Hymenoptera Venom Allergy
Dario Antolin-Amerigo MD, PhD. Servicio de Enfermedades del Sistema Inmune-Alergia. Hospital Universitario Principe de Asturias. Departamento de Medicina. Universidad de Alcala. Madrid. Spain.
Gunter Sturm MD, PhD. Associate Professor. Department of Dermatology. Medical University of Graz. Graz. Austria.
Ewa Cichocka-Jarosz MD, PhD. Associate Professor. Department of Pulmonology, Allergy and Dermatology. Jagiellonian University Medical College. Krakow. Poland
Due to the increase in outdoor activities and temperature during the summer, insect bites and stings are frequent reasons for consultation in any clinical setting, mainly in Dermatology and Allergy Departments (Picture 1). Most of them are due to mosquitoes; however emergency visits after stings from wasps or bees are relatively common. In general, hymenoptera (namely, mainly bees and wasps) are not aggressive, and they sting exclusively when threatened. Around 10% of the people who were stung develop an exaggerated cutaneous reaction called large local reaction (LLR).
Here are several easy-to-follow tips in order to prevent stings and subsequent reactions:
1. Wearing white or light-colored clothing.
2. Kindly keep food and drinks covered and remove leftovers quickly.
3. Inspect liquids before drinking outdoors.
4. Do not walk outside without shoes.
5. Do not flail your arms close to a stinging insect.
Different reactions can occur after being stung by an insect:
1. Normal reaction
2. Large Local Reaction
3. Systemic Allergic Reaction
1. Normal reaction
Usually a painful wheel smaller than 2 cm and redness occur at the sting site.
2. Large local reaction:
A large local reaction (LLR), is defined as an itchy or even painful area of redness, warmth, swelling of more than 10 cm in diameter, which persists at least 24 hours and sometimes over several days.
This reaction, although cumbersome, does not mean that the patient has a high risk for anaphylaxis: only 5-10% suffers from systemic reactions after subsequent stings. If you have LLR after stings you may follow the recommendations below:
1. Remove the stinger from the sting site
2. Apply something cold immediately to the site of the sting.
3. Take oral antihistamines and glucocorticoids (after medical prescription).
3. Systemic allergic reaction:
About 3% of the general population develops systemic allergic reactions. Mild allergic reaction symptoms include hives, swelling or redness even away from the sting site may occur. Nausea, vomiting or abdominal pain might be likewise seen. Shortness of breath or difficulty breathing, dizziness or loss of consciousness constitute severe symptoms in a limited number of patients. Severe allergic reactions comprising diverse systems of the body are named anaphylaxis.
In order to assess a patient who has suffered a reaction that may be allergic, there are different means of evaluation, skin testing for hymenoptera and specific immunoglobulin E (sIgE) being the most widely used. Some other techniques are emerging options as they have proved to be effective.
Skin testing is usually performed by allocating a drop of a standardized diagnostic extract, containing both bee and wasp venoms (each drop one venom). If the test is performed over the skin, by scratching with a lancet the outer layer of the epidermis, then the technique is called skin prick testing. On the other hand, intradermal testing is performed in inner parts of the skin, using different concentrations.
Another method of study, usually performed before skin testing is measuring the levels of IgE to different venoms. This test is very convenient for patients. However, due to the high sensitivity of the test, often false double positive tests for bee and wasp venom occur. Thus a combination with skin tests is important.
Additionally, more modern techniques such as component-resolved diagnosis and basophil activation test account among new techniques available in some laboratories.
Venom allergy shots (venom immunotherapy)
Immune tolerance is achieved by administering increasing doses of allergens to induce specific long-term tolerance. Adverse reactions are generally mild and usually limited to the arm where it was injected. If this is the case, don´t worry, as this kind of reaction does not mean that the immunotherapy will be more or less effective, or that it may modify your immune system, and is easily overwhelmed by a pill. Sometimes LLR will just require cold-compressive agents to avoid inflammation.
Venom Immunotherapy (allergy shots) is a highly effective therapy, as up to 95% of treated patients are protected against future sting reactions. Usually patients are rapidly protected after reaching the maintenance dose. However, therapy should be performed monthly over 3-5 years to ensure lifelong protection. Please ask your allergy specialist for further information.
If you have suffered any symptoms of an allergic reaction or anaphylaxis after being stung, it is highly recommended to make an appointment to see a specialist in order to receive more information and practical advice. Venom immunotherapy is a highly effective treatment to prevent future undesired sting reactions.