Diagnosing and treating venom and fire ant allergies
Up to 25% of the adult population may show antibodies, and thus positive skin testing, to venoms from flying insects such as bees, yellow jackets and wasps. However, not all of these patients are allergic to the stinging insects. Generally, one is not more likely to have an insect sting allergy if there is a family history of sting reactions. Thus it is important to look at a patient’s history when determining if they should be skin tested and if they need to receive allergy shots to decrease the risk of subsequent reactions with stings.
Yellow jackets are the most frequent cause of stinging insect allergy in North American. An immediate and only localized, transient reaction after a sting is considered normal and does not statistically increase the risk of developing an anaphylactic reaction with a subsequent sting. In children up to age 16, full body hives occurring after a sting are also considered low risk as far as the chance of anaphylaxis with a subsequent sting. However, an adult who develops full body hives as their only symptom; and any adult or child with symptoms outside of just hives (as described below) are at increased risk of developing anaphylaxis with subsequent stings and therefore should be skin tested and started on allergy shots if deemed appropriate by their allergist.
Fire ants can cause several types of reactions which are considered “non-allergic.” A normal reaction to a fire ant is development of a localized pustule, or pus filled blister. These pustules can sometimes become infected. Also people who develop large but only localized reactions are not considered to be at risk of anaphylaxis after subsequent bites. Only systemic reactions, in which the patient has swelling, difficulty breathing, vomiting, feeling faint, or any other symptoms outside of localized reactions, are considered dangerous and in need of testing and possibly allergy shots.
Allergy shots for venom stings and fire ant bites are helpful to reduce the risk of life threatening reactions after a sting or bite. Regardless, a patient with a history of anaphylaxis to bees/wasps/yellow jackets/hornets or fire ants should ALWAYS carry an EpiPen and Benadryl on their person and let their allergist or provider know if they are bitten or stung again and describe the type of reaction they experienced.
For additional information or to discuss questions you have, please talk to your local Allergy Partners board-certified allergist.
By Geetu Deogun, MD