An allergy to insect bites is a reaction to insect venom or saliva, generally local, that causes inflammation, pain and redness (erythema) and affects a specific area, but in cases of hypersensitivity the reaction can be generalized.
Stings of hymenoptera, such as bees or wasps, among which is the sting of the Asian wasp (Vespa vetulina) are usually the most serious since in hypersensitized individuals they can cause a systemic or generalized reaction affecting several vital organs with risk of produce anaphylaxis that, in its most extreme case, can cause death, as occurred in Asturias on June 2 despite the fact that the deceased had self-injected adrenaline. urgently.
Children are less likely to have more intense reactions; Most deaths from bee or wasp stings occur in adulthood. Currently, immunotherapy is the option that appears to be most effective in preventing systemic reactions.
Causes of allergy to hymenoptera bite
Immune system reaction
It is an immune system response produced by an antibody: immunoglobulin E (IgE). IgE antibodies are normally in small quantities in the blood, but a high concentration of antibodies, which are different depending on the allergen to which they respond, can cause a disproportionate reaction that leads to anaphylaxis. In the case of the Hymenoptera bite, you react to the venom, which is a compound of peptides, vasoactive amines and proteins.
It is crucial to recognize the Hymenoptera insect as:
-The Apis mellifera or honey bee forms permanent hives near fields and fruit or flowering trees. They measure between 5 and 15 millimeters in length and have a body covered with brown hair with alternating black and tan brown stripes.
– Bombus or bumblebees create seasonal colonies in nests built in holes or in the ground. They are louder and larger than the honey bee, with body hair and alternating yellow and black stripes. They don’t usually bite.
– The Vespidae. Black with yellow transverse stripes and sparse hair. They measure between 10 and 20 millimeters long. Their nests are temporary and are in holes, underground or hanging in the air. Their bites usually cause allergies. Are:
– The Vespa (hornets), their nests are in holes.
– The Vespula or Dolichovespela have their nests in holes or underground.
– The Vespula vulgaris measures between 12 and 17 millimeters and has parallel black and yellow stripes with black dots on its abdomen. They usually have a black mark on their forehead.
– The Vespula germanica or yellow jacket has yellow legs and hardly any hair on its legs and body. The abdomen is bulging and has black and yellow stripes. It differs from vulgaris in that it has three points on the forehead. It can be confused with Polistes. Its venom is highly toxic.
– The Vespa vetulina or Asian wasp is native to Southeast Asia but arrived in Europe in 2004. The queen can measure up to 3.5 centimeters. The size of the workers can vary depending on the food, the situation and the temperature. They are generally larger than the usual species in Spain but their presence has been detected throughout the northern region of Spain. It can be distinguished, in addition to its size, by having dark-colored wings, a black thorax and abdomen with a yellow fourth segment. Its legs are brown with yellow tips. It feeds on insects such as bees, ants, aphids… and generally avoids attack. This usually occurs near the nest because the colony perceives a threat. They usually build their nest in trees, about 15 meters from the ground. In Europe it has predators such as the European honeybee and the European bee-eater. They also do not tolerate temperatures of more than 45 ºC. The reaction to Asian wasp venom can be very serious or fatal in cases of more than twelve stings or in hypersensitive individuals. The pain is intense and sharp and results in intense burning.
– Polistes or wasps are smaller than vespules, their body is black with yellow rings with reddish areas on the abdomen. They create aerial nests, which hang litter bins. They differ from the Vespula because they have an eyelet-shaped abdomen. Its venom usually causes allergic reactions.
Hymenoptera bite allergens are:
For Apis: Api m1 and m2 (phospholipase A2 function); Api m4 (hyaluronidase function); and m6 (melittin function).
For the Vespidae: group 1 (phospholipase A1 function); group 2 (hyaluronidase function); Pol d4 (serine protease function); and group 5 (antigen 5).
The main risk factors for the Hymenoptera bite are:
– Rural habitat, proximity to fields, fruit trees, gardens and beekeeping facilities.
– Having already received bites from Hymenoptera on previous occasions.
– Suffer from mastocytosis.
Symptoms of hymenoptera bite allergy
Erythema, pruritus, pain and anaphylaxis
The symptoms of a Hymenoptera bite are:
– Erythema. Inflammation, pain and redness.
– Itching and/or burning.
– Affectation of an area of skin greater than 10 centimeters in diameter and lasting more than 24 hours.
– Anaphylaxis. Systemic reaction without a history of previous significant local reaction and occurs between 30 and 60 minutes after the bite. It has four grades according to Müeller’s classification: grade I (generalized urticaria, itching, anxiety and general malaise). Grade II (swelling of the skin, mucous membranes and submucosal tissues –angioedema-, chest tightness, nausea, vomiting, diarrhea, abdominal pain and dizziness). Grade III (difficulty breathing or shortness of breath –dyspnea-, wheezing or breathing with a high-pitched sound, difficulty swallowing –dysphagia-, difficulty making sounds –dysarthria-, confusion and feeling of imminent death). Grade IV (all or part of the previous grades but, in addition, hypotension, collapse, loss of consciousness, incontinence and bluish or livid discoloration of the skin –cyanosis-).
Diagnosis of allergy to hymenoptera sting
Type of reaction and number and location of bites
The clinical history, the type of reaction, the number of bites and their location will be the first step in the diagnosis by the doctor or allergist. The age and time elapsed between the sting and the appearance of symptoms is also relevant in addition to being able to provide the identification of the hymenoptera (type of bee or type of wasp) that made the sting.
Pathological history will also be taken into account. As tests, blood tests will be performed to determine IgE (the presence of values of more than 0.35 units per milliliter of blood indicate sensitization) and basal tryptase, a protease, an enzyme that breaks protein bonds, which is released during allergic reactions.
Skin tests will also be performed, usually intradermal prick; controlled sting testing that is carried out in the hospital under controlled conditions,
Treatment and medication of allergy to hymenoptera sting
Treat spontaneous bite or immunotherapy
The first step is to treat the sting by removing the stinger, cleaning the area with soap and water, and then applying cold to the sting to soothe the pain. The limb is then immobilized if it is where the bite occurred.
Pharmacologically, antihistamines such as hydroxyzine or deschlorpheniramine and corticosteroids such as prednisone can be administered. If there is anaphylaxis, self-injectable adrenaline must always be at hand for the patient and if the response is still refractory to treatment or there is severe hypotension or cardiorespiratory arrest, via hospital, the option is intravenous adrenaline if the patient is monitored.
Immunotherapy is another treatment option but long-term. The goal is to prevent future reactions to stings. The treatment consists of administering progressively increasing doses of poison over a period of time until reaching a maintenance dose. It must be done under specialist supervision.
Prevention of allergy to the bite of a hymenoptera
Avoid bites
You should always avoid being exposed to bites, but this is especially important for people with hypersensitivity who must:
– Avoid eating and drinking outdoors. Special care must be taken if a soda can has been left open because a Hymenoptera can sneak inside without warning.
– Do not wear bright colored clothing and perfumes.
– Do not leave food outdoors.
– Avoid approaching areas of beehives, fruit trees or garbage containers.
– Do not travel by car with the windows open or ride a bicycle through countryside areas.
– Avoid making sudden movements if there is a bee or wasp.
It is also important to use insect repellent when outdoors and shake out clothes if they dry outdoors and be careful in areas with swimming pools.
If you receive a bite, it is important to move away from the place because a pheromone is released that encourages other members of the colony to attack. You should also try to remove the stinger as soon as possible by carefully scraping it with a fingernail or a blunt object. Tweezers should not be used because they squeeze the venom sac from the stinger.
If you have moderate to severe symptoms, you should go to the emergency room and if anaphylaxis occurs, use adrenaline self-injection. It may even be necessary to perform two injections.
In addition, immunotherapy is the prevention measure that is considered most effective in preventing anaphylactic reactions.
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