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Allergies to insect venom
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Frequency of allergic reactions to insect venom is different for different countries which is primarily attributable to specific weather conditions. In the countries within the mild climate belt, allergic reactions caused by insect venom occur in 0.4-1.2% of the total population. Anaphylactic reaction occur in 1-3% of the patients sensitive to insect venom. In the USA, 40 sensitive individuals die annually due to severe allergic reactions and in France 16 to 38 individuals.
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What insects most frequently cause allergies?
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Even though there are approx. one million of insect species, only a small amount causes allergic reaction in people. Such allergic reactions are most frequently caused by stings of the insect of the order Hymenoptera, bees, bumble-bees, wasps, hornets and ants. There are some differences among these insects that should be borne in mind. Bees and bumble-bees sting only when agitated. After the bee sings, the stinger containing a small bubble of venom from the insect abdomen remains on the sting location. Venom is gradually released and causes localized and/or systematic (general) symptoms. Thus, it is recommended to remove the bee stinger as soon as possible. Bee and bumble-bee venoms are most poisonous in spring. They have the same components and contain different harmful substances that can trigger allergic reactions in sensitive individuals. Allergic reactions to the bee sting occur usually after numerous previous stings and thus are more frequent in people professionally exposed to bees (bee-keepers). Unlike bees, wasps and hornets do not leave the stinger in the skin and can sting several times. These insects are often aggressive and attack even when not agitated, especially in late summer and autumn. Wasp and hornet venoms contain chemically active substances thus causing more serious allergic reactions, especially in case of hornet sting which contains a bigger amount of venom. Allergic reactions to wasp sting can occur after the first sting even though they are more frequent after the 2nd or 3rd sting. Allergic reactions to ant venom are less frequent. Ant venom content changes depending on the time of the year and is the most "poisonous" in early summer.
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How are allergic reactions to insect venom manifested?
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In almost every individual, the sting causes localized toxic and not allergic reaction (swelling, pain, redness) of a highly different scale. Allergic reactions occur only in sensitive individuals. They can be localized around the spot of the sting or systematic. Systematic reactions can be divided into 4 stages:
1st stage is characterized by urticaria.
2nd stage is characterized by urticaria, swelling, nausea, vomiting and diarrhea.
3rd stage is characterized by obstructed and audible respiration, wheezing in the chest, obstructed swallowing and confusion.
4th stage is marked by the above mentioned, including collapse, hypotension, loss of consciousness, dark-blue color of the skin and mucous membrane, fecal or urinary incontinence.
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How to diagnose allergic reactions to insect venom
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Diagnosis of allergy caused by insect venom is based on the patient's data (description of the event, types of symptoms, development and velocity of symptoms, insect description) and on the results of different tests. Laboratory analysis usually reveals the total concentration of IgE antibodies and IgE working against the venom of a given insect (see other articles in the Manual). It is necessary to test the stung skin, specially in case of bee, wasp and hornet venom. If test results of the stung skin are not definite, additional skin tests can be performed and very rarely provocative (challenge) tests in which the patient is exposed to the sting of a given insect. This test can be performed only in a highly specialized institution and its goal is to estimate effectiveness of the performed specific immunotherapy.
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What to do in case of allergy caused by insect venom
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Treatment depends on the type of allergy reaction following the stung. After the stung, the stinger should be removed as soon as possible. In case of a localized reaction it is enough to put a cold compress over the stung and possibly apply locally a corticosteroid ointment. If the swelling increases, it is recommended to take antihistamine tablets (see question no. 21).
Systematic reactions are treated as other anaphylactic conditions. It is important to inform the patient about the self-help measures in case of an allergic reaction to insect venom, especially in case of early anaphylactic reactions. It is recommended to use adrenaline via syringes prepared for fast and simple application administered by the patient himself/herself, antihistamine tablets, and under certain conditions, corticosteroids. Upon administering self-help, the patient should contact the doctor as soon as possible for the purpose of further medical and hospital treatment. Allergic reactions to insect venoms can often have a delayed reaction (after 8 to 12 hours). Thus, it is necessary to admit to hospital all patients that have experienced systematic allergic reactions, angioedema (swelling of soft tissue, especially eye lids, lips, etc.) and bronchospasm (constricted respiration).
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What treatment is recommended for the patients allergic to insect venom?
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As other allergic diseases, allergy to insect venom cannot be cured completely. The stated drugs (antihistamines, adrenaline, corticosteroids) are effective for mitigating symptoms. The only therapeutic method influencing the allergic nature of the disease is a specific SIT immunotherapy. SIT (hyposensitization) is performed in patients with systematic reactions of the 3rd and 4th stage (see questions no. 22 and 28), on the basis of the previously performed skin test that has shown positive results and increased concentration of IgE antibodies against insect venom. In specialized institutions, the patient receives gradually increasing concentration of the allergen (insect venom) under a strict supervision of the expert. Treatment is performed pursuant to a corresponding protocol until the patient becomes "resistant" to the venom, subsequently followed by "maintenance injection" administered for the next 3 years. This treatment gives children 100% protection.
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Instructions for persons allergic to insect venom:
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•if the stinger has remained in the skin, it is necessary to remove it immediately by using fingernails or tweezers;
•put a cold compress over the stung
•have ready corresponding drugs and if necessary, apply urgent therapy (self-administered syringe, antihistamine, corticosteroid);
•avoid sudden movements (waving with hands) in order to scare away the insect because that makes them more aggressive;
•avoid strong fragrances (perfumes, sun lotions, lotions) because they attract insects;
•do not go to flower gardens or orchards and do not eat sweet and succulent fruit in the open;
•be careful when working in the garden (protect exposed parts of the body)
•do not walk barefooted on the grass (bees frequently reside in the clover patches);
•avoid wide and fluttering clothes (an agitated insect can sneak in under the clothes) in bright colors;
•avoid harder physical activities (the smell of the sweat attracts insects);
•cover sweet groceries;
•keep trash cans closed;
•keep the window in the sleeping room shut during the day or install a protective net against insects.
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How schools handle food allergy?
A survey of nurses in elementary and middle schools in the U.S. found that food allergy action plans for students with food allergies are used inconsistently.
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