Diagnosis of an Insect Sting Allergy
Allergic reactions to insect stings are usually easy to diagnose. You will most likely feel the sting when it occurs. In addition to knowing that your condition is an allergic reaction to an insect sting, you will want to know which insect you are allergic to.
Most of the time, you will know whether you have been stung by a bee, ant, mosquito, or other type of insect. If not, inspect the surroundings in which you were stung. What types of insects are active there? Are there nests or hives? Are there a lot of bees or ants present? This might help you narrow down the possibilities.
The following information might help with identification.
Yellow jackets have yellow and black stripes and are especially attracted to food. Their nests are made of a papier maché–like substance. The nests are usually underground but may be found in the walls of buildings, in cracks in masonry, or in woodpiles.
Honeybees and Bumblebees
Honeybees and bumblebees do not sting unless provoked. Africanized honeybees (killer bees) are more aggressive and may sting in swarms. In the US, killer bees were initially found in the southwestern United States. However, over the past several years they have been reported in both California and Florida. Honeybees live in honeycombs in hollow trees or the cavities of buildings. Their hives can be massive. They may house tens of thousands of bees and weigh hundreds of pounds. The honeybee has a barbed stinger that usually stays in the victim.
Wasps are long and thin and have droopy legs. Their small nests are made of a papery substance in a circular comb of cells that opens downward. They build nests in attics, under eaves, behind shutters, in mailboxes, under deck railings, or in most any small nook or cranny.
Hornets are larger than yellow jackets. They are able to sting you through your clothing. They build their nests of a papery substance in the shape of a football. Their nests are outdoors, usually in high places such as in the braches of trees or high in the eaves.
Fire ants look similar to ordinary ants, but there are some differences. Fire ants are reddish brown on their head and body, darker on the abdomen. They build nests in the ground that can be up to 5 feet deep with a mound as much as 18 inches high and 15 inches in diameter. They are very aggressive and will attack anything that disturbs their nest.
If you believe you have had an allergic reaction to a sting and do not know what insect caused it, your doctor may suggest one or more of the following tests to determine the source of your symptoms.
If there is any question about a person’s sensitivity to a certain insect’s venom, allergy skin-prick testing can be used to verify it. During a skin-prick test, the skin (usually on the forearm, upper arm, or back) is pricked with the potential allergen and is then monitored for a reaction, such as swelling or redness. Results can be seen within 20 minutes. Testing is available for honeybee, paper wasp, yellow jacket, yellow hornet, white-faced hornet, fire ant, harvester ant, and several biting insects.
If the skin-prick test is inconclusive, your doctor may suggest intradermal testing. In this method, a small amount of the insect venom is injected just under the skin and the site is monitored for a reaction.
If both skin tests are inconclusive, your doctor may choose to do a blood test. A radioallergosorbent (RAST) test can measure your immune system’s response to an insect’s venom by detecting the amount of IgE antibodies made in response to any suspected venom proteins. In a RAST test, a sample of your blood is added to the suspected venom and then tested for the amount of IgE antibodies made in response.