DENV3–OROV co-infection in Portugal
Standard arbovirus PCR detected dengue — but Illumina viral-surveillance sequencing went further, also revealing Oropouche virus (OROV) in a clinical sample from an imported dengue case in Portugal. Reported as a Clinical Pearls piece in Journal of Travel Medicine by Dr. Líbia Zé-Zé and colleagues at INSA Portugal, with Prof. Nuno R. among the co-authors, the case appears to be the first DENV–OROV co-infection documented in Europe.
Whole-genome sequencing places the DENV-3 strain in lineage 3III B.3.2 — clustering closely with 2022–2024 strains from Cuba, Puerto Rico and the USA — while the partial OROV sequences group with the 2024 Cuban outbreak. The relatively low OROV viral load suggests an earlier OROV exposure followed by an acute DENV-3 infection, a pattern that targeted PCR alone would have missed.
The takeaway is methodological, not epidemiological: amid overlapping arbovirus epidemics in Latin America and the Caribbean, broad-panel and metagenomic platforms catch what targeted assays cannot — and that matters for both clinical mnagement and for understanding the spread of these pathogens at global scales.
Figure. Maximum likelihood phylogenetic analysis of DENV3 detected in this clinical case. The figure provides a zoom-in view of the phylogenetic branch where the DENV3 detected in Portugal (highlighted in orange), following importation from Cuba, is positioned. Tips are coloured according to the country of infection (inferred from available travel history data).