Millions of people suffer from a variety of food allergies, with a number of reactions, but it's not always easy to understand where allergies come from. This was not the case for an 8-year-old boy who developed an anaphylactic allergy to fish and peanuts after receiving a blood transfusion.
In an issue of the Canadian Medical Association Journal, Dr. Julia Upton of the Hospital for Sick Children in Toronto detailed how the boy experienced anaphylactic symptoms including swelling of the lips, facial redness, throat discomfort and fatigue within 10 minutes of eating salmon — a food he had eaten numerous times before without any ill effects. A few days later he experienced an allergic reaction to peanuts after eating a chocolate peanut butter cup, despite having eaten the candy and other peanut products before.
The boy's symptoms abated following treatment with an antihistamine. Doctors suspected that the child's blood transfusion had transferred allergen antibodies in the plasma, antibodies specifically created to fight against salmon and peanuts.
"It's rare to have an allergic reaction to a previously tolerated food," said Upton, a staff physician in Sick Kids' clinical immunology and allergy department. "It's extremely rare to have a new allergy come from a blood product. Thankfully, the prognosis is excellent and it typically resolves within a few months."
Blood donors are usually asked if they are experiencing allergy symptoms at the time of donation but are not asked to disclose other allergies they suffer from. According to Upton, asking donors to undergo allergy tests would not be of much use, since the results wouldn't be able to definitively tell doctors if the donor or recipients would experience allergies in the real world. Instead Upton suggests that doctors be aware of the possibility of allergies developing following a transfusion and guide individuals and families in allergy solutions.
