Venom Immunotherapy (vit)

allergy vaccine kitsThe great majority of insect sting allergic responses are mild inconveniences that can be controlled by taking anti-histamines. For some the response is so aggressive that it needs to be treated because a sting can potentially lead to the life threatening allergic reaction called anaphylaxis.

The principal approach to this treatment is Venom Immunotherapy, or desensitization.

In February 2012 the National Institute of Clinical Excellence (NICE) issued a technical appraisal which confirmed the efficacy of the treatment to patients and its cost effective.  The Technical Appraisal on Venom Immunotherapy  may be read on this link .

The fact is that for the great majority of patients it does seem to work and thousands of people around the world are very grateful that it does. The principle behind venom immunotherapy is that you are injected on a regular basis with gradually increasing doses of venom until you reach the maintenance level of 100 micrograms of venom. This is equivalent to being stung by quite a few wasps and bees!

You therefore start off with a tiny dose and over the period of the immunotherapy one somehow reaches the target maintenance dose  without any major allergic response. You are then “cured” of your allergy but have to be dosed up for the next few years just to keep de-sensitized. The theory is that eventually you don’t need the maintenance injections and you are “cured” of the allergy!  The typical length of treatment is between three and five years.

The Risk

The major risk of venom immunotherapy is anaphylaxis during the treatment. The immunotherapy can cause a serious allergic reaction which is why it should always take place in hospital next to the Emergency Room or in a clinic with full resuscitation services.

The treatment protocol varies depending on which country you are located and which allergist you are being treated by, but the following protocols are typical:

  • Rush Immunotherapy – a rapid form of treatment with injections every few hours for typically 3 to 5 days at the end of which the patient becomes desensitized
  • Standard Immunotherapy – typically this is between 10 and 15 weeks with an injection offered to the patient each week
  • Slow Immunotherapy – typically this happens in the event that the patient suffers a systemic response during treatment.  The allergist will typically halve the next dose and then continue at a less aggressive rate than the standard immunotherapy.

Testing for wasp and bee sting is not straightforward.   Patients are usually offered a skin prick test or a blood test which in theory determines to which insects the patient is allergic; once established then the patient starts off a course of build up injections with the venom specified by the blood test. In the opinion of most doctors, immunotherapy should not start without a specific IgE identified by the relevant testing and a definite history of suspected anaphylaxis.

However, there have been a significant number of cases of people who have had systemic life threatening reactions but have had negative test results. So  generally speaking case history is a key indicatior for immunotherapy.

Preparing InjectionImmunotherapy Injections: The strength, number, frequency and duration of these injections varies according to country, the practitioner, government advice, financial conditions and the general fashion at the particular point in time. Once again, there are no hard and fast rules about this treatment although my own experience and those of others who have contacted me from this website are that the frequency starts off weekly until maintenance dose is achieved in 12 weeks.  After this the patient is injected monthly for a period of 2 to 3 years.

The jury is still not completely decided as to whether rush immunotherapy is more risky than traditional 12 week immunotherapy although most allergists would err on the site of caution and claim that rush immunotherapy does carry more risk.   An accelerated treatment programme is certainly more convenient and I know of a number of visitors to this site that have successfully had this treatment in Continental Europe and the UK.

Whatever the protocol it is important that following each injection you stay in the hospital for up to an hour – allergic reactions are not always immediate, so don’t be lulled into a false sense of security if nothing happens immediately!
Strength of Injections – Whilst most people seem to agree that the target 100 mg of venom is an appropriate target dose for the end of the course, the starting dose depends on many factors – usually completely unrelated to the patient but more determined by the established practice in the particular country of treatment. Thus Americans seem to start their injections at much lower levels of venom than Europeans.

In the UK at least, we usually look to start at around 1/5000 of a sting. The key to success is to use the potency of the injection to ensure that desensitisation starts before an allergic reaction takes place.

Once the maintenance sting level has been achieved then you are “cured” but still have to have maintenance injections for a period of time to keep desensitised.

Finally, one of the urban myths surrounding venom immunotherapy is that a wasp sting is equivalent to 50 mg of venom.  In fact, a bee sting is around 50 mg of venom and a wasp sting can vary from around 6 mg of venom to 30 mg of venom.  The shots you are getting for wasp and bee immunotherapy is therefore much more than one wasp sting – probably nearer five or six.

The leaflet which one of the leading manufacturers in Europe distributes with the venom kit is available for viewing below:

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Venom immunotherapy is serious stuff – but professionally conducted is relatively safe and offers the patient a wonderful way to sort out what is one of the most dangerous allergies of them all. A recent paper shows quite clearly that simply carrying an epipen does little if anything to improve the quality of life of an insect sting allergic patient. Venom Immunotherapy on the other makes a huge difference – as I can personally testify.