Feb. 8, 2002 -- For parents and doctors confused about the much-reported and much-refuted link between the combined MMR (measles, mumps and rubella) vaccine and developmental disorders such as autism, a new study is sure to spark even more debate.
The study, to be published in the April issue of Molecular Pathology, raises questions about whether the measles virus plays a role in triggering an inflammatory bowel disease found in children with developmental disorders.
Researchers identified a portion of the measles virus in the guts of 75 out of 91 children who had the both conditions, but only five out of 70 healthy children had the virus.
"The interpretation of this finding is difficult," writes Alan Morris of the Department of Biological Sciences at the University of Warwick in an editorial that accompanies the study. "It would be entirely wrong to jump to the conclusion that the measles component of MMR 'causes' the [inflammatory bowel disease] or the developmental disorder in these particular (or any other) children."
The MMR vaccine contains a disabled version of the measles virus.
Morris says most diseases are caused by many factors and to single out one cause-and-effect relationship in this case would be wrong.
Researchers say the findings raise some important questions about the link between the measles virus and developmental disorders but caution against jumping to any hasty conclusions based on their study.
"I stand behind the findings of our research," said study author John O'Leary, molecular pathologist at Coombe Women's Hospital in Dublin, Ireland, in a news release. "But the research did not set out to investigate the role of MMR in the development of either bowel disease or developmental disorder, and no conclusions about such a role could, or should, be drawn from our findings."
The parents of some children with autism and very limited research have suggested that the MMR vaccine may be associated with a form of autism that isn't apparent at birth. However, experts have disputed this claim, arguing that symptoms of the developmental disorder typically appear at the same age, 12 to 15 months, that children receive the MMR vaccine, which makes the relationship coincidental -- not causal.
In addition, a comprehensive review of the research conducted by the Institute of Medicine in 2001 found no evidence to support a link between the MMR vaccine and autism, but it said more research is needed to better understand the causes of autism in general.