Enterovirus D68 circulation in Portugal, 2024–2025

Enterovirus D68 (EV-D68) is a reemerging respiratory pathogen that is increasingly associated with severe respiratory disease and occasional neurological complications, yet its circulation in Portugal remains poorly documented. In the present study, we conducted molecular surveillance in southern Portugal (Algarve region) from October 2024 to February 2025. Screening of 150 respiratory samples from patients (115 from children and 35 from adults), all positive for rhinovirus/enterovirus, revealed eight EV-D68–positive cases, corresponding to a detection rate of 5.44%, spanning a broad age range from infancy to the elderly. Clinical manifestations ranged from mild respiratory illness to severe conditions, including pneumonia and acute respiratory distress syndrome. In addition, neurological involvement such as complex febrile seizures and encephalomyelitis was observed. Some cases involved coinfections, while others presented with EV-D68 as the sole detected pathogen. Genomic characterization from one isolate revealed a VP1 fragment belonging to clade B3, and a complete genome from another isolate clustered within clade A2. Phylogenetic analysis confirmed clustering with contemporary European isolates. These findings highlight the circulation of multiple EV-D68 clades in Portugal, underscore the clinical diversity of infections, and reinforce the importance of genomic surveillance to monitor viral evolution and potential public health impact.