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Fire Ant Bites

  • Author: James P Ralston, MD; Chief Editor: Joe Alcock, MD, MS  more...
 
Updated: Oct 08, 2014
 

Background

The fire ant is a wingless member of the order Hymenoptera, which includes wasps and bees. It is a potentially lethal environmental hazard in the United States, infesting more than 310 million acres of land. Fire ants are resistant to control efforts and can overwhelm an environment. They damage farm equipment, electrical systems, irrigation systems, and land. They build mounds in sunny, open areas (eg, lawns, playgrounds, parks, golf courses) and aggressively attack anyone who disrupts their mound. See the images below.

Red imported fire ant worker. From http://fireant. Red imported fire ant worker. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Fire ant mound in lawn. From http://fireant.tamu.e Fire ant mound in lawn. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.

See Arthropod Envenomation: From Benign Bites to Serious Stings, a Critical Images slideshow, for help identifying and treating various envenomations.

Fire ants are thought to have arrived in the United States between 1918 and the 1930s from South America by ships that docked in Mobile, Alabama. They are now found throughout the Southeast and are migrating rapidly. One contributing factor to this expansion is progressive urbanization in the United States, which creates the type of disturbed habitat that the fire ants prefer.[1] Their mobility and ability to establish colonies in diverse habitats makes the detection of new infestations difficult. Sometimes, colonies exist several years before detection.

Each year, fire ants sting more than one half of the population in endemic areas of the Southeast. They cause a variety of medical problems, including increasing numbers of hypersensitivity reactions, secondary infections, neurologic complications, and even death.[2]

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Pathophysiology

The fire ant uses its mandibles to grasp its victim. It arches its body and drives an abdominal stinger into the skin to release venom. If not quickly removed, it then pivots around its mandibles and inflicts further stings in a circular pattern.

The stinger is a modified ovipositor that consists of a dorsal stylet and 2 ventrolateral lancets. These structures surround the venom canal, which connects to the venom sac. A pair of coiled glands produces the venom that discharges into the venom sac. See the image below.

Venom sac and stinger of a fire ant. From http://f Venom sac and stinger of a fire ant. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.

Fire ant venom differs from bee and wasp venom, which are mostly proteinaceous solutions. About 95% of fire ant venom is water-insoluble, is nonproteinaceous, and contains dialkylpiperidine hemolytic factors. These hemolytic factors induce the release of histamine and other vasoactive amines from mast cells, resulting in a sterile pustule at the sting site. These alkaloids are not immunogenic, but their toxicity to the skin is believed to cause the pustules to form.

The venom also contains several allergenic proteins, measuring about 1.5% by dry weight. Four major allergenic proteins exist; Soli 1-4 induce immunoglobulin E (IgE) responses, including anaphylaxis, in patients who are allergic. Antigenic similarity exists between these proteins and bee and wasp venoms.

Many patients have venom-specific IgE-mediated wheal and flare reactions that develop over hours into pruritic edematous, indurated, and erythematous lesions that persist for up to 72 hours. These lesions may involve an entire extremity. They histologically resemble late-phase mast cell–dependent reactions and show an infiltrate of eosinophils, neutrophils, and fibrin deposition. Large, local reactions rarely can cause edematous tissue compression, leading to vascular compromise of an extremity.

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Epidemiology

Frequency

United States

Because most fire ant stings are not severe enough to cause the victim to seek medical attention, estimating the frequency of stings is difficult; however, annually, more than one half of the population in endemic areas is stung, and the incidence appears to be increasing.

See the image below.

Imported fire ant national distribution map. From Imported fire ant national distribution map. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.

Mortality/Morbidity

Fire ants are becoming an increasingly important public health concern in the United States. More than 80 fatalities have been reported from fire ant-induced anaphylaxis.

Race

Fire ant stings may occur in people of any race. No race has been shown to have an increased risk of being stung or to have a higher predisposition to complications.

Sex

Fire ants sting both males and females without discrimination.

Age

Fire ants sting people of all ages, but children are overrepresented, probably because of greater environmental exposure.

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Contributor Information and Disclosures
Author

James P Ralston, MD President, Dermatology Center of McKinney

James P Ralston, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, Texas Medical Association

Disclosure: Nothing to disclose.

Coauthor(s)

Ronald P Rapini, MD Professor and Chair, Department of Dermatology, The University of Texas MD Anderson Cancer Center; Distinguished Chernosky Professor and Chair of Dermatology, Professor of Pathology, University of Texas McGovern Medical School at Houston

Ronald P Rapini, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Society for Investigative Dermatology, Texas Medical Association

Disclosure: Received royalty from Elsevier publishers for independent contractor; May receive consulting fee from FDA panel for consulting in future, since I am on one of their committees, but at this time so far have received zero from FDA.

Specialty Editor Board

Michael J Wells, MD, FAAD Associate Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine

Michael J Wells, MD, FAAD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, Texas Medical Association

Disclosure: Nothing to disclose.

Jeffrey J Miller, MD Associate Professor of Dermatology, Pennsylvania State University College of Medicine; Staff Dermatologist, Pennsylvania State Milton S Hershey Medical Center

Jeffrey J Miller, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Society for Investigative Dermatology, Association of Professors of Dermatology, North American Hair Research Society

Disclosure: Nothing to disclose.

Chief Editor

Joe Alcock, MD, MS Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center

Joe Alcock, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Daniel J Hogan, MD Clinical Professor of Internal Medicine (Dermatology), Nova Southeastern University College of Osteopathic Medicine; Investigator, Hill Top Research, Florida Research Center

Daniel J Hogan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Contact Dermatitis Society, Canadian Dermatology Association

Disclosure: Nothing to disclose.

References
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  2. Hoffman DR. Ant venoms. Curr Opin Allergy Clin Immunol. 2010 Aug. 10(4):342-6. [Medline].

  3. More DR, Kohlmeier RE, Hoffman DR. Fatal anaphylaxis to indoor native fire ant stings in an infant. Am J Forensic Med Pathol. 2008 Mar. 29(1):62-3. [Medline].

  4. Smith KE, Fenske NA. Cutaneous manifestations of alcohol abuse. J Am Acad Dermatol. 2000 Jul. 43(1 Pt 1):1-16; quiz 16-8. [Medline].

  5. Ford JL, Dolen WK, Feger TA, Hoffman DR, Stafford CT. Evaluation of an in vitro assay for fire ant venom-specific IgE. J Allergy Clin Immunol. 1997 Sep. 100(3):425-7. [Medline].

  6. Jerrard DA. ED management of insect stings. Am J Emerg Med. 1996 Jul. 14(4):429-33. [Medline].

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  8. deShazo RD. My journey to the ants. Trans Am Clin Climatol Assoc. 2009. 120:85-95. [Medline]. [Full Text].

  9. [Guideline] Moffitt JE, Golden DB, Reisman RE, Lee R, Nicklas R, Freeman T, et al. Stinging insect hypersensitivity: a practice parameter update. J Allergy Clin Immunol. 2004 Oct. 114(4):869-86. [Medline]. [Full Text].

  10. Williams DF, deShazo RD. Biological control of fire ants: an update on new techniques. Ann Allergy Asthma Immunol. 2004 Jul. 93(1):15-22. [Medline].

  11. Lee YC, Wang JS, Shiang JC, Tsai MK, Deng KT, Chang MY. Haemolytic uremic syndrome following fire ant bites. BMC Nephrol. 2014. 15:5. [Medline].

  12. Burroughs R, Elston DM. What's eating you? Fire ants. Cutis. 2005 Feb. 75(2):85-9. [Medline].

  13. Champion RH, Burton JL, Burns DA. Rook/Wilkinson/Ebling Textbook of Dermatology. 6th ed. London, England: Blackwell Science; 1998. Vol 2: 1436-7.

  14. Cotran RS, Kumar V, Collins T, eds. Robbins Pathologic Basis of Disease. 6th ed. Philadelphia, Pa: WB Saunders; 1999. 1212.

  15. Dambro MR, Griffith JA. Griffith's 5-Minute Clinical Consult. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999. 570-1.

  16. Ellis AK, Day JH. Clinical reactivity to insect stings. Curr Opin Allergy Clin Immunol. 2005 Aug. 5(4):349-54. [Medline].

  17. Freedberg IM, Eisen AZ, Wolff K, eds. Fitzpatrick's Dermatology in General Medicine. 5th ed. New York, NY: McGraw-Hill; 1999. Vol 2: 2693-5.

  18. Odom RB, James WD, Berger TG. Andrews' Diseases of the Skin: Clinical Dermatology. 9th ed. Philadelphia, Pa: WB Saunders; 2000. 559.

  19. Rakel RE. Conn's Current Therapy 2000. 52nd ed. Philadelphia, Pa: WB Saunders; 2000. 753-5.

 
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Imported fire ant national distribution map. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Red imported fire ant worker. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Fire ant mound in lawn. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Venom sac and stinger of a fire ant. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Fire ant worker biting and stinging. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Pustules and blisters formed following fire ant stings on the arm. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Pustules and blisters formed following fire ant stings on the hand. From http://fireant.tamu.edu. Reproduced with permission from B.M. Drees, Texas Imported Fire Ant Project Coordinator, Texas A&M University, College Station, Texas.
Fire ant bites on the foot.
 
 
 
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