Symptoms
Fire ant stings manifest as pain, spreading redness, itching, and a burning sensation at the sting sites. A wheal develops, and within 24-48 hours a characteristic and pathognomonic pustule develops, which dries up after 2-3 weeks and can be superinfected. As with other insect bites, a large local reaction with swelling, itching, and redness may develop and last for several days. Contact with the insects is potentially life-threatening, as they inject a venom that can cause a severe allergic reaction. A single ant is enough to cause this. The venom also has cytotoxic, hemolytic, neurotoxic, insecticidal, antibacterial, and cardiodepressant properties. More than 50-100 stings can be expected to produce a toxic reaction that is fatal to small animals.
Causes
The cause of the symptoms is stings by the aggressive red fire ants and the brown-black and their hybrids. In the United States, the ants were introduced to Mobile, Alabama, via ships from their original home in South America around 1918. They spread extensively, especially in the southern states, and were further carried to Australia and China. The omnivorous insects first bite and then insert the stinger on their abdomen into the skin one or more times. In doing so, they inject a venom containing piperidine alkaloids and proteins, which is responsible for the formation of the pustule. The proteins Sol i I-IV are significant as allergens.
Prevention
Direct contact with ants should be avoided whenever possible. To prevent a severe allergic reaction, immunotherapy with a subcutaneous injection of the insecticide is possible in sensitive individuals. Insecticides, insect-growth regulators, ant poisons, biological, physical methods and other control measures are used for active control. However, eradication is difficult. For example, a single queen lays 2000 eggs per day and can rebuild a colony with between 100,000 to 250,000 workers after its destruction.
Treatment
The literature recommends not opening the pustules or they may become superinfected. Treatment of skin lesions is similar to that for other insect bites. If the reaction is mild, an antipruritic and analgesic gel or liquid can be applied. Products used include antihistamines, local anesthetics, acetic-tartaric alumina solution, essential oils (menthol, camphor), and ammonia solution 10%. Numerous products are commercially available. In a moderately severe course with extensive swelling, internally applied antihistamines, glucocorticoids and analgesics are recommended. They can be supplemented by locally applied agents and the application of cold compresses. Therapy for anaphylaxis includes epinephrine, glucocorticoids, antihistamines, beta2-sympathomimetics, oxygen, and intravenous fluids.
