Diagnosis and therapy of bee and wasp venom allergy
Diagnosis and therapy of bee and wasp venom allergy Allergic reactions caused by stings of honey bees (Apis mellifera) or social wasps (particularly Vespula vulgaris, V germanica) nearly always present as large local reactions (in up to 25% of the population) or as systemic reactions with symptoms of immediate type allergy (anaphylaxis; in up to 3.5% of the population). Systemic sting reactions are induced by IgE antibodies interacting with venom components. Other clinical presentations of allergic reactions (\\\\\\"unusual sting reactions\\\\\\") and toxic reactions after numerous stings are very rare. Particularly severe anaphylactic reactions may be fatal or result in disability. Acute reactions are managed by symptomatic treatment. Patients with allergic reactions profit from long-term treatment comprising education to avoid further stings, and from training to be prepared for self-management including the use of emergency medication in case of further stings. Adrenaline for self-administration is part of the emergency kit in those patients presenting with systemic immediate type reactions. Specific immunotherapy (SIT) is the main treatment option to prevent subsequent systemic reactions. Diagnostics in patients with systemic immediate type reactions are based on history, skin tests, and assessment of specific IgE antibodies to whole venom. Sometimes, these tests may not yield a venom sensitization which corresponds with the patients history. In such cases, it is recommended to determine concentrations of specific serum IgE antibodies to relevant single venom allergens (currently Api m 1 and Ves v 5 are available) and to perform cellular tests, if appropriate. The results of diagnostic procedures, however, are sensitive to a variety of interferences. Therefore, \\\\\\"false-negative\\\\\\" or \\\\\\"false-positive\\\\\\" reactions may occur in any system. Patients with an elevated serum concentration of baseline tryptase (95th percentile 11.4 mu g/l) and/or with mastocytosis frequently suffer from very severe anaphylactic sting reactions. To recognize these risks, baseline serum tryptase concentration should be determined and the skin should be inspected for the presence of cutaneous mastocytosis. SIT with bee or wasp venom is mandatory for patients who have experienced sting reactions with respiratory or cardiovascular symptoms. For patients with mild systemic sting reactions limited to the skin and with individual risk factors, SIT is also urgently recommended. Beyond that, SIT is advisable to all adult patients with systemic immediate type sting reactions independently of the severity grade. Only for children with systemic immediate type reactions confined to the skin data are available showing that SIT is not mandatory. There are numerous protocols for dose increase during the initial phase of venom SIT: The maintenance dose may be reached within one day (ultrarush), alter 3 5 days (rush) or within weeks or months (conventional SIT). The frequency of adverse effects is related to the speed of dose increase. The standard maintenance dose is 100 mu g. Bee venom SIT is less effective than wasp venom SIT. Therefore, high-risk patients suffering from bee venom-allergy may receive an increased maintenance dose of 200 mu g right from the start; this strategy may be also indicated in selected high-risk patients with wasp venom allergy. Systemic anaphylactic reactions and subjective complaints are the most important adverse effects of venom SIT, occurring particularly during the incremental phase. Mostly, these reactions are mild. Rarely, there are repeated anaphylactic reactions which substantially hamper treatment or even necessitate its termination. In such cases, co-treatment and/or pre-treatment with the anti-IgE antibody omalizumab appears to be the best option currently available to achieve tolerance of SIT; it has to be considered, however, that using omalizumab for this indication would be an off-label use. Also, these patients are treated with an increased maintenance dose (> = 200 mu g). There are no laboratory tests to determine the efficacy of SIT. A sting challenge test using a living insect should be performed about 6 18 months alter the maintenance dose has been reached to identify treatment failure. If necessary, this interval may be shortened in high-risk patients. Sting challenge tests need to be performed with utmost caution providing emergency room conditions. If a patient continues to develop a systemic reaction despite SIT, administration of an increased maintenance dose nearly always provides protection (usually 200 mu g are sufficient). In most patients, SIT can be stopped after 3 5 years, if SIT and a re-sting were tolerated without systemic reactions. If there is no tolerance or if a patient presents with individual risks, a decision has to be made as to whether SIT should be continued or not. This decision largely depends on the patients individual risk profile, and usually prolonged treatment is necessary. Life-long SIT is indicated for some patients, e.g. for those with mastocytosis or in case of a prior sting reaction requiring cardiopulmonary resuscitation.