Fire ants represent an important risk for anaphylaxis among residents of an endemic region.

Background: Imported fire ants (IFA) represent a potential anaphylactic risk to IFA-sensitized individuals.

Objective: We examined the prevalence of allergic sensitization to IFA, yellow jacket venom (YJV), and peanut in an adult population from an IFA-infested region, Augusta, Georgia.

Methods: Specific IgE to IFA, YJV, and peanut were determined by using the Pharmacia UniCAP assay in 200 random blood donors from an Augusta blood bank. These results were compared with specific IgE to identical allergens in a random sample of blood donors from Oklahoma City, Oklahoma (OKC), a nonendemic region for IFA.

Results: Prevalence of IFA-specific IgE (17%) in the Augusta population was significantly higher than to YJV (10%, P =.04) or peanut (7.5%, P =.004). The majority of individuals who had significant IgE to IFA (> or =0.35 kIU/L) did not have IgE to YJV (24/34 = 71%). YJV caused significantly more inhibition of IgE binding to a YJV solid phase than to an IFA solid phase when the 10 dual-positive sera were analyzed (58% vs 11%, P =.005). The prevalence of IFA-specific IgE in adults from Augusta was higher than in OKC (17% vs 2%, P =.0002). YJV-specific IgE was also more prevalent in Augusta compared with OKC (10% vs 6.0%, P =.04), whereas no difference was demonstrated for peanut-specific IgE (7.5% vs 6.5%, P =.6).

Conclusions: Allergic specific IgE to IFA is 1.7 times more common in adults living in an endemic area than specific IgE for other allergens associated with potentially fatal anaphylaxis. This suggests that IFA may pose the greatest risk of anaphylaxis for adults residing in IFA-endemic regions.