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Insect Sting Allergies
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Fire Ant Stings
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ACAAI > Patients & Public > Allergies > Types of Allergies > Insect Sting Allergies

Fire Ant Sting Allergy

Most people are not allergic to insect stings. Recognizing the difference between an allergic reaction and a normal reaction will reduce anxiety and prevent unnecessary medical expense.

More than 500,000 people enter hospital emergency rooms every year suffering from insect stings. A severe allergic reaction known as anaphylaxis occurs in 0.5 percent to 5 percent of the U.S. population as a result of insect stings. At least 40 deaths per year result from insect sting anaphylaxis.

The majority of insect stings in the United States come from wasps, yellow jackets, hornets and bees. The red or black imported fire ant now infests more than 260 million acres in the southern United States, where it has become a significant health hazard and may be the number one agent of insect stings. While there are native fire ant species, the species that causes the most problems for us were accidentally imported to the United Stated from South America.

Fire ant sting allergy symptoms

The most serious reaction to a fire ant sting is an allergic one. This condition requires immediate medical attention. Symptoms of an allergic reaction may include one or more of the following:

  • Hives, itching and swelling in areas other than the sting site
  • Abdominal cramping, intense nausea, vomiting or diarrhea
  • Tightness in the chest and difficulty in breathing
  • Hoarse voice or swelling of the tongue or throat, or difficulty swallowing

An even more severe allergic reaction, or anaphylaxis, can occur within minutes after the sting and may be life-threatening. Symptoms may include those listed above as well as:

  • Dizziness or a sharp drop in blood pressure
  • Unconsciousness or cardiac arrest

People who have experienced an allergic reaction to a fire ant sting have a 60 percent chance of a similar or worse reaction if stung again.

Fire ant sting allergy treatment

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

1) The first step is the emergency treatment of the symptoms of a serious reaction when they occur;

2) 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 (EpiPen® or TwinJect®) for self-administration 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.

A large local reaction can occur. This will result in swelling that extends beyond the sting site. For example, a sting on the forearm could result in the entire arm swelling. Although alarming in appearance, this condition is often treated the same as a normal reaction. An unusually painful or very large local reaction may need medical attention. Because this condition may persist for two to three days, antihistamines and corticosteroids are sometimes prescribed to lessen the discomfort.

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, ask your doctor to send a consult to an allergist-immunologist, a physician who is a specialist in the diagnosis and treatment of allergic diseases. Based on your past history and certain tests, the allergist will determine if you are a candidate for skin testing and immunotherapy.

How can I avoid fire ant stings?

Knowing how to avoid stings from fire ants leads to a more enjoyable summer for everyone. Fire ants are most active from spring to fall. Insect repellents do not work against them.

Effective methods for insecticide treatment of fire ant mounds use attractant baits. These baits often contain soybean or corn meal combined with chemical agents. The bait is picked up by the worker ants and taken deeper into the mound to the queen. When the queen dies the mound will slowly disappear. It can take weeks for the mound to disappear.

Allergists-immunologists recommend the following additional precautions to avoid fire ant stings:

  • Avoid wearing sandals or walking barefoot in the grass. Shoes and socks provide protection and time to get away from a fire ant mound if stepped on accidently.
  • Yard work and gardening should be done with caution. Wearing shoes and socks and using work gloves will prevent stings on hands and feet and provide time to get away from an unexpected mound.
  • Keep prescribed medications handy at all times and follow the attached instructions if you are stung. These medications are for immediate emergency use while en route to a hospital emergency room for observation and further treatment.
  • If you have had an allergic reaction to a fire ant sting, it's important that you see an allergist-immunologist.

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