Wednesday, 6 February, 2002, 11:55 GMT

Q&A: Measles research

Baby receiving MMR vaccination

The latest research on possible links between measles, bowel disease and autism has provoked a storm - but what does it actually say?

Dr Andrew Wakefield, who authored the latest research on measles virus, was the source of the original storm over MMR.

His research, published in the Lancet medical journal, seemed to speculate on the safety of the triple vaccination.

The latest paper is a continuation of his investigation into the links between measles virus and bowel disease - or even autism.

What does the latest paper actually say?

The research, published in the journal Molecular Pathology, looked at gut tissue samples from children with a particular type of inflammatory bowel disease.

This type of disease is particularly associated with children with developmental disorders such as autism.

The samples were analysed to see if they had any traces of measles virus in the gut tissue.

They found that 75 out of 91 children with the unusual inflammatory bowel disorder had traces of the measles virus in gut tissue.

This compared to only five out of 70 among children who didn't have this particular bowel condition.

What does this prove?

The small scale of the study mean that it does not actually "prove" anything.

What it suggests is that the measles virus, persisting in the body, is linked in some way to this bowel disorder.

Indirectly, scientists might draw the inference that a link between the virus and the gut condition means a link between the virus and developmental disorder - because of the earlier study suggesting a relationship between autism and the bowel disorder.

However, the paper does not claim this directly.

The reasons behind the association are not clear.

The research does not offer evidence that measles "caused" the gut problem and autism.

No-one knows the correct sequence of events - did measles infection in these children cause the gut problem, which then somehow led to the developmental problem?

Or did the gut problem develop independently, allowing the persistence of measles virus in the gut as a side-effect?

One theory is that the presence of measles virus triggers problems with the immune system, leading to the developmental and digestive disorders. But it must be stressed that this is only a theory.

What does this add to the MMR debate?

This study did not set out to look at MMR in particular, only measles virus in general.

There is no evidence that the strains of virus indentified in these children's guts is the same as the strains they were given in MMR - or even that they had been given MMR in the first place.

However, the MMR jab is composed of a combination of live measles, mumps and rubella viruses, so any study which examines the role of measles virus has an indirect relevance to MMR.

But what it most certainly is not is evidence of a direct link between the vaccine and this bowel disorder, or autism.

The study makes no claims about MMR, although it does suggest that measles itself may, in some cases, trigger an immune response which leads to the gut disorder.

See also:

06 Feb 02 | UK Politics
Tories call for MMR rethink

05 Feb 02 | Health
Single vaccine hunt continues

Internet links:

Department of Health

Molecular Pathology

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