A 1-day imported fire ant rush immunotherapy schedule with and without premedication

Stinging Ant Anaphylaxis: Advances in Diagnosis and Treatment

Stinging ants represent a wide range of over 200 different species across the world, of which Solenopsis, Myrmecia, Pogonomyrmex, and Brachyponera genera account for a substantial economic and healthcare burden. S. invicta (red imported fire ant [IFA]) and M. pilosula (jack jumper ant [JJA]) are 2 species of high clinical importance, known to cause anaphylaxis in humans, with numerous reported fatalities. Diagnostic testing should be performed in patients with a history of a systemic reaction with skin testing and/or in vitro specific immunoglobulin E (IgE) testing. In vitro testing is commercially available for IFA through whole-body extract specific IgE and JJA venom-specific IgE, but not widely available for other stinging ant species. Commercial venom component testing for IFA and JJA is currently not available. Patients with a clinical history and positive specific IgE testing should undergo treatment with specific immunotherapy, which is currently available for IFA and JJA. Buildup may be performed using conventional, semi-rush, rush, or ultra-rush schedules with similar risk profiles for IFA. Optimal duration for whole=body extract immunotherapy for IFA and specific JJA venom immunotherapy is not well studied, but generally recommended for at least 3 to 5 years. Sting challenges are used in research settings, primarily to assess treatment efficacy of immunotherapy.

Imported fire ant immunotherapy

Imported fire ants (IFAs) permeate many areas of the United States. The IFA allergy is a significant health problem for children and adults. Stings from IFAs cause pustules, localized reactions, and anaphylaxis. There have been at least 32 deaths attributed to IFA stings. Because of the difficulty with the extraction of venom from the fire ants, whole body extracts are the only commercially available serum for immunotherapy. Fortunately, whole body extract immunotherapy given conventionally or through the rush method has proven to be efficacious and safe. It is recommended for the treatment of IFA hypersensitivity. Maintenance immunotherapy is typically given at 4-week intervals. However, more recent research has revealed that these intervals can gradually be extended up to 12 weeks similar to flying Hymenoptera venom immunotherapy. Long-term adherence to IFA immunotherapy remains an obstacle for many patients despite its potential as a life-saving treatment.

Updates and Recent Advances on Venom Immunotherapy

Purpose of Review

Venom immunotherapy has been utilized to treat Hymenoptera venom allergy since the 1920s. Over the last century, significant advances in the fields of immunology and genetics have led to improvements in the practice of venom immunotherapy. This review encompasses recent advances in the use of venom immunotherapy to provide precise, patient-centered care.

Recent Findings

Research about the mechanism of action of venom immunotherapy continues to highlight the modification of both the innate and adaptive immune systems. Molecular techniques have allowed for the identification of specific venom allergens to improve the diagnostic accuracy and safety of venom immunotherapy. Research continues to support the safety of accelerated schedules which can impact the cost, adherence, and quality of life for patients receiving this treatment modality. Finally, significant advances have led to the elucidation of risk factors that place patients at risk for reactions during and after venom immunotherapy. Creation of risk profiles for venom-allergic patients can thus inform the process of immunotherapy in order to provide personalized and precise care.

Summary

Significant progress in the use of venom immunotherapy makes the practice a dynamic and active field for continued research. Future research needs to build on these recent advances to continue to optimize and enhance this life-saving treatment.

Diagnosis and Management of Insect Allergy: Barriers and Facilitators in the United States

While guidelines recommend testing and treatment for patients with venom-induced anaphylaxis to prevent morbidity and mortality, significant barriers prevent most patients from receiving the evaluation and treatments that they need. This review examines these barriers in the United States along with the facilitators that can be used to overcome them.

Accelerated/rush allergen immunotherapy

Accelerated allergy shot schedules for inhalant and venom allergens provide individuals with allergy symptom relief but in a shorter time frame than conventional therapy. Accelerated immunotherapy (IT) protocols allow patients to reach therapeutic doses in a shorter time frame while improving adherence and reducing direct costs (e.g., fewer office visits and medications) and indirect costs (e.g., less travel time, missed work or school). Rush IT and cluster IT are believed to work through mechanisms similar to conventional subcutaneous IT (SCIT). The risk for severe systemic reactions during accelerated IT is low when appropriately administered; however, life-threatening and fatal reactions do occur. To reduce the incidence of systemic allergic reactions during cluster and rush IT protocols, premedication is recommended. It is important to exclude individuals at high risk such as those with poorly controlled asthma or those who are on β-blockers to mitigate the risk for developing systemic allergic reactions. However, accelerated SCIT regimens offer increased convenience, faster improvement in allergy symptoms, and the potential to reduce health-care costs while providing equivalent safety outcomes compared with conventional IT protocols.

Antihistamine premedication improves safety and efficacy of allergen immunotherapy

BACKGROUND

Allergen immunotherapy (AIT)-associated adverse events are a major concern for safety and efficacy of AIT. Presently, there is no consensus to whether antihistamine premedication could improve such conditions.

OBJECTIVE

To identify the superiority of antihistamine pretreatment in AIT.

METHODS

A comprehensive literature search for randomized controlled trials reporting the effects of antihistamine premedication on safety and efficacy of AIT was performed in MEDLINE, Embase, and Cochrane Library databases. Safety was evaluated according to the number of patients reporting systemic adverse reactions (SARs, the primary outcome) and efficacy according to the number of patients achieving target maintenance dose (TMD) and sustained unresponsiveness to allergen.

RESULTS

A total of 11 randomized controlled trials (including 609 patients) satisfied the inclusion criteria for the meta-analysis. All premedication protocols were temporary. Pooled analysis revealed that compared with control patients, significantly fewer antihistamine-pretreated patients reported total and moderate-to-severe SARs (odds ratio [OR], 0.36; 95% confidence interval [CI], 0.23-0.56; P < .05 and OR, 0.20; 95% CI, 0.06-0.74; P < .05, respectively) and total and moderate-to-severe SAR episodes (OR, 0.42; 95% CI, 0.34-0.53; P < .05 and OR, 0.09; 95% CI, 0.01-0.50; P < .05, respectively). Similarly, antihistamine pretreatment significantly increased the number of patients achieving TMD (OR, 2.94; 95% CI, 1.72-5.03; P < .05), but not sustained unresponsiveness (OR, 1.65; 95% CI, 0.77-3.54; P = 0.2), compared with the control group. Subgroup analysis according to different allergens and dose-escalating approaches also displayed superiority of antihistamine pretreatment than control.

CONCLUSION

Antihistamine premedication can markedly improve safety and efficacy of AIT by reducing frequency and severity of SAR and increasing TMD.

Approach to Patients with Stinging Insect Allergy

Stinging insect allergy is uncommon but can be life threatening. Diagnosis requires clinical history and confirmative skin or blood testing by an allergist. Baseline serum tryptase level can be used to stratify risk. Treatment is supportive for all reactions except for anaphylaxis, which is treated with intramuscular epinephrine, recumbent posture, and adjunct measures such as IV fluids, and oxygen. Venom immunotherapy is most effective for long-term management in patients with a history of anaphylaxis. Venom immunotherapy rapidly reduces the risk of sting anaphylaxis by up to 98% and maintenance treatment can be stopped after 5 years in most cases.

Worldwide perspectives on venom allergy

Venom immunotherapy is the standard of care for people with severe reactions and has been proven to reduce risk of future anaphylactic events. There is a moral imperative to ensure production, supply and worldwide availability of locally relevant, registered, standardized commercial venom extracts for diagnosis and treatment. Insects causing severe immediate allergic reactions vary by region worldwide. The most common culprits include honeybees (Apis mellifera), social wasps including yellow jackets (Vespula and Dolichovespula), paper wasps (Polistes) and hornets (Vespa), stinging ants (Solenopsis, Myrmecia, Pachycondyla, and Pogonomyrmex), and bumblebees (Bombus). Insects with importance in specific areas of the world include the Australian tick (Ixodes holocyclus), the kissing bug (Triatoma spp), horseflies (Tabanus spp), and mosquitoes (Aedes, Culex, Anopheles). Reliable access to high quality venom immunotherapy to locally relevant allergens is not available throughout the world. Many current commercially available therapeutic vaccines have deficiencies, are not suitable for, or are unavailable in vast areas of the globe. New products are required to replace products that are unstandardized or inadequate, particularly whole-body extract products. New products are required for insects in which no current treatment options exist. Venom immunotherapy should be promoted throughout the world and the provision thereof be supported by health authorities, regulatory authorities and all sectors of the health care service.

Characteristics of venom allergy at initial evaluation: Is fire ant hypersensitivity similar to flying Hymenoptera?

BACKGROUND

Hymenoptera venom allergy (HVA) is a well-established cause of anaphylaxis; however, studies comparing patients with imported fire ant (IFA) to flying hymenoptera (FH) allergies are lacking.

OBJECTIVE

This study sought to characterize the initial presentation and examine differences between patients with IFA and FH reactions.

METHODS

A multiyear (2007-2014), observational, single-institution analysis of patients referred for evaluation of HVA was performed. Data was obtained via physician interview, chart review and specific IgE results.

RESULTS

175 patients were enrolled with no difference between FH and IFA patients when analyzing mean age, sex or likelihood to seek emergency department (ED) care. Asthma was similar in all groups at 21%. ED treatments were also similar (epinephrine: 32/150, 21%; antihistamines: 141/155, 91%; corticosteroids: 67/148, 45%). Reaction severity correlated with likelihood of ED visit (P <.001), use of epinephrine (P <.001) and corticosteroid use (P <.05). Patients presenting to the ED with anaphylaxis received epinephrine in 27/73 (37%) of cases. Overall, 149/175 (85%) patients in our cohort were confirmed to be sensitized to hymenoptera. Of those with positive testing 127/149 (85%) chose to pursue VIT.

CONCLUSION

IFA and FH patients have many similarities at presentation. Asthma occurred 2.5 times more frequently our cohort compared to the general US population. Epinephrine administration in our cohort was suboptimal. Children have initial reactions and are treated in the ED similarly to adults, with a notable (although not statistically significant) reduced use of epinephrine. The majority of patients seen in the ED and subsequently followed up in an allergy clinic had their venom allergy confirmed and initiated life-saving immunotherapy.