[Round Table: Urticaria caused by arthropod bites and stings (excluding Hymenoptera)].

Adverse reactions to arthropod bites (hymenoptera excluded) can be faced with systemic reactions and local reaction. Among the numerous families of arthropods the species most commonly responsible are mosquitoes,. flea, horsefly and tick. In this article we explain the characteristics of reaction caused by arthropods and the mechanisms proposed. An IgE mechanism is incriminated in severe anaphylactic reactions. Various mechanisms have been proposed for local reactions. In order to know the incidence of sensitization and cross-reactivity with other arthropods, we have done a study where we have found that 31% of patients with reaction to mosquito bite had sensitization to Aedes communis and 53% of this group also had sensitization to other arthropods, probably due to a cross-reactivity.