Beyond the Tropics: Clinical Presentation and Epidemiology of Travel-Associated Dengue Fever in a Non-Endemic European Setting

Dengue is a rapidly spreading mosquito-borne viral disease with increasing incidence in Europe, driven by international travel and climate-related expansion of Aedes mosquito habitats. Data on imported dengue in Central Europe remain limited. The aim of this study was to characterize clinical and epidemiological features of imported dengue infections in Austria and identify factors associated with dengue warning signs. A retrospective, single-centre observational study conducted from January 2013 to October 2024. We retrospectively analyzed 175 adults with confirmed travel-associated dengue treated in Vienna, Austria. Demographics, travel history, symptoms, laboratory values, and clinical outcomes were extracted from electronic records. WHO criteria were applied to classify dengue severity. Most infections were acquired in Southeast Asia (72.6%), particularly Thailand. Common symptoms were fever (97.1%), fatigue (97.1%), arthralgia (59.4%), and rash (53.8%). Dengue warning signs were observed in 16% of cases and associated with significantly prolonged leukopenia (p = 0.003), increased hospitalization rates (50.0% vs. 23.8%, p = 0.005), and higher frequencies of vomiting, abdominal pain, mucosal bleeding, and petechiae at first medical contact. Women reported rash, arthralgia, and retro-orbital pain more frequently, while men showed lower platelet counts. No cases of severe dengue or deaths occurred. Dengue should be considered in febrile returning travellers, particularly from Southeast Asia. The presence of warning signs predicts more complicated disease courses and should prompt closer clinical monitoring. These findings underscore the importance of awareness and preparedness for dengue in non-endemic European settings.