An insect sting allergy is a response by your immune system. It occurs when your immune system overreacts to the presence of a foreign substance. Such substances might include pollen, food, or an insect sting.
Immunoglobulin E (IgE) is an antibody that has a big part in allergies. IgE binds to allergens and starts to cause inflammation. When this happens, allergic reactions begin. Your immune system is designed to identify and attack threatening microorganisms such as viruses, bacteria, fungi, and parasites.
It is not clear why some people become allergic and others don’t. Allergies tend to run in families. This suggests a genetic component.
There are two steps to developing an allergy: sensitization and allergic reaction.
Your first encounter with the allergen (substance you are allergic to) is called sensitization. You will not necessarily notice a reaction, but your immune system will be at work. Your body will produce IgE antibodies specific for that allergen. After sensitization, your immune system has the capacity to produce large amounts of these specific IgE antibodies rapidly. This capacity persists for many years after the initial exposure.
The next time you encounter the allergen (perhaps a yellow jacket sting), your immune system is ready. The IgE antibodies go to work. They cause mast cells to release histamine and other chemicals. These chemicals cause the inflammation and other symptoms of allergy that you experience.
Several different kinds of insects can cause serious allergic reactions.
The most common cause of an insect allergic reaction is the honey bee. Bumblebees and sweat bees are two other types of bees that occasionally (though rarely) cause allergic reactions. Honey bees will die once their stingers are removed from their body, but a few bee varieties, such as bumblebees, can withdraw their stingers from a target without damage to themselves. Most bees are not aggressive and will only sting if provoked. Africanized honey bees (commonly known as “killer bees”) have behaviors that make them a more significant threat, even in the absence of provocation.
This group of insects includes hornets, yellow jackets, paper wasps, and other types of wasp. Vespids do not die when they sting and can be more aggressive than bees.
Fire ants and harvester ants are two types of ants that can cause allergic reactions. The red imported fire ant, originally native to Brazil, is now prevalent throughout the southeastern United States, especially in the Gulf Coast states. Large groups of fire ants will attack a human (or other animal) that steps on their hill or mound.
Although rare, there have been reports of allergic reactions to deer flies, bed bugs, and mosquitoes.
There are several possible risk factors for insect sting allergy.
Allergy tends to run in families. If you have a family history of allergy, you are more likely to develop allergies yourself, including insect sting allergy.
Previous exposure to an insect’s venom (sensitization) is necessary to have a true allergic reaction. Some stings and bug bites may cause reactions that mimic allergies but are actually reactions to toxins passed on by the bug. Of course, frequenting or disturbing (digging, tree pruning, etc.) outdoor areas that are favorite nesting places for insects (clover-covered fields, for instance) may provoke a stinging response.
If your work requires spending a lot of time outdoors, especially in yards, you’re at a much higher risk for being stung. Bees, wasps, and dangerous ants are also more common in some parts of the world than others. Fire ants, for example, only inhabit the southeastern states of the Unites States.
If you have other allergies, such as a food allergy or hay fever, you’re more likely to have an allergic reaction to an insect sting.