Insect Venom Allergy
What is it?
Insect venom allergy is a harmful reaction to insect stings that occurs in people who have an abnormally high sensitivity to insect venom. It is an acquired trait, which is not present at the first exposure to the venom, but sensitization can occur after the first or subsequent exposures. Animals classified as insects usually have three main body segments (head, thorax and abdomen), six legs and a pair of sensory antennae. Winged insect species have two sets of wings, such as mosquitoes, bees, and wasps. Other biting or stinging insects include fleas, lice, and ants. Many other related animals that are frequently mistaken for insects such as ticks, spiders and mites also bite human beings. They can transmit infectious diseases or cause poisoning but generally do not cause allergic reactions. Allergic reactions to the venom of some stinging insects, such as honey bee, yellow jacket, hornet, wasp or fire ant can be life threatening.
Who gets it?
Anyone can experience an allergic reaction to an insect bite or sting. However, only a small number of people with insect bite or sting allergies suffer fatal reactions.
What causes it?
An allergic reaction occurs when the immune system produces antibodies and other disease fighting cells in response to an allergen, in this case the insect venom. The antibodies release chemicals that actually injure the surrounding cells and cause the physical symptoms of an allergic reaction. Certain antibodies release histamines, which affect the skin, mucous membrane, mucous gland, and smooth muscle cells. Life-threatening allergic reactions can occur without any previous symptoms of allergy. In fact, most people with insect bite or sting allergies do not experience a severe reaction with their first bite. Multiple bites or stings increase the risk of an allergic reaction, but just one bite will cause serious symptoms for someone who is severely allergic.
What insects are usually involved?
Most serious allergic reactions to insect venom are caused by stinging insects, such as bees, yellow jackets, hornets, wasps and imported fire ants. As natives of the tropics, fire ants can live only in the warmer climate of the southern states and cannot survive in Pennsylvania. They are extremely aggressive and sting exposed parts of the skin when they feel threatened. Bites or stings from other insects usually do not cause allergic reaction.
What are the symptoms?
Symptoms of insect venom allergy often begin within 15 to 30 minutes and arise distant from the site of sting. The first symptom is often itchiness that can affect all or any part of the skin, the eyes and the nose. As symptoms progress, the patient begins to sneeze, cough and wheeze, feel congested, and develop hives or swelling. These symptoms may be warning signs of a dangerous condition called anaphylaxis. Symptoms of anaphylaxis include sudden anxiety and weakness, difficulty breathing, tightness in the chest, lightheadedness and palpitation, and loss of consciousness. Anaphylactic shock can occur within minutes and result in death. Anaphylaxis is a medical emergency that needs immediate medical treatment, and any delay may reduce the chance of survival.
How is it diagnosed?
Insect venom allergy is suspected based on a constellation of suggestive symptoms that follow an insect sting. The diagnosis is confirmed by performing a skin test with the venom of specific insects, such as honey bee, yellow jacket, hornet, wasp or fire ant that may be the culprit of the allergic reaction.
What is the treatment?
If you have been bitten or stung by an insect, carefully remove the stinger, if it is left behind. Wash the bite/sting area gently with soap and water. Apply ice to the site of sting. People who are allergic to insect bites should, of course, avoid situations in which they are likely to get stung or bitten. Mild reactions, such as pain, itching, and swelling, can be treated with an over-the counter antihistamine, pain reliever and topical corticosteroid creams. Anaphylactic shock is treated with an injection of epinephrine, a hormone that stimulates the heart and relaxes the airways. This may be combined with an injection of an antihistamine, which counteracts the histamine produced by the immune cells during an allergic reaction. Those who are known to have severe insect venom allergies should carry a self-injection kit, including antihistamine tablets, for emergency treatment. However, they should still seek emergency medical care after any type of reaction to an insect bite or sting.
People who are severely allergic to the venom of stinging insects, such as bees, yellow jackets, hornets, wasps or fire ants may, undergo a desensitization. First, skin testing is performed by an allergy specialist to determine the type of insect that responsible for the venom allergy. Then the patient receives a series of injections of the venom from the same insect.