Wasp and Insect Allergy

Wasp and Insect Allergy

Most individuals experience pain, discomfort, redness, and localized swelling after a wasp or bee sting. This type of reaction, known as a “local reaction,” typically resolves on its own within a few days without any treatment. However, if the swelling enlarges (10 cm or more) or spreads along an arm or leg, it’s advisable to see a GP, who may prescribe medication to reduce the swelling.

In more serious cases, such as stings on the face or neck that result in swelling affecting the throat, tongue, or airways, immediate medical attention is required as the airway may become blocked.

If symptoms escalate rapidly from the sting site or cause difficulty breathing, choking, or fainting, this could indicate a systemic allergic reaction (anaphylaxis). Anaphylaxis is a medical emergency that demands immediate action. Call 911 or administer an adrenaline auto-injector immediately if the person has an adrenaline auto-injector. Look for a medical alert bracelet, which might confirm the allergy.

Additionally, if you are stung on the hand and notice swelling in the face or hives across the body, this is a systemic reaction requiring urgent emergency treatment.

Types of Sting Allergic Reaction

  1. Normal reaction

This reaction typically persists for a few hours. The sting site may be red, painful, swollen, or itchy.

  1. Large local reaction

This reaction lasts for several days. The sting site becomes more painful and swollen, and itchiness may extend beyond the sting site to nearby areas.

  1. Severe allergic reaction (anaphylaxis):

A severe allergic reaction can begin within minutes after being stung. It can affect the entire body and trigger symptoms like dizziness (feeling lightheaded), nausea, weakness, stomach cramps, and diarrhea. It may also cause itching around the eyes, a warm sensation, coughing, hives, vomiting, and swelling. Some people report a sudden feeling of being extremely unwell, often described as a “sense of impending disaster.”

Anaphylaxis is usually characterized by:

  • Severe difficulty breathing (shortness of breath) caused by tongue and throat swelling. This may also result in trouble swallowing, a hoarse voice, noisy breathing (stridor), and wheezing or bronchospasm.
  • A significant drop in blood pressure, leading to dizziness, faintness, collapse, and unconsciousness (anaphylactic shock). Reactions can develop within minutes, and the most severe life-threatening symptoms typically appear in 30 minutes.

Diagnosis and Testing

To confirm a venom allergy and identify the specific stinging insect responsible, allergists can measure allergen-specific IgE antibody levels through a simple blood test. On the other hand, a diagnostic skin prick test with insect venom(s) may be conducted.

In some cases, skin prick testing alone may not provide sufficient sensitivity. If this occurs, intradermal testing may be done, which involves injecting a small amount of highly diluted purified venom beneath the skin. This test must be carried out by an experienced professional in an allergy clinic, as it may cause minor discomfort and carries a very small risk of an additional severe reaction.

Treating Local Reactions to Stings

For stings that cause itching, pain, redness, and swelling at the site, these approaches may help:

  • Cleaning the sting area and maintaining good hygiene to minimize the risk of infection. You should also avoid scratching.
  • Applying an ice pack or cold compress to alleviate discomfort and reduce swelling.
  • Using an ammonia solution (1-2.5%) available from pharmacies to relieve irritation.
  • Applying a topical antihistamine cream to soothe itching.
  • Using topical steroid cream to help with swelling.
  • Applying a local anaesthetic cream or spray to ease the pain.
  • Taking antihistamine tablets for overall relief.
  • For larger or persistent painful local swellings, steroid tablets may be prescribed by your doctor.

Keep these treatments in a portable first aid kit and store them at room temperature for easy access.

Emergency Treatment for Severe Systemic Reactions to Stings

Individuals with an allergy to wasp or bee venom who experience a systemic reaction after a sting should always carry two emergency adrenaline auto-injectors (AAIs), as recommended by their doctor. It’s important to regularly practice how to use the injector to avoid any mistakes. Also, ensure the AAI kit is always readily available, and train family and friends in its use.

Two doses of adrenaline should be kept on hand, as a second dose may be required while awaiting emergency services.

Many AAI suppliers provide trainer devices, instructional videos, and alert systems to notify you when your AAI is approaching its expiration date.

Immunotherapy (Desensitisation Treatment)

Over 50% of adults who have had a systemic reaction to a sting are at high risk of experiencing a similar or more severe reaction with subsequent stings, which can be fatal. While the risk in children is lower, it remains significant.

Immunotherapy (desensitization) effectively prevents severe allergic reactions in over 95% of wasp allergy cases and approximately 80% of bee sting allergies. Even if a patient does experience a reaction after treatment, its severity is greatly reduced.

The treatment consists of weekly injections for about 12 to 15 weeks, with progressively higher concentrations of the purified insect venom to which the person is allergic. This process is safe when conducted in an allergy clinic, and patients must remain under observation for an hour after each injection to monitor for rare reactions that may require prompt treatment.

After the initial treatment phase, “maintenance doses” are administered every six to eight weeks for three to five years. Although this treatment is time-consuming, it is highly effective and available at allergy clinics.

Many people with venom allergies experience anxiety due to the fear of a fatal reaction to a subsequent sting. Immunotherapy offers significant reassurance, as it is both effective and long-term protection, often lasting for years after treatment completion.

When to Seek Further Medical Advice

Anyone who experiences a systemic reaction to a sting should visit their GP and, if necessary, request a referral to an NHS allergy clinic for further evaluation and advice. Systemic reactions can pose a future risk to health and may be life-threatening.

For local reactions, seek medical attention if you notice any of the following:

  • A large local reaction, where the swelling and redness exceed 10 cm in diameter, peaking 24 to 48 hours following the sting.
  • Severe or worsening cellulitis (increased swelling, redness, and pain) develops several days after the sting. This could indicate a secondary infection of the sting site, potentially requiring antibiotics.

Sting Avoidance Strategies

Although insect repellents can be applied to exposed skin, they may not be effective against stinging insects. Insecticide aerosols (such as wasp sprays) are useful indoors for killing wasps but should be used cautiously to avoid inhalation, particularly around children, because of possible toxicity.

Persons with sting allergies should follow specific precautions to reduce the risk of being stung:

Outdoors

  • Wasp nests: Have wasp nests removed by a skilled exterminator. Never attempt to burn or flood a nest with water, as this may provoke the insects, making them more aggressive.
  • Food and garbage: Always cover food, particularly soft drinks, and ripe fruit, whenever you are outdoors. The aroma of eating, cooking, pet feeding, or nearby garbage cans can attract stinging insects, particularly wasps. Store refuse in tightly closed containers and frequently dispose of food waste, especially during seasons when insect activity is highest.
  • Nest disturbance: Be cautious not to disturb ground nests or nests in trees or building eaves, as this can incite stinging behavior.
  • Insect approach: If a bee or wasp approaches, stay still or slowly move away. Do not swat at the insect, as it may become trapped against your body and sting.
  • Alarm pheromones: Wasp venom contains an “alarm pheromone” that signals other wasps to come to the area, increasing the risk of stings.
  • Insects in vehicles: If a bee or wasp enters a moving vehicle, remain calm. The insect will likely try to exit the vehicle on its own by flying against the windows. Pull over safely and open the windows to allow the insect to leave. Avoid swatting at the insect, as this could lead to accidents.
  • Fruit trees and lawns: Pick fruit from trees as soon as they ripen and promptly dispose of the fallen, rotting ones. Avoid walking barefoot near fruit trees and be cautious when handling decaying fruit, as it may harbor wasps. Also, keep lawns clear of clover and dandelions, as they are known to attract honeybees, and avoid being close to flowering trees and shrubs when insects are collecting nectar.
  • Vines and nests: Remove vines near the house that may conceal nests.

Individual

  • Cosmetics and clothing: Avoid using strong perfumes, hair sprays, suntan lotions, aftershave and highly scented cosmetics, as these can attract insects. Also, do not wear shiny jewelry or buckles; opt for light-colored clothing (such as white, beige, or light gray). Wear closed shoes instead of sandals and avoid brightly colored, loose-fitting outfits or flowery prints, which may attract insects.
  • Safety during outdoor activities: People with venom allergies should avoid being alone when engaging in outdoor activities like swimming or hiking, particularly in remote areas where medical treatment may not be easily accessible. Always carry an identification card or Medic Alert bracelet that indicates an allergy to stings, along with instructions for administering adrenaline in case of a systemic reaction.
  • Risk of systemic reactions: A large local reaction to a sting does not significantly raise the risk of a severe systemic reaction in the future. Therefore, individuals with only local reactions do not typically require specialist investigation or treatment unless they experience general effects like hives, breathing difficulties, or faintness.

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