TORONTO — A boy being cared for at Toronto's Hospital for Sick Children got more than he bargained for when he was given blood transfusions while being treated for a brain tumour.
Doctors say the boy temporarily acquired food allergies after receiving a range of blood products.
The boy had no known allergies before receiving the blood transfusions, and regularly ate fish and peanut butter.
But after receiving the transfusions, he developed an anaphylactic reaction after eating salmon; four days later a peanut butter cup induced the same reaction.
An investigation revealed that one of the donors whose blood the boy received had severe allergies to peanuts, tree nuts, shellfish and other fish.
The boy tested positive for all those allergens, but later the foods were reintroduced into his diet without any problems.
Canadian Blood Services says this isn't the first time this type of event has happened. In fact, the first known case was reported in 1919.
But reports have been rare and this is only the second in Canada in the past decade.
Officials with Canadian Blood Services say they ask potential blood donors if they are experiencing allergy symptoms when they are being screened at blood donation clinics. It they say yes, they are asked to come back another day.
But the agency does not ask all people with food allergies to refrain from giving blood, nor is it considering doing so. A survey the agency conducted around 2010 disclosed that allergies are common among blood donors and nearly eight per cent reported having severe allergies.
Asking so many people to refrain from giving blood would jeopardize Canada's blood supply, says Dr. Mindy Goldman, the agency's medical director.
"We could not defer eight per cent of donors to prevent a ... one in less than one million occurrence," says Goldman, who notes that Hema-Quebec, which runs that province's blood supply, and the U.S. blood system take the same approach.
The report is published in this week's issue of the Canadian Medical Association Journal.
Senior author Dr. Julia Upton, an immunologist at the Hospital for Sick Children, says the proteins in the donated blood that cause the reaction to foods clear from the blood within a couple of months.
But she suggests that if someone who has received a blood transfusion goes on to have an allergic reaction to foods they could previously eat, those foods should be reintroduced into their diets carefully, possibly under medical observation.
