Species-specific outcomes in wasp sting challenges during venom immunotherapy and their respective follow-up

Insect venom allergy is a major cause of life-threatening anaphylaxis, with venom immunotherapy (VIT) being the gold standard for prevention. Sting challenges (SC) are used to assess immune tolerance and VIT efficacy, but factors influencing outcomes remain unclear. This study examined whether the stinging insect species affects SC outcomes during VIT and evaluated outcomes during long-term follow-up.

A retrospective analysis of 1,163 patients undergoing SC during wasp venom VIT was performed. The stinging species was entomologically confirmed. Associations between SC tolerance and species, skin prick test (SPT) results, venom-specific IgE levels, and treatment duration were analyzed using multivariable logistic regression adjusted for demographics. Follow-up assessed subsequent field stings and systemic reactions.

SCs were conducted with Vespula vulgaris (n = 479), Vespula germanica (n = 615), Dolichovespula media (n = 40), and Dolichovespula saxonica (n = 29). SC was tolerated without systemic reaction in 1,141 patients (98.1%). Vespula spp. were associated with a significantly higher likelihood of tolerance (odds ratio (OR) 7.69, 95% CI 2.66 - 20.43) compared with Dolichovespula spp. A decline in SPT positivity occurred after VIT, and conversion from positive to negative at 10 µg/mL showed a trend toward improved sting tolerance (OR 2.26, 95% CI 0.68 - 11.53). During follow-up (mean 53.2 ± 38.5 months), 167 patients experienced field stings; 6 developed systemic reactions, none of whom had been challenged with Dolichovespula spp.

Species-specific differences influence sting challenge outcomes, suggesting incomplete cross-protection of Vespula VIT against Dolichovespula spp. Declining SPT reactivity may predict sting tolerance. SCs remain a reliable indicator of post-therapy protection against anaphylaxis.