2.4.8 Bee and Wasp

Hymenoptera stings.

According to the European network of severe allergic reactions (NORA), 20.2% of all cases of anaphylaxis in children and 48.2% of documented anaphylaxis in adults were due to insect venom. Patients with increased number of mast cells and mastocytosis with increased blood tryptase levels ( cca. 7.9% of population) have a higher risk of local and systemic reactions. Serious systemic reactions are 2–3 times higher in beekeeping.

Allergic and pseudoallergic reactions to stings of bees and wasps.

Honeybee stings are generally not more severe than wasp stings but they inject more venom. Both liberate different pain inducer peptide 401, prostaglandins, serotonin, kinins and acetycholine. Bees can sting once but wasps multiple times. Insect sting allergy may cause local, large local (>10 cm ) or even systemic reactions (SR), and potentially life threatening anaphylactic reactions. Anaphylaxis is IgE mediated. In individuals who have previously been sensitized to bee venom, IgE antibodies attach to tissue mast cells and basophils. Once these cells are activated, the progression of the cascade reaction increases vasoactive substances, which stimulate release of leukotrienes, histamine, and eosinophil chemotactic factor-A. The number of mast cells in the skin and mucosa influences the deliberation of histamine, bradykinin and platelet activating factor (PAF).

In addition to local reaction, systemic reactions are classified in stages (see complications). First sign is usually pruritus. Complete picture includes flushing, urticaria, angioedema, hypotension, bronchospasm, nausea, abdominal colic, cramping, incontinence of urine and stool. 50% of symptoms appear within 5 minutes, another 40% within 30 minutes (see classification of allergic reactions /Mueller grading system I - IV).

Exposed skin areas: head, neck, extremities. Mucosal area mouth, tongue and by swallowing larynx and trachea and esophagus.

See symptoms and grading of allergic reaction according to Mueller:

Grading of allergic reactions to Hymenoptera: 

• Grade 0: increased local reaction (>10 cm, >24 h). 

• Grade 1 (mild generalized reaction): widespread urticaria, pruritus, malaise, anxiety.

• Grade 2 (moderate generalized reaction): the above symptoms and two or more of the following: angioedema (Grade 2 even if solitary), tightening of chest, nausea, vomiting, diarrhoea. 

• Grade 3 (severe generalised reaction): any of the above and two or more of the following: dyspnoea (Grade 3 even if solitary), stridor, dysphagia, dysarthria, excitement, confusion, fear of death. 

• Grade 4 (shock reaction): any of the above and two or more of the following: cyanosis, hypotension, collapse, incontinence of urine or stool, loss of consciousness. 

Identification of total and specific IgE in serum (ImmunoCAP, RAST). Tryptase.

Not necessary.

Varies from self-limited mild local reaction to life threatening anaphylactic reaction.

Clinical features (local reaction, general features). After thorough case history specific IgE titer in serum, scratch, prick and intracutaneous testing can be performed to identify threshold of reactivity (titration with aqueous solutions of wasp and bee toxins). 

Bites from other insects, particularly other Hymenoptera (hornets and bumblebees), hives, angioedema (see chapter Arthropod reactions and Angioedema).

Prevention: protective clothing, sleep under fine-mesh nets, repellents. Local reaction: topical steroids or antipruritic agents, short term ice packs, oral antihistamines.

Hymenoptera allergy: Mild generalized reaction: antihistamines i.v., perhaps corticosteroids p.o. or i.v. (at least 100 mg prednisolone or equivalent).

Severe generalized reaction: treat as anaphylactic reaction. Counselling for future exposure, emergency set (soluble prednisolone liquid 100 mg to swallow, 2 tablets of a rapid-acting antihistamine, epinephrine self-injector - e.g.Epipen - or metered aerosol inhaler).

Venom Immunotherapy (always with Grade 3-4 reactions), initial hyposensitization under in patient condition ( rush / ultrarush hyposensitization).

None.