MedWire News: Infections in early life do not protect children against hayfever and other allergic diseases, results of a UK study show.

"The 'hygiene hypothesis' proposes that infections in infancy protect against hay fever," explain lead researcher Dr Derek Cook, from the University of London, and colleagues.

But they add that previous studies into the association have produced conflicting results.

The researchers used a UK medical database to identify 3549 children who suffered from hayfever and the same number of children without allergic diseases.

The team examined each child's medical records to identify all those who had suffered from one or more of 30 infections, including chicken pox, measles, influenza, laryngitis and croup, during infancy.

The researchers found that, overall, children with hayfever were just as likely to have suffered one or more of the infections in early life as those without the allergic disease.

Further analysis also revealed no significant protection against hayfever associated with any specific infection.

Writing in the journal Allergy, Dr Cook and team conclude: "We found little evidence of any associations between hayfever and a wide variety of acute infectious illnesses presenting to primary care in infancy."

They add: "If infections do play any important role in the aetiology of hayfever in the UK, it must arise from common milder infections which do not present to the GP."