Professor Nicholas Christakis at the Department of Health Care Policy at Harvard Medical School has stirred up a furore by claiming, in the BMJ Online, that measures to control nuts are actually making things worse in a cycle of over-reaction and increasing sensitisation. But does he have a point?

About 3.3 million Americans are allergic to nuts; 6.9 million are allergic to seafood. All told, serious allergic reactions to all foods cause just 2,000 hospitalisations a year and 150 deaths (children and adults). Meanwhile 50 people die each year from bee stings, 100 die from lightning strikes and 45,000 die in motor vehicle collisions while 10,000 children are hospitalised each year for traumatic brain injuries acquired during sports, and 2,000 drown.

But while no one has suggested banning athletics to prevent brain injury, schools in both US and the UK are taking draconian measures to ban peanuts to prevent allergic reactions. Professor Christakis quotes his own children’s school where parents were told they could only collect Christmas gifts containing sealed tins of nuts from a loading dock outside the school so that the nut tins did not come on school premises, and another incident where a school bus of ten-year olds was evacuated and cleaned because a peanut had fallen on the floor.

He maintains that these responses represent a gross over-reaction to the magnitude of the threat, that there is no scientific evidence that the restrictions being imposed are either effective or cost effective and, most importantly, they are making things worse.

Professor Christakis says that this type of reaction is very similar to mass psychogenic illness (MPI) or epidemic hysteria. Often seen in small towns, schools and factories, outbreaks of MPI involve healthy people in a flow of anxiety, most often triggered by a fear of contamination. Being around individuals who are anxious heightens others’ anxiety. Extreme measures to reduce exposure to nuts are fuelling anxiety in parents, leading to more sensitisation, and creating the very epidemic they are designed to stop.

Professor Christakis does not deny the seriousness or unpredictability of nut allergy but calls for a level headed strategy to deal with ‘nut hysteria’ before it spirals out of control.

The full article

First published in January 2009

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