Summary

Bumble bees (Bombus terrestris; Bombus pennsylvanicus) are insects of the Apidae family, found in many countries. There are many different bumble bee species, which vary in phenotype. The venom injected by the bee’s stinger is the cause of hypersensitivity and allergic reactions. A number of bumble bee venom allergens have been described.

Allergic reactions to bumble bee venom present with symptoms ranging from localized to systemic, including severe anaphylaxis. Cross reactivity with other bumble bee and honey bee venom allergens may occur.

Epidemiology

Worldwide distribution

Bumble bee venom hypersensitivity has been described in several countries, including Sweden, Finland, The Netherlands, and China.

Risk factors

Certain occupations such as gardeners, greenhouse and plant nursery workers present high exposure to bumble bees; these workers are at higher risk of becoming sensitized to the venom and develop severe allergic reactions. The length of time the person has worked in proximity to bumble bees is also a potential risk factor. In a study of greenhouse workers, 38% showed positivity to bumble bee venom. Compared to the non-hypersensitive patients, those with bumble bee hypersensitivity had worked in a greenhouse environment for longer and had higher number of stings in the preceding 12 months.

Scientists studying bumble bees are also at higher risk of developing hypersensitivity.

Route Of Exposure

Main

Injection of the venom by the stinger

Clinical Relevance

Other diseases

Systemic reactions to Hymenoptera venom have been described in 0.34–3% of the population, with children usually less affected. It is estimated that a quarter of fatalities due to anaphylaxis had been triggered by insect venoms. Anaphylaxis induced by bumble bee stings is possible but rare, presenting usually in people working with plants.

Symptoms of Hymenoptera venom hypersensitivity can be varied, ranging from localized skin reactions, to various degrees of severity in systemic reactions. The allergic reactions described as mild presented with erythema, urticaria and angioedema; moderate presented with nausea, dizziness and dyspnea; or severe presented as anaphylactic shock, asthma, loss of consciousness and potentially also cardiac and respiratory arrest.

In a study of 39 greenhouse workers with a confirmed bumble bee venom hypersensitivity, the type of allergic reaction ranged from skin reactions measuring less than 10 cm (74%), to larger skin reactions more than 10 cm (21%), or systemic sting reactions (5%). In a case report, a 27-year old patient developed severe systemic allergic reactions to bumble bee venom, characterized by local swelling, urticaria, Quincke edema and asthma.

Central retinal artery occlusion (CRAO), edema and blurred vision, which progressed into unilateral loss of eyesight, were described as consequence of a bumble bee sting in a 66-year old patient. The patient also reported other severe systemic symptoms, which included coma, dizziness, nausea, vomiting and diarrhea, headache; the patient also suffered myocardial and hepatic damage.

In another case report, a patient suffered coronary artery ischemia following anaphylactic shock caused by a bumble bee sting. This was described as Kounis syndrome – i.e. allergic angina syndrome which may progress into myocardial infarction.

Diagnostics

Testing for venom allergies involves measuring serum specific IgE responses, using radio allergosorbent tests (RAST) or skin tests. Studies recommend using the appropriate bumble bee venom to diagnose primary bumble bee hypersensitivity, as partial cross-reactivity with honey bee venom might occur but not disclose the primary sensitizing species.

Prevention And Therapy

Allergen immunotherapy

Specific immunotherapy (SIT) has been shown to be useful for the treatment of hymenoptera venom allergy (HVA). In particular, there appears to be two distinct populations of patients with bumble bee hypersensitivity: those with IgE highly cross-reactive with honey bee venom, and those who appear have specific bumble bee hypersensitivity. In the first category, SIT should be carried out using honey bee venom, as the reactions to bumble bee stings result from earlier exposure to honey bee venom and antigen cross-reactivity. In the second patient category, heavily exposed to bumble bee stings only, SIT would be more effective if carried out with purified bumble bee venom. SIT is an appropriate treatment option for patients who cannot completely avoid exposure to bumble bee venom and its efficacy can be monitored by sting challenge. Furthermore, SIT for Hymenoptera venom has been shown to be safe to administer to patients undergoing treatment for cardiovascular disease. Purified bumble bee venom is however not always readily available for therapy.

Prevention strategies

Bumble bee stings in the general population are an infrequent occurrence, due to the environment and habits of this insect. For people in at risk professions such as gardeners, avoidance consists of changing job.

Cross-Reactivity

Evidence of cross-reactivity with honey bee venom has been described. Sera from patients with a previous history of bumble bee allergies showed positive response to honey bee venom proteins in 85% of tests. However, some patients who are primarily sensitized to bumble bee venom may not have cross-reactivity to honey bee venom, or only show partial cross-reactivity.

A study of 6 serum samples from patients sensitized to Bombus terrestris showed that although cross-reactivity exists between venom of this species and the American bumble bee (B. pennsylvanicus), there are also significant species-specific differences in the allergen composition of their venom.