Stinging Insect Allergy and Avoidance

The Asthma Center, Allergic Disease Associates, P.C.
Professional Arts Building
205 North Broad Street, Ste 300
Philadelphia, PA 19107

215-569-1111
http://www.asthmacenter.com

WHICH INSECTS CAUSE ALLERGY?

An insect bite can result in an allergic reaction, skin irritation, or in some cases, in infection. When insects bite human skin (like mosquitoes, fleas, stable flies, black flies and lice, but not ordinary house flies) their saliva or body produces reactions by contact with the skin.

Stinging insects, on the other hand (like bees, wasps, yellow jackets and hornets), actually inject venom into the skin of their victims. In sensitive individuals (estimated to be about .4-.5% of the population), such insect stings may cause sudden allergic reactions. Although most reactions are of the mild to moderate degree, some reactions are severe and on rare occasions fatalities have been reported. In fact, it is estimated that between 40 to 100 people in the United States die each year from insect sting reactions. Therefore, knowledge about insect sting reactions, insect avoidance and treatment may help in avoiding and/or managing potentially serious reactions.

The HYMENOPTERA class of insects are the only stinging insects. However, only a few of the hymenoptera (honeybees, wasps, hornets, yellow jackets and fire ants) cause serious reactions. Overall, the yellow jacket is the most common offender followed by honeybees, wasps, and then hornets. Bumblebees rarely sting humans. The base of the stinger of hymenoptera insects is attached to a small venom filled sac. Most stinging insects except the honeybees can reuse their stingers, inflicting multiple venom injections. In contrast, the honeybees stinger is barbed so when it tries to remove its stinger from the skin, both the stinger and venom sacs are torn off and left in the victim. Most hymenoptera actually use their stingers in self defense, for defense of the hive or for killing other insects.

Africanized honeybees (known as Killer Bees) are a tropical variety of honeybees imported from Africa into Brazil in 1956 to increase honey production. They invaded the southwestern United States (Texas, Arizona, New Mexico, and California) in 1990 and have been migrating northward 200-300 miles each year. These bees are much more aggressive and may swarm individuals even over long distances inflicting multiple stings (8-10 times more than other honeybees) in defense of their hives. They warrant greater caution if encountered. Their presence in our area is still limited.

The imported fire ant (Solenopsis invieta, black and red) is another venomous insect known to cause severe allergic reactions. It gets its name from the intense burning and itching at the site of the sting. Fire ants were accidentally introduced to Mobile, Alabama in the 1930’s from South America and now are found in over twelve states ranging from south Atlantic seaboard, southern and southwestern United States (25%). Severe allergy reactions (anaphylaxis) have been reported from 0.6% to 16% of those stung with more than 80 deaths reported. While this insect is presently not found in the northeastern United States, it is spreading northward at about 120 miles per year.

WHAT KINDS OF REACTIONS ARE THERE TO STINGING INSECTS?

Local Reaction
For most individuals, insect stings cause immediate local reactions at the sting site and produce a temporary discomfort of redness, pain, itching, and swelling lasting only a few hours. A large local reaction may be more painful with itching and swelling at the sting site and in surrounding areas that may last for a few days. For these latter two reactions, local skin care and occasional oral antihistamines, corticosteroids and perhaps antibiotics may be required for relief. These reactions, however, do not necessitate venom skin testing and/or desensitization injections with venom extracts.
In a small number of people, a severe allergic reaction involving the entire body, remote from the sting site, can occur very rapidly. In children less than 16, a generalized hive reaction confined to the skin does not necessarily require skin testing or desensitization injections. However, in individuals 16 and older, this same reaction DOES require venom skin testing evaluation.

A very severe reaction called anaphylaxis may occur causing symptoms of dizziness, weakness, stomach pains, diarrhea, wheezing, difficulty breathing and hives. Because blood pressure may quickly fall during these reactions, immediate medical attention is required. Since this type of reaction is potentially fatal and effective injection therapy is available, all individuals with a history of insect sting anaphylaxis must undergo insect venom testing.

AVOIDANCE INSTRUCTIONS

Individuals allergic to stinging insects should avoid exposure to such insects. A few simple precautions can decrease one’s chance of being stung. The following list of avoidance maneuvers should be reviewed each spring season.
 

  1. When a stinging insect approaches it is best to try to stay still. Never slap or brush off an insect. These insects will not sting unless frightened or antagonized.
  2. Avoid wearing scents (perfumes, hair sprays, fragranced cosmetics and suntan lotion) which often attract insects. Eating or cooking outdoors, open garbage cans and/or fallen fruits or foods rotting on the ground can attract hymenoptera insects. Highly sensitive individuals should not eat outdoors when possible. never drink out of an open can or bottle without first inspecting for the presence of a stinging insect. Keeping food covered outdoors until eating, cleaning around garbage areas, burning insect repellant candles and spraying the patio and garbage cans with a wasp and hornet insecticide will help keep these insects away.
  3. Clothing – Wear shoes outdoors at all times; closed shoes are preferable to sandals. Loose fitting clothing may trap insects and should be avoided. Bright colored, flowery clothing seems to attract insects more than white, green, tan, or khaki. Shiny jewelry will also draw insects to people.
  4. Gardening should be done cautiously. Stay away from scented flowers which may attract insects. Accidentally disturbing a wasp hive in a tree or house eave or mowing over a yellow jacket hive can provoke these insects. Vines which may conceal hives should be removed from the house. Removal of a hive should be done by an exterminator or someone known not to be allergic to insect venom. The home and garden should be periodically inspected for new hives. For example wasps typically build open-comb hive under leaves, in shrubs, or in wood planters. Yellow jacket hives are usually located in underground burrows, between cracks of rock walls or between walls of framed buildings. Hornets build gray football-shaped hives usually in shrubs or trees. Honeybees are found in commercial hives but may be found in hollow tree limbs or between the outside walls of buildings.
  5. Stinging insects often find their ways into cars. It is a good idea to carry a wasp and hornet insecticide in the car with a 20 foot spraying range, as well as some cheese cloth to trap the insects.

Unfortunately there are no effective repellents one can preventively spray on the skin that will discourage these insects from approaching.

What should you do if you are stung?

If you are attacked by Africanized honeybees, cover your face with your arms and run away from the direction the bees are coming from. Even a car with the air conditioning on will provide good shelter. It is advisable that you call 911 since anyone who is stung by a large number of bees (greater than 50) should be evaluated in the emergency room.

If you are stung by a honeybee, the stinger and venom sac remain attached in your skin. Venom continues to be released from the sac for 2-3 minutes after the sting, so removing the sac may lesson the severity of the reaction. To remove the venom sac (looks like a tiny splinter) scrape the spot with your fingernail. Do not grab the stinger or squeeze it between your fingers since it will inject more venom into the wound.

All insect stings should be washed thoroughly with soap and water, and antiseptic should be directly applied to the site. Cold compresses for 15-20 minutes followed by Calamine lotion will reduce swelling and itching. Taking an oral antihistamine may also reduce itching. Large local reactions may require treatment with corticosteroids such as Prednisone. Meat tenderizer in the wound is not recommended and may lead to increased inflammation.

If you notice signs of an allergic reaction such as widespread swelling, chest tightness, or dizziness, you should get medical attention immediately. If you have been instructed to carry epinephrine (Epi-Pen or Twinject), you should self-inject it according to the instructions (see anaphylaxis sheet.) This medication should be carried at all times and is best kept in multiple sites like the home, car, workplace, and on your person. Convenient Epi-Pen or TwinJect kits with prednisone, antihistamines, and full instructions are available through The Asthma Center. Epinephrine is susceptible to extreme temperature fluctuations and light and should be stored properly.

If the sting is on the arm or leg, use a handkerchief or cloth strip as a tourniquet and apply it 2-5” above the site. This band should be snug but not too tight. You should be able to slip a finger under it. Keep the sting area below the heart level an loosen the tourniquet for a few seconds every 3-5 minutes.

Other medications that may be helpful to you for repeat reactions will be reviewed with you. Since most highly sensitive individuals with positive venom skin tests are susceptible to severe allergic reactions, we recommend many of these individuals be treated with venom injections. This form of therapy is effective in greater than 95% of individuals.

Is is advisable for those who have had severe reactions to stinging insects to carry or wear an ID bracelet identifying him/her as a person sensitive to hymenoptera. These can be obtained from the MedicAlert Foundation (888) 633-4298 or www.medicalert.org.

Printed with permission from The Asthma Center, Copyright 2008.