Some families may be living with unnecessary worry over potentially fatal peanut allergy reactions because of misdiagnosis. And some children simply outgrow an allergy to peanuts, medical experts say.

To detect allergies, children are deliberately exposed to the foods that can potentially make them sick as doctors and nurses stand by in a controlled setting to intervene in case of a reaction.

• INDEPTH: Peanut food safety

Jaeden and Wanda Marchand

Up to four per cent of Canadian children are diagnosed with a food allergy, according to the allergy support group Anaphylaxis Canada.

But skin and blood tests to diagnose food allergies are inaccurate up to half of the time, according to Dr. Stuart Carr, a pediatric allergist in Edmonton.

"There's a lot of work that has gone in to trying to predict which kids are more likely to outgrow their allergy, and unfortunately it's not very clear," said Carr.

Dr. Stuart Carr, pediatric allergist.

• FROM : Pediatricians say kids may outgrow peanut allergy

Carr suspected Jaeden Marchand, 5, was one of the 20 per cent of children who seem to outgrow their peanut allergy.

In a "peanut challenge," Jaeden was fed peanut butter over a three-hour period, starting with a small dose and gradually building up to about a teaspoon.

Doctors do everything possible to minimize the likelihood of an anaphylactic reaction as they carefully monitored Jaeden during the challenge. He passed.

"It's hard to imagine," said Jaeden's mother, Wanda Marchand. "It's going to take some time to actually sink in that we're past it."

New evidence suggests the allergy can redevelop in some children and the risk is higher for those who continue to avoid peanuts after they've passed the challenge.

The results mean children like Jaeden should eat peanuts at least once a month to keep the allergy from recurring. For his part, Jaeden said he has plans for the childhood staple, a peanut butter and jam sandwich.

Many other children and families that could benefit from a food challenge, said Laurie Harada of Anaphylaxis Canada in Toronto, although not all will pass like Jaeden.