Honey bee stings and anaphylaxis
An allergy is a hypersensitivity (overreaction) of the immune system to something that usually causes no problem to most people. Overall, the prevalence of allergies seems to be increasing, probably owing to several different factors including changing environment (overuse of antibiotics, reduced early-life exposure to infectious agents and an increased exposure to allergens and air pollutants) and genetic factors.
Bee venom allergy usually occurs in beekeepers or their family members. Many honey bee stings can also happen when non-beekeepers are walking barefoot in grass or clover. Bumblebees are very uncommon causes of sting reactions but have been reported to cause anaphylaxis during occupational exposure in greenhouse workers.
Bee venom
Bee venom contains several different allergenic components including protein enzymes: phospholipases, hyaluronidases and acid phosphatases. Bees release a large amount of venom per sting (50–140 micrograms) and they have a complex stinging apparatus which drives venom deep into the tissue. In contrast, the amount of venom in a wasp sting is relatively less (2–17 micrograms). There is only limited cross-reactivity between bee and wasp venom, but there is significant cross-reactivity between honey bee and bumblebee venom.
Most bee stings cause just mild local reactions and the majority of these resolve without treatment. Some people develop extensive swelling at the site of the sting which can persist for several days or more and can usually be managed with antihistamines – although some cases require the use of steroids. This is called a large local reaction and occurs in about 14–43% of beekeepers.
Systemic reaction
A more worrying type of reaction is a systemic reaction where the body reacts at distant sites from the sting. Systemic reactions feature a spectrum of symptoms and signs including a rash all over the body, wheezing, abdominal pain and vomiting, throat tightness and collapse. These occur rapidly after being stung. Some patients also report a sense of impending doom. Others may suffer from sudden collapse without the presence of any other features.
The more severe end of the spectrum is known as anaphylactic shock. A systemic reaction is reported in 14–32% of beekeepers. Fatalities are rare and occur in 0.03–0.48/1,000,000 inhabitants/year.
Systemic reactions are more common in the early years of beekeeping and beekeepers who have about 15–25 stings per year are at higher risk for systemic reactions after bee stings compared with those receiving over 200 stings who appear to be protected.
Treatment
It is important that systemic reactions are treated promptly and appropriately. Following a bee sting it can take a few minutes for all the venom to be injected, thus quick removal of the sting is important. It is important to avoid squeezing the venom sac as this may result in more venom being injected. The sac can be flicked away with one scrape of a finger nail.
If the person develops features of anaphylaxis following a sting, including throat closure, difficulty in breathing or dizziness, then adrenaline should be administered if available. In cases of fatal anaphylaxis, the average time from sting to death was 10–15 minutes. It is therefore important that adrenaline is administered quickly.
Adrenaline is a lifesaving medication which helps to reverse the symptoms of anaphylaxis. There are three adrenaline autoinjectors available currently (Epipen, Jext and Emerade) so it is important that an allergic individual is familiar with his/her own device and aware of how to use it. An ambulance should be called whenever an adrenaline autoinjector has been administered or if no adrenaline autoinjector is available. If the patient is feeling dizzy, it is important to lie them down. If breathing difficulty is the main problem, then the patient should be positioned at 45 degrees. If the patient has become unconscious, they should be placed in the recovery position.
Allergy clinics
All patients who have experienced a systemic reaction should be referred to their local allergy clinic for assessment of their allergy, as patients with a history of systemic reactions have a 50% likelihood of a systemic reaction to a future sting. In the allergy clinic a patient will undergo skin-prick testing and some blood tests to check for allergy to bee venom. During that visit the doctor will also produce a treatment plan which will detail how to treat future allergic reactions, and will decide whether the patient is an appropriate candidate for venom desensitisation, also known as immunotherapy.
Immunotherapy
The aim of immunotherapy is to reduce the patient’s allergic reaction to a sting, so that if one occurred in the future the individual would suffer a local reaction only rather than a systemic reaction.
Immunotherapy consists of a course of injections of purified bee venom which starts at very low doses and steps up over a period of time (usually weekly for 12 weeks) to reach a maintenance dose of venom. The maintenance dose is then delivered at regular intervals (every eight weeks) for three years. It is a very well-tolerated therapy and is about 77–84% effective in patients treated with honey bee venom.
Immunotherapy is available at many specialist centres nationally but a patient’s need for such treatment must be assessed at an allergy clinic.
Reduce exposure risk
Management should also focus on reducing the risk of exposure to future stings. Simple measures include wearing double gloves when tending to bees and wearing a face veil along with a full protective beesuit. Allergic individuals are also advised to go to the hive accompanied by another person. The assistant should be instructed where the adrenaline autoinjector is kept and should be trained how to deliver the adrenaline in case the allergic individual is too ill to self-administer it.
To avoid family members being stung, beehives should be kept away from the house and clothing should be changed before entering the home. Honey extraction at home also increases the risk of being stung.
In summary
Bee venom allergy has the potential to be severe although fatalities are rare.
Quick recognition of anaphylaxis and timely delivery of adrenaline can be life-saving.
Anyone who has a suspected allergy should be reviewed in their local allergy clinic to assess their need for desensitisation.
References
Krishna, MT, et al (2011). Diagnosis and management of hymenoptera venom allergy: British Society for Allergy and Clinical Immunology (BSACI) guidelines. Clinical and Experimental Allergy, 41(9), 1201–20.
https://doi.org/10.1111/j.1365-2222.2011.03788.x
Müller, UR (2005). Bee venom allergy in beekeepers and their family members. Current Opinion in Allergy and Clinical Immunology, 5(4), 343–7.
https://doi.org/10.1097/01.all.0000173783.42906.95
Golden, DB, et al (2017). Stinging insect hypersensitivity: A practice parameter update 2016. Annals of Allergy Asthma and Immunology, 118(1), 28–54. https://doi.org/10.1016/j.anai.2016.10.031
Written by Dr Shelley Dua. This article appears in the April 2019 edition of Bee Craft Magazine.
Dr Shelley Dua is a consultant allergist at Addenbrooke’s Hospital in Cambridge. Her areas of research interest include peanut allergy, reaction-severity assessment, reactivity thresholds, co-factors and symptom patterns and progression during anaphylaxis.
Dr Dua is vice-chair of the specialty advisory committee for allergy at the Royal College of Physicians and writes national guidelines on the Standards of Care Committee at the British Society for Allergy and Clinical Immunology.
