Venom Immunotherapy (VIT) is a series of injections of small doses of venom into the body in an attempt to build up the body’s tolerance to venom and prevent future anaphylaxis. Doses are gradually increased over a span of weeks until the target maintenance dose of 100mg is reached (Krishna et al., 2011). The ideal duration of VIT is unclear as some sources claim the optimum length is three years and others claim the therapy is needed for between five years and life (Krishna et al., 2011; Tracy, 2011).
VIT is not reccomended for all people but when reccomended it is effective for 95% of people with wasps allergies and 80% of people with bee allergies (Krishna et al., 2011). It is currently the only curative treatment for hymenoptera allergy, and when successful it provides long-term protection against allergic reactions to stings (Ozdemir et al., 2011; Tracy, 2011).
VIT is recommended for people with moderate to severe reactions to stings. People with mild sting allergies who work closely with hymenoptera or who have raised tryptase levels may also undergo VIT. VIT is not recommended for most children as they generally have less severe reactions to stings than adults do (Krishna et al., 2011).
Figure reproduced with permission from Dr. Nasser.
VIT works by modulating the T and B cell responses to the venom. It allows for earlier production of IL-10, which works by blocking the phosphorylation of CD28 cells to prevent the hyper-response associated with anaphylaxis (Krishna et al., 2011).
There are some downsides to VIT. Up to 50% of VIT patients experience uncomfortable reactions to the venom during the VIT process (Tracy, 2011). These side effects are more common in people with bee allergies than those with allergies to other hymenoptera species. Occationally the side effects are adverse enough to warrant prematurely discontinuing VIT (Przybilla and Ruëff, 2010). Even in patients who complete the entire VIT process, those with honeybee allergies may relapse after discontinuation of VIT (Bilò, 2011).
Recently, scientist have been purifying venom extracts for VIT. The use of these extracts has correlated with fewer local reactions. It is likely purified extracts will become more popular in the future. It is also likely that soon chemically modified venoms in order to increase the safety and efficacy of VIT (Bilò, 2011).
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