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.
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 want to do a blood test rather than a skin test, depending on the patient’s condition and other factors. A RAST test (short for “radioallergosorbent 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 the patient’s blood is added to the suspected venom, and then tested for the amount of IgE antibodies made in response.