Chester T. Stafford

Survey of fatal anaphylactic reactions to imported fire ant stings

A physician questionnaire survey was conducted by the Fire Ant Subcommittee of the American Academy of Allergy and Immunology to document deaths caused by imported fire ant stings. From the 29,300 physicians surveyed, reports of 83 fatal and two near-fatal fire ant-sting reactions were received. Most anaphylactic deaths were reported from Florida (22) and Texas (19). After excluding duplicate reports, four confirmed deaths were documented in Alabama, 10 in Florida, two in Georgia, two in Louisiana, and 14 in Texas.

Hypersensitivity to Fire Ant Venom

LEARNING OBJECTIVES Reading this article will reinforce the readers knowledge of the taxonomy, origin, and distribution of fire ants and will increase his ability to diagnose and manage reactions caused by the two imported species, Solenopsis invicta and richteri. This review will also enhance the readers knowledge of the available diagnostic methods and therapeutic measures, including the role of fire ant venom versus whole body extract in the management of fire ant allergy. DATA SOURCES Information for this review was obtained primarily from abstracts and articles written by investigators recognized for their expertise in fire ant venom research. STUDY SELECTION References were selected based on their clinical applicability and relevance to the epidemiology and pathophysiology of imported fire ant hypersensitivity. CONCLUSIONS The imported fire ant represents a significant health hazard for persons living in fire ant endemic areas in the southern United States. Sting reactions range from local pustules and large, late-phase responses to life-threatening anaphylaxis. Fire ant allergen-specific immunotherapy can reduce the risk of subsequent systemic reactions. Four important Sol i venom allergens have been isolated and characterized. Clinical studies have been designed to compare the safety and efficacy of fire ant venom with whole body extract for diagnosis and treatment of fire ant allergy.

Allergens in Hymenoptera venom: XXI. Cross-reactivity and multiple reactivity between fire ant venom and bee and wasp venoms

The relationships between fire ant venom and bee and wasp venoms were explored by studying sera from five groups of subjects. Group 1 included adults not allergic to any venoms and who were not exposed to fire ants. Group 2 included adults with fire ant exposure who were not allergic to venoms. Group 3 included patients with recent systemic reactions to fire ant venom. Group 4 included patients allergic to bee and vespid venoms with no fire ant exposure. Last, group 5 included patients allergic to bee and vespid venoms with fire ant exposure. None of the serum samples from group 1 was RAST reactive to fire ant venom, but 24% of those from group 2 were fire ant positive, as were 100% of those from group 3, 51% of those from group 4, and 87% of those from group 5. The RAST-positive patients in groups 2 and 5 were also skin test positive. RAST inhibition studies demonstrated cross-reactivity in some cases and multiple reactivity in others. The serum samples were further investigated via nondenaturing electrophoretic immunoblot studies and RAST with highly purified allergens. Serum samples from group 4 reacted to a single band on immunoblots and with only one of the four purified allergens from fire ant venom (Solenopsis invicta I, or Sol i I). Serum samples from groups 2, 3, and 5 showed various patterns of allergen reactivity. All serum samples from patients allergic to fire ant venom who also reacted to bee and/or vespid venoms by RAST contained IgE antibodies binding to Sol i I.(ABSTRACT TRUNCATED AT 250 WORDS)

Double-blind comparison of terfenadine, chlorpheniramine, and placebo in the treatment of chronic idiopathic urticaria

The efficacy of terfenadine, a nonsedating H1 antihistamine, in the management of chronic idiopathic urticaria was compared with chlorpheniramine and placebo in a parallel multicenter trial. Subjects with symptoms of hives for 3 days per week for at least 6 weeks were initially screened and admitted if no identifiable cause for symptoms could be determined. Patients entered a single-blind placebo period, and if hives of moderate severity were present for at least 3 days during the week, they were randomly assigned in a double-blind fashion to take terfenadine, 60 mg twice daily, chlorpheniramine, 4 mg three times a day, or placebo for 6 weeks. Data were analyzed for 122 patients. Those patients receiving both active treatments noted significant improvement in symptoms: pruritus, redness, number of hives, and waking hours during which hives were present, at the end of the first day of therapy. Symptom control by terfenadine was statistically superior to placebo during all 6 weeks, as rated by both patients and investigators. However, statistical significance was not achieved for chlorpheniramine at all observation points. Diphenhydramine was permitted as a relief medication for refractory symptoms and was taken by 52% of subjects receiving placebo, 26% taking chlorpheniramine, and only 9% of patients who were receiving terfenadine. In addition to providing superior symptom control, terfenadine caused less drowsiness and fatigue than chlorpheniramine. Terfenadine is a useful therapeutic agent for primary management of chronic idiopathic urticaria.

Seasonal variation in antigens of the imported fire ant Solenopsis invicta

Eight sequentially collected lots of aqueous extracts of imported fire ant (IFA) front end and abdominal end segments were assayed for phospholipase A (PLA), N-acetyl-beta-glucosaminidase (NAG), and hyaluronidase. Relative potency of each extract lot and pooled venom was measured by RAST inhibition against a venom standard. More than a hundredfold difference in PLA activity was observed. Early summer collections had the highest activity. The May to June collection had more than twice the PLA activity of the next most potent lot. Discordancy in enzyme patterns was noted only in AE extract. NAG levels peaked earlier in the spring and summer and fluctuated less widely. Front end extract had lower activity levels for both enzymes, with no seasonal fluctuation in NAG and a single elevation in PLA activity in the April to May collection. RAST inhibition varied directly with PLA activity (p less than .05) but not with NAG nor hyaluronidase activities. Fifty-one percent of systemic allergic reactions to IFA stings occurred in summer, and 19% occurred in spring. A reported demographic survey demonstrated a higher incidence of IFA stings in the spring (39.9%) with a lower attack rate in the summer (31.9%). These findings suggest that the rate of systemic reactions to stings of the IFA may be related to seasonal variations in allergenic potency, as measured by PLA and RAST inhibition, rather than the sting attack rate.

Safety and efficacy of fire ant venom in the diagnosis of fire ant allergy

Thirty-three adult patients who had had systemic allergic reactions to fire ant stings and 33 insect-nonallergic control subjects were skin tested with single lots of Solenopsis invicta (Sol i) fire ant venom (IFAV) and two commercially available imported fire ant whole body extracts (IFA WBEs). All three extracts were analyzed for protein concentration. Sol i II and Sol i III concentrations were each assayed by means of two ELISAs with complementary monoclonal antibodies, one species specific and one cross-reactive. Radioallergosorbent test (RAST) to IFAV and both IFA WBEs was performed on sera from all study subjects. Both IFA WBEs contained high concentrations of fire ant body proteins. Sol i II and III concentrations each varied twofold between the two IFA WBE preparations. Patients were generally more reactive to IFAV than IFA WBE by skin testing and RAST. IFAV RAST appeared to be a more sensitive assay than IFA WBE RAST. No adverse reactions occurred to skin testing with IFAV, but intradermal testing with higher concentrations of IFA WBE caused delayed large local reactions in 16 of 30 (53%) control subjects. These reactions were attributed to the large amounts of extraneous body proteins in IFA WBE. These results (1) demonstrate that skin testing with IFAV is safe, (2) indicate that IFAV is more potent than IFA WBE, and (3) suggest that IFAV may be the superior reagent for diagnosis of fire ant allergy.

Management of imported fire ant allergy : results of a survey

BACKGROUND Fire ant allergy is a significant health problem in the southern United States. Management of fire ant allergy is less clearly defined than management of allergy to the winged Hymenoptera. OBJECTIVE To determine how fire ant allergy is managed by practicing allergists. METHODS A survey form was developed and distributed to American College of Allergy, Asthma & Immunology members practicing in fire ant endemic states. Completed forms were returned to the American College of Allergy, Asthma & Immunology central office and forwarded to the authors for analysis. RESULTS Three hundred twenty-nine of 879 (37.4%) surveys were returned; 81% of respondents have evaluated patients with imported fire ant allergy. Immunotherapy is used by 96.7% of respondents to treat fire ant allergy. A wide range of maintenance dosages are prescribed. Skin testing is the most common diagnostic method. Systemic reactions to stings while on maintenance immunotherapy were reported by 19%. Allergists utilize different criteria in consideration for stopping immunotherapy; 19% continue it indefinitely. CONCLUSIONS There are many areas of general uniformity and other areas of divergence in how allergists manage imported fire ant allergy. These findings suggest continued need for further investigation regarding the efficacy, dosage, and duration of immunotherapy, as well as further elucidation of the natural history of fire ant allergy.

Sparfloxacin for the treatment of acute bacterial maxillary sinusitis documented by sinus puncture

PURPOSE To evaluate the efficacy and safety of sparfloxacin in the treatment of patients with acute bacterial maxillary sinusitis, the microbiologic etiology of which was determined by maxillary sinus puncture. PATIENTS AND METHODS Two hundred fifty-three patients enrolled in the open, noncomparative trial received sparfloxacin as a 400-mg loading dose followed by 200 mg once daily doses for a total of 10 days. One hundred ninety-eight patients were clinically evaluable and 82 were also bacteriologically evaluable. All treated patients were included in the safety analysis. Overall success was determined based on clinical success (resolution or reduction of signs and symptoms and sinus x-rays) and bacteriologic success (eradication and presumed eradication of baseline pathogens obtained by maxillary sinus puncture and aspiration). RESULTS Overall success in the bacteriologically evaluable population at test-of-cure was 91.5% [75/82; 95% confidence interval (85.4%, 97.5%)]. For all pathogens, the eradication rate was 93.2% (109/117 baseline pathogens); individual pathogen eradication rates were 88.9% (16/18) for S. pneumoniae (including those strains exhibiting decreased susceptibility to penicillin); and 100% for H. influenzae (17/17), S. aureus (14/14), and M. catarrhalis (11/11). The majority of adverse events were of mild or moderate severity; the most frequently related adverse events were photosensitivity reaction, headache, nausea, and diarrhea. CONCLUSION Sparfloxacin had an overall success rate of 91.5% for patients in this study and was generally well tolerated in the treatment of acute bacterial maxillary sinusitis.

Laboratory evaluation of a commercial immunoassay for fire ant allergen-specific IgE antibodies.

BACKGROUND In vitro testing for fire ant sensitization would be useful for research purposes and in special clinical situations. METHODS Laboratory performance of a commercial assay (Pharmacia CAP System, [PCS]), for specific IgE to Solenopsis invicta whole body extract was studied in 46 persons. Assay results were compared with those of venom skin testing, RAST, and ELISA. The manufacturers global cutoffs were compared with cutoffs set by using methods derived from analytical detection limit theory. RESULTS Thirty-two study subjects had positive skin test results, and 14 had negative results. Raw PCS data demonstrated a high level of correlation with RAST (rho = 0.941) and ELISA (rho = 0.931), and showed good correlation with skin testing (rho = -0.769). Analysis of binormal receiver operating characteristic curves, using skin test results as the reference standard, demonstrated no difference in performance among the three assays. The fixed global quantitative cutoff of 0.35 kUa/L was relatively insensitive. Use of the manufacturers qualitative alternate scoring method cutoff substantially increased sensitivity without loss of specificity, as did lower limit of detection set by use of diluent. CONCLUSIONS In situations in which skin testing for fire ant sensitization is not feasible, PCS appears to be an acceptable in vitro alternative method for determination of fire ant allergen-specific IgE.

Modification of the fluorescent allergosorbent test as an inhibition assay for determination of cross-reactivity among aeroallergens

The fluorescent allergosorbent test was adapted as an inhibition assay to determine cross-reactivity between aeroallergens. With this method, similar antigenic determinants were found between short ragweed and giant ragweed, cocklebur, lambs-quarter, rough pigweed, marsh elder, and goldenrod. Cocklebur and giant ragweed were highly potent in their ability to competitively bind to short ragweed IgE. The other pollens demonstrated lower potency of cross-reacting antigens. The fluorescent allergosorbent test-inhibition assay appears to be a useful method to determine cross-reactivity among aeroallergens.