Specialists in Allergy, Asthma and Sinusitis
PA: 215 569 1111
NJ: 856 235 8282
Newsletter:
Ready to schedule an appointment?
Simply call (215) 569-1111 or click to find your nearest location.
Daily pollen and mold spore counts for Tuesday, February 21, 2012
TREES: n/a
GRASSES: n/a
MOLDS: n/a
RAGWEED: n/a
OTHER WEEDS: n/a
.jpg)
We specialize in:
Drug Allergy (medication desensitization)
For more information on asthma & allergy management, click below:
Insect-sting allergy
Download physician edition
When a mosquito or fly takes a bite, the skin around the bite swells as a reaction to chemicals in the insect’s saliva. However, stinging insects actually inject a small amount of venom into the skin, that can make you itch, and if you’re allergic, you might be at risk for anaphylaxis.
What is anaphylaxis?
Anaphylaxis—a severe allergic reaction—is often triggered by substances that are injected or ingested, and thereby gain access into the blood stream. An explosive allergic reaction involving the skin, lungs, nose, throat, and gastrointestinal tract can then result. Although severe cases of anaphylaxis can occur within seconds or minutes of exposure and be fatal if untreated, many reactions are milder and can be ended with prompt medical therapy.
Stinging insects that commonly cause allergic reactions fall into two groups:
Apids – these include honeybees, bumble bees and sweat bees.
Vespids –these include yellow jackets, hornets and wasps.
Honeybees are common in the northeast, not particularly aggressive, and are prominently involved in honey production and plant pollination. Disturbing the hive often results in multiple stings, which could lead to venom toxicity or a major anaphylactic reaction. Africanized honeybees are found in the southern U.S. and are very aggressive, but fortunately, they’re not in the Delaware Valley at this time.
Yellow jackets are the most common stinging insects in our area. They primarily come out in the late summer and fall. Since these insects nest in the ground, gardening or mowing the grass can elicit a full-scale attack. They’re often uninvited guests at outdoor picnics and may swarm around people wearing bright colors or perfumes. And of course, they’ll often convene at one of their favorite hangouts—an overflowing trash can.
Hornets—the yellow jackets’ close relation—nest in hedges, and are often compelled to defend their home when a hedge needs trimming. Wasps are fewer in number in our area, but they’re not aggressive unless disturbed and prefer to build their nests under the eaves of buildings.
Hornets—the yellow jackets’ close relation—nest in hedges, and are often compelled to defend their home when a hedge needs trimming. Wasps are fewer in number in our area, but they’re not aggressive and prefer to build their nests under the eaves of buildings.
Common local reaction
Redness and swelling at the site of the sting is common, lasting a few hours or a day or two.
Anaphylactic reactions
Allergic reactions can be severe—even life threatening—but only 0.5-3% of the population suffer an anaphylactic reaction due to an insect sting. This happens most commonly in children, but adults suffer the most serious outcomes and are at the highest risk.
Most people who have an anaphylactic reaction to insect stings have no history of respiratory allergy. The worst reactions usually begin within a few minutes after the sting. Symptoms commonly include skin reactions—hives, flushing, itching, or swelling.
The most serious reactions cause any of the following: tongue/throat swelling (angioedema), shortness of breath and/or wheezing, and/or a drop in blood pressure, fainting, or vertigo. Less common symptoms involve the GI tract—abdominal cramps, diarrhea and occasionally severe uterine cramps.
Uncommon reactions
Serum sickness like disease—symptoms of swelling at the site of the sting followed some days later with symptoms of arthralgia, arthritis, general malaise, rash, lymphadenopathy, and/or fever is an uncommon immunological response to the insect sting. A bout of serum sickness following a sting increases the chance of future anaphylactic reactions after the next sting. Rarely reported allergic responses to insect stings include: nephritis, vasculitis, encephalitis and other acute neurological problems.
Mortality and insect-sting anaphylaxis
Although death can occur due to insect-sting anaphylaxis at any age, it most commonly occurs in adults. Perhaps adults are more susceptible to severe hypotension and cardiovascular shock because of underlying cardiovascular disease. Many of these individuals have had no prior history of severe insect-sting allergy. Furthermore, adults on beta-blockers carry a particular risk. The only way to objectively identify the presence of insect-sting hypersensitivity is through allergy testing. Assuming a person is currently allergic to insect stings because of a prior history of anaphylaxis can lead to a false assumption.
Some patients lose their hypersensitivity over time following documented insect sting anaphylaxis. Both allergy skin testing and the in-vitro RAST assay (blood test) are used to identify those with elevated specific IgE antibodies directed at insect venom. Allergy skin testing appears to be more sensitive than the RAST assay and has the advantage of using the same material for testing and treatment. Insect venom for testing is limited to the following insects: honey bee, yellow jacket, white face hornet, yellow hornet, fire ant, and wasp.
Insect-sting anaphylaxis recurs in 60% of patients who reported anaphylaxis from a prior sting. Therefore, it stands to reason that 40% of individuals apparently have lost their prior hypersensitivity! A positive skin or blood test to insect venom can indicate who might be at risk for a recurrence of anaphylaxis. In contrast, a negative allergy skin test and blood test for venom usually indicates that future venom anaphylaxis is unlikely.
If anaphylaxis occurs, use Epipen™ or Twinject™. These adrenaline-filled auto injectors are self-administered—children receive 0.15 mg, and adults receive 0.3 mg. Adrenaline should be administered at the first sign of an anaphylactic reaction and the patient should be transported to the emergency room immediately. If available, both an antihistamine (Benadryl) and a corticosteroid may offer some benefit after the adrenaline has been administered.
In the emergency room or a well-equipped physician’s office, patients may require I.V. fluids in large amounts, additional adrenalin, I.V. corticosteroids, oxygen, and less commonly, intubation. When it comes to insect-sting anaphylaxis, prevention is the best medicine. With insect venom immunotherapy, this life-threatening reaction is preventable in 95-100% of affected individuals.
Specific insect venom immunotherapy
Allergy injection treatment (immunotherapy) with stinging insect-venom allergen became available in 1980. These treatments for honeybee, yellow jacket, hornet, and wasp stings have effectively prevented recurrence of anaphylaxis in previously sensitive individuals. At this time, any individual with a history of systemic anaphylaxis and a positive skin test must be offered treatment with venom immunotherapy. We recommend this therapy to adults and children with a history of systemic anaphylaxis, as well as adults with skin anaphylaxis (hives) and angioedema (swelling). Venom immunotherapy consists of weekly injections of small doses of the purified venom collected from insects causing the anaphylactic reaction.
The doses increase with each injection and the patient will usually reach his or her maintenance dose (maximum dose) over a period of three to four months. Maintenance therapy is administered every four to six weeks and treatment usually lasts about five years or can be discontinued when the insect venom skin test converts to a negative test. However, there is a 10% risk of systemic reaction with each sting after discontinuation. Patients that have had severe hypotension or upper airway angioedema (swelling) should continue on venom immunotherapy indefinitely or until the venom skin test is negative, indicating that the patient has truly lost his/her hypersensitivity to the insect venom sting.
Side effects from insect venom immunotherapy
Even small amounts of insect venom in the skin can lead to a large local reaction, swollen arms, hives, or anaphylaxis including wheezing, hypotension, and/or angioedema. Slow and careful buildup of insect venom injections is effective in most cases. But when severe reactions occur, patients may require adrenaline, tourniquets, I.V. fluids, oxygen, as well as intubation equipment. Our office is also equipped with an EKG and oximeter, which will be helpful in managing severe reactions.