Classification of severity of reaction to bee or wasp sting

Bees and wasps inject venom when they sting

• when a person is stung by a bee or wasp they typically have an intense, burning pain followed by erythema (redness) and oedema (swelling) at the site of the sting
  • usually subsides within a few hours
    
    
  • after an initial sting, some people have an immune response and produce IgE antibodies. In these people, subsequent stings can trigger a rapid inflammatory response referred to as a 'type I' hypersensitivity reaction
    
    
    • hypersensitivity reactions to bee or wasp venom can be local or systemic, can vary in severity, and are typically of rapid onset
      • large local reactions are characterised by oedema, erythema and pruritus, cover more than 10 cm in diameter and peak at between 24 and 48 hours after the sting
      • systemic reactions can be measured using the Mueller grading system
        • severity ranges from grade I to grade IV
          • grade I systemic reaction is characterised by generalised urticaria or erythema, itching, malaise or anxiety
            
            
          • grade II reactions may include symptoms associated with grade I reactions as well as generalised oedema, tightness in the chest, wheezing, abdominal pain, nausea and vomiting, and dizziness
            
            
          • grade III reactions may include symptoms associated with grade I or II reactions as well as symptoms of dyspnoea, dysarthria, hoarseness, weakness, confusion, and a feeling of impending doom
            
            
          • grade IV reactions may include symptoms associated with grade I, II or III reactions as well as loss of consciousness, incontinence of urine or faeces, or cyanosis
            
            
      • guidelines for the treatment of bee and wasp venom allergy issued by the British Society for Allergy and Clinical Immunology classify systemic reactions as mild, moderate or severe
        • mild systemic reaction is characterised by pruritus, urticaria, erythema, mild angio-oedema, rhinitis and conjunctivitis
          
          
        • moderate systemic reactions may include mild asthma, moderate angio-oedema, abdominal pain, vomiting, diarrhoea and minor or transient hypotensive symptoms such as light-headedness and dizziness
          
          
        • severe systemic reactions may include respiratory difficulty such as asthma or laryngeal oedema, hypotension, collapse or loss of consciousness, as well as double incontinence, seizures, or loss of colour vision
          
          
        • anaphylaxis is defined by the European Resuscitation Council as a severe, life-threatening, generalised or systemic hypersensitivity reaction

Reference:

• 1) NICE (February 2012). Pharmalgen for the treatment of bee and wasp venom allergy
• 2) Mueller UR. Clinical presentation and pathogenesis. In: Mueller UR, editor. Insect sting allergy. Stuggart: Gustav Fischer; 1990. p. 33-65.