Ant venoms: a rare cause allergic reactions in Switzerland

In Switzerland, unlike other countries, allergic reactions to ants are a ra re phenomenon when compared to the well known allergies to bee and wasp ven om. In this report we present a series of case reports and a review of the different types of allergy to ants. Due to increased travel and heterogenei ty of the population, we have observed several patients with sensitisation or allergy to the venom of imported fire ants (Solenopsis), a species of an t found in the Americas. Furthermore, allergic reactions to bites of the mo und-building wood ant (Formica rufa), whose habitat is Central and Northern Europe, have been documented. Whereas reactions to fire ants can be life-t hreatening, reactions to mound-building wood ants have led to marked local reactions and in 2 cases to dyspnoea and wheezing. These reactions could be due either to primary sensitisation to ant venom or cross-reactivity in th e presence of an allergy to wasp venom. Evaluation of patients presenting w ith a potential ant venom allergy includes a detailed personal history, ski n testing and determination of specific IgE. However, to date only extracts from fire ants are commercially available for diagnostic tests. In the lig ht of our observations we assume cross-reactivity between the venoms of fir e ants and mound-building wood ants, and it therefore seems appropriate to use fire ant diagnostics in determining sensitisation to mound-building woo d ants. In patients with severe fire ant-venom allergy we recommend desensi tisation by immunotherapy, whereas in patients presenting with minor allerg ic reactions, e.g. after bites by mound-building wood ants, we provide the patients with emergency medication. Since current knowledge of ant allergie s in Europe is limited, further studies are warranted.