I would really appreciate your advice on this unusual hymenoptera venom patient who is a 13 year old otherwise healthy boy.
In September 2011 and May 2012, the patient had delayed systemic reactions after stings. One sting was thought to be caused by a honey bee; on the other occasion the insect was not seen. On both occasions, he had only a local reaction right after the sting, but the next day (12 to 18 hours later) began with a slowly progressive systemic reaction starting with hives, progressing over a few hours to itching in his throat, sensation of swelling of his throat, swollen tongue, chest tightness, nausea, abdominal cramping, diarrhea and dizziness. The reactions responded to epinephrine and benadryl.
Skin testing was done in July 2012 and was positive for honey bee and white faced hornet, both at 0.1 mcg/mL, and negative for yellow jacket, wasp and yellow hornet. Serum IgEs were negative for all 5 venoms.
He started on venom allergy shots for honey bee and white faced hornet; had 2 episodes of abdominal cramping 2 hours after the injections at 0.4mL of 1 mcg/mL dose, but this did not recur once he started taking Singulair on the day of his injections. He reached the full dose in January and has continued to receive his venom allergy shots at 4 week intervals.
A few weeks ago, "D" was stung again, this time by a yellow and black striped insect, on the ankle. He had a large local reaction and about 30 minutes later had a systemic reaction, with dizziness, chest tightness, swelling of his lips and tongue. He took his EpiPen and benadryl, and recovered.
Repeat skin testing now shows positive reactions to all 5 venoms: honey bee and WF hornet at 0.1mcg/mL and the other 3 at 1 mcg/mL. Immunocaps were positive for WF hornet (0.87) and "indeterminate" (meaning > 0.1 but < 0.35) for the other 4 venoms.
So, we have a boy who previously had late phase systemic reactions, is on IT for honey bee and SF hornet, and now had an immediate reaction to a yellow and black striped insect, probably either yellow jacket or yellow hornet. But he is sensitized to all 5 venoms.
1. Are the reactions at 1 mcg/mL ID sometimes just irritant reactions? or representing cross reactivity with the white faced hornet?
2. Are the indeterminate serum IgE levels (which were previously all < 0.1) relevant?
3. Should I treat him with all 5 venoms? I guess the main question is whether to leave out the wasp venom, since he has no history of having a reaction to wasp and only had a + skin test at the highest concentration, and the serum IgE level is only 0.11? or is he at risk for a systemic reaction to a wasp sting in the future?
Thank you for your advice!