lederhosen

The Daily Mail screams: "Scientists fear MMR link to autism... New American research shows that there could be a link between the controversial MMR triple vaccine and autism and bowel disease in children." Which, if you're an anti-vacc campaigner, is all you need to hear, so why muddy the waters with facts?

Reading a little more closely, the finding appears to be that in a study of children who were selected because they had both autism and bowel disease, many have vaccine-strain measles virus in the gut. I haven't found a good source for the 2011 publication, but the team leader is Dr. Stephen Walker of the Wake Forest University School of Medicine, and he commented on some similar findings back in 2006:

An American scientist whose research replicates a connection published in England in 2002 between the measles virus and bowel disease in autistic children strongly warns against making the “leap” to suggesting that the measles vaccine might actually cause autism.

“That is not what our research is showing,” said Stephen J. Walker...

Some observers have said that the presence of the measles virus indicates a strong possibility that the measles vaccine, a possible source of the virus, could have caused the children’s autism... Walker says the new [2006] research does not support the connection, and he notes that the results have not even been published in a peer-reviewed journal. “Even if we showed association (between measles virus and bowel disease) and we published it in a peer-reviewed journal, the conclusion will be simply that there is measles virus in the gut of a large number of children who have regressive autism and bowel disease. End of story. We haven’t done anything to demonstrate that the measles virus is causing autism or even causing bowel disease.”

The Daily Mail goes on to quote-mine to the effect of "Wakefield was correct", which is misleading: Wakefield may have been correct in claiming a correlation between measles in the gut and autism, but what he is best known for is the follow-up claim that MMR causes autism. AFAICT, Walker is not arguing for that claim, nor is he defending Wakefield against Brian Deer's allegations of fraud and unethical conduct.

The Mail also goes on to report another study in 2001 (John O'Leary) as "backing up Dr Wakefield", but as Leary's letter to Brian Deer clarifies:

At no time have I set out to prove that MMR causes autism. Instead, I have sought to investigate a novel bowel pathology in children with autism. In our Molecular Pathology paper we have described an association between the presence of measles virus and new variant inflammatory bowel disease. We have never claimed that this is causal and indeed I have been forthright in transmitting this information to the public at large in the form of press statements. I have and continue to urge people to vaccinate their children. My advices and findings were consistently and persistently to vaccinate children and to use MMR.

AFAIK, it does seem to be well-established that there's a correlation between autism and bowel disease, but the reason for that correlation is unclear. There are several ways you can interpret this stuff:

- Bowel disease leads to autism (Wakefield's preferred interpretation)
- Autism leads to bowel disease
- Both autism and bowel disease are caused by some third factor

Assuming that autistic kids with bowel disease tend to have measles in their gut, there are several interpretations for that too:

- Having measles in the gut causes bowel disease (Wakefield's interpretation, coupled with "bowel disease causes autism" above)
- Having bowel disease compromises the immune system in the bowel, making children more likely to retain measles virus in the gut
- Having autism causes other health issues that make children prone to retaining measles virus (especially if they also have bowel disease)