- The order hymenoptera includes bees, wasps, hornets, and ants.
- Hymenoptera stings cause toxic and allergic reactions that present across a broad clinical spectrum: from mild, localized reactions to severe, systemic, and potentially fatal reactions. The clinical presentation is determined by both the type of insect involved and host factors, including immunologic status and history of prior sensitization.
The order hymenoptera includes bees, wasps, hornets, and ants. Hymenoptera stings cause toxic and allergic reactions.
Toxic reactions, also termed local reactions, result from local tissue effects of venom containing histamine, hyaluronidase, mellitin, or phospholipase. The toxic reactions are often mild, lasting several hours. Localized pain, edema, fever, urticaria, serum sickness, and arthralgias may ensue. They can be severe or even fatal if many stings occur.
Allergic responses are IgE dependent and present in a previously sensitized individual as a local exaggerated reaction or a generalized systemic (anaphylactic) reaction. Local exaggerated reactions may be recognized when erythema, swelling, and itching extend beyond the site of the sting. Anaphylaxis involves more systemic involvement, including circulatory and respiratory compromise. It is a medical emergency requiring prompt diagnosis and immediate emergent management. Risk factors for anaphylaxis include a history of repeated stings and may be an occupational hazard for those frequently exposed to these insects; other associated risk factors include male gender, older age, elevated serum tryptase level, cutaneous or systemic mastocytosis, and medications such as angiotensin-converting enzyme inhibitors. Vespid (wasp) stings are more commonly associated with anaphylactic reactions.
Different hymenoptera members have distinct stinging patterns. Most nest in the ground or in walls and sting only if provoked, with the exception of Africanized bees. Honeybees typically leave a barbed ovipositor (stinger) in the skin, whereas bumble bees, wasps, and hornets can withdraw their stinger. Ant stings are painful and usually multiple; fire ant stings are notably painful. Tender urticarial lesions may result with development of a pruritic sterile pustule.
Any hymenoptera sting may cause eosinophilic cellulitis (Wells’ syndrome) with flame figures seen on histopathology. Dramatic reactions, including anaphylaxis, may be a presenting manifestation of mastocytosis and likely is not mediated by IgE.