Increased frequency of large local reactions among systemic reactors during subcutaneous allergen immunotherapy.

BACKGROUND: Large local reactions are not uncommon during allergen immunotherapy (AIT). Dosage adjustments after large local reactions are commonly instituted despite literature that suggests individual large local reactions do not seem to predict subsequent systemic reactions. OBJECTIVE: To investigate the relationship between large local reactions and the risk of systemic reactions to AIT. METHODS: Retrospective review of the AIT database of a large, multicenter allergy practice group was conducted between June 1, 2003, and May 31, 2005. Numbers of large local reactions in 258 patients who experienced systemic reactions to AIT were compared with 299 age-, sex-, and sensitivity-matched control patients who did not experience systemic reactions during AIT. RESULTS: A total of 283 systemic reactions occurred in 258 patients during the surveillance period, which included 661,123 patient visits for 1,108,621 allergy injections. The systemic reaction rate was 0.043% of visits and 0.025% of injections. The large local reaction rate was 35.2% of visits and 19.5% of injections among systemic reactors compared with 8.9% of visits and 5.3% of injections in the controls (P < .001 each). Thus, the odds of experiencing large local reactions were significantly increased among systemic reactors. CONCLUSIONS: Although AIT is a safe and effective immunomodulatory therapeutic option for the treatment of allergic diseases, patients with increased frequency of large local reactions may have increased risk for future systemic reactions. Identifying additional risk factors remains viable. Recognizing the relevance of frequent large local reactions is important for designing safer protocols for successful AIT in these patients.

Allergic reactions to insect stings and bites.

Insect stings are an important cause of anaphylaxis. Anaphylaxis can also occur from insect bites but is less common. Insect venoms contain several well-characterized allergens that can trigger anaphylactic reactions. Effective methods to diagnose insect sting allergy and assess risk of future sting reactions have been developed. Management strategies using insect avoidance measures, self-injectable epinephrine, and allergen immunotherapy are very effective in reducing insect-allergic patients' risk of reaction from future stings. Diagnostic and management strategies for patients allergic to insect bites are less developed.

Allergic reactions to Triatoma bites.

BACKGROUND: Triatoma bugs are best known in the medical community as vectors of trypanosomiasis (Chagas disease). However, bites of Triatoma bugs are a cause of local cutaneous reactions and anaphylaxis, mainly in the western and southwestern United States. The reactions typically occur at night during sleep, and the bite may not be recognized. There is continuing public interest in medical complications of bites of these bugs, although the scope of the problem remains undefined. OBJECTIVE: To review the relevant medical literature, identify present knowledge, and determine future research goals for allergy to Triatoma. DATA SOURCES: Computerized databases were used to search the medical literature for articles in the English language on Triatoma bites, allergy and entomology, and Chagas disease. STUDY SELECTION: Almost all identified articles on Triatoma allergy were used. Only selected articles on Triatoma bites and entomology were pertinent to the objectives. Articles on Chagas disease were limited to cases in the United States. RESULTS: Bites of Triatoma bugs have been known to cause anaphylaxis for more than a century. These insects inhabit a large area of the United States, but to date most reports of allergic reactions to their bites have originated in the West and Southwest. The reactions typically occur at night during sleep following a bite on uncovered skin and may be unrecognized. Procalin has been identified as the major salivary allergen of Triatoma protracta and was recently cloned and expressed through recombinant technique. Allergenic reactivity has been demonstrated to salivary gland extracts of 2 species. The extracts of these 2 species have not shown immunologic cross-reactivity. Immunotherapy using a salivary gland extract appeared to be beneficial in a small number of patients; however, no commercial testing or treatment allergen is available. CONCLUSIONS: Triatoma bites appear to be an important cause of anaphylaxis, especially in the western and southwestern United States. Because exposure to these insects often occurs during sleep, the incidence of allergic reactions to them is unclear. An epidemiologic study should be performed to determine the incidence, prevalence, and range of allergic responses to the bites of these insects. The lack of commercial antigen limits diagnostic and treatment capabilities. The development of an allergen under the Orphan Drug Act should be encouraged.