Allergies to insect stings (Bee stings)

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Allergy Types: Other Allergies: Allergies to Insect Stings (Bee Stings)

Definition

Insect sting allergy is the term commonly given to the allergic response of an animal in response to the bite or sting of an insect. Typically, insects which generate allergic responses are either stinging insects (wasps, bees, hornets and ants) or biting insects (mosquitoes, ticks). Stinging insects inject venom into their victims, whilst biting insects normally introduce anti-coagulants into their victims.

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The great majority of insect allergic animals just have a simple allergic response – a reaction local to the sting site which appears as just a swelling arising from the release ofhistamine and other chemicals from the body tissues near to the sting site. The swelling, if allergic, can be helped by the provision of an anti-histamine ointment as well as an ice pack. This is the typical response for all biting insects and many people have this common reaction to one extreme or another.

Mosquito allergy may result in a collection of symptoms called skeeter syndrome that occur after a bite. This syndrome may be mistaken for an infection such as cellulitis.

In anaphylactic patients the response is more aggressive leading to a systemic reaction where the response progresses from the sting site around the whole body. This is potentially something very serious and can lead to anaphylaxis, which is potentially life-threatening.

Bee, wasp, yellow jacket, hornet, or fire ant stings are the insect stingsthat most often trigger allergies. However, most people are not allergic to insect stings and may mistake a normal sting reaction for an allergic reaction. By knowing the difference, you can prevent unnecessary worry and visits to the doctor.

The severity of an insect sting reaction varies from person to person. There are three types of reactions — normal, localized, and allergic:

  • A normal reaction will result in pain, swelling, and redness around the sting site.
  • A large local reaction will result in swelling that extends beyond the sting site. For example, a person stung on the ankle may have swelling of the entire leg. While it often looks alarming, it is generally no more serious than a normal reaction.
  • The most serious reaction to an insect sting is an allergic one (described below). This condition requires immediate medical attention.

Symptoms of a severe insect sting allergy (called an anaphylactic reaction) may include one or more of the following:

  • Difficulty breathing
  • Hives that appear as a red, itchy rash and spread to areas beyond the sting
  • Swelling of the face, throat, or mouth tissue
  • Wheezing or difficulty swallowing
  • Restlessness and anxiety
  • Rapid pulse
  • Dizziness or a sharp drop in blood pressure

Although severe allergic reactions are not that common, they can lead to shock, cardiac arrest, and unconsciousness in 10 minutes or less. This type of reaction can occur within minutes after a sting and can be fatal. Get emergency treatment as soon as possible.

A mild allergic reaction to an insect sting may cause one or more of the following symptoms at the site of the sting:

  • Pain
  • Redness
  • Pimple-like spots
  • Mild to moderate swelling
  • Warmth at the sting site
  • Itching

People who have experienced an allergic reaction to an insect sting have a 60% chance of a similar or worse reaction if they are stung again.

http://www.webmd.com/allergies/guide/insect-stings

Causes 

An allergic reaction occurs when the immune system of the body overreacts to an “invader” such as insect venom (the allergen). This overreaction is sometimes referred to as a hypersensitivity reaction.

The white blood cells produce an antibody to the protein in the venom.

  • The allergic reaction occurs when the antibody, known as immunoglobulin E, or IgE, comes in contact with the protein, either at the first sting or later.
  • IgE promotes release from certain cells of chemicals and hormones called “mediators.” Histamine is an example of a mediator.
  • It is the effects of these mediators on organs and other cells that cause the symptoms of the allergic reaction.

Ants, bees, and wasps have a stinger or venom sac and gland on their tail that they use to inject venom.

  • Several stings may occur, particularly if you accidentally disturb a hive or nest.
  • This is particularly true with fire ants and so-called Africanized bees.
  • Africanized bees are the result of breeding of domesticated and wild honeybees in Africa that resulted in a very aggressive honeybee. The venom of these bees is no more potent than that of normal honeybees, but their aggressive nature increases the likelihood that they will swarm and sting you many times, sometimes hundreds of times.
  • Such a large number of stings may result in serious reactions or death, even if you are not allergic to bee venom.
  • If you are allergic to the venom, then you may have an allergic reaction from even a single sting. This is called an anaphylactic reaction. It can be dangerous, even life threatening.
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An anaphylactic reaction does not usually occur on the first sting.

  • The immune system makes the antibody at the first sting and stores it on special cells until the next sting. This is called “sensitization.”
  • At the first sting, therefore, the body does not have antibodies specific to the venom.
  • Only on a second or later sting can the body mount a major defense against the venom.
  • This is when a life-threatening anaphylactic reaction may occur.
  • Anaphylactic reactions are rare, and do not happen to every person who is stung by an insect.
  • When an anaphylactic reaction seems to occur on the very first sting, probably the person was stung before without realizing it.

Insect venom is used to treat certain medical conditions.

  • In Chinese herbal medicine, the venoms of various insects in this class are used either as direct stings (as a treatment for arthritis and other chronic diseases) or are applied to the skin or the eyes.
  • Such apiotherapy (the medicinal use of honeybee products) may result in an anaphylactic reaction in people who are allergic.
  • Allergy shots given by an allergy specialist also contain venom but are specifically designed to be given to allergic people to reduce their sensitivity to the allergen.

 http://www.emedicinehealth.com/allergy_insect_sting/article_em.htm 

Diagnostics

If you are concerned that you may have an allergy to insect venom, see an allergist.

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Your allergist should take a detailed medical history, including questions about previous stings (how many there have been and where you were stung), your reaction to those stings (what you experienced, how long the reaction lasted and what you did to get relief) and any additional symptoms.

Your allergist may diagnose an allergy to insect venom through a skin-prick test, a blood test or an intradermal skin test.

In the skin-prick test, a small amount of a liquid containing insect venom is placed on the back or forearm, which is then pricked with a small, sterile probe to allow the liquid to seep into the skin. If a raised, reddish spot forms within 15 to 20 minutes, that can indicate an allergy. In the blood test, a blood sample is sent to a laboratory to test for the presence of immunoglobulin E (IgE) antibodies to insect venom.

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If the results are inconclusive (for example, if your skin-prick or blood test is negative, but your medical history indicates that you have had an allergic reaction), your allergist will likely recommend an intradermal skin test, in which a small amount of venom extract is injected just under the skin. The site is examined after about 15 minutes for signs of an allergic reaction. This test is considered more accurate than the skin-prick or blood tests in determining the presence of IgE antibodies.

The strength of a reaction to a skin or blood test does not indicate how severe your allergic reaction will be the next time you are stung.

http://acaai.org/allergies/types/insect-sting-allergies

Treatment 

Bees, wasps, hornets and yellow jackets are found throughout the United States and are most active during late summer and early fall. The red or black fire ant, found mainly in the southern United States, is a serious health hazard year-round. Avoidance of insect stings is the first line of defense. Here are some proven strategies:

  • Don’t walk barefoot in the grass, where stinging insects forage.
  • Don’t drink from open soft drink cans; stinging insects are attracted to them and may crawl inside.
  • Keep food covered when eating outdoors.
  • Don’t use sweet-smelling perfume, hairspray or deodorant.
  • Avoid wearing brightly colored clothing with flowery patterns.
  • Wear long pants, long-sleeved shirts, socks, shoes and work gloves when working outdoors.
  • Be cautious near bushes, eaves and attics, and avoid garbage containers and picnic areas.
  • Have a professional exterminator remove known nests and inspect for other potential nesting areas.

For emergency treatment, an allergist can prescribe and give instructions on how to use an epinephrine auto-injector. A person who has had a systemic allergic reaction to an insect sting has an increased risk of having a similar or worse reaction if stung again and should always have two epinephrine auto-injectors close at hand. The risk of an allergic reaction can persist for a long time, even when the systemic allergic reaction was many years earlier.

Epinephrine is the only approved treatment for anaphylaxis. A delay in using epinephrine has been shown to increase the risk of death. For long-term protection, an allergist can treat the allergic person with allergy shots (immunotherapy), which build tolerance over time through gradually increasing doses of purified insect venom. Venom immunotherapy significantly reduces the risk of a systemic reaction to future stings. The length of venom immunotherapy is usually three to five years, but it can be continued indefinitely depending on the severity of past reactions and the risk to the patient of future stings.

Fire ant sting allergy treatment

Fire ant sting allergy is treated in a two-step approach:

  • The first step is the emergency treatment of the symptoms of a serious reaction when they occur;
  • The second step is preventive treatment of the underlying allergy with whole body extract immunotherapy.

Life-threatening allergic reactions can progress very rapidly and require immediate medical attention. Emergency treatment usually includes administration of certain drugs, such as epinephrine, antihistamines, and in some cases, corticosteroids, intravenous fluids, oxygen and other treatments. Once stabilized, these patients sometimes require close observation in the hospital overnight.

Injectable epinephrine is often prescribed as emergency rescue medication for treating an allergic reaction. People who have had previous allergic reactions and rely on epinephrine must remember to carry it with them at all times. Also, because one dose may not be enough to reverse the reaction, immediate medical attention following a fire ant sting is recommended.

What is a normal reaction to a fire ant sting, and how is it treated?

The severity of a fire ant sting reaction varies from person to person. One of the main differences between fire ants and other insects is that a usual sting event consists of multiple fire ants stinging. This is because when a fire ant mound is disturbed hundreds to thousands of fire ants respond. In addition, each ant can sting repeatedly. Each ant will bite and hold on with its mandibles (jaw) and sting several times. If not removed, this results in a little semi-circular pattern of stings. Since fire ants hold on with their mandibles, they often have to be pulled off individually and are not easily brushed off when they are stinging.

Almost all people stung by fire ants develop an itchy, localized hive or lump at the sting site, which usually subsides within 30 to 60 minutes. This is followed by a small blister within four hours. This usually appears to become filled with pus-like material by eight to 24 hours. However, what is seen is really dead tissue, and the blister has little chance of being infected unless it is opened. When healed, these lesions may leave scars.

Fire ant sting treatment is aimed at preventing secondary bacterial infection, which may occur if the pustule is scratched or broken. Clean the blisters with soap and water to prevent secondary infection. Do not break the blister. If a blister is accidently opened, careful attention to keeping the area clean with soap and water should still prevent infection. Topical corticosteroid ointments and oral antihistamines may relieve the itching associated with these reactions.

What is whole body extract immunotherapy?

The long-term treatment of fire ant sting allergy is called whole body extract immunotherapy, that contains the entire body of the ant, not just the venom, as is the case with other stinging insects. It is a highly effective program administered by an allergist-immunologist, which can prevent future allergic reactions to fire ant stings. At this time, we are not able to milk venom from fire ants.

Whole body extract immunotherapy involves administering gradually increasing doses of extract to decrease a patient’s sensitivity to the fire ant sting. This can reduce the risk of a future allergic reaction to that of the general population. In a matter of weeks to months, people who previously lived under the constant threat of severe reactions to fire ant stings can return to leading normal lives.

If you think you might be allergic to fire ant stings, see an allergist. Based on your past history and certain tests, the allergist will determine if you are a candidate for skin testing and immunotherapy.

http://acaai.org/allergies/types/insect-sting-allergies

Prophylaxis

Take precautions to avoid insect stings in the future.

  • Avoid nests or hives of stinging insects.
  • Do not wear bright clothing or perfumes that might attract bees and wasps.
  • Remain calm and quiet around flying insects. Move slowly.
  • Take special care when around food or drinks outdoors, as at cookouts or picnics. Stinging insects are attracted to foods, especially sweet foods such as soft drinks.

Evaluation by an allergist for desensitization injections has been shown to be of benefit.

Obtain one or more epinephrine injection kits if this has been prescribed for you.

  • Keep the kit(s) in convenient locations and have one near you at all times.
  • Read the instructions right away and review them often.
  • It is important that you be able to get to the kit and use it quickly in case of a reaction.
  • Make sure your family members and closest friends know how to use the kit as well.
  • Any time this device is used, you must go immediately afterward to your health care provider or to a hospital emergency department.

Useful advice

For most insect stings, home care is all that is necessary.

  • If insects are on or around you, remain calm.
    • Gently brush any insects from your skin.
    • Quietly leave the area as quickly as you can.
  • If the stinger is still lodged in the skin, as it usually is after honeybee stings, it should be removed promptly.
    • You can do this by scraping the site with a credit card or similar device, perpendicular to the skin. A fingernail can be used.
    • Pinching the stinger to pull it out is not advised, because this may inject more venom.
  • Control local swelling
    • Elevate the part of the body where the sting is located.
    • Apply ice to the area of the sting.
    • If the sting is on the hands or feet where rings or other tight-fitting jewelry is worn, these should be removed immediately before swelling develops, to avoid any compression of the blood supply to these areas.
  • Control pain: Ibuprofen (Advil) or acetaminophen (Tylenol) is usually sufficient to relieve pain.
  • Treat the itch
    • Take an antihistamine pill, such as diphenhydramine (Benadryl). This helps counteract one of the mediators of the reaction and will help control itching. Diphenhydramine is available without a prescription. Caution – this medication makes most people too drowsy to drive or operate machinery safely. It can be taken every 6 hours for the first few days, until the swelling begins to improve.
    • Hydrocortisone cream, available over-the-counter, can be applied to the site of the insect sting to relieve itching.
    • A paste of baking soda or salt and water, rubbed on the skin, may provide relief.
    • An over-the-counter lotion such as Calamine can help.
    • If a blister develops at the site, keep the area clean but do not break the blister.

Do not be alarmed if the reaction takes 2-5 days to heal. Continue treatment until all symptoms are gone.

For more severe reactions, self-treatment is not recommended. Call your health care provider or 911, depending on the severity of your symptoms. Do not attempt to drive yourself. If no one is available to drive you right away, call for an ambulance. If you have symptoms of anaphylaxis, here’s what you can do while waiting for the ambulance:

  • Try to stay calm.
  • Remove yourself from the area where the insects are.
  • Take an antihistamine (1-2 tablets or capsules of diphenhydramine [Benadryl]) if you can swallow without difficulty.
  • If you are wheezing or having difficulty breathing, use an inhaled bronchodilator such as albuterol (Proventil) or epinephrine (Primatene Mist) if one is available. These inhaled medications dilate the airway.
  • If you are feeling light-headed or faint, lie down and raise your legs higher than your head to help blood flow to your brain.
  • If you have been given an epinephrine kit, inject yourself as you have been instructed. The kit provides a premeasured dose of epinephrine, a prescription drug that rapidly reverses the most serious symptoms (see Follow-up).
  • Bystanders should administer CPR to a person who becomes unconscious and stops breathing or does not have a pulse.
  • If at all possible, you or your companion should be prepared to tell medical personnel which medications you have taken today, which you usually take, and any known allergies.

Outcome 

Prompt treatment usually avoids any short-term complications, but any delay in the treatment of a severe allergic reaction can result in rapid deterioration and death.

The long-term outlook is usually good as well. Local infection at the sting site can occur but is rare.

Arthritis, kidney failure, or nervous system disorders are late complications of a sting (weeks or possibly months later).

  • This is extremely rare.
  • If you have joint pain or swelling, urinary problems, or unexplained numbness, tingling or burning sensation, or pain in the weeks after an insect sting, you should see your health care provider.

If you develop anaphylactic shock following an insect sting, you are at an increased risk of developing anaphylaxis in the future if you are stung again.

http://www.emedicinehealth.com/allergy_insect_sting/page9_em.htm#outlook

Complications

In rare cases, wasp stings can contribute to complications involving the nervous system. A report by Annals of Tropical Medicine and Public Health examined unusual cases in which a pediatric patient experienced muscle weakness, pupil dilation, and motor aphasia following a wasp sting. Motor aphasia is the impairment of speech and writing abilities. The patient’s problems were precipitated by a blood clot that was caused by a severe reaction to a wasp sting. These particular complications are extreme and highly unlikely to occur.

http://www.healthline.com/health/wasp-sting#Treatment4

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