and autism, nor ties between intestinal symptoms and onset of autism.

The research is the latest of more than 20 studies that have dismissed a link between the vaccine and autism and is aimed at reassuring parents of the benefits of vaccinating against childhood diseases. The 1998 paper touched off a wave of anxiety among parents, including many who refused to inoculate their children, leading to an increase in U.S. measles cases this year.

``We in the scientific community had not addressed the issue with definitive research and this study was undertaken to fill that specific void,'' said Ian Lipkin, an epidemiology professor and the director of the Center for Infection and Immunity at Columbia University's Mailman School of Public Health in New York, in a conference call yesterday with reporters. ``This is the first study to rigorously examine MMR vaccination and autism.''

The results were published yesterday online in the journal of the Public Library of Science.

Autism Symptoms

Autism and related disorders, some of them less severe, affect 1 in 150 U.S. children, according to the Centers for Disease Control and Prevention in Atlanta. Children with symptoms may refuse to engage with people, avoid eye contact, echo words and phrases, or repeat actions many times. Some children regress, losing skills they once had. Eighty-eight percent of the autistic children in the study regressed, the authors wrote.

The study analyzed 25 children with autism and 13 without the disorder. All of the children had gastrointestinal disturbances, as the 12 children in the 1998 report did. The timing of the first MMR shot was about the same in both groups. There were no links found between the timing of the vaccine, which typically is first given when children are 12- to 15- months old, and the onset of autism, or vaccination and the bowel ailments.

``These results underscore the idea that this subset of autistic children may have different factors contribute to illness,'' said lead author Mady Hornig, an epidemiologist also at the Mailman school, during the conference call.

Targeting Inflammation

Some scientists have suggested that MMR might create inflammation in the gastrointestinal tract, allowing chemicals from the gut to leak into the blood stream and affect neural development. For that to be the case, the immunization would have to happen before any stomach complaints and before the onset of autism, Lipkin said.

The new report doesn't confirm that the MMR vaccine is safe, said David Kirby, author of ``Evidence of Harm,'' a book on the debate about autism and vaccination.

``This study is way too small to extrapolate the conclusion that MMR doesn't cause autism,'' Kirby said yesterday in an interview.

Measles, which is highly infectious, causes rashes, fevers, coughs, and runny noses and may lead to complications including pneumonia, seizures and death.

From January through July, 131 cases of the infectious disease were reported, the highest since 1996, the CDC said in a report. The cases included 95 children who were not vaccinated though they were eligible.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net.

Last Updated: September 4, 2008 00:01 EDT