i70 Fire ant

Allergens within Insects

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  • Latin name: Solenopsis invicta
  • Family: Myrmicidae
  • Source material: Whole insect bodies
The name fire ant comes from the pain that occurs soon after stinging.

Allergen Exposure

Exposure is by venom through stings from disturbed insects. The fire ant was unintentionally imported into Alabama, US from South America (1). The mounds can be found in lawns, beside walks and in rods in fields (2). Solenopsis species are found over most of the tropical and temperate parts of the world, including Central-Europe, Central Asia, Pacific Asia, Africa, Australia and the Pacific Islands.

Potential Cross-Reactivity

Cross-reactivity is reported with venom of other Solenopsis species (3) as well as with venoms of other Hymenoptera (4).

Clinical Experience

Serious systemic allergic reactions occur in about 2% of fire ant sting patients who seek medical care (2, 5). Fire ant stings have been reported to cause life-threatening and even fatal anaphylaxis. It can manifest as flushing, urticaria, angiodema laryngeal endema, bronchospasm or loss of consciousness (2, 6).
 
Review
Exposure is by venom through stings from disturbed insects. The fire ant was unintentionally imported into Alabama, US from South America (1). The mounds can be found in lawns, beside walks and in rods in fields (2).

Solenopsis species are found over most of the tropical and temperate parts of the world, including Central-Europe, Central Asia, Pacific Asia, Africa, Australia and the Pacific Islands. The name fire ant comes from the pain that appears soon after the stinging. The ants are aggressive and they bite the victim with their mandible and insert the stinger, located on the ant’s back, on average seven or eight stings in a circular pattern. The site developes a wheal and flare rection. Later, a sterile pustule appears due to the alkaloid components of the venom (2). Serious systemic allergic reactions occur in about 2% of fire ant stin patients who seek medical care (2, 5). Fire ant stings have been reported to cause life threatening, and even fatal anaphylaxis. It can manifest as flushing, urticaria, angiodema laryngeal endema, bronchospasm or loss of consciousness (2, 6).
 
As mentioned above, cross-reactivity is reported with venom of other Solenopsis species (3) as well as venoms of other Hymenoptera (4). Fire ant venom is unique because of its low protein content and high concentration of piperidine toxins consisting of 90-95% water insoluble alkaloids (6).
 
Four major protein allergens have been isolated and characterized (7);
  • Sol i1 approx. 37 kD, a phospolipase of vespid venom type is supposed to cross-react with sera from many veslid allergic patients, 2-5 % of venom protein.
     
  • Sol i2 approx. 26 kD, disulfide-bounded dimeric protein, 67% of venom protein
     
  • Sol i3 approx. 24 kD, a member of the antigen 5 family of venom proteins but does not show any significant cross-reaction with antigen 5 from other vespids, 20% of venom protein.
     
  • Sol i4 approx. 13 kD, 9% of venom protein.

Sol i2 and i4 are not similar to any other known proteins. 

References:

    1. Lofgren CS, Banks WA, Glancey BM. Biology and control of imported fire ants. Ann Rev Entomol 1975;20:1-30.
    2. Hoffman DR. Fire and venom allergy. Allergy 1995;50:535-44.
    3. Baer H, Liu T-Y, Anderson MC, Blum M, Schmid WH, James FJ. Protein components of fire ant venom (Solenopsis invicta). Toxicon 1979;17:397-405.
    4. Hoffman DR, Dove DE, Moffitt JE, Stafford CT. Allergy in Hymenoptera venom. XXI. Cross-reactivity and multiple reactivity between fire ant venom and bee and wasp venoms. J Allergy Clin Immunol 1988;82:828-34.
    5. Stafford CT, Hutto LS, Rhoades RB, Thompson WO, Impson LK. Imported fire ant as a health hazard. South Med J 1989;82:1515-9.
    6. Stafford CT. Hypersensitivity to fire ant venom. Ann Allergy Asthma Immunol 1996;77:87-99.
    7. Hoffman DR. Reations to less common species of fire ants. J Allergy Clin Immunol 1997;100:679-83.

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