Blood test which can identify children with peanut allergies is developed

A new blood test could make it easier and safer to identify children with peanut allergies.

The test correctly identifies 98 per cent of sufferers and it is hoped it will replace existing tests which give children tiny amounts of peanuts, at a risk of sending them into anaphylactic shock.

The rate of peanut allergies in Western children has doubled in the past decade. It is the most common food allergy, thought to affect one in 40 youngsters.

Currently they are diagnosed using an unreliable skin-prick test and an ‘oral food challenge’, which involves giving children incrementally larger doses of peanuts. The new blood test looks for biomarkers in white blood cells which are triggered by the immune system.

Study leader Dr Alexandra Santos, a Medical Research Council scientist at King’s College London, said: ‘The current tests are not ideal.

‘If we relied on them alone, we’d be over-diagnosing food allergies.

‘Only 22 per cent of school-aged children in the UK with a positive test to peanuts are actually allergic when they’re fed the food in a monitored setting. 

‘The new test is specific in confirming the diagnosis so when it’s positive, we can be very sure it means allergy. We would reduce by two-thirds the number of expensive, stressful oral food challenges conducted.’

The new test is more accurate than a finger-prick test, which can pick up false positives of children who just have a sensitivity to peanuts but are not allergic. The study is reported in the Journal of Allergy and Clinical Immunology.