Insect stings can cause local or systemic allergic reactions. Systemic reactions in children, unlike in adults, are usually limited to cutaneous signs with only infrequent hypotension. The prevalence of systemic reactions to insect stings is estimated at 1% in children and 3% in adults. Although 20% to 25% of adults have positive venom skin test or RAST, half of these will lose sensitivity in two to three years. In adults with positive skin test and no prior history of reaction, a subsequent sting caused a systemic reaction in 17%. There is no specific test that can distinguish those who will react. Patients with prior large local reactions have a 5% to 10% risk of having a systemic reaction to a future sting, even though they often have higher levels of venom-IgE than systemic reactors. Patients who have had previous systemic reactions have a variable risk of reaction to future stings: as low as 10% to 15% in the mildest reactors and some children, but as high as 70% in adults with the most recent and most severe reactions. Contrary to popular belief, the reactions to future stings are generally the same or less severe, and very infrequently get worse. Venom immunotherapy is recommended for patients at highest risk for severe systemic reactions to future stings, particularly those with the most severe previous reactions, but not for those at lowest risk such as those with large local reactions or children with mild reactions. The severity of reaction is not reliably correlated with the level of skin test reactivity. Skin tests become negative in only 20% of patients after 5 years of therapy, but in 60% to 70% after 7 to 10 years. In untreated patients, the frequency of systemic reaction to a sting falls from 50% initially, to 25% after 7 to 10 years. In treated patients, the risk is 2% during therapy, but rises to 10% to 15% after stopping therapy. A patient may not react to one sting but then may react to another sting at a later time. Some patients have reactions despite having had negative venom skin tests. Children commonly outgrow insect sting allergy, but untreated children with severe reactions to stings in childhood had a 36% frequency of systemic reactions to stings 10 to 15 years later. Children with milder reactions had an 11% risk of reaction as adults, and children who received venom immunotherapy for three to five years had only a 4% incidence of systemic reactions as adults, showing a remarkable lasting suppression of the venom allergy.
|Original language||English (US)|
|Number of pages||7|
|Journal||Canadian Journal of Allergy and Clinical Immunology|
|State||Published - Jan 1 2000|
ASJC Scopus subject areas
- Immunology and Allergy