Supplementary Material for: Chronic Urticaria in Returning Travellers: The Role of Anthelmintic Treatment

Background: Chronic urticaria often poses a therapeutic challenge. The human immune response to helminths has a high degree of similarity to an allergic response in terms of skin manifestations, eosinophilia, and IgE elevation. Unfortunately, it is often complicated to diagnose such infections. Objective: We sought to assess the effect of empirical anthelmintic treatment among returning travellers diagnosed with chronic urticaria, without clear proof of helminthic infection. Methods: This is a retrospective case series of 19 returning travellers with chronic urticaria. All patients were treated with anthelmintic treatment given based on clinical suspicion only. A randomly selected control group of 20 patients with chronic urticaria, with no history of travel, was also enrolled. Results: A positive clinical response was reported in 68.4% (13 patients) of the travellers' group within 3 months after treatment with anthelmintic therapy compared with 10% (2 patients) of chronic urticaria patients in the control group. No adverse effects from treatment were recorded. Conclusion: In patients with chronic urticaria, travel history to developing countries must be obtained. Empiric anthelmintic therapy might be beneficial, even in the absence of findings suggestive of helminthic infection.