I have a 16yo female patient who reported hanging out in a field of grass and weeds with her boyfriend. Within several minutes it was noted that she had swelling, itching and hives on the right side of her face and right hand. She began to experience trouble breathing and the sensation of throat closure. She felt nauseated and became confused. In the next 24 hrs it was noted that she also had several scattered pustules on the right hand. It was also noted that her boyfriend developed what they described as red bumps, looked like bug bites on his neck but not described as pustules. She cannot recall the presence of ants or feeling ant bites nor can she recall presence of any flying insects or flying insect stings. There was no identifiable sting site either. She denies any other identifiable trigger and denied sexual activity, exposure to seminal fluid or latex at the time. She also denied previous rhinitis symptoms. Per a geographical map of fire ant distribution our area could have fire ants but not necessarily confirmed.
She was treated in an ED with IV steroid and H1/H2 blocker with improvement. About 24 hours later she began to have recurrence of the right hand and face itching, swelling and rash resolved by systemic steroid.
About 2-3 weeks out from reaction, lab was obtained with normal tryptase level 1.5mcg/L, total IgE 112 IU/mL, negative regional respiratory immunocapRAST IgE panel.
Serum IgE to fire ant was positive at 9.97 kU/L, class 3. Skin prick to fire ant not done yet because we were waiting to be about 4-6 weeks out from reaction to ensure time for antibody formation.
My questions are, given the history and findings would you do any further work up or test to other venoms, or simply proceed from here with VIT to fire ant?