Chronic urticaria and infections

Purpose of review The pathogenesis of chronic urticaria is multifactorial and a specific treatment is lacking. In acute urticaria there is no doubt of a causal relationship with infections and all chronic urticaria must start as the acute form. However, in the chronic form a primary role for infection is controversial, although it is undeniable that concurrent infections exacerbate the condition. This is the first English language review based on a detailed analysis of current peer-reviewed publications dealing with infections and chronic urticaria. Recent findings In chronic urticaria there is a lot of evidence for different infections, but randomized controlled trials are missing. The prevalence of infections is not increased but in susceptible patients the immune response may lead to the development of chronic urticaria. Interestingly, there is evidence for an infection associated autoreactive response at least in the subgroup with a positive autologous serum skin test. A variety of mechanisms have been invoked to explain these observations, including molecular mimicry. Summary Actually the arguments for an important role of underlying causal infections in chronic urticaria are weak, from an evidence-based viewpoint, but there are data suggesting a link. Moreover, an association with underlying or precipitating infectious causes is difficult to establish because there is no possibility for challenge and the number of other urticarial triggers is vast. For the future it will be necessary to reveal the link between urticaria, autoreactivity, non-immunoglobulin E-mediated hypersensitivity reactions and infections to find attractive and specific therapeutic interventions for urticarial symptomatology.