How to identify and treat common bites and stings
A thorough history and physical are key to proper diagnosis and treatment following a patient’s encounter with an insect, arachnid, or other arthropod.
PRACTICE RECOMMENDATIONS
❯ Recommend that patients use an insect repellent, such as an over-the-counter formulation that contains DEET, picaridin, or PMD (a chemical constituent of Eucalyptus citriodora oil) to prevent flea bites. C
❯ Prescribe nonsedating oral antihistamines as first-line symptomatic treatment of mild-to-moderate pruritus secondary to an insect bite. C
❯ When indicated, refer patients for venom immunotherapy, which is approximately 95% effective in preventing or reducing severe systemic reactions and reduces the risk of anaphylaxis and death. C
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
After VIT is complete, counsel patients that a mild systemic reaction is still possible after an insect bite or sting. More prolonged, even lifetime, treatment should be considered for patients who have58,59
- a history of severe, life-threatening allergic reactions to bites and stings
- honey bee sting allergy
- mast-cell disease
- a history of anaphylaxis while receiving VIT.
Absolute contraindications to VIT include a history of serious immune disease, chronic infection, or cancer.58,59
Managing anaphylaxis
This severe allergic reaction can lead to death if untreated. First-line therapy is intramuscular epinephrine, 0.01 mg/kg (maximum single dose, 0.5 mg) given every 5 to 15 minutes.14,60 Epinephrine auto-injectors deliver a fixed dose and are labeled according to weight. Administration of O2 and intravenous fluids is recommended for hemodynamically unstable patients.60,61 Antihistamines and corticosteroids can be used as secondary treatment but should not replace epinephrine.56
After preliminary improvement, patients might decompensate when the epinephrine dose wears off. Furthermore, a biphasic reaction, variously reported in < 5% to as many as 20% of patients,61,62 occurs hours after the initial anaphylactic reaction. Patients should be monitored, therefore, for at least 6 to 8 hours after an anaphylactic reaction, preferably in a facility equipped to treat anaphylaxis.17,56
Before discharge, patients who have had an anaphylactic reaction should be given a prescription for epinephrine and training in the use of an epinephrine auto-injector. Allergen avoidance, along with an emergency plan in the event of a bite or sting, is recommended. Follow-up evaluation with an allergist or immunologist is essential for proper diagnosis and to determine whether the patient is a candidate for VIT.14,17
CORRESPONDENCE
Ecler Ercole Jaqua, MD, DipABLM, FAAFP, 1200 California Street, Suite 240, Redlands, CA 92374; ejaqua@llu.edu.
