Wasp, Bee and Hornet Stings When to Worry and When to Not Dan Onion, MD, MPH
Mt. Vernon/Vienna Health Officer
293-2076; firstname.lastname@example.org July 2017
Summer brings many more encounters with various insects in Maine than the other seasons, some are no bother, some temporarily irritating, and some painful and potentially downright dangerous. Hornet, wasp and bee stings predominate in the last group. These stings are usually quite painful, at least for several hours; they cause local swelling, which if around the eye, can even close it; and if a person has been previously stung, they can cause anaphylaxis, a medical term for the variable combination of shock and wheezing, a potentially fatal condition. Although not really a public health problem, I discuss stings here because August is the peak time of the year people are afflicted by them. I want townspeople to be aware of what to do and worry about if family or friends are stung.
First the culprits. Hornets, wasps and honey bees are all classified as members of the order hymenoptera. Many of their members can sting. Among the bees, honeybees and ground dwelling bumblebees (apidae family) can both sting. But the latter are fairly uncommonly the source of stings mainly because their numbers are decreasing (pesticides?) and because they live in nests with only a few bees unlike wild and domestic bees, which in the summer usually have 6-10,000 bees per hive or wild nest. Most honey bees are surprisingly unaggressive unless badly disturbed. My friend Gary Dubord works with his hives bare headed and handed often. My bees only became crazed after a bear knocked over their hive, and, I think, perceived me as the bear returned to do it again. Hornets and yellow jackets (both in the vespidae or wasp family) are at the other end of the spectrum, attacking people just for walking or working nearby. Unlike bees, the individual insects don't die from stinging once, but rather can repeatedly sting their target. I've had two of my medical friends die from yellow jacket stings; and I myself have now developed a severe reaction to yellow jacket wasp stings, probably brought on over the years from many hornet stings when attacked high on a ladder cleaning the rain gutters of our house, and several yellow jackets stings from stirring up their ground nests while mowing my lawn. Think of these two different groups of insects as relatively pacific vegetarians who use stings only in self defense, vs the predatory wasps that kill what they eat!
The physiology of why stings have the effect on us they do is interestingly complicated. To mangle Shakespeare, the fault lies not in our stars but in ourselves. That is because, stings induce a defensive immune reaction in our bodies, which, with repeated stings over our lifetimes, can involve not just the local area of the sting but the whole body, with sometimes fatal consequences. The reaction is triggered when the stinger venom injected is bound to an immunoglobulin (IgE, an antibody) attached to mast cells scattered throughout our bodies, especially in our lungs, nose, eyes, and mouth. When the venom hits the IgE, it is bound there and causes the IgE to release a small molecule called histamine into the surrounding tissue. This system is designed to get rid of local germs when they penetrate our body's defenses; the histamine dilates local blood vessels to get more antibodies and white blood cells to the area to kill and remove the foreign invasion. Pollen allergic symptoms, runny nose and eyes and cough, are caused by this same system. But when the system is triggered body-wide with blood vessels dilating everywhere, blood pressure can drop dangerously low, itching and or hives usually happens, and wheezing from fluid-blocked bronchi can cause respiratory failure. Those symptoms are called anaphylaxis and usually happen within minutes of the sting. For years I worked in emergency rooms and saw a lot of stings there; our mantra of reassurance for those afflicted was "if you're not dead within 20 minutes you'll be ok", a slight exaggeration but pretty close to right. The greatest risk is usually over in 20-30 minutes.
So what should/can you do to avoid these risks? First avoid stings. Wear protective beekeeper gear (hood, gloves and overalls) if you keep bees or plan to work around hornets or yellow jackets; that equipment is quite effective if properly maintained. Avoid or destroy nests around your house. Honey bee and hornet nests are quite obvious; wasp and yellow jacket nests are much harder to locate. If stung, treatment with ice packs to diminish the amount of swelling and pain should be sufficient. However, if a person has been stung multiple times in the past, as many of us have over the years, AND has a large local painful swelling (fist-sized or greater) OR diffuse itching, swelling or wheezing associated with faintness, get medical attention ASAP! And better also get tested eventually for what you are allergic to and how much. Desensitization shots for the guilty insect's venom can protect you from future stings, albeit by a long series of increasing doses of the venom itself. Another trick with a sting on your arm or leg is to use a tourniquet to cut off blood return to the central body and thereby trap the venom in the hand or arm for 10-20 minutes. This technique clearly doesn't work for body or head stings, but does in the extremities. I used my belt. Finally, there is debate whether antihistamines (like over the counter diphenhydramine [Benadryl]) help, but I'd say there is little harm in 25-50 mg for adults or proportionately less for children, used as soon as possible.
It's worth thinking about all this ahead of time, so you are ready when it happens, as it will for most of us working or playing outside in the summer.