Chronic urticaria and infectious diseases

Introduction. Infectious diseases are often considered as a classic cause of chronic urticaria. Nevertheless, laboratory investigations greatly vary from one centre to the other and the link between the infection and skin signs does not rely on hard data. The purpose of this work was a systematic analysis of the published cases of urticaria associated with infection. Methods. We did a Medline search, using the key-words "urticaria" and "infection/infectious disease"; a second analysis was carried out in groups of infectious agents (viruses, bacteria, parasites) and using each germ name as a key-word. We excluded cases of acute urticaria and articles without English abstract, as well as general reviews without clinical data. Results. No viral cause has ever been clearly documented in chronic urticaria; the screening of viral markers does not yield significant results, compared to the general population (hepatitis B, hepatitis C, HIV). Among bacterial infections, sinusitis and dental infection are not significantly associated with urticaria, and their treatment produces variable and poorly documented results. Helicobacter pylori infection was studied in numerous series, which produced contrasted results: the prevalence was not higher than in controls in the majority of comparative studies; conversely, the outcome of antibiotic treatment was not significant in randomised trials. Only anecdotal series of cases documented a link between parasites and chronic urticaria. Two French studies have suggested a high prevalence of Toxocara canis markers in chronic urticaria, but anti-parasitic treatment had only inconstant effects. Conclusion. There is not enough clear-cut data to affirm a direct link between chronic unticaria and infectious diseases, except in occasional case reports. Therefore, systematic screening for infectious markers cannot be recommended in chronic urticaria. A role of Toxocara canis infections should be re-evaluated by controlled studies.