Fire Ant Allergy

Fire ants are stinging insects that can attack with little warning and without being provoked. However, they are more likely to swarm and sting when their nests or mounds are disturbed. These insects live in many locations around the world. In the United States, they are widespread in Southeastern United States, as far north as Kentucky and as far west as California.

Fire ants bite with their jaws and attach to the skin. They can then rotate and sting several times with their back stinger in a matter of seconds. Fire ants can leave a semi-circle pattern of multiple stings. Stings are most common during the summer months, although they can occur year-round.

When a fire ant stings, its stinger injects venom into the skin. Their sting can cause a painful, burning feeling, followed by a small blister.

What Is Fire Ant Allergy?

When a fire ant stings, its stinger injects venom into the skin. The venom of the fire ant contains a small number of proteins that are allergens for many people. An allergen is a substance that causes an allergic immune reaction.^1,2

Fire ants are aggressive and known to swarm and sting any living human or animal they come into contact with. Children are most commonly stung by fire ants, usually on the legs and feet. People with limited mobility are also at risk because they may have difficulty moving away from the ants.¹

What Are the Symptoms of Fire Ant Allergy?

Fire ant stings and bites are associated with some typical non-allergic symptoms, localized at the sting site. These are normal reactions and include:^1,3

• Immediate pain and burning which lasts about 10 minutes.
• A hive-like bump that looks like a red spot with a raised white center. This occurs at the sting site within 30 minutes.
• Blisters at the sting site within 4 hours that develop into pustules (pimples with yellow fluid) within 24 hours. These pustules are characteristic of fire ant stings and cause an intense itch. Usually, they open on their own within 3 days and dry up. They can last for up to a week.
• Redness.
• Local reactions are usually confined to a small area at the sting site.

Some people may experience a large local reaction:

• Swelling which may become severe and interfere with function if it crosses the wrist or ankle after hand or foot bites
• Swelling that affects an area larger than 10 centimeters around the sting site. These large local reactions are often associated with an intense pain and itch that can last for 5 or more days

Serious allergic reactions can occur. These are systemic reactions, called anaphylaxis [anna-fih-LACK-sis]. Anaphylaxis can progress rapidly. It usually occurs in people who have been stung in the past. Typical symptoms of anaphylaxis include:^1,4

• Itching (beyond the local sting site)
• Hives (beyond the local sting site)
• Swelling of the throat or tongue
• Difficulty breathing
• Flushing (sudden redness or warm feeling of the skin)
• Dizziness
• Stomach cramps, nausea, or diarrhea

Other less common symptoms of anaphylaxis include:

• Rapid fall in blood pressure
• Shock
• Loss of consciousness

What Is the Treatment for Fire Ant Sting Allergy?

Most ant stings only need supportive care with over-the-counter medicine. Applying a corticosteroid [kor-tick-OH-stair-ROID] (usually hydrocortisone) or an antihistamine cream to the sting site is usually enough to relieve the localized symptoms such as itching and swelling. A pain reliever (such as acetaminophen or ibuprofen) may also be helpful for the pain. The localized pain and swelling may also be improved by applying a cold compress.^1,3

The blisters formed at the sting site are sterile (free of microbes), but they may become infected if scratched or opened. If a blister breaks open, it should be cleaned with water and soap, and an antibiotic cream should be applied at the site to prevent skin infections.^1,3

Oral corticosteroids, usually prednisone, may be prescribed by your doctor to manage large local reactions.¹

Prognosis (how well a person will do) is usually very good for people who get stung by fire ants, and most cases do not need medical assistance. However, some reactions may become severe and cause systemic reactions such as anaphylaxis. If you experience symptoms like severe chest pain, nausea, shortness of breath, severe swelling in areas other than the sting, or slurred speech, you should immediately seek medical care.¹

Epinephrine [ep-uh-NEF-rin] can reverse severe systemic reactions and is the most important treatment available for anaphylaxis. If you have a severe allergy to insect bites or stings, you should carry epinephrine and understand how and when to use it. You should also consider wearing a medical identification bracelet or necklace containing information about your allergy.^1,4

Your allergist may consider immunotherapy [eh-mu-no-THER-ah-pee] (allergy shots). Allergy shots contain small doses of your allergen. Immunotherapy for the fire ant allergy uses an extract of the whole body of the ant, which has been shown to be effective in treating the fire ant allergy. This approach allows your body to build an immunity to the allergen and results in an effective and safe long-term treatment for the fire ant allergy for most patients. Immunotherapy helps prevent or reduce the severity of allergic reactions.⁴

How Do Doctors Diagnose Fire Ant Allergy?

To diagnose a fire ant allergy, your doctor may give you a physical exam and discuss your symptoms and your history of allergic reactions to stings. The development of a typical blister at the sting site within 24 hours is characteristic of a fire ant sting and can help with the diagnosis. The identification of the ant can also be helpful.¹

If your doctor thinks you have a fire ant allergy, they may suggest a skin or blood test.^1,4

Skin prick test (SPT) – In prick/scratch testing, a small drop of the possible allergen is placed on your skin. Then the nurse or doctor will lightly prick or scratch the spot with a needle through the drop. If you are allergic to the substance, you will develop redness, swelling, and itching at the test site within 20 minutes. You may also see a wheal. A wheal is a raised, round area that looks like a hive.

Specific IgE blood test – Blood tests are helpful when people have a skin condition or are taking medicines that interfere with skin testing. They may also be used in children who may not tolerate skin testing. Your doctor will take a blood sample and send it to a laboratory. The lab adds the allergen to your blood sample. Then they measure the amount of IgE antibody your blood produces to attack the allergens. This test is called specific IgE (sIgE) blood testing (also known as RAST or ImmunoCAP testing).¹

How Can I Prevent Allergic Reactions to Fire Ants?

If you have a known allergy to insect bites or stings, then you should carry an easy-to-use form of epinephrine, so you can quickly treat a reaction wherever you are.¹

Also, keep in mind that the best way to prevent allergic reactions to fire ants is to avoid being stung by staying away from ant nests. If you find a nest, move away quickly. Teach your children to identify and stay away from ant nests.^3,4

Also, always be careful when lifting anything from the ground and wear gloves and socks outdoors, as fire ants cannot bite through them. Wear closed-toe shoes and consider tucking pants into socks or boots to avoid being stung or bit by fire ants.^1,4

How Can I Identify Fire Ants?

Left image: Copyright © 2023 by Mississippi State University. All rights reserved. https://extension.msstate.edu/sites/default/files/publications/publications/P2429_web.pdf

There are 2 types of fire ants, the red imported fire ant and the black imported fire ant. Red fire ants have red-brownish bodies and dark abdomens, while black fire ants have black or dark-brownish bodies and 2 golden spots on their abdomens. Red fire ants are widespread in several different states, including Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, New Mexico, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. On the other hand, black fire ants can only be found in northern Alabama, northern Mississippi, and southern Tennessee.^1,5

A strong evidence of fire ants is the existence of nests or mounds on the ground. Fire ants build their nest of dirt, and these structures may have different appearances depending on the type of soil where they are built. The mounds can vary from being flat when built in a dry and sandy soil, to reaching up to 18 inches tall when built in moist, clay-type soil. Sometimes the mounds can be difficult to see since they may be covered by the surrounding vegetation.⁴

Copyright © 2023 by Mississippi State University. All rights reserved. https://extension.msstate.edu/sites/default/files/publications/publications/P2429_web.pdf