What is the clinical evidence from this study?

Study design: Observational. Population: Rhinovirus/Enterovirus-positive acute and severe respiratory infections (n=150). Primary outcome: EV-D68 detection rate.

What does this research mean for the field?

Enterovirus D68 clades A2 and B3 are circulating in southern Portugal, causing a heterogeneous range of clinical manifestations from mild respiratory illness to severe respiratory and neurological conditions across various age groups. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.NEUTRAL.

May 22, 2026Open Access

Molecular surveillance and genomic characterization of enterovirus D68 in southern Portugal, 2024–2025

SSSérgio Santos‐SilvaUniversidade do Porto GMGuilherme MoreiraUniversidade do Porto APAndré PalmaAlgarve Biomedical Center

Key Result

Screening of 150 rhinovirus/enterovirus-positive respiratory samples in southern Portugal revealed an enterovirus D68 detection rate of 5.44%, with isolates belonging to clades A2 and B3.

Study Design

Type

Observational (n=150)

Multicenter

Structured PICO

Population

150 patients (115 children, 35 adults) who attended the emergency department or were hospitalized with acute and severe respiratory infections between October 2024 and February 2025, all previously positive for rhinovirus/enterovirus.

Outcome

Detection rate and genomic characterization of EV-D68

This study provides preliminary evidence of EV-D68 circulation (clades A2 and B3) in southern Portugal among patients with severe respiratory infections.

Limitations

Season restricted and geographically limited to the Algarve region, preventing assessment of national-level trends.
Only one VP1 sequence and one complete genome were recovered, limiting broader inferences regarding lineage circulation.
Targeted sampling strategy (only RV/EV positive samples) may introduce selection bias and should not be interpreted as a population-level prevalence estimate.
Small number of EV-D68-positive cases and the presence of coinfections prevent inferring a causal relationship between EV-D68 infection and clinical severity.

Abstract

Abstract Enterovirus D68 (EV-D68) is a re-emerging 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 investigated the presence of EV-D68 in respiratory samples collected 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 previously 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. Neurological manifestations, including complex febrile seizures and encephalomyelitis, were also observed in EV-D68–positive patients. Some cases involved coinfections, while others presented with EV-D68 as the sole detected respiratory 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 provide preliminary evidence of EV-D68 detection in southern Portugal and document the presence of clades A2 and B3 among the characterized samples. The results illustrate the heterogeneous clinical presentations observed in affected patients and highlight the value of continued molecular monitoring and genomic characterization of EV-D68.

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