Whilst the safe “in vitro” tests are usually preferred there is no doubt that most allergists would prefer the greater reliability of a sting challenge test in determining the level of insect sting allergy of any particular patient. Whilst on the one hand there is an undoubted risk associated with introducing a high level of venom to a potentially anaphylactic patient, the huge advantage is that it offers a reliable and more definitive result. Sting challenge testings is really the gold standard of determining whether or not a patient is anaphylactic to a particular insect but clearly the risks and ethics make this method of testing generally unpopular among the medical community.
METHODS OF STING CHALLENGE TESTS
The sting challenge test usually consists of either
- placing a live stinging insect on the arm or a patient and provoking it sufficiently to sting the patient and so introduce venom into the patient, or
- introducing venom into the patient by injection with the reconstituted dried venom powder which is traditionally used for venom immunotherapy.
The response to the challenge is usually by grading according to the four levels of anaphylaxis as described by Mueller.
precautions when using sting challenge testing
It is strongly recommended that individuals undergoing this form of testing are as a minimum offered immediate access to either an intensive care unit or an emergency room with full resuscitation services. The majority of allergists would also place a venous cannula into the patient and offer continuous heart and blood pressure monitoring.