Reactions from bee stings vary in their severity, from mild to massive evenomation. Nevertheless, they are all medical emegencies and patients need to be diagnosed and treated based on the allergic reactions and clinical manifestations.

Bee (order Hymenoptera) venom is composed of allergens such as vasoactive amines, and small polypeptides which may cause an allergic reaction ranging from normal (mild) local reactions, to large local reactions, systemic anaphylactic reactions which could be either mild, moderate or severe.

Hypotension, bronchoconstriction, respiratory distress, syncope, laryngeal oedema and death are possible systemic manifestations of bee stings. Serious airway obstruction may be seen in cases when bees sting people in their mouths, even if people are not hypersensitive to venom. In allergic individuals, immunotherapy may lower the risk of anaphylaxis.

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Diagnosis of bee sting

Patients suspected of having exposure to allergen bee venom are diagnosed for anaphylaxis in cases when there is acute onset of illness with skin or mucosal involvement with either:

• Respiratory compromise such as dyspnea, bronchospasm, wheezing, hypoxemia, stridor
• Hypotension with a systolic BP less than 90 mmHg or 30% decrease from the baseline, syncope or indication of end organ damage

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Management of bee sting patients

Out of hospital management: It entails self administration of epinephrine, if available, at a dose of:

• 0.3 ml of 1:1000 intramuscularly for adults
• 0.01 ml/kg of 1:1000 intramuscularly for children as soon as they see the first signs of clinical manifestations of anaphylaxis
• In suspectible patients, serious anaphylaxis manifestations such as laryngeal oedema and bronchoconstriction can be counteracted by using aerosolised epinephrine from a metered-dose inhaler (10 to 20 doses)

In-hospital management: It entails airway patency, breathing, and circulation (ABC) evaluation.

1. Aqueous epinephrine in a ratio of 1:1000 should be given intravenously as a dose of:
   • 0.3 to 0.5 mL for adults
   • 0.01 mL/kg to a maximum of 0.3 mL for children
2. In cases of profound hypotension, 2 to 5 mL epinephrine in a ratio of 1:10,000 is given as slow IV or through intravenous infusion by mixing 1 mg of epinephrine in 250 ml saline at the rate of 0.25 to 1 ml/min. Epinephrine may also be given via an endotracheal tube, intralingually or intramuscularly if setting up an IV access is not feasible.
3. Crystalloids should be given intravenously in cases of hypotension. For persistent hypotension, vasopressors such as dopamine and norepinephrine are required.
4. Apart from epinephrine, antihistaminics should be given as a drug not as a substitute. Diphenhydramine is given intravenously at a dose of 50 mg.
5. Bronchospasm can be relieved by using a nebulised β2 agonist such as salbutamol at a dose of 2.5 mg by diluting it in 3 ml of saline.
6. Hydrocortisone or methylprednisolone at a dose of 125–250 mg can be given intravenously
7. Glucagon is given to patients on beta blockers to counteract the beta blockade as a dose of 1 to 5 mg IV over 5 minutes followed by 5 to 15 mcg/min infusion as they do not respond well to epinephrine.
8. It is advised to remove the stinger immediately but not by squeezing it since it will release more venom from the venom sac.
9. In cases of mild reactions, an ice pack or a diluted vinegar application usage is sufficient at the site of the sting. Oral and topical antihistaminics will also be of benefit.
10. In cases of massive envenomation caused by multiple bee stings, aggressive treatment with epinephrine, antihistaminics, steroids and calcium gluconate (10 mL of 10% solution slow IV) for hyperkalemia may be required. Since coagulopathy, renal and neurological damage may occur the patient should be kept under observation for 12–24 hours.

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Prevention- Venom Immunotherapy (VIT)

Immunotherapy candidates require skin testing. The following tests for allergy are recommended by the British Society for Allergy and Clinical Immunology:

Skin prick test (SPT)

1. In this test, standardized bee venom extract 1 to 100 mcg/ml is used to prick the epidermis layer of the skin. For comparisons, a positive control with histamine and a negative control with saline is done.
2. Specific IgE antibody against bee venom is confirmed when a wheal measuring 3 mm more than the negative control is seen.

Intradermal testing

1. It is done by using allergen concentrations between 0.001 mcg/ml and 1 mcg/ml in cases when SPT is found to be negative in patients who have a strong clinical history of bee venom allergy.
2. 0.03 ml of the extract is injected intradermally to create a bleb of 3 to 5 mm and the test is said to be positive when the wheal diameter increases by a minimum 3 mm in 20 minutes.

Serum specific IgE antibody assay

1. It is done by using solid-phase enzyme immunoassay. A serum specific IgE assay of greater than or equal to 35 KU/mL is said to be positive.
2. Since a raised serum tryptase level and mastocytosis are considered as risk factors for severe reactions to bee stings, all patients that develop a systemic reaction, should have their baseline tryptase level checked.
3. A bone marrow biopsy should be done if the baseline tryptase level is >20 mcg/ml for further investigation for systemic mastocytosis.

Asymptomatic sensitisation is indicated when the total serum IgE is more than 250 KU/ml and these patients are likely to be safe from severe anaphylactic shock.

Venom immunotherapy (VIT) can help to avoid fatal reactions in hymenoptera allergy. VIT and allergy testing are advised in patients who have suffered from systemic reaction due to bee sting previously. In cases of recurrent stings, VIT may lower the risk of a fatal allergic reaction. It is a highly effective and specific form of treatment that should be given to bee keepers who want to continue with their bee keeping occupation despite having had an earlier severe systemic reaction.

VIT is not advised in cases of pregnant women, asthma patients and patients taking beta blockers. In younger patients who previously suffered from cutaneous reactions without other systemic manifestations, and in patients of 16 years and younger, VIT is usually not needed.

These are the indications after a bee sting in which hymenoptera immunotherapy is given to patients with clinical reactions:

• If specific IgE is positive and systemic reaction is severe
• If specific IgE is positive and systemic reaction is moderate
• If specific IgE is positive and there is a proof of psychological affection with mild systemic reaction

Dosage schedule

The dosage schedule for VIT includes increasing the amount of purified bee venom extract in injections given subcutaneously as two phases,

1. The build-up phase of VIT where tolerance to the allergen is slowly induced in the build-up phase.

• In the upper arm of the patient, a 1 cc syringe containing 0.1 cc of 1:10,000 dilutions is used to inject the lowest dose of the most dilute allergen extract subcutaneously
• The size of the local reaction is recorded and graded by keeping the patient under observation for 30 minutes
• Till a maximum tolerated dose of 0.5 cc of 1:1 concentration is reached, the injected dose is increased every week for up to 1 year till this dose becomes the maintenance dose

2. In the maintenance phase of VIT,

• The time duration between the maintenance doses is subsequently increased to two, three and 4 weeks till no large local reactions are taking place
• After gaining control of the allergic reactions, injections should still be continued for 2 to 5 years
• Every year, immunotherapy patients should visit their doctors for yearly follow-ups even after completing their injections

Rush and ultrarush VIT are accelerated schedules of VIT.