1.1.3 · Allergy and Immunology · Anaphylaxis

Stinging insect hypersensitivity: who needs testing and venom immunotherapy

<2% of the exam 7 min

What the exam asks

From the kind of sting reaction, who needs venom testing and venom immunotherapy (VIT) and who needs only reassurance; how long VIT lasts; who carries epinephrine; what a raised baseline tryptase means; and whether to stop a beta-blocker or ACE inhibitor. ABIM's tasks here: tests, treatment, risk and prognosis.

The one-minute version

A large local reaction (10 cm or more around the sting) carries under 10% risk of a systemic reaction next time in adults: no testing, no VIT¹.
Anaphylaxis to a sting carries a 40 to 70% risk of recurrence: test for venom IgE; anaphylaxis plus venom IgE is the definitive indication for VIT¹.
VIT prevents most systemic reactions (in the first trial 1 of 18 reacted, against 7 of 12 on placebo) and is given for 3 to 5 years²¹.
Raised baseline tryptase and mastocytosis mark the patients at risk of the most severe reactions³⁴.
Beta-blockers and ACE inhibitors are usually continued; they do not contraindicate VIT⁵⁴.

Sort the reaction

Reaction	Risk with the next sting	Testing and VIT
Large local: 10 cm or more, contiguous with the sting	Systemic reaction under 10% in adults, 2 to 7% in children¹	Not recommended¹
Systemic, skin only (urticaria, flushing away from the sting)	About 10 to 15% recurrence, under 3% more severe¹	Not required; consider for quality of life or frequent exposure¹
Anaphylaxis (more than one organ system)	40 to 70% recurrence¹	Test for venom IgE; VIT if positive¹

Do not test people who have never had a systemic reaction: about 40% of the population carries venom IgE without any clinical relevance⁴.

Evidence: the sources' own words

1 defined as erythema and edema 10 cm or larger contiguous to the sting site
1 the risk of insect-triggered systemic symptoms is less than 10% in adults and 2% to 7% in children
1 current guidelines do not recommend testing or treatment
1 have approximately a 10 to 15% risk of recurrent symptoms though < 3% chance of more severe symptoms with a subsequent sting
1 patients with systemic cutaneous symptoms do not require testing or VIT treatment, though both can be considered
1 have a 40 to 70% risk of recurrence with future stings and thus should undergo testing and evaluation for the presence of venom sIgE
4 ~ 40% of the total population and up to 50% of children show HV sIgE in serum

Test and treat

Indication: the definitive indication for VIT is a history of sting anaphylaxis with venom-specific IgE¹.
Timing of tests: if venom IgE is negative within 2 weeks of the sting, repeat it at least 4 to 6 weeks after the sting⁴.
Efficacy: in the first controlled trial, systemic reactions to stings followed in 1 of 18 patients on venom, 7 of 11 on whole-body extract and 7 of 12 on placebo²; VIT lowers the risk of anaphylaxis to under 5%, though only 75 to 85% for honeybee¹.
Doses (US): maintenance 100 µg of a single venom (300 µg of mixed vespid), monthly for 12 to 18 months, then every 6 to 8 weeks¹.
Duration: 3 to 5 years, 5 protecting better; indefinite for high-risk patients such as honeybee allergy or systemic reactions to the injections¹.
Children: treated children reacted far less often than untreated ones (3% against 17%) 10 to 20 years later⁶.

Evidence: the sources' own words

1 The sole definitive indication for VIT is a patient with a clinical history of insect-triggered anaphylaxis who has evidence of venom sIgE.
4 If the results are negative less than 2 weeks after the sting, the tests shall be repeated (at least 4 - 6 weeks after the sting).
2 systemic reactions to stings occurred in seven of 12, seven of 11, and one of 18 patients treated with placebo, whole-body extract, and venom, respectively
1 VIT can reduce the risk of anaphylaxis to flying Hymenoptera to < 5%
1 in honeybee allergy where VIT effectiveness is only 75 to 85%
1 Maintenance Dose100 µg for single venom extracts300 µg for mixed Vespid extracts
1 doses are spaced out to monthly injections for 12 to 18 months with consideration for 6-to-8-week dosing intervals thereafter
1 VIT is recommended for 3 to 5 years with the latter providing better protection
6 Systemic reactions occurred less frequently in patients who had received venom immunotherapy (2 of 64 patients, or 3 percent) than in untreated patients (19 of 111 patients, or 17 percent

The high-risk patient

Baseline tryptase: in 962 patients, severe sting reactions rose with baseline tryptase; vespid allergy, older age, male sex and ACE inhibitors were also associated³.
Mastocytosis: about 5% of adults evaluated for sting allergy have indolent systemic mastocytosis, and a baseline tryptase above 20 µg/L is a minor criterion for it; a lower value does not exclude it⁴.
Work-up: the US 2023 parameter advises considering a mastocytosis evaluation, including bone marrow biopsy, in adults with severe sting anaphylaxis⁵.
Beta-blockers and ACE inhibitors: for most indications, stopping them carries more risk than continuing, especially in sting anaphylaxis, and neither contraindicates VIT⁵⁴.

Evidence: the sources' own words

3 The frequency of this event increased significantly with higher tryptase concentrations
3 vespid venom allergy, older age, male sex, angiotensin-converting enzyme inhibitor medication
4 ~ 5% of adult patients presenting for evaluation of insect sting allergy are diagnosed with indolent systemic mastocytosis
4 bST > 20 µg/L is a minor diagnostic criterion for the diagnosis of indolent systemic mastocytosis
4 mastocytosis cannot be excluded when bST is < 20 µg/L
5 Evaluation for mastocytosis, including a bone marrow biopsy, should be considered for adult patients with severe insect sting anaphylaxis
5 the risk of stopping or changing beta-blocker or angiotensin-converting enzyme inhibitor medication may exceed the risk of more severe anaphylaxis
4 The use of β-blockers and ACE inhibitors is not a contraindication to VIT.

Who carries epinephrine

Patients with only large local or skin-only systemic reactions, those on maintenance VIT and those who completed 5 years without high-risk factors are less likely to need an auto-injector; anaphylaxis without VIT, reactions during VIT, honeybee allergy, raised basal tryptase and frequent exposure make it more likely⁷.

Evidence: the sources' own words

7 A history of only large local or cutaneous systemic reactions or patients on maintenance venom immunotherapy (VIT) or who have completed a 5-year course of VIT with no high-risk factors
7 allergy to honeybee, an elevated basal tryptase level, or frequent exposure to stinging insects

Board traps

"Refer for venom testing after a large local reaction." The risk of a systemic reaction is under 10%; testing and VIT are not recommended¹.
"Test everyone stung, to be safe." About 40% of people have venom IgE without disease; a positive test without a systemic reaction misleads⁴.
"Stop the beta-blocker before VIT." It is not a contraindication, and stopping may carry the greater risk⁴⁵.
"Whole-body extract for bee or wasp allergy." Venom, not whole-body extract, prevents reactions; whole-body extract worked no better than placebo².

Evidence: the sources' own words

1 current guidelines do not recommend testing or treatment
4 ~ 40% of the total population and up to 50% of children show HV sIgE in serum
4 The use of β-blockers and ACE inhibitors is not a contraindication to VIT.
5 especially in patients with insect sting anaphylaxis
2 Placebo and whole-body extract gave similar results and were significantly less effective than venom immunotherapy

Europe differs

Skin-only systemic reactions in adults: EAACI 2018 recommends VIT for its gain in quality of life over carrying an auto-injector⁸; the US makes it optional¹.
Emergency kit: EAACI adds an H1-antihistamine and a corticosteroid to the auto-injector⁸.
Maintenance interval: Germany gives VIT every 4 weeks in the first year and every 5 to 6 weeks from the second⁴.

Evidence: the sources' own words

8 Venom immunotherapy is also recommended in adults with only generalized skin reactions as it results in significant improvements in quality of life compared to carrying an adrenaline autoinjector.
1 though both can be considered in cases of significant morbidity, impaired QOL, or frequent unavoidable exposure
8 Patients should carry an emergency kit containing an adrenaline autoinjector, H1 -antihistamines, and corticosteroids
4 be given at 4-weekly intervals during the first year and, following the manufacturer's instructions, every 5 - 6 weeks from the second year

Think it through

A 34-year-old landscaper is stung on the hand by a yellow jacket. Within an hour the whole forearm is swollen, red and itchy, about 20 cm across; it takes 5 days to settle. He has no hives elsewhere, no breathing trouble and no dizziness. He asks whether he needs allergy testing and "the shots".

What do you advise?

Show the answer

No venom testing and no immunotherapy; treat the swelling symptomatically. This is a large local reaction (10 cm or more, contiguous with the sting). The chance of a systemic reaction with the next sting is under 10% in adults, so guidelines do not recommend testing or VIT¹. Testing could mislead: many people carry venom IgE without disease⁴. VIT would become a shared decision only if recurrent large local reactions impaired his life or exposure was frequent and unavoidable¹.

Evidence: the sources' own words

1 the risk of insect-triggered systemic symptoms is less than 10% in adults
4 ~ 40% of the total population and up to 50% of children show HV sIgE in serum
1 Shared medical decision-making should be considered for patients who experience recurrent LLRs

References

Every claim above carries its number. Records come from PubMed; the evidence lines quote each source's own words.

1.

Floyd ML, Adams KE, Golden DBK Updates and Recent Advances on Venom Immunotherapy. Curr Treat Options Allergy 2023.

review PMID 37361640 DOI 10.1007/s40521-023-00336-7 PMC10148014 Read: full text

This article is made available via the PMC Open Access Subset for unrestricted research re-use and secondary analysis in any form or by any means with acknowled
2.

Hunt KJ, Valentine MD, Sobotka AK, et al. A controlled trial of immunotherapy in insect hypersensitivity. N Engl J Med 1978.

trial PMID 78446 DOI 10.1056/NEJM197807272990401 Read: abstract

Not open access: cited and paraphrased, abstract read; no text reproduced beyond short evidence quotes.
3.

Ruëff F, Przybilla B, Biló MB, et al. Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: importance of baseline serum tryptase-a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity. J Allergy Clin Immunol 2009.

study PMID 19895993 DOI 10.1016/j.jaci.2009.08.027 Read: abstract

Not open access: cited and paraphrased, abstract read; no text reproduced beyond short evidence quotes.
4.

Ruëff F, Bauer A, Becker S, et al. Diagnosis and treatment of Hymenoptera venom allergy: S2k Guideline of the German Society of Allergology and Clinical Immunology (DGAKI) in collaboration with the Arbeitsgemeinschaft für Berufs- und Umweltdermatologie e.V. (ABD), the Medical Association of German Allergologists (AeDA), the German Society of Dermatology (DDG), the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (DGHNOKC), the German Society of Pediatrics and Adolescent Medicine (DGKJ), the Society for Pediatric Allergy and Environmental Medicine (GPA), German Respiratory Society (DGP), and the Austrian Society for Allergy and Immunology (ÖGAI). Allergol Select 2023.

guideline PMID 37854067 DOI 10.5414/ALX02430E PMC10580978 Read: full text

https://creativecommons.org/licenses/by/2.5/This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permit
5.

Golden DBK, Wang J, Waserman S, et al. Anaphylaxis: A 2023 practice parameter update. Ann Allergy Asthma Immunol 2024.

guideline PMID 38108678 DOI 10.1016/j.anai.2023.09.015 Read: abstract

Not open access: cited and paraphrased, abstract read; no text reproduced beyond short evidence quotes.
6.

Golden DB, Kagey-Sobotka A, Norman PS, et al. Outcomes of allergy to insect stings in children, with and without venom immunotherapy. N Engl J Med 2004.

study PMID 15306668 DOI 10.1056/NEJMoa022952 Read: abstract

Not open access: cited and paraphrased, abstract read; no text reproduced beyond short evidence quotes.
7.

Wang J Epinephrine autoinjectors for individuals with food allergy: Who, how many, and when to use. J Food Allergy 2024.

study PMID 39257596 DOI 10.2500/jfa.2024.6.240004 PMC11382762 Read: full text

Open access, CC BY-NC-ND
8.

Sturm GJ, Varga EM, Roberts G, et al. EAACI guidelines on allergen immunotherapy: Hymenoptera venom allergy. Allergy 2018.

guideline PMID 28748641 DOI 10.1111/all.13262 Read: abstract

Not open access: cited and paraphrased, abstract read; no text reproduced beyond short evidence quotes.

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