MMR and autistic enterocolitis: Consistent epidemiological failure to find an association

A study of 12 children with pervasive developmental disorders (PDD) claimed that a new variant of autism, induced by immunization with the combined measles, mumps and rubella vaccine, was responsible for increasing rates of PDD worldwide. Subsequent studies from the same authors claimed to have identified evidence of the persistence of measles virus in peripheral blood white cells and gut biopsies. These studies were criticized because they lacked clear definition of the clinical phenotype and independent replication of the findings.