HYMENOPTERA
(honeybee , wasp, hornet, yellowjacket) ALLERGY
Allergic reactions including anaphylaxis to Hymenoptera stings are very common. I will list in point form several things that individuals should be aware of with regard to Hymenoptera stings.
Local swelling from Hymenoptera stings does not usually imply any increased risk of having a severe systemic (anaphylactic) reaction from a future sting.
There are few possible exceptions to the point above. Usually, a sting involving the face or neck has more swelling than other areas. Multiple stings have significant more swelling. Huge local swelling (for example an entire arm or leg) that lasts for days and a history of progressive increasing large local swelling with each subsequent sting may indicate increased risk for future systemic reaction. Individuals who have a generalized skin reaction ONLY, are at less risk of severe/multisystem anaphylaxis on re-sting than those who have had a prior severe/multisystem reaction.
Most individuals cannot identify the specific Hymenoptera sub species that caused their sting. Many individuals refer to these insects as bees, but the honeybee actually leaves its stinger with venom sack attached in the victims skin. If there is no stinger seen immediately after a sting it is unlikely to be a honeybee. Very few individuals can tell the difference between a yellowjacket, wasp, and yellow hornet as these insects all are yellow and black/white. If an individual clearly identifies the insect as being large and white and black only, this represents a white faced hornet.
Many individuals are not sure exactly what insect was involved at all. However, Hymenoptera stings cause significant immediate pain after sting which will persist for at least several minutes. If there is no pain associated with the sting it is not from Hymenoptera.
A critical part of the history (assuming a true Hymenoptera sting occurred) is whether there is any evidence of non-local reaction. By this I mean did anything occur immediately after the sting that was not at the sting site. For example feeling itchy in other areas other than where the sting occurred, any hives occurring (even a single hive) away from where the sting occurred, any difficulty breathing, a feeling of general illness or weakness (which could represent mild low blood pressure), etc. if there is a chance that there was any non-local symptoms from a sting this could suggest the individual was having a generalized reaction and this markedly increases the risk of a more severe reaction in the future. Any individual with a history of possible non-local symptoms should always be assessed by an allergist and skin tested to assess the possibility of genuine allergy to Hymenoptera.
As is outlined in my introductory section, to develop a true IgE mediated reaction an individual must have a prior exposure to that allergen to become allergic. However, Hymenoptera stings seem to represent an exception, as many individuals have reported an anaphylactic reaction to what appears to be their first ever sting.
There are several situations where individuals could be at increased risk of a severe anaphylactic reaction. Persons that have asthma are clearly at more risk of a severe systemic reaction if they are allergic to Hymenoptera. Individuals who are dermatographic (scratching the skin causes a welt) or have chronic urticaria (hives) have inherently unstable mast cells and could be more prone to a severe reaction. Individuals that have an increased number of mast cells (mastocytosis and its variants) are also at increased risk.
Individuals who are taking specific medications for heart, diabetes, or blood pressure can be at increased risk. ACE inhibitors (the true drug name ends in pril) are clearly implicated in more severe reactions. Beta blockers (the true drug name ends in olol) are also dangerous as this group of medications blocks the treatment of acute anaphylaxis (epinephrine).
The treatment of anaphylaxis from a Hymenoptera sting is epinephrine immediately injected into the upper outer thigh. At this moment we have the EpiPen autoinjector available. Please see the subsection in the Contents section on injector(s) for details on how and when to use.
It is critical that every individual understand that the treatment is epinephrine for an acute anaphylactic reaction. Particularly, for individuals allergic to Hymenoptera, taking an antihistamine every morning during bug season prior to going outside can reduce the severity of many reactions, BUT NOT ALL. The antihistamine must be long acting and non-sedating (Benadryl TM is not appropriate). Having an extra antihistamine available taped to your autoinjector is useful to take as additional medication after using the autoinjector. In individuals with a history of severe reactions and those with a history of late phase reactions (also called biphasic - LPR) in addition to an antihistamine to be taken immediately after use of autoinjector, I will often also give these individuals prednisone to take along with the antihistamine. However, the EARLY use of injectable epinephrine is the only treatment that can reduce severity of reaction and reduce the risk of a delayed (LPR) reaction. Using epinephrine for an anaphylactic reaction is appropriate for ALL individuals the risk of anaphylaxis is more than that of underlying heart disease, etc.
Hymenoptera allergic patients should ensure that individuals who accompany them on outdoors activities during insect season should know where your autoinjector is located and how to use it in case of a severe reaction where the allergic individual is not capable of self-administering.
AVOIDANCE MEASURES
There are several specific avoidance measures that can be useful for Hymenoptera stings.
Hymenoptera are attracted to food, and while any food can attract this group of insects carbonated beverages (pop, beer) and wine are particularly strong attractants. I always recommend individuals who have a history of even significant local swelling never drink from a closed container outside (pop can, beer can, etc.). I have had several individuals swallow a wasp that was inside the can and got stung in the mouth or back of the throat and the local swelling that ensued was almost fatal. These individuals should always drink liquids in an open container where the fluid is clearly visible-a plain open glass-so they can always see the fluid that they are drinking. Individuals who are highly allergic to Hymenoptera really should avoid outdoor picnic/food/beverages completely.
Hymenoptera are attracted to colours and scents. I always recommend the following during bug season:
a) You should not look like a flower. Any colour you can imagine that a flower is should be avoided and in particular the colour black should be avoided as these colours specifically attract these insects. If you wear clothing that is brown or green this will significantly decrease your chance of random stings as Hymenoptera are not attracted to these two colours. Individuals who are allergic to Hymenoptera should always wear brown and green clothing when outside during the insect season.
b) You should not smell like a flower. Because many scents attract these insects, substances such as perfumes, colognes, underarm deodorant with scent, etc. should never be used during bug season by Hymenoptera allergic patients.
TREATMENT
The recommended treatment for those individuals who have a history of a systemic reaction to a Hymenoptera sting and confirmatory positive skin testing to one or more of the Hymenoptera venoms (or positive RAST blood testing) is to undergo immunotherapy (allergy shots) for the specific venoms that the individual is allergic to. The recommended minimum immunotherapy is three years duration with a preference for a full five years of immunotherapy. Discontinuation of venom immunotherapy depends on multiple factors that have to be individualized for each patient. Regardless of whether the patient is undergoing or has had previously immunotherapy it is recommended that individuals who have a history of a systemic reaction to Hymenoptera always have an epinephrine autoinjector on their person during insect season for the rest of their life (the risk of anaphylaxis does not become zero). Individuals who have had a systemic reaction to a Hymenoptera sting have approximately a 40-60% chance of having another systemic reaction on re-sting. After five years of immunotherapy the risk of a systemic reaction on re-sting is reduced to less than for 5% for individuals allergic to the vespids (wasp, hornet, yellowjacket). Immunotherapy does not appear to be as effective for honeybee anaphylaxis, with risk of anaphylaxis on re-sting as high as 15%.
Bruce Sweet MD 2017