Position paper The sting challenge test in Hymenoptera venom allergy

Diagnosis and treatment of Hymenoptera venom allergy in adults: A single-center experience in Lithuania

Background

Venom-specific immunotherapy (VIT) is a major treatment for patients allergic to Hymenoptera venom. Thus, correct diagnosis of sensitization, identification of the risk factors, and choice of venom for the treatment are the key issues.

Objective

We aimed to describe diagnostic and treatment experience data of VIT performed in a single center in Lithuania.

Methods

In this retrospective study, we analyzed 9 years of clinical data (severity of the allergic reaction, recognition of the culprit insects, diagnostics, VIT protocol safety and efficacy, sting challenge outcomes) of patients treated with cluster VIT. Sting challenge helped to reveal the influence of venom preparation quality and to adjust the dosage of venom.

Results

Data from 83 patients were analyzed. Double sensitization confirmed by component diagnosis was found in 39.4% (13/33), and double immunotherapy was initiated in 9.1% (n = 3/33). The cluster immunotherapy protocol was used in 81 patients. Systemic reactions occurred in 7.4% (n = 6/81) patients during the build-up phase. VIT failure was related to bee venom immunotherapy and systemic reactions during a build-up phase. The efficacy in the short term of our approach to cluster VIT was confirmed by the sting challenge in 97% (42/43). Nine patients (10.8%, n = 9/83) voluntarily stopped the treatment due to a lack of motivation.

Conclusion

Our protocol regarding the investigation and treatment of patients allergic to Hymenoptera venom has been safe and effective. Patient's motivation to continue VIT is one of the concerns, but the biggest challenge is the patients with bee venom allergy and repeated systemic reactions during VIT.

[Basophil activation test to follow-up of patients treated with hymenoptera venom immunotherapy: a review of current evidence]

Hymenoptera venom immunotherapy (HVI) is a long-term effective treatment to avoid new systemic reactions in patients with Hymenoptera allergy. The sting challenge test is considered the gold standard to confirm the tolerance. However, the use of this technique is not generalized in clinical practice, being the basophil activation test (BAT), which functionally explores allergen response, an alternative that does not entail any of the provocation risks associated with the sting challenge test. This study reviews the publications that used the BAT to follow up and evaluate the success of the HVI. Studies assessing the changes between a baseline BAT before the start and BATs performed between the starting and maintenance phases of the HVI were selected. Ten articles were found, comprising information from 167 patients, of which 29% used the sting challenge test. The studies concluded the importance of evaluating the responses with submaximal allergen concentrations, which reflect basophil sensitivity, to monitor the HVI using the BAT. It was also observed that changes in the maximum response (reactivity) could not reflect the clinical status of tolerance, particularly in the initial phases of HVI.

Evaluation and validation of a bee venom sting challenge performed by a micro-syringe

BACKGROUND

The honeybee sting challenge is considered a reliable procedure to evaluate the efficacy of specific immunotherapy, but it is difficult and unpractical to perform in clinical practice, because live insects are required.

OBJECTIVE

To assess the feasibility and reliability of a challenge test using a micro-syringe, and compared the procedure with sting challenge.

METHODS

Patients on bee venom immunotherapy and without systemic reactions at field sting were enrolled. They underwent a sting challenge with live bee, and large local reactions were assessed up to 48 hours. Those patients displaying systemic reactions at the sting challenge were excluded from the syringe challenge for ethical reasons. The syringe challenge was done by injecting 0.5 μL fresh unfiltered bee venom at 2 mm depth (the length of the sting left by a bee). The same follow-up as at the first challenge was performed. Bee-specific immunoglobulin E (IgE) and tryptase were measured after each challenge.

RESULTS

Nineteen patients underwent the sting challenge with live bees. Four had immediate systemic reactions (urticaria or asthma) and were excluded from the second challenge. The remaining 15 patients with large local reaction underwent the syringe challenge. No significant difference was seen in the maximum area of the large local reactions between the challenge with live bees and the syringe challenge. Also, no change was seen in tryptase and specific antibodies.

CONCLUSION

This preliminary study suggests that the micro-syringe challenge with honeybee venom is feasible and produces results indistinguishable from those of the traditional sting challenge.

Insect stings: clinical features and management

BACKGROUND

In human beings, local and systemic reactions can be caused both by blood-sucking insects and by venomous insect stings. In Central Europe, the insects that most commonly cause such reactions are honeybees, certain social wasps, mosquitoes, and flies.

METHODS

This article is based on a selective literature review, including guidelines from Germany and abroad.

RESULTS

Insect venom induces a toxic reaction at the site of the sting. Large local reactions are due to allergy and occur in up to 25% of the population; as many as 3.5% develop IgE-mediated, potentially life-threatening anaphylaxis, of which about 20 people die in Germany each year. Mastocytosis is found in 3% to 5% of patients with sting anaphylaxis, rendering these patients prone to very severe reactions. Blood-sucking by hematophagous insects can elicit a local allergic reaction, presenting as a wheal or papule, in at least 75% of the population. Large local reactions may ensue, but other diseases are rare. The acute symptoms of an insect sting are treated symptomatically. Patients who have had a systemic reaction or a large local reaction due to insect allergy must take permanent measures to avoid further allergen contact, and to make sure they can treat themselves adequately if stung again. Most patients with systemic anaphylactic reactions to bee or wasp stings need specific immunotherapy.

CONCLUSION

Insect stings can cause severe disease. Anaphylaxis due to bee or wasp stings is not a rare event; specific immunotherapy protects susceptible persons from further, potentially life-threatening reactions.

Stinging insect hypersensitivity: a practice parameter update 2011

These parameters were developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Stinging insect hypersensitivity: a practice parameter update II." Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or the ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma and Immunology. This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. These parameters are not designed for use by pharmaceutical companies in drug promotion. The Joint Task Force understands that the cost of diagnostic tests and therapeutic agents is an important concern that may appropriately influence the work-up and treatment chosen for a given patient. The Joint Task Force recognizes that the emphasis of our primary recommendations regarding a medication may vary, for example, depending on third party payer issues and product patent expiration dates. However, since a given test or agent's cost is so widely variable, and there is a paucity of pharmacoeconomic data, the Joint Task Force generally does not consider cost when formulating Practice Parameter recommendations. In extraordinary circumstances, when the cost benefit of an intervention is prohibitive as supported by pharmacoeconomic data, commentary may be provided.

Three days rush venom immunotherapy in bee allergy: safe, inexpensive and instantaneously effective

BACKGROUND

Rush venom immunotherapy (VIT) is highly effective in vespid venom allergy, but comparable data regarding bee venom (BV) allergy are sparse. We evaluated its safety, efficacy and cost in BV-allergic patients.

METHODS

Conventional or rush VIT were offered to all patients with systemic reaction to insect sting. Rush VIT was also given to hyperreactive patients who failed to reach the maintenance dose with conventional VIT due to multiple systemic reactions. In BV-allergic patients, honeybee sting challenge was performed within 1 week after reaching the maintenance dose.

RESULTS

179 patients, some of them allergic to more than one venom, received 246 rush VIT courses. Bee VIT was administered to 132 patients (73.7%); 173 patients (96.6%) reached the maintenance dose. The incidence of systemic reactions was 29.6%. They were more common in VIT with BV than with vespid venoms (31.1 and 16.3%, respectively, p = 0.01). After excluding the hyperreactive subgroup (n = 20), this difference was not significant (23.7 and 16%, respectively, p = 0.19). Despite the high incidence of systemic reactions (15 of 20, 75%) among hyperreactive patients, 17 patients (85%) achieved the maintenance dose. Sting challenges resulted in systemic reaction in 4 of 8 (50%) hyperreactive patients and in 2 of 47 (4.3%) ordinary patients. The cost of rush VIT was 41% of that of conventional VIT.

CONCLUSIONS

Rush VIT with BV is safe, instantaneously effective, less expensive and enables most patients with previous failures of conventional VIT to reach the maintenance dose.

[Venom immunotherapy. Side effects and efficacy of treatment]

Venom immunotherapy (VIT) protects patients with Hymenoptera venom anaphylaxis from subsequent potentially life-threatening reactions. The most important side effect are systemic anaphylactic reactions (SAR). Compared to the administration of aqueous extracts according to a rush protocol, the frequency of systemic and also local side effects will be lower if depot extracts are used and a slow conventional dose schedule is used, as compared to rush desensitization with aqueous extracts. However, protection often has to be achieved rapidly, and adequate surveillance of sufficient duration is hardly feasible in outpatients. Therefore, VIT according to rush schedules in inpatients remains indispensable. Pre-treatment with H(1)-blocking antihistamines reduces frequency and intensity of local and mild systemic adverse reactions during VIT. Up to 25% of patients again develop a SAR when re-stung while on VIT with the usual maintenance dose of 100 microg venom. Patients with honeybee venom allergy or with mastocytosis are at a higher risk for treatment failure. Almost all of them will become fully protected by increasing the maintenance dose, 200 microg venom being sufficient in most cases. Patients with significant risk factors may be treated from the beginning with an elevated maintenance dose, particularly when they are allergic to honeybee venom.

Insect sting anaphylaxis

Anaphylaxis to insect stings has occurred in 3% of adults and can be fatal even on the first reaction. Large local reactions are more frequent but rarely dangerous. The chance of a systemic reaction to a sting is low (5% to 10%) in large local reactors and in children with mild (cutaneous) systemic reactions, and varies between 25% and 70% in adults depending on the severity of previous sting reactions. Venom skin tests are most accurate for diagnosis, but the radioallergosorbent test (RAST) is an important complementary test. The degree of sensitivity on skin test or RAST does not predict the severity of a sting reaction reliably. Venom sensitization can be detected in 25% of adults, so the history is most important. Venom immunotherapy is 75% to 98% effective in preventing sting anaphylaxis. Most patients can discontinue treatment after 5 years, with very low residual risk of a severe sting reaction.

Allergy to bumblebees

PURPOSE OF REVIEW

Field stings by bumblebees are uncommon because of the habitat and nonaggressiveness of these insects. More stings have been reported in the Netherlands because of the increasing use of bumblebees in flowering industries such as tomato growing. The purpose of this review is to summarize the recent literature concerning bumblebee anaphylaxis and describe our own experience with immunotherapy in an occupational group of bumblebee-venom-allergic workers.

RECENT FINDINGS

Two distinct categories of patients are sensitized to bumblebee venom. First are patients with IgE highly cross-reactive with honeybee venom allergens. Venom immunotherapy with honeybee venom will be adequate in these nonprofessionally exposed bumblebee-allergic patients. These patients react to bumblebee venom as a result of a primary earlier exposure and sensitization to honeybee venom. Secondly, with heavily exposed greenhouse workers or bumblebee workers, frequently stung only by bumblebees, it is recommended to use immunotherapy with purified bumblebee venom, due to the low or absent degree of cross-reactivity with honeybee venom. Otherwise, the best preventive therapy is to avoid further exposure, which means changing profession.

SUMMARY

Immunotherapy with purified bumblebee venom is as well tolerated and effective as immunotherapy with other Hymenoptera venoms.

Venom immunotherapy: adverse reactions and treatment failure

PURPOSE OF REVIEW

Side effects of venom immunotherapy and lack of efficacy represent significant problems in the treatment of patients allergic to Hymenoptera venom. Among these side effects systemic anaphylactic reactions and large local reactions are the most important. This review aims to discuss new insights in frequency, pathogenesis and handling of these common side effects and of treatment failure during venom immunotherapy.

RECENT FINDINGS

Several studies showed that severe side effects due to venom immunotherapy are rare. Recently published studies focus on ultrarush protocols and report good tolerance of an ultrarush venom immunotherapy in which the maintenance dose was reached within several hours or 2 days, respectively. Compared to the use of aqueous extracts (administered according to a rush protocol), frequency of local and also systemic side effects was lower when depot extracts and schedules with a slow conventional dose increase were applied. Concomitant treatment with H1-antihistamines was found to reduce local and mild systemic adverse reactions during venom immunotherapy. Up to 25% of patients are not protected when re-stung while on venom immunotherapy with the usual maintenance dose of 100 microg of venom every 4-8 weeks. These patients can achieve full protection by increasing the maintenance dose.

SUMMARY

Conventional dose increase using depot extracts is better tolerated than if aqueous extracts are being administered. Concomitant treatment with H1-antihistamines may be helpful. Increasing the venom dose to 200 microg or even more may be therapeutically effective in patients not protected by a lower maintenance dose. To compare tolerance of different treatment protocols prospective comparative studies are required.

Diagnostic methods for insect sting allergy

PURPOSE OF REVIEW

This review overviews advances from mid-2002 to the present in the validation and performance methods used in the diagnosis of Hymenoptera venom-induced immediate-type hypersensitivity.

RECENT FINDINGS

The general diagnostic algorithm for insect sting allergy is initially discussed with an examination of the AAAAI's 2003 revised practice parameter guidelines. Changes as a result of a greater recognition of skin test negative systemic reactors include repeat analysis of all testing and acceptance of serology as a complementary diagnostic test to the skin test. Original data examining concordance of venom-specific IgE results produced by the second-generation Pharmacia CAP System with the Johns Hopkins University radioallergosorbent test are presented. Diagnostic performance of honeybee venom-specific IgE assays used in clinical laboratories in North America is discussed using data from the Diagnostic Allergy Proficiency Survey conducted by the College of American Pathologists. Validity of venom-specific IgE antibody in postmortem blood specimens is demonstrated. The utility of alternative in-vivo (provocation) and in-vitro (basophil-based) diagnostic testing methods is critiqued.

SUMMARY

This overview supports the following conclusions. Improved practice parameter guidelines include serology and skin test as complementary in supporting a positive clinical history during the diagnostic process. Data are provided which support the analytical performance of commercially available venom-specific IgE antibody serology-based assays. Intentional sting challenge in-vivo provocation, in-vitro basophil flow cytometry (CD63, CD203c) based assays, and in-vitro basophil histamine and sulfidoleukotriene release assays have their utility in the study of difficult diagnostic cases, but their use will remain as supplementary, secondary diagnostic tests.

Rush venom immunotherapy in patients experiencing recurrent systemic reactions to conventional venom immunotherapy

BACKGROUND

An unknown number of venom-allergic patients fail to reach the maintenance dose (MD) during the build-up period of conventional venom immunotherapy (VIT) due to recurrent systemic reactions (SRs).

OBJECTIVE

To establish an alternative VIT protocol that will enable these patients to reach a full protective MD.

METHODS

Venom-allergic patients who had experienced recurrent SRs during the build-up period of conventional VIT underwent rush VIT.

RESULTS

Of the 9 patients who participated in this study, the 6 who underwent 8 treatment courses tolerated the rush VIT well and reached the MD within 3 days. In 3 of these patients, mild cutaneous SRs were overcome with loratadine. In 2 patients who experienced recurrent and more severe SRs, the original 3-day rush VIT had to be modified and extended to 5 days until the MD was reached. In a single patient who experienced an anaphylactic reaction, VIT was discontinued.

CONCLUSIONS

Rush VIT is an appropriate therapeutic alternative that enables most patients with recurrent SRs throughout the build-up period of conventional VIT to reach a full protective MD.

Maintenance venom immunotherapy administered at 3-month intervals is both safe and efficacious

BACKGROUND

Maintenance venom immunotherapy (MVIT) is usually administered to patients with venom allergy at 4- to 6-week intervals for at least 3 to 5 years. The small number of studies assessing the possibility of extending the maintenance interval (MI) included either too small a population and patients with only vespid and not bee venom (BV) allergy or relied on reaction to field stings only.

OBJECTIVE

We sought to assess the safety and efficacy of MVIT given at 3-month intervals to a large population of patients allergic to both yellow jacket venom and BV.

METHODS

In all patients undergoing venom immunotherapy, MI was gradually extended to 3 months. Systemic reactions (SRs) to immunotherapy injections or to field stings were regularly recorded. Some of the patients were also deliberately sting challenged during the 3-month interval. Patients discontinuing MVIT were interviewed regarding their responses to field re-stings, and in some of them, an in-hospital sting challenge was performed.

RESULTS

One hundred sixty patients mostly allergic to BV were enrolled in the study. Failure to reach the 3-month interval was observed in 6 (3.8%) patients, originating in failure to reach the full maintenance dose in most of them. SRs to MVIT administered at 3-month intervals were observed in 2.6% of the patients. One of 36 patients who experienced a field sting during the 3-month interval had an objective mild SR (2.8%). Two (4.5%) of 44 patients who were deliberately stung during the 3-month interval had mild SRs. After discontinuation of MVIT, 2 (8.3%) of 24 patients who experienced a field sting had an SR. Both were allergic to yellow jacket venom. Three to 82 months after discontinuation of MVIT, 22 patients allergic to BV were sting challenged. Only one (4.5%) patient had a mild objective SR.

CONCLUSIONS

The conventional 4- to 6-week MI can easily be extended to 3 months in most patients without any adverse events. MVIT given at a 3-month interval is safe and effective while being administered, as well as after its discontinuation. This fact should be applied to almost every patient allergic to insect venom.

Insect sting-inflicted systemic reactions: attitudes of patients with insect venom allergy regarding after-sting behavior and proper administration of epinephrine

BACKGROUND

Patients with insect venom allergy are at higher risk for development of a recurrent systemic reaction after re-sting. This risk significantly decreases with venom immunotherapy. Patients with insect venom allergy should be able to distinguish a life-threatening systemic reaction from all other various reactions after an insect sting. Accidental epinephrine injection by EpiPen has been reported in the past. Therefore patients with venom allergy should also be well trained in self-administration of their epinephrine when needed.

OBJECTIVE

Our objective was to assess patients' attitudes regarding after-sting behavior and their capability to correctly self-administer the epinephrine autoinjector.

METHODS

All patients with venom allergy attending our allergy unit either before commencement of or during venom immunotherapy answered a questionnaire addressing various aspects of their intended after-sting behavior. Using an EpiPen trainer device, patients' performance of EpiPen self-administration was evaluated.

RESULTS

Ninety-six patients participated in the study. Seventy-six of them were equipped with an EpiPen device. Less than 30% of these patients carried it at all times. After re-sting, 50 (54%) patients planned to wait for the development of other symptoms before taking any further action. Twenty-two percent of the patients said that after re-sting they would immediately administer their EpiPen. Proper EpiPen administration technique was demonstrated by 44% of the patients. Having not reached the maintenance dose correlated with a better compliance with carrying of the EpiPen. EpiPen instruction provided by an allergist correlated with a better EpiPen administration technique by the patients.

CONCLUSION

Many patients with venom allergy hold wrong ideas about after-sting behavior. Compliance with carrying EpiPen at all times and the ability to correctly administer it are both poor in most patients. Thorough and probably repeated instruction, both written and oral, provided by knowledgeable physicians is mandatory.