Stings can trigger deadly reactions

At least 50 people in the United States will die this year from an event that, to most of us, is no more than a minor irritation.

The sting of a honeybee, yellow jacket, hornet, paper wasp or fire ant can send a susceptible person into a state of anaphylactic shock, a potentially life-threatening allergic reaction. The reaction results when the protein in the insect's venom causes an excessive release of chemicals from a person's body, said Dr. Raquel Watkins, an allergist in Winston-Salem, N.C.

Three percent to 5 percent of people can have a potentially dangerous reaction to stings, and about 500,000 allergy- and anaphylaxis-related emergency-room visits occur each year.

Most people just feel pain and may have a little swelling when they are stung, Watkins said. People who are allergic might react more dramatically. If someone who is stung on the finger develops swelling in the entire arm, "that's concerning," she said.

That person's next sting could produce a far more violent reaction, including itching and hives all over the body, swelling in the throat or tongue, difficulty breathing, dizziness, stomach cramps, nausea, vomiting and diarrhea.

"In severe cases, someone could be found unresponsive," she said. "They're out doing the lawn, and they're just found down." A sting can cause a person to go into shock and lose consciousness.

Symptoms can develop within minutes or take several hours to appear.

The death risk from stings has gone down in recent years, said Dr. Brian Duncan, an emergency room physician in Winston-Salem, N.C. More people have become aware that they can be tested for insect allergies, and people who know that they are allergic have access to EpiPens.

EpiPens are devices that people can use to inject themselves or someone else with epinephrine, a fast-acting drug that combats the immediate consequences of anaphylactic shock.

The EpiPen should be used when someone who is stung develops difficulty breathing or other serious reactions. The epinephrine keeps the person's airway open and blood pressure up for about 30 minutes, hopefully allowing the person enough time to receive medical care.

"If you think you need your pen, inject yourself immediately, then call the ambulance," Duncan said. "By the time the ambulance gets there, you may need an additional dosage. You think you're cured, but the problem will recur, and you will be in much more trouble."

Allergies to insect stings are often determined in childhood, Duncan said, and people who know that they have them often take precautions to avoid being stung and to prepare themselves and members of their family to treat a reaction promptly. A reaction could develop so rapidly that the person who is stung is not coherent enough to administer epinephrine.

People who have stronger-than-normal reactions to a sting should be tested to see if they are allergic, Watkins said. Skin tests and blood tests can help determine the allergy, and she repeats the tests to try to get the most accurate information.

"History is the most compelling thing," Watkins said. "Our tests are not perfect."

Recently, the most worrisome sting reactions that Duncan has seen were adults who didn't know they were allergic, had stumbled into a yellow-jacket nest and received multiple stings.

Yellow jackets tend to be aggressive, especially when their nests are disturbed, Duncan said. Although some people could receive 50 stings and suffer nothing more than typical reactions at the sting sites, others will become seriously ill within minutes.

People who are allergic to stings can be treated with venom immunotherapy, the injection of small amounts of venom over a long period of time, which can allow them to build up tolerance. Some doctors advocate continuing the therapy through a person's life; others recommend trying it for five years, then reassessing the situation, Watkins said. Injections are given about once a month. The time-consuming treatment can be worth it for people who spend a lot of time outdoors.

People who know that they are allergic to stings should exercise caution when they work or play outdoors, Watkins said. They should avoid wearing bright colors and sweet scents that attract insects and wear closed-toe shoes to walk in the yard. Loose clothing could allow a bee or wasp to fly inside, so wear clothes that fit close to the body.

At picnics or cookouts, cover sweet drinks and food to avoid attracting insects, and don't take a swig from a canned sugary drink that has been left uncovered.