Food allergy and the holidays

December 22nd, 2010

We typically see a bump in new and follow up evaluations for food allergy around the holidays. This time of year we tend to get together with friends and family whom we may see only occasionally. We enjoy parties, go out to eat, and snack on seasonal treats that may be homemade, unique, or exotic (part of the fun of the season!). Many of these goodies contain tree nuts, peanuts, milk, egg, corn, wheat, or soy–which (along with vertebrate fish and shellfish) are the most common food allergens. Prospective studies on food allergic individuals suggest that accidental ingestions are most likely to occur away from home and due to food prepared by people who are non-professionals and unaware of our allergies. This seems intuitive. The take-home message here is: “ASK QUESTIONS”, even when we feel reluctant. Hosts prefer questions rather than a distressed guest who needs emergent epinephrine.
Kevin Parks MD

Stinging Insect Allergy: Hymenoptera hypersensitivity

December 16th, 2010

Although the typical season for stinging insect exposure is over, we are asked year-round whether certain reactions are typical, dangerous, or just a nuisance. Here’s a brief overview of the ins and outs of “hymenoptera hypersensitivity”.
In Southern Oregon, we have aerial hymenoptera, but no fire ants (also from the order hymenoptera–these are largely confined to the Southern US but are making inroads into other areas). Wasps, yellow jackets, white faced hornets, yellow hornets, and honey bees are all hymenoptera as well, each producing at least one major allergen in its venom. These insects sting as a defense mechanism, and the injected venom is designed to produce a noxious response in the recipient: swelling, pain, burning and itching. If this response is confined to the area of the sting, even if large, the reaction is considered a large local reaction only, and is typical of most stings. Each sting involves a variable amount of venom and sting sites vary in potential reactivity.
A small proportion of the population has pre-formed allergic antibodies (IgE) specific to the major or minor allergens contained in the venom of hymenoptera. In these individuals, a more dangerous reactions is possible, including anaphylaxis, AKA allergic shock. This specific IgE is demonstrable via skin testing in the allergy clinic.
Typically, individuals with a history of anaphylaxis to a sting are asked to maintain a self-injectable epinephrine device (such as an Epipen) at all times, but especially during activities that place them at elevated risk for a sting: outdoors sports, hiking, fishing, picnics, gardening, etc. For individuals with a history of anaphylaxis to hymenoptera AND positive testing to one or more of the 5 species, venom immunotherapy is a very effective treatment option. This is a desensitization process (allergy shots) that significantly reduces the risk of a future reaction in the context of a sting.
Additional avoidance measures also make good sense. Check out the stinging insect avoidance section under “care info” on the AAC site for more.
Kevin Parks MD