Summary
A bioRxiv preprint uses dengue virus genome data and phylodynamic analysis to reconstruct global lineage spread. It finds an asymmetric pattern, with Asia continuing to seed transmission elsewhere and spread to the Americas increasing.
A global analysis of dengue virus genomes finds that the virus’s international spread is uneven: Asia remains a major source of lineages entering Africa and the Americas, while spread to the Americas has increased in recent years. The study, posted as a bioRxiv preprint on September 30, 2026, reconstructs these movements using phylogeographic and phylodynamic methods.
The researchers report that the diversity of urban dengue virus circulating today traces back to Asia in the first half of the 20th century. Their reconstruction covers more than a century of spread, based on a large global genome dataset beginning in the 1940s. A phylodynamic analysis uses genetic relationships among virus samples, alongside their locations and dates, to infer how lineages have moved and changed over time.
A lopsided pattern of global spread
The analysis identifies Asia as the region with the highest density of virus movement between countries. It also finds that dengue lineages have more often moved from Asia into Africa and the Americas than in the reverse direction. The authors suggest that greater genetic diversity in Asia may make it harder for lineages arriving from elsewhere to establish themselves there. They present this as a possible explanation, rather than a directly measured mechanism.
The routes into the Americas are also not simply a reflection of where the most travel occurs. Although the authors note more travel to South America, their analysis finds that lineages primarily enter North America from South Asia. They describe the connection as shaped by seasonal synchrony across the Northern Hemisphere: regions with similarly timed seasonal patterns can be linked in the reconstruction even when travel volume alone would suggest a different route.
Within the Americas, the inferred dispersal network begins mainly in North America, especially the Caribbean, and is then sustained by major hubs in South America. This describes the study’s reconstruction of lineage movement, not a count of all dengue infections or a ranking of current disease burden.
Travel and the increase in spread to the Americas
The authors report that the rate of dengue spread to the Americas has risen alongside a substantial increase in global travel starting around 2010. They connect this period of faster spread with the establishment of new lineages associated with large recent outbreaks. Across the long-term patterns they examined, the analysis identifies travel volume as a stronger explanation for dengue spread than climate factors, including within the Americas.
That finding concerns the patterns reconstructed by the study; it does not mean climate is irrelevant to dengue transmission. The preprint’s central contribution is a broad account of how lineages have moved between regions, which can help identify important routes and hubs for surveillance. Its results also suggest that increasing global connectivity may facilitate further spread.
The work is a preprint and has not yet undergone peer review. The supplied abstract describes the dataset as large but does not give the number of genomes, so the scale of sampling cannot be assessed from that text. The conclusions are reconstructions from available virus sequences, rather than a census of every infection or movement.