Fire Ant Bites Workup

Updated: Jul 12, 2022
  • Author: James P Ralston, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Laboratory Studies

Laboratory studies are not necessary for most people with fire ant stings; however, in severe reactions, a CBC count, coagulation studies, and a urinalysis could be obtained for the following uncommon but possible manifestations:


Other Tests

Skin testing, enzyme-linked immunosorbent assay (ELISA), and radioallergosorbent testing (RAST) can be used to confirm a clinical history of fire ant hypersensitivity.

A venom ELISA assay has demonstrated equivalent sensitivity to venom RAST and is less expensive. [12] Reagents containing venom proteins are required for these tests. Because pure venom vaccines are not commercially available, whole-body extracts are used.

Patients without a clinical history of allergic reactions to fire ants should not be tested because of the high degree of asymptomatic IgE production in an exposed population.


Histologic Findings

The histologic findings depend on the stage of evolution of the lesion. In early lesions, a perivascular infiltrate of lymphocytes, neutrophils, and eosinophils is found within the dermis. Later, an intraepidermal vesicle or pustule (containing mostly neutrophils) is usually present, often with a central focus of epidermal necrosis. Dermal edema is often present. Compared with other arthropod assaults, fire ant stings are far more pustular, with more neutrophils and fewer eosinophils.