AVOIDANCE OF STINGS
REACTIONS TO MOSQUITO
Stinging insects belong to the order Hymenoptera including the honeybee, bumblebee, yellowjackets, wasps and hornets.
IgE Anti-venom in the General Population: In the general population, bee venom-specific IgE antibody has been found in 6 -17% of the population Abstract while beekeepers, who are frequently stung have a higher rate of IgE antibody to bee venom in their serum. Abstract Abstract Golden et al. studied a randomized population of 269 adults and found that 26.5% of them had venom-specific IgE antibody detected by RAST or positive skin test. Fifteen percent of the group had detectable IgE antibody without a history of reaction to sting and 3.3% of them had a systemic reaction in the past. Abstract
Mortality from insect stings has been estimated at between 0.09 and 0.45 deaths per million people per year. Reference although post-mortem studies suggest tht this is an underestimation. Abstract
Natural History of Venom Sensitivity: Despite the apparently threatening nature of reactions to bee sting, with a relatively high level of anaphylactic reactions, the natural history of venom sensitivity is much more benign than one would expect. In studies following venom sensitized individuals over time there appears to be a natural waning of clinical sensitivity in association with decreasing levels of IgE anti-venom antibodies. Abstract Abstract Abstract That is especially true in children. Abstract In one 4 year follow-up study it was found that repeated stings in children whose initial reactions were confined to the skin, resulted in a reaction in only 9.2% of stings and the great majority were milder than the initial reaction. Only 11% were deemed to be of the same severity as the original sting and none were more severe. Abstract
Recurring stings tend to present the same clinical symptoms as the original sting Abstract and local reactions tend to recur as local reactions. Abstract Abstract This has been shown to be true in children. Abstract As a result, Venom immunotherapy is not indicated after large local reactions.
Protection by Venom Immunotherapy: Initially immunotherapy was performed with preparations of the whole body of the bee and that has quite clearly been shown to be poorly effective while desensitization with venom works very well. Abstract This has been proven for children as well as adults. Abstract Abstract
Reactions in Children: As discussed previously, reactions to hymenoptera venoms in children are generally milder than adults. When a child has an anaphylactic reaction, it usually involves respiratory symptoms and less commonly cardiac or neurologic. The majority of reactions to bee stings in children result only in symptoms confined to the skin as hives either locally or with a large local reaction or as generalized hives. The patients with simple urticarial reactions are not candidates for venom immunotherapy since the majority of such reactions do not go on to anaphylactic reactions and on repeat sting the chnces are good the reaction will be less than on the first occasion. Such children and their families are taught the use of an adrenaline auto-injector, epipen or epipen jr. Go to Epipen Teaching They do not need to undergo specific venom skin testing since there is no need to identify the exact stinging insect.
Venom Immunotherapy: If the reaction to a sting has led to respiratory symptoms then the child would be a candidate for immunotherapy with venom. This involves injections of diluted venom beginning with a dose that is very inlikely to create a reaction and then increasing the dose until the subject is able to tolerate 50 - 100 mcg of venom i.e. the equivalent of 1 or 2 stings. In order to choose which venom species to use for desensitization, skin testing is performed using dilutions of each of the different hymenoptera species.
The procedure for desensitization is cumbersome and an attempt is made to choose patients for this treatment who are truly at risk for an anaphylaxis. This is especially true in view of the fact that initially after immunotherapy has been started, the concentration of IgE anti-venom actually rises making it imperative that the desensitization is started out side of the season when stinging insects are present and that once started the protocol is continued. The subject will require injection of maintenance doses of venom for 5 years or more creating a considerable investment of time and effort not to mention potential for adverse effects. As a result, it is very important to select patients who will truly benefit from the procedure. Even a history of an anaphylactic reaction and a positive skin test to venom does not mean that the patient is at risk for further anaphylaxis when re-stung. In fact many studies have been performed with the patient being stung purposefully under controlled circumstances to help select patients for venom immunotherapy. It is generally agreed that re-stinging is the best way to select patients for immunotherapy but this is not practical and even re-stinging does not perfectly identify candidates for venom immunotherapy.
REFERENCE ABSTRACTS FOR PUBLICATIONS ON RE-STINGING:
Duration of Venom Immunotherapy: After initially proving that venom immunotherapy was protective, the question arose as to how long therapy should be maintained. This was approached in both retrospectively and prospectively in studies by Golden et al. and Reisman. Golden how long to desensitize Golden Discontinue venom immuno after 5 yrs Reisman follow after VIT Reisman duration of vit re: severity
DISCONTINUING VENOM IMMUNOTHERAPY: The Recommendations of the Committee on Insects (AAAAI 1998): REFERENCE
"The following recommendations are made for adults and children who have been treated with Hymenoptera VIT. First, the duration of VIT is a decision that should be made on the basis of a thorough discussion of the issues by the physician and patient. Individual patient variables include the presence of coexistent diseases and the need for concomitant medications, the patient's leisure lifestyle, the possible impact on the patient's career or job opportunities, and financial considerations. If treatment is stopped, the use of self-injectable epinephrine should be discussed.
Second, the conversion to a negative venom skin test response is one criterion for stopping VIT. However, there have been isolated reports of individuals who had subsequent anaphylaxis after re-stings after negative venom skin test responses. At present, some experts recommend that VIT be continued indefinitely despite conversion to a negative venom skin test response in those individuals who have had life-threatening anaphylaxis.
Third, patients who have had mild (hives or angioedema limited to the skin) or moderate (mild respiratory symptoms) reactions may discontinue VIT after 3 to 5 years of treatment. For this group of patients, the risk of sting-induced reaction is small, and the chance of a severe reaction is very low.
Fourth, for patients who experienced severe (hypotension, laryngeal edema, or bronchospasm) sting reactions before VIT was initiated and therefore have a higher risk of more severe sting-induced systemic reactions if VIT is stopped, the physician may wish to continue venom injections for more than 5 years and perhaps indefinitely. However, because even the majority of these most-at-risk patients tolerate discontinuation of VIT after 5 years of treatment, stopping treatment is an option."
AVOIDANCE OF STINGS
REACTIONS TO MOSQUITO