Screening for stowaway exotic arthropods imported into Europe via aircraft: A cross-sectional analysis

Background: International air mobility is increasing. With a changing climate in Europe, and the associated expansion of regions suitable for exotic vector habitats including mosquitoes, it is crucial to investigate possible routes for their transport over long distances. This study investigated whether exotic vectors are introduced to Europe via air traffic. Methods: At Zürich Airport, passenger cabins of selected aircraft were vacuumed after passengers had disembarked. The samples were examined microscopically, the findings identified, and the arthropod species morphologically determined. The take-off airports were selected based on the occurrence of exotic mosquitoes of interest. Results: A total of 37 aircraft were sampled between 2021 and 2023. No mosquitoes were detected in any of the samples. However, 12 flights, one third of all flights screened, showed the presence of different arthropods. These included beetles (Coleoptera), ants (Hymenoptera), and a fly (Diptera). None of the insects found were vectors of importance for human diseases, and there was no correlation found between presence of insects on the aircraft and the aircraft size or jetty type at destination. Conclusions: The results of this study indicate that the risk of mosquitoes being introduced into the passenger cabin of an airplane is low. However, the survival of mosquitoes introduced from tropical regions is favoured by warming climatic conditions in Europe. We suggest that further studies using traps at airports and in aircraft cargo holds are warranted. Constant surveillance and random sampling of aircraft for arthropods, particularly at high volume hubs, are recommended.